REVIEW | doi:10.20944/preprints202002.0015.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: cholangiocarcinoma; autophagy inhibition; autophagy inhibition; chemoresistance
Online: 3 February 2020 (05:20:36 CET)
Autophagy is a multistep catabolic process through which misfolded, aggregated or mutated proteins and damaged organelles are internalized in membrane vesicles called autophagosomes and ultimately fused to lysosomes for degradation of sequestered components. The multi-step nature of the process offers multiple regulation points prone to be deregulated and cause different human disease, but also offers multiple targetable points for designing therapeutic strategies. Cancer cells have evolved to use autophagy as an adaptive mechanism to survive under extremely stressful conditions within tumor microenvironment, but also to increase invasiveness and resistance to anti-cancer drugs such as chemotherapy. This review collects all clinical evidences of autophagy deregulation during cholangiocarcinogenesis together with all pre-clinical reports evaluating compounds that modulate autophagy to induce cholangiocarcinoma (CCA) cell death. Altogether, experimental data suggests an impairment of autophagy during initial steps of CCA development and increased expression of autophagy markers on established tumors and in invasive phenotypes. Pre-clinical efficacy of autophagy modulators promoting CCA cell death, reducing invasiveness capacity and resensitizing CCA cells to chemotherapy open novel therapeutic avenues to design more specific and efficient strategies to treat this aggressive cancer
ARTICLE | doi:10.20944/preprints202102.0267.v2
Subject: Behavioral Sciences, Applied Psychology Keywords: response inhibition; behavioral inhibition; psychopathy traits; Go/NoGo task; smokers
Online: 11 February 2021 (13:32:51 CET)
Aims: Adolescence is a critical period because the brain is involved in the process of maturation that entails cognitive functions. On the way of maturation, an individual’s inhibitory control undergoes many changes and becomes vulnerable to different thrill-seeking like smoking, drinking, and so on. Smoking is highly prevalent among teenagers that are trying to take control of their behaviors in order to join society. They experience antisocial behavior too which is a trait that can lead adolescents to addiction. This trait is an inevitable part of psychopathy. Inhibitory deficits and psychopathy have been widely reported in addiction studies. The current study tried to investigate the relationship between psychopathic traits and behavioral inhibition between male smokers and non-smoker teenage students.Materials & Methods: Statistical sample of this research is 62 teenage students aged 17 years that are divided into smoker and non-smoker groups. The participants have been chosen through random sampling from the population of 10 high schools. The data have been gathered in Kordkoy and Gorgan in Golestan province. Behavioral bias has been measured by Go/NoGo task and psychopathic traits through youth psychopathic traits inventory. Also, the short form of Wechsler Adult Intelligence Scale test has been executed and used as a control variable.Findings: A meaningful difference has been found between the performance of smoker and non-smoker groups in Go/No Go task and psychopathic traits that are smokers performed weaker in comparison with non-smokers and psychopathic traits of smokers were meaningfully higher than non-smokers. On the other hand, there was no significant difference between these two groups in their Wechsler Adult Intelligence Scale scores.Conclusion: The results have shown that smokers have higher psychopathic traits and lower behavioral inhibition when compared with their non-smoker peers. According to the results of current research, smoking can decline the cognitive functions.
ARTICLE | doi:10.20944/preprints202108.0468.v1
Online: 24 August 2021 (13:57:51 CEST)
We used agar overlay assays to assess if 24 circulating and historical isolates of Neisseria mucosa could inhibit the growth of 28 circulating and historical isolates of N. gonorrhoeae. We found no evidence of inhibition by N. mucosa (n=24). Positive controls Streptococcus pneumoniae and Escherichia coli demonstrated a strong inhibitory effect against the growth of N. gonorrhoeae.
ARTICLE | doi:10.20944/preprints202002.0018.v1
Online: 3 February 2020 (05:45:33 CET)
The amyloid fibril formation by $\alpha$-synuclein is a hallmark of various neurodegenerative disorders, most notably Parkinson's disease. Epigallocatechin gallate (EGCG) has been reported to be an efficient aggregation inhibitor of numerous proteins, among them $\alpha$-synuclein. Here we show that this applies only to a small region of relevant parameter space and that under some conditions, EGCG can even accelerate α-synuclein amyloid fibril formation through facilitating its heterogeneous primary nucleation. Furthermore, we show through quantitative seeding experiments that contrary to previous reports, EGCG is not able to re-model α-synuclein amyloid fibrils into seeding-incompetent structures. Taken together, our results paint a complex picture of EGCG as a compound that can under some conditions inhibit the amyloid fibril formation of α-synuclein, but the inhibitory action is not robust against various relevant changes in experimental conditions. Our results are important for the development of strategies to identify and characterise promising amyloid inhibitors.
ARTICLE | doi:10.20944/preprints201705.0174.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: steroid; metabolism; anti-inflammatory drug; inhibition
Online: 24 May 2017 (08:25:26 CEST)
In vitro studies show that diclofenac inhibits enzymatic steroid glucuronidation. This study was designed to investigate the influence of diclofenac on the excretion of stanozolol and 3'-hydroxystanozolol via analyses in hair, blood and urine in vivo in a rat study. Brown Norway rats were administered with stanozolol (weeks 1-3) and diclofenac (weeks 1-6). Weekly assessment of steroid levels in hair was complemented with spot urine and serum tests. Levels of both stanozolol and 3'-hydroxystanozolol steadily increased in hair during stanozolol treatment and decreased post-treatment, but remained readily detectable for 6 weeks. In contrast, compared to control rats, diclofenac significantly reduced urinary excretion of 3’-hydroxystanozolol which was undetectable in most samples. This is the first report of diclofenac altering steroid metabolism in vivo, detrimentally affecting detection in urine, but not in hair which holds considerable advantages over urinalysis for anti-doping tests.
ARTICLE | doi:10.20944/preprints202209.0010.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: neuromodulation; baroreflex sensitivity; dmNTS; pain inhibition; fibromyalgia
Online: 1 September 2022 (07:32:51 CEST)
The study presents a novel approach of programing pain inhibition in chronic pain patients based on the hypothesis that pain perception is modulated by dysfunctional dorsal medial nucleus tractus solitarii (dmNTS) reflex arcs that produce diminished baroreflex sensitivity (BRS) resulting from a conditioned response. This study tested whether administration of noxious and non-noxious electrical stimuli synchronized with the cardiac cycle resets BRS, reestablishing pain inhibition. 30 pain-free normotensives controls (NC) and 32 normotensives fibromyalgia (FM) patients received two, ≈8 minute-epochs of cardiac-gated, peripheral electrical stimuli. Non-painful and painful electrical stimuli were synchronized to the cardiac cycle as the neuromodulation experimental protocol (EP) with 2 control conditions (CC1, CC2). BRS, heart-rate-variability (HRV), pain threshold and tolerance, and clinical pain intensity were assessed.Reduced BRS in FM at baseline increased by 41% during two, ≈8 minute-epochs of stimulation. Thresholds in FM increased significantly during the experimental protocol (all Ps<0.001) as did HRV. FM levels of clinical pain significantly decreased by 35.52% during the experimental protocol but not during control stimulations (P<0.001). Baroreceptor training may reduce FM pain by BRS-mediated effects on intrinsic pain regulatory systems and autonomic pain modulation. These processes seem to be linked by classical and operant conditioning.
ARTICLE | doi:10.20944/preprints202108.0001.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Antitumoral drug; Choline kinase inhibition; Choline uptake
Online: 2 August 2021 (08:42:22 CEST)
Choline kinase inhibitors are an important class of cytotoxic compounds useful for the treatment of different forms of cancer since aberrant choline metabolism is a feature of neoplastic cells. Here we present the characterization and the structure activity relationship of a series of non-symmetrical choline kinase inhibitors characterized by a 3-aminophenol moiety, bound to 4-(dimethylamino)- or 4-(pyrrolidin-1-yl)pyridinium cationic heads through several linkers. These derivatives were evaluated both for their inhibitory activity on the enzyme and for their antiproliferative activity in a panel of six human tumor cell lines. The compounds with the best inhibitory results were those connected to the linker by the N-atom (4a-h) and these results are supported by docking studies. The compounds with the best antiproliferative results were those connected to the linker by the O-atom (3a-h). On the other hand, as was predictable in both families, the inhibitory effect on the enzyme is greater the shorter the length of the linker, while in tumor cells, lipophilicity and choline uptake inhibition could play a decisive role. Interestingly compounds 3c and 4f, selected for both their ability to inhibit the enzyme and good antiproliferative activity, are endowed with a low toxicity in non-tumoral cells (e.g human peripheral lymphocytes) respect to cancer cells. These compounds were also able to induce to induce apoptosis in Jurkat leukemic cells without causing significative variations of cell cycle. It is worth to mention that these derivatives, beside their inhibitory effect on choline kinase, displayed a modest ability to inhibit choline uptake thus suggesting that this mechanism may also contribute to the observed cytotoxicity.
ARTICLE | doi:10.20944/preprints202011.0597.v1
Subject: Life Sciences, Biochemistry Keywords: Arylsulfatase; β-glucuronidase; Hydrogen peroxide; Hypochlorite; Inhibition
Online: 23 November 2020 (19:22:12 CET)
Arylsulfatase and β-glucuronidase are two important enzymes in human, which play important role on dynamic equilibrium of steroidal estrogens. This work probably for the first time reported that hydrogen peroxide (H2O2), hypochlorite and peracetic acid (PAA) could effectively inhibit the activities of arylsulfatase and/or β-glucuronidase. The 50 percent of inhibitions (IC50) of H2O2, and PAA on arylsulfatase were found to be 142.90±9.00, 91.83±10.01, and 43.46±2.92 μM, respectively. The corresponding respective IC50 of hypochlorite and PAA on β-glucuronidase were 704.90±41.40 and 23.26±0.82 μM, while H2O2 showed no inhibition on β-glucuronidase. It was further revealed that the inhibition of hypochlorite on both arylsulfatase and β-glucuronidase was irreversible. On the contrary, the inhibition by H2O2 and PAA was reversible. Moreover, it was found that the inhibitions of arylsulfatase and/or β-glucuronidase by these three chemicals were pH-dependent, among which the inhibition by H2O2 was competitive and non-competitive for PAA. In general, H2O2 and hypochlorite can be endogenously produced in human, which suggested that the two compounds are potential endocrine disruption compounds (EDCs) as they can cause endocrine disruption via inhibition of arylsulfatase and β-glucuronidase. This work further indicated that any agent that can induce production of H2O2 or hypochlorite in human is potential EDC, which explains why some EDCs with very weak or no estrogenic potency can cause endocrine disruption that confirmed in epidemiological studies.
ARTICLE | doi:10.20944/preprints201810.0355.v1
Subject: Chemistry, Medicinal Chemistry Keywords: assay; diarrhea; isolate; hydrolysis; proteins; inhibition zone
Online: 16 October 2018 (11:26:59 CEST)
The study compared antibacterial potential of hydrolysates of casein and alpha-lactalbumin from cow and goat milk on diarrhea-causing Escherichia coli and Staphylococcus aureus. Milk samples were aseptically obtained from lactating cows and goats. The samples were skimmed; casein was isolated using acetic acid and alpha-lactalbumin by filtrate thermoprecipitation at 75 °C. 50% of each isolate was reconstituted in a buffer and hydrolyzed with papain at 55 °C for 2 hours. The hydrolysates were heated to 75 °C to inactivate papain, cooled and their antibacterial activity determined by disc diffusion method. Results showed alpha-lactalbumins had higher degrees of hydrolysis and antibacterial activity than caseins; goat alpha-lactalbumin had the highest antibacterial activity with mean inhibition zones of 19.60 mm and 19.50 mm on E. coli and S. aureus. Cow alpha-lactalbumin inhibited E. coli more than S. aureus with inhibition zones of 16.80 mm and 12.50 mm. Cow and goat milk casein hydrolysates inhibited E. coli with mean inhibition zones of 8.00 mm and 10.90 mm and inhibited S. aureus with inhibition zones of 4.13 mm and 1.90 mm respectively. The research showed that the milk hydrolysates can be a source of antibiotics for diarrhea treatment. Research should be done to establish the peptide fractions associated with the observed bioactivity.
REVIEW | doi:10.20944/preprints202208.0236.v1
Subject: Life Sciences, Microbiology Keywords: Archaea; transcription inhibition; RNA polymerase; viruses; evolution; antibiotics
Online: 12 August 2022 (11:25:05 CEST)
Multisubunit RNA polymerases (RNAP) carry out transcription in all domains of life; during vi-rus infection, RNAPs are targeted by transcription factors encoded by either the cell or the virus, resulting in the global repression of transcription with distinct outcomes for different host-virus combinations. These repressors serve as versatile molecular probes to study RNAP mechanisms, as well as they aid the exploration of druggable sites for the development of new antibiotics. Here, we review the mechanisms and structural basis of RNAP inhibition by the viral repressor RIP and the crenarchaeal negative regulator TFS4, which follow distinct strategies. RIP operates by occluding the DNA-binding channel and mimicking the initiation factor TFB/TFIIB. RIP binds tightly to the clamp and locks it into one fixed position, thereby preventing conformational oscil-lations that are critical for RNAP function as it progresses through the transcription cycle. TFS4 engages with RNAP in a similar manner to transcript cleavage factors such as TFS/TFIIS through the NTP-entry channel; TFS4 interferes with the trigger loop and bridge helix within the active site by occlusion and allosteric mechanisms, respectively. The conformational changes of RNAP described above are universally conserved and are also seen in inactive dimers of eukaryotic RNAPI and several inhibited RNAP complexes of both bacterial and eukaryotic RNA polymer-ases, including inactive states that precede transcription termination. A comparison of target sites and inhibitory mechanisms reveals that proteinaceous repressors and RNAP-specific antibiotics use surprisingly common ways to inhibit RNAP function.
ARTICLE | doi:10.20944/preprints202205.0156.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Antimycin A; wheat blast; inhibition; biopesticide; biological control
Online: 12 May 2022 (04:02:42 CEST)
Application of chemical pesticides to protect agricultural crops from pests and diseases is discouraged due to their harmful effects on human and environment. Therefore, alternative approaches for crop pro-tection through microbial or microbe originated pesticides have been gaining momentum. Wheat blast is a destructive fungal disease caused by Magnaporthe oryzae Triticum (MoT) pathotype, which poses a seri-ous threat to global food security. Screening of secondary metabolites against MoT revealed that antimy-cin A isolated from a marine Streptomyces sp. had significant inhibitory effect on mycelial growth in vitro. This study aimed to investigate the inhibitory effects of antimycin A on some critical life stages of MoT and evaluate the efficacy of wheat blast disease control by this natural product. Bioassay indicated that antimycin A suppressed mycelial growth, conidiogenesis, germination of conidia and formation of ap-pressoria in germinated conidia of MoT in a dose-dependent manner with minimum inhibitory concen-tration 0.005 μg/disk. If germinated, antimycin A induced abnormal germ tubes (4.8%) and suppressed the formation of appressoria. Interestingly, application of antimycin A significantly suppressed wheat blast disease in both seedling and heading stages of wheat supporting the results from invitro study. This is the first report on inhibition of mycelial growth, conidiogenesis, conidia germination, detrimental morphological alterations in germinated conidia, and suppression of wheat blast disease caused by a Triticum pathotype of M. Oryzae. Further study is required to unravel the precise mode of action of this promising natural compound for considering it as a biopesticide to combat wheat blast.
COMMUNICATION | doi:10.20944/preprints202004.0220.v1
Subject: Keywords: alphaherpesvirus; EHV-1; phosphatidylserine; inhibition; pathogen host interaction
Online: 14 April 2020 (08:54:01 CEST)
Exposure of phosphatidylserine (PS) in the outer leaflet of the plasma membrane is induced by infection with several members of the Alphaherpesvirinae subfamily. There is evidence that PS is used by the equine herpesvirus type 1 (EHV-1) during entry, but the exact role of PS and other phospholipids in the entry process remains unknown. Here, we investigated the interaction of differently charged phospholipids with virus particles and determined their influence on infection. Our data show that liposomes containing negatively charged PS or positively charged DOTAP [N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium)] inhibited EHV-1 infection, while neutral phosphatidylcholine (PC) had no effect. Inhibition of infection with PS was transient, decreased with time, and was dose dependent. Our findings indicate that both cationic and anionic phospholipids can interact with the virus and reduce infectivity, while acting through different mechanisms. Charged phospholipids were found to have antiviral effects and can may be used to inhibit EHV-1 infection.
ARTICLE | doi:10.20944/preprints201901.0086.v1
Subject: Social Sciences, Finance Keywords: Quinoxaline Analogs, Synthesis, Thymidine phosphorylase inhibition, Molecular docking
Online: 9 January 2019 (13:23:49 CET)
We have synthesized quinoxaline analogs (1-25), characterized by 1HNMR and HREI-MS and evaluated for thymidine phosphorylase inhibition. Among the series, nineteen analogs showed better inhibition when compared with the standard inhibitor 7-Deazaxanthine (IC50 = 38.68 ± 4.42 µM). The most potent analog among the series is analog 25 with IC50 value 3.20 ± 0.10 µM. Sixteen analogs 1, 2, 3, 4, 5, 6, 7, 12, 13, 14, 15, 16, 17, 18, 21and 24 showed outstanding inhibition which is many folds better than the standard 7-Deazaxanthine. Two analogs 8 and 9 showed moderate inhibition. A structure- activity relationship has been established mainly based upon the substitution pattern on the phenyl ring. The binding interactions of the active compounds were confirmed through molecular docking studies.
ARTICLE | doi:10.20944/preprints201807.0472.v1
Subject: Life Sciences, Microbiology Keywords: chitosan; quorum sensing; antibacterial activity; quorum sensing inhibition
Online: 25 July 2018 (08:32:31 CEST)
New approaches to deal with drug-resistant pathogenic bacteria are urgent. We studied the antibacterial effect of chitosans against an E. coli quorum sensing biosensor reporter strain, and selected a non-toxic chitosan to evaluate its QS inhibition activity and its effect on bacterial aggregation. To this end, chitosans of varying DA (12 to 69%) and Mw (29 to 288 KDa) were studied. Only chitosans of low DA (~12%) inhibited the bacterial growth, regardless of the Mw. Chitosan MDP DA30 (DA 42% and Mw 115 kDa) was selected for further QS inhibition and SEM imaging studies. MDP DA30 chitosan exhibited QS inhibition activity in an inverse dose-dependent manner (≤12.5 µg/mL). SEM images revealed that this chitosan, when added at low concentration (≤30.6 µg/mL), induced substantial bacterial aggregation, whereas at high concentration (234.3 µg/mL), it did not. Aggregation explains the QS inhibition activity as the consequence of retardation of the diffusion of AHL.
ARTICLE | doi:10.20944/preprints201803.0116.v1
Subject: Chemistry, Chemical Engineering Keywords: oxazole-triazole; inhibition corrosion; mild steel; EIS; DFT
Online: 15 March 2018 (05:10:29 CET)
1-[(4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)methyl]-4-phenyl-1H-1,2,3-triazole (Ph4) and1-[(4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)methyl]-5-phenyl-1H-1,2,3-triazole (Ph5) are new isomers of the triazole derivative family, were synthesized and tested on the corrosion of mild steel in molar hydrochloric acid molar media using weight loss, electrochemical polarization and impedance spectroscopy. Then the experimental results were confirmed by quantum chemical calculations using DFT at B3LYP /6-31G (d,p). The compound Ph4 is the best inhibitor and its inhibitory efficiency increased with increasing concentration and reaching 95% at 10−3 M. Polarization curves studies show that both compounds tested are mixed-type inhibitors. Nyquist curves presented a single capacitive loop, their diameter increases progressively with both inhibitors concentration. The change of the substitution phenyl from position 5 to position 4 in the triazole ring increases the inhibitory effect of the triazole compounds. The effect of temperature on the corrosion behavior of iron indicates that the inhibitory efficiency of the two inhibitors decreases with increasing temperature in the range of 308 to 338K. DFT study is in good correlationwith the experimental results.
ARTICLE | doi:10.20944/preprints202206.0274.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Cyclea peltata; Diabetes Mellitus; Docking; Schrodinger; Alpha amylase; Inhibition
Online: 20 June 2022 (14:33:11 CEST)
The primary goal of this research is to examine the α-amylase inhibitory effect of phytoconstituents found in the roots of the Cyclea peltata plant. The extract will also be used to investigate the effect of root extract on α-amylase inhibition assay. The roots were gathered, processed, and extracted in petroleum ether before being kept at 4ºC. The extract was exposed to a preliminary phytochemical examination. The extract was employed in the α-amylase inhibition experiment at concentrations of 50, 100, 200, 400, 600, 800, and 1000 µg/ml with acarbose as a control. Molecular docking analysis was performed on the phytoconstituents cycleapeltine, cycleadrine, cycleacurine, cycleanorine, cycleahomine chloride, and acarbose on human pancreatic alpha-amylase 1B2Y. A preliminary phytochemical study revealed the presence of alkaloids, saponins, and terpenoids. The tests came back negative for flavonoids, steroids, and tannin. The root extract inhibited α-amylase at 69.42 ± 0.74 % at 1000 µg/ml and acarbose at 94.63 ± 0.57 %. The IC50 value was calculated and found to be 484.08 µg/ml for the extract and 42.47 µg/ml. The docking studies, revealed that cycleacurine (-4.751 Kcal/mol) has a comparable anti-diabetic effect to Acarbose (-6.713 Kcal/mol). Furthermore, the function groups –OH and –NH found in phytoconstituents interacted with the active site of 1B2Y similarly to acarbose. This provides evidence that the function groups –OH and –NH present in the phytoconstituents might inhibit alpha amylase.
ARTICLE | doi:10.20944/preprints202111.0348.v1
Online: 19 November 2021 (12:23:16 CET)
Antibiotic-sparing treatments are required to prevent the further emergence of anti-microbial resistance in Neisseria gonorrhoeae. Commensal Neisseria species have previously been found to inhibit the growth of pathogenic Neisseria species. For example, a previous study found that 3 out of 5 historical isolates of Neisseria mucosa could inhibit the growth of N. gonorrhoeae. In this study, we used agar overlay assays to assess if 24 circulating and historical isolates of Neisseria mucosa could inhibit the growth of 28 circulating and historical isolates of N. gonorrhoeae. Although pitting around each colony of N. mucosa created an optical illusion of decreased growth of N. gonorrhoeae, we found no evidence of inhibition (n=24). In contrast, positive controls of Streptococcus pneumoniae and Escherichia coli demonstrated a strong inhibitory effect against the growth of N. gonorrhoeae.
REVIEW | doi:10.20944/preprints201908.0112.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: active sensing; navigation; neural circuits; inhibition; C. elegans; invertebrate
Online: 8 August 2019 (17:24:40 CEST)
From single-cell organisms to complex neural networks, all evolved to provide control solutions to generate context and goal-specific actions. Neural circuits performing sensorimotor computation to drive navigation employ inhibitory control as a gating mechanism, as they hierarchically transform (multi)sensory information into motor actions. Here, we focus on this literature to critically discuss the proposition that prominent inhibitory projections form sensorimotor circuits. After reviewing the neural circuits of navigation across various invertebrate species, we argue that with increased neural circuit complexity and the emergence of parallel computations inhibitory circuits acquire new functions. The contribution of inhibitory neurotransmission for navigation goes beyond shaping the communication that drives motor neurons, instead, include encoding of emergent sensorimotor representations. A mechanistic understanding of the neural circuits performing sensorimotor computations in invertebrates will unravel the minimum circuit requirements driving adaptive navigation.
REVIEW | doi:10.20944/preprints201811.0631.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: adipogenesis; bioactive compounds; fat accumulation; hibiscus sabdariffa; lipase inhibition
Online: 30 November 2018 (10:33:47 CET)
Obesity is a condition associated with the accumulation of excess fat in the body, energy imbalance, lipogenesis etc. which increases adipose tissue mass through adipogenesis and probes a health risk. Its prevalence has become a large burden on the world at large. One of the solutions to tackling obesity is with the use of bioactive compounds. We critically examined the effectiveness of hibiscus sabdariffa (HS) on various parameters associated with development of obesity such as; effect of HSE on body weight and energy expenditure, effect of HSE on fat accumulation, effect of HSE on lipase inhibition, effect of HSE on adipocyte differentiation/adipogenesis. This review has gathered reports on the various anti-obesity effects of HS bioactives in cell and animal models, as well as in humans. Reports have shown that hibiscus sabdariffa derived bioactives are potent in the treatment of obesity with evident reduction in body weight, inhibition of lipid accumulation and suppression of adipogenesis through PPARγ pathway and other transcriptional factors.
REVIEW | doi:10.20944/preprints201805.0145.v1
Subject: Life Sciences, Biochemistry Keywords: carbonic anhydrase, enzyme inhibition, metalloenzymes, amino acid, glaucoma, tumors
Online: 9 May 2018 (13:55:15 CEST)
Carbonic Anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life kingdoms, classified into seven genetically different families (α-θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3-) and protons (H+). Fifteen isoforms of human CA (hCA I-XV) have been isolated, their presence being fundamental for the regulation of many physiological processes. In addition, overexpression of some isoforms has been associated with the outbreak or the progression of several diseases. For this reason, for a long time CA inhibitors (CAIs) are used in the control of glaucoma and as diuretics. Furthermore, the search for new potential CAIs for other pharmacological applications is a very active field. Amino acids constitute the smallest fundamental monomers of protein and, due to their useful bivalent chemical properties, are widely used in organic chemistry. Both proteinogenic and non-proteinogenic amino acids have been extensively used to synthesize CAIs. This article provides an overview of the different strategies that have been used to design new CAIs containing amino acids, and how these bivalent molecules influence the properties of the inhibitors.
COMMUNICATION | doi:10.20944/preprints201705.0050.v1
Subject: Life Sciences, Molecular Biology Keywords: ABCC transporter; lateral roots; Triticum aestivum; auxin; transport inhibition
Online: 8 May 2017 (07:48:20 CEST)
TaABCC13 is member of wheat ABCC subclass of transporters. The RNAi mediated silencing of this transporter in wheat results in lowering of seed phytic acid level and other developmental defects. In addition to that, wheat ABCC13 was involved in cadmium detoxification as evident by the complementation assays in yeast. The appearance of early lateral roots in these transgenic seedlings speculated the possibility for studying the role of localized auxin-mediated effects. In the current study, firstly, the expression of auxin related genes was studied in the transgenic roots. Enhanced expression of genes pertaining to either auxin biosynthesis or its transport was observed in transgenic wheat seedling roots suggesting the direct effect of the hormone. Further, the early emergence of lateral roots in transgenic wheat seedlings was affected due to the presence of auxin-transport inhibitor suggesting the direct effect of hormones in root development. In conclusion, herein we provide the novel evidence for the auxin mediated regulation of lateral root emergence in TaABCC13:RNAi seedlings.
REVIEW | doi:10.20944/preprints202207.0024.v1
Subject: Life Sciences, Molecular Biology Keywords: post-translation modifications; CK2; Huntington’s Disease; Kinase Inhibition; HTT phosphorylation
Online: 1 July 2022 (17:47:10 CEST)
Huntington’s Disease (HD) is a devastating neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene, for which no disease modifying therapies are currently available. Much of the recent research has focused on developing therapies to directly lower HTT expression, and while promising, these therapies have presented several challenges regarding administration and efficacy. Another promising therapeutic approach is the modulation of HTT post-translational modifications (PTMs) that are dysregulated in disease and have shown to play a key role in HTT toxicity. Among all PTMs, modulation of HTT phosphorylation has been proposed as an attractive therapeutic option due to the possibility of orally administering specific kinase effectors. One of the kinases described to participate in HTT phosphorylation is Protein Kinase CK2. CK2 has recently emerged as a target for the treatment of several neurological and psychiatric disorders, although its role in HD remains controversial. While pharmacological studies in vitro inhibiting CK2 resulted in reduced HTT phosphorylation and increased toxicity, genetic approaches in mouse models of HD have provided beneficial effects. In this review we discuss potential therapeutic approaches related to the manipulation of HTT-PTMs with special emphasis on the role of CK2 as a therapeutic target in HD.
REVIEW | doi:10.20944/preprints202201.0314.v1
Subject: Behavioral Sciences, Other Keywords: executive functions; executive control; birds; inhibition; working memory; shifting; flexibility
Online: 20 January 2022 (20:52:34 CET)
Executive functions comprise top-down cognitive processes that exert control over information processing, from acquiring information to issuing a behavioural response. These cognitive processes of inhibition, working memory and shifting underpin complex cognitive skills, such as episodic memory and planning, which have been repeatedly investigated in several bird species in recent decades. Until recently, avian executive functions were studied in relatively few bird species, but have gained traction in comparative cognitive research following MacLean and colleagues’ large-scale study (2014). Therefore, in this review paper, relevant previous findings are collected and organized to facilitate further investigations of these core cognitive processes in birds. This review can assist in integrating findings from avian and mammalian cognitive research and further current understanding of executive functions’ significance and evolution.
ARTICLE | doi:10.20944/preprints202104.0670.v1
Subject: Life Sciences, Biochemistry Keywords: Mayaro; MAPKs; p38, SB203580; PROTACs; NR-7h; Losmapimod; replication; inhibition
Online: 26 April 2021 (13:17:06 CEST)
Mayaro virus (MAYV) hijacks the host´s cell machinery to effectively replicate. The mitogen-activated protein kinases (MAPKs) p38, JNK and ERK1/2 have emerged as crucial cellular factors implicated in different stages of the viral cycle. However, whether MAYV uses these MAPKs to competently replicate has not yet been determined. The aim of this study was to evaluate the impact of MAPKs inhibition on MAYV replication using primary human dermal fibroblasts (HDFs) and HeLa cells. Viral yields in supernatants from MAYV-infected cells treated or untreated with inhibitors SB203580, SP600125, U0126 or Losmapimod were quantified using plaque assay. Also, viral protein expression was analyzed using immunoblot and immunofluorescence. Knockdown of p38⍺/p38β isoforms was performed in HDFs using the PROTACs molecule NR-7h. Our data demonstrated that HDFs are highly susceptible to MAYV infection. SB203580, a p38 inhibitor, reduced MAYV replication in a dose-dependent manner in both HDFs and HeLa cells. Additionally, SB203580 significantly decreased viral E1 protein expression. Similarly, knockdown or inhibition of p38⍺/p38β isoforms with NR-7h or Losmapimod, respectively, affected MAYV replication in a dose-dependent manner. Collectively, these findings suggest that p38 could play an important role in MAYV replication and could serve as a therapeutic target to control MAYV infection.
ARTICLE | doi:10.20944/preprints202103.0541.v1
Subject: Chemistry, Analytical Chemistry Keywords: α-Amylase inhibition; Tannic acid; Mixing order; Binding interactions; Adsorption
Online: 22 March 2021 (15:35:35 CET)
The effects of mixing orders of tannic acid (TA), starch and α-amylase on the enzyme inhibition of TA were studied, including mixing TA with α-amylase before starch addition (order 1), mixing TA with pre-gelatinized starch before α-amylase addition (order 2) and co-gelatinizing TA with starch before α-amylase addition (order 3). It was found that the enzyme inhibition was always highest for order 1 because TA could bind with the enzyme active site thoroughly before digestion occurred. Both order 2 and 3 reduced α-amylase inhibition through decreasing binding of TA with the enzyme, which resulted from the non-covalent physical adsorption of TA with gelatinized starch. Interestingly, at low TA concentration, α-amylase inhibition for order 2 was higher than order 3, while at high TA concentration, the inhibition was shown with opposite trend, which arose from the difference in the adsorption property between the pre-gelatinized and co-gelatinized starch at the corresponding TA concentrations. Besides, both the crystalline structures and apparent morphology of starch were not significantly altered by TA addition for order 2 and 3. Conclusively, although a polyphenol may have an acceptable inhibitory activity in vitro, the actual effect may not reach the expected one when taking processing procedures into account.
Subject: Earth Sciences, Atmospheric Science Keywords: environmental risk assessment; polycyclic musk compounds; acute toxicity; growth inhibition; larvae development
Online: 11 February 2021 (13:23:39 CET)
The current research investigated the environmental risk of the polycyclic musk compounds, Galaxolide® (HHCB) and Tonalide® (AHTN), in the marine environments. These substances are lipophilic, bioaccumulated and potentially biomagnified in aquatic organisms. To understand the toxicity of HHCB and AHTN, we performed acute toxicity tests by exposing marine microalgae (Phaeodactylum tricornutum, Tretraselmis chuii and Isochrysis galbana), crustaceans (Artemia franciscana), echinoderms (Paracentrotus lividus), bivalves (Mytilus galloprovincialis), fish (Sparus aurata) and a candidate freshwater microalga (Raphidocelis subcapitata) to environmentally relevant concentrations (0.005 - 5 µg/L) following standardized protocols. The effects of both substances on microalgae growth were incipient and only I. galbana was sensitive to HHCB and AHTN, with IC10 values of 5.22 µg/L and 0.328 µg/L, respectively. Significant (p < 0.01) concentration dependent responses were measured in P. lividus and M. galloprovincialis larvae developments as well as S. aurata mortality tested with HHCB. The effect of HHCB on P. lividus larvae development was the most sensitive endpoint recorded, producing an EC50 value of 4.07 µg/L. Our results show that HHCB represents a high risk to P. lividus larvae development for early life stages in marine environments.
ARTICLE | doi:10.20944/preprints202102.0016.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: development; adolescents; perceptual inhibition; joint visual search task; executive function
Online: 1 February 2021 (11:38:03 CET)
Recent studies suggest that the developmental curves in adolescence, related to the development of executive functions, could be fitted to a non-linear trajectory of development with progressions and retrogressions. Therefore, the present study proposes to analyze the pattern of development in Perceptual Inhibition (PI), considering all stages of adolescence (early, middle, and late) in intervals of one year. To this aim, we worked with a sample of 275 participants between 10 and 25 years, who performed a joint visual and search task (to measure PI). We have fitted exGaussian functions to the probability distributions of the mean response time across the sample and performed a covariance analysis (ANCOVA). The results showed that the 10- to 13-year-old groups performed similarly in the task and differ from the 14- to 19-year-old participants. We found significant differences between the older group and all the rest of the groups. We discuss the important changes that can be observed in relation to the nonlinear trajectory of development that would show the PI during adolescence.
ARTICLE | doi:10.20944/preprints202003.0360.v2
Subject: Life Sciences, Genetics Keywords: SARS-CoV-2; transcriptional inhibition; COVID-19; drug repurposing; TMPRSS2
Online: 28 April 2020 (09:39:02 CEST)
There is an urgent need to identify effective therapies for COVID-19. The SARS-CoV-2 host factor protease TMPRSS2 is required for viral entry and thus an attractive target for therapeutic intervention. In mouse, knockout of tmprss2 led to protection against SARS-CoV-1 with no deleterious phenotypes, and in human populations genetic loss of TMPRSS2 does not appear to be selected against. Here, we mined publicly available gene expression data to identify several compounds that down-regulate TMPRSS2. Recognizing the need for immediately available treatment options, we focused on FDA-approved drugs. We found 20 independent studies that implicate estrogenic and androgenic compounds as transcriptional modulators of TMPRSS2, suggesting these classes of drugs may be promising therapeutic candidates for clinical testing and observational studies of COVID-19. We also note that expression of TMPRSS2 is highly variable and skewed in humans, with a minority of individuals having extremely high expression. Combined with literature showing that inhibition of TMPRSS2 protease activity reduces SARS-CoV-2 viral entry in human cells, our results raise the hypothesis that modulation of TMPRSS2 expression is a promising therapeutic avenue for COVID-19.
ARTICLE | doi:10.20944/preprints202002.0297.v1
Subject: Chemistry, Electrochemistry Keywords: light alloys; magnesium; corrosion; vanadate; phosphate; fluoride; inhibition; conversion coating
Online: 21 February 2020 (02:21:19 CET)
The anodic polarization response of magnesium alloy AZ31 was characterized during exposure to aerated 0.1M NaCl solutions with millimolar additions of NaVO3, Na3PO4, Na2HPO4, NaF and various pairings to assess their ability to inhibit corrosion kinetics and retard localized corrosion. Each of the candidate inhibitors reduced the corrosion rate of the alloy to some degree. A Na3PO4 - NaVO3 pair produced a powerful inhibiting response decreasing the corrosion rate to about 10-7 A/cm2, which was two orders of magnitude lower than the uninhibited control case. A Bliss Independence assessment indicated that this inhibitor pair acted synergistically. A Na2HPO4 - NaVO3 pair reduced the corrosion rate to 10-6 A/cm2 but was not assessed to be acting synergistically. The NaVO3 - NaF pair did not reduce the corrosion rate significantly compared to the control case and was an antagonistic pairing. SEM imaging showed film formation due to exposure, which appears to be the origins of the observed inhibition. The resistance to localized corrosion was assessed as the difference in the breakdown potential and the corrosion potential with larger values indicating a lower probability of localized corrosion during free corrosion exposures. Effects of the inhibitors on this characteristic were mixed, but each of the inhibitor pairs yielded potential differences in excess of 100mV. A conceptual conversion coating process based on a mixture of vanadate and phosphate compounds were demonstrated. A fluoride-bearing formulation produced coatings whose total impedance was increased by a factor or 2 compared to an uncoated control. A fluoride-free formulation produced coatings whose corrosion resistance was increased by more than a factor of 3.
COMMUNICATION | doi:10.20944/preprints201906.0278.v1
Subject: Life Sciences, Biophysics Keywords: photosystem II; redox potential; electron transfer; charge separation; photo-inhibition
Online: 27 June 2019 (05:54:13 CEST)
Structural perturbations in the Mn4CaO5 cluster site, an oxygen-evolving complex of photosystem II, such as those induced by Ca2+/Sr2+ exchanges or Ca/Mn-removal have been known to induce long-range positive shifts (+30 mV to +150 mV) in the redox potential of the primary quinone electron acceptor plastoquinone A (QA) located 40 Å distant from the OEC. Here, we reanalyzed the crystal structure of Sr-PSII solved at 2.1 Å and compare it with the native Ca-PSII of 1.9 Å with focus on the acceptor site and report on the possible long-range interactions between the donor, Mn4Ca(Sr)O5 cluster, and acceptor sites.
ARTICLE | doi:10.20944/preprints202209.0287.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: Coffea arabica; antioxidant; acetylcholinesterase inhibition; catalepsy; unilateral 6-hydroxydopamine lesion; caffeine
Online: 20 September 2022 (03:22:27 CEST)
Epidemiologic studies suggest an inverse correlation between coffee consumption and the occurrence of neurodegenerative diseases, but the role of caffeine and roasting degree are still matter of debate. The objective of this work was to evaluate the effects of caffeinated (light, medium, and dark roast) and decaffeinated instant coffee samples in acetylcholinesterase inhibition and antioxidant assays, as well as in animal models of Parkinson’s disease. Caffeinated coffees inhibited the acetylcholinesterase in much smaller concentrations than decaffeinated coffee. All coffee samples showed antioxidant capacity without relation with the caffeine content. Dopaminergic-like activity in the haloperidol-induced catalepsy test was observed with caffeinated coffee, but not in the decaffeinated sample. The medium roast coffee reduced the number of rotations of rats after methamphetamine administration on the 6-hydroxydopamine unilateral lesion of the medial forebrain bundle. However, the coffee treatment did not avoid the loss of dopaminergic neurons on substantia nigra pars compact and only the smallest dose of coffee was able to avoid the decrease of dopamine levels in the lesioned side of the striatum. Altogether, these results suggest that coffee exerts moderate pro-cholinergic and pro-dopaminergic effects and caffeine seems to be the main responsible for these effects.
Subject: Materials Science, Biomaterials Keywords: concrete; pore solution; silica; pozzolan; corrosion; cyclic voltammetry; silicate; corrosion inhibition
Online: 14 October 2020 (10:48:58 CEST)
Reinforcement corrosion due to chloride attack is of major economic significance for reinforced concrete structures. Pozzolans are known to inhibit corrosion initiation mainly by reducing concrete permeability. However, there is evidence in the literature that changes in the chemical environment in the concrete due to the pozzolans may be creating improved corrosion resistance, by themselves. In this study, the composition of a pore solution of mature hydrated cement paste containing silica-fume at different ratios was analyzed. The electrochemical behavior of reinforcing steel was studied in simulated pore solutions with silicate concentrations ranging from 0 to 35.6 mM, which are within the concentration range found by pore solution extraction to be up to 49 mM. Polished reinforcing steel specimens were used for cyclic voltammetry in simulated pore solutions with chloride concentrations of 10-20%. Better corrosion protection was found with increasing silicate concentration up to 3.56 mM. This was indicated by lower corrosion currents both in the passive state and after anodic activation. Anodic activation of steel in a 35.6 mM silicate solution with 20% NaCl yielded a higher potential than the anterior potential.
REVIEW | doi:10.20944/preprints202007.0275.v2
Subject: Keywords: Transcranial magnetic stimulation; Corticospinal excitability; Cortical inhibition; Cortical facilitation; Eccentric cycling
Online: 4 August 2020 (07:57:25 CEST)
Corticospinal excitability and particularly the balance between cortical inhibitory and excitatory processes (assessed in a muscle using transcranial magnetic stimulation), are affected by neurodegenerative pathologies or following a stroke. Non-fatiguing conventional locomotor exercise, such as cycling or walking, decreases intracortical inhibition and/or increases intracortical facilitation. These modifications notably seem to be a consequence of neurotrophic factors (e.g., brain-derived neurotrophic factors) resulting from hemodynamic solicitation. Furthermore, it can be inferred from non-invasive brain and peripheral stimulation studies that repeated activation of neural networks can endogenously shape neuroplasticity. Such mechanisms could also occur following eccentric exercises (i.e., active lengthening of the muscle), during which motor-related cortical potential is of greater magnitude and lasts longer (assessed by electroencephalography) than during concentric exercises (i.e., muscle shortening). As single-joint eccentric exercise decreased short- and long-interval intracortical inhibition and increased intracortical facilitation (assessed by paired-pulse transcranial magnetic stimulation immediately after), locomotor eccentric exercise may be even more potent by adding hemodynamic-related neuroplastic processes to endogenous processes. Besides, eccentric exercise is especially useful to develop relatively high force levels at low cardiorespiratory and perceived intensity, which can be a training goal in addition to inducing neuroplastic changes. Further studies are required to understand how neuroplasticity is 1) acutely influenced by locomotor exercise characteristics (e.g., intensity, duration), 2) modulated by an exercise-based rehabilitation program, 3) related to functional cognitive and motor outcomes relevant to pathological population.
ARTICLE | doi:10.20944/preprints202006.0358.v1
Subject: Chemistry, Medicinal Chemistry Keywords: Enzyme inhibition; Secondary Metabolites; In-silico Analysis; Molecular docking; Drug candidates
Online: 30 June 2020 (08:11:28 CEST)
Metabolic enzymes are often targeted for drug development programs of metabolic diseases such as diabetes and its complications. Many secondary metabolites isolated from natural products have shown therapeutic action against these enzymes. However, some commercially available synthetic drugs have shown unfriendly impacts with various side effects. Thus, this research has focused on a comprehensive study of secondary metabolites showing better inhibitory activities towards metabolic enzymes such as α-amylase, α-glucosidase, aldose reductase, and lipase. Further receptor-based virtual screening was performed against the various secondary metabolites database designed in-silico. Using Gold combined with subsequent post-docking analyses, the score was obtained as methyl xestospongic ester (Gold score 65.83), 2,″4″-O-diacetylquercitrin (Gold score 65.15), kaempferol-3-O-neohesperidoside (Gold score 53.37) and isosalvianolic acid C methyl ester (Gold score 53.44) for lipase, aldol reductase, α-amylase, and α-glucosidase, respectively. Besides, vitexin and isovitexin for α-amylase; N-trans-Caffeoyl-tyramin for α-glucosidase; purpurolide F and schaftoside for lipase; acteoside and orientin for aldose reductase could be potential drugs for respective enzymes based on in-silico analyses, supported by experimental IC50 values reported. They could bind to the competitive sites of the various targets of metabolic enzymes, and finally, toxicity analysis using ProTox-II was also performed.
ARTICLE | doi:10.20944/preprints201908.0028.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: vegetable waste; phenolics; hyperglycemia-induced oxidative stress; antioxidant activity; AGE inhibition
Online: 2 August 2019 (10:36:17 CEST)
Pomegranate peel is a natural source of phenolics, claimed to possess healing properties, among which antioxidant and antidiabetic. In line with this evidence, the ethyl acetate PGE extract, obtained by Soxhlet from the peel of Dente di cavallo DC2 variety and characterized by a 4% amount of ellagic acid, has been studied for its hypoglycemic, antiglycation and antioxidative cytoprotective properties, in order to support a possible further nutraceutical interest. The α-amylase and α-glucosidase enzyme inhibition, interference with advanced glycation end-products (AGE) formation and metal chelating abilities were evaluated as hypoglycemic mechanisms. Also, considering that oxidative stress is associated with hyperglycemia complications, PGE antioxidant cytoprotective properties under hyperglycemic conditions were assayed. Phenolic profile was characterized by integrated chromatographic and spectrophotometric methods. Under our experimental conditions, PGE strongly inhibited the tested enzymes, especially α-glucosidase, and exerted chelating and antiglycation properties. Also, it reduced both ROS and GSH levels under hyperglycemic conditions, thus suggesting its ability to support cell functions by counteracting intracellular oxidative stress. Along with ellagic acid, rutin was the major identified flavonoid (about 4 %) of PGE. Present results suggest PGE to be a possible remedy for hyperglycemia management and encourage further studies to exploit its promising properties.
ARTICLE | doi:10.20944/preprints201802.0177.v1
Subject: Earth Sciences, Environmental Sciences Keywords: shortcut nitrification; constructed rapid infiltration system; potassium chlorate inhibition; domestic sewage
Online: 27 February 2018 (08:50:13 CET)
Constructed rapid infiltration system (CRI) is a new type of sewage biofilm treatment technology, but due to its anaerobic zone lacks of the carbon sources and the condition for nitrate retention, its nitrogen removal perfomance is very poor; However, shortcut nitrification-denitrification process presents distinctive advantages, as it saves oxygen, requires less organic matter and needs less time for denitrification compared to conventional nitrogen removal method. Thus, if the shortcut nitrification-denitrification process could be applied to CRI system properly, the simpler, more economic and efficient nitrogen removal method will be obtained. But, as its reaction process shows that the first and the most important step of achieving shortcut nitrification-denitrification is to achieve shortcut nitrification. Thus, in this study, we explored the feasibility to achieve shortcut nitrification, which produces nitrite as the dominant nitrogen species in effluent, by addition of potassium chlorate (KClO3) to the influent. In an experimental CRI model system, the effects on nitrogen removal, nitrate inhibition and nitrite accumulation were studied, and the advantages of achieving shortcut nitrification-denitrification were also analysed. The results showed that shortcut nitrification was successfully achieved and maintained in a CRI system by adding 5 mM KClO3 to the influent at a constant pH of 8.4. Under these conditions nitrite accumulation rate was increased, while a lower concentration of 3 mM KClO3 had no obvious effect. The addition of 5 mM KClO3 in influent presumably allowed sufficient activity of ammonia-oxidizing bacteria (AOB) but inhibited nitrite-oxidizing bacteria (NOB) strongly enough to result in a maximum nitrite accumulation rate of up to over 80%. As a result, nitrite became the dominant nitrogen product in the effluent. Moreover, if the shortcut denitrification will be achieved in the subsequent research, it could save 60.27 mg carbon source (CH3OH) consumption when treatment of per liter sewage in CRI system compared with full denitrification process.
ARTICLE | doi:10.20944/preprints201708.0060.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Passiflora cincinnata Mast; redox activity; cell cytotoxicity; α-amylase inhibition; antihyperglycaemic
Online: 17 August 2017 (10:29:55 CEST)
Passiflora cincinnata Mast is a plant popularly used in traditional medicine in northeastern Brazil. The present study aimed to evaluate the anti-lipoperoxidative and anti-α-amylase properties, and cytotoxicity of an extract and fraction of passion fruit leaves (P. cincinnata Mast), as well as the antihyperglecemiant activity of the fraction rich in glycosylated flavonoids and showing low cytotoxicity in rats with a postprandial hyperglycaemia condition. The ethyl acetate fraction (F.ACT) of the P. cincinnata leaves presented the best anti-lipoperoxide properties with TBARs 81.49%, 95.48% and 75.62% lower than AAPH, FeSO4 and H2O2 induced controls, respectively, at 200 μg.mL-1. In addition, it presented an anti-α-amylase potential, with a better ability to inhibit the α-amylase enzyme in comparison to the acarbose control (IC50 6.49 ± 0.11 and 12.01 ± 0.4 μg.mL-1, respectively). The hydroalcoholic extract of P. cincinnata (ExEt) presented high content of total tannins, flavonoids and flavonols. However, F.ACT had the highest concentration of flavonoids among the fractions studied. HPLC analysis of this fraction revealed the presence of the flavonoids isovitexin, orientin and isoorientin. F.ACT showed low to no cytotoxicity below 150 μg.mL-1. Regarding the post-prandial antihyperglycaemic activity of F.ACT, it was observed at 50 and 100 mg.kg-1.
ARTICLE | doi:10.20944/preprints201609.0123.v1
Subject: Life Sciences, Biochemistry Keywords: carbonic anhydrase; acetylcholinesterase; β-Lactam; 2-Azetidinone; enzyme inhibition; enzyme purification
Online: 30 September 2016 (05:38:45 CEST)
β-Lactams are pharmacologically important compounds because of their various biological uses, including antibiotic and so on. β-Lactams were synthesized from benzylidene-inden derivatives and acetoxyacetyl chloride. The inhibitory effect of these compounds was also examined for human carbonic anhydrase I and II (hCA I, and II) and acetylcholinesterase (AChE). The results reveal that β-lactams are inhibitors of hCA I, II and AChE. The Ki values of β-lactams (2a-k) were 0.44-6.29 nM against hCA I, 0.93-8.34 nM against hCA II, and 0.25-1.13 nM against AChE. Our findings indicate that β-lactams (2a-k) inhibit both CA isoenzymes and AChE at low nanomolar concentrations.
CONCEPT PAPER | doi:10.20944/preprints202005.0182.v1
Subject: Life Sciences, Virology Keywords: Coronavirus Nsp proteins; ribosomal proteins homology; inhibition of ribosome turn over; rRNA methyltransferase; protein synthesis inhibition; low ATP formation; blood clotting; low blood pressure and coma
Online: 10 May 2020 (18:14:55 CEST)
Multi-Alignment method coupled with phylogenetic analysis we disclosed the Nsp9 and Nsp10 non-structural proteins of Corona Virus as rRNA RlmH/K methyltransferases with similarities with bin recombinase and int-core integrase fold. Further, Nsp9 has similarities to S8 ribosomal protein and Nap10 has similarity to S10 ribosomal protein. Previously, we showed Nsp13, Nsp14, Nsp15 and Nsp16 are also different types of rRNA RlmE/N and Cfr-like methyltransferases-ribonuclease with RNA helicase domains. Two domains of Nsp13 astonishingly have similarities to ribosomal proteins L6 and L9. Taken together, Nsp9/10 and Nsp13-16 proteins could mimic host ribosome assembly and also could methylate rRNA of mitobibosome preventing mitochondrial protein synthesis and oxidative phosphorylation. Low ATP synthesis causes lowering blood pressure following coma but very ATP concentration (1-10nM) surely induces platelets aggregation through vWA, collagen and GpIIb/IIIa proteins followed by fibrin formation and blood clotting as recently have seen in the lung of many Corona virus infected patients. We have also postulated that two polyproteins itself resemble like 28S and 38S mitoribosome subunits and compete with rRNAs inhibiting the ribosome turnover and new protein synthesis due to their similarities with many ribosomal proteins. Such finding may be valuable in computer-based novel drug design against Corona virus.
REVIEW | doi:10.20944/preprints202209.0057.v1
Subject: Life Sciences, Other Keywords: enteric methane; ruminants; mitigation; rumen; adoption; cost effectiveness; methanogenesis inhibition; feed additives
Online: 5 September 2022 (10:29:25 CEST)
This paper analyzes the mitigation of enteric methane (CH4) emissions from ruminants with the use of feed additives inhibiting of rumen methanogenesis to limit global temperature increase to 1.5 °C. A mathematical simulation conducted herein predicted that pronounced inhibition of rumen methanogenesis with pure chemicals or bromoform-containing algae can contribute to limit global temperature increase by 2050 to 1.5 °C only if widely adopted at a global level and considering an efficacy higher than obtained in most studies. Currently, the most important limitations to the adoption of antimethanogenic feed additives are probably increased feeding cost without a consistent return in production efficiency, and achieving sustained delivery of inhibitors to the rumens of non-supplemented, extensively ranging animals. Economic incentives, and changes in rumen microbial metabolism caused by inhibiting methanogenesis, could potentially be used to make the methanogenesis inhibition intervention cost effective. Also, the composition of the methanogenic community, and rate of disappearance of inhibitors of methanogenesis in the rumen can influence the effective dose of the inhibitors, and hence the cost of their adoption. Possible means for sustained delivery of antimethanogenic compounds to extensively grazing animals are discussed. Limitations and knowledge gaps of these approaches, and future research directions, are examined.
ARTICLE | doi:10.20944/preprints202102.0195.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: Executive functions; music education; cognitive development; planning; inhibition; decision making; working memory
Online: 8 February 2021 (11:44:19 CET)
In recent years, music education in Ibero-America has been losing ground within the school environment in favor of the development of curricular systems that benefit academic results in standardized tests. Despite this, several studies in the field of cognitive neurosciences have found evidence of great relevance and in which it can be observed how music education can favor cognitive development and performance in practically all stages of human development, with important results in language tasks, attention, and executive functions such as planning, inhibition, cognitive flexibility and working memory.
REVIEW | doi:10.20944/preprints202010.0234.v1
Subject: Keywords: myostatin inhibition; Duchenne Muscular Dystrophy; skeletal muscle; muscle development; clinical trials; translation
Online: 12 October 2020 (12:07:43 CEST)
Myostatin inhibition therapy has held much promise for the treatment of muscle wasting disorders. This is particularly true for the fatal myopathy, Duchenne Muscular Dystrophy (DMD). Following on from promising pre-clinical data in dystrophin-deficient mice and dogs, several clinical trials were initiated in DMD patients using different modality myostatin inhibition therapies. All failed to show modification of disease course as dictated by the primary and secondary outcomes measures selected: the myostatin inhibition story thus far, is a failed clinical story. These trials have recently been extensively reviewed and reasons why pre-clinical data collected in animal models has failed to translate into clinical benefit to patients has been purported. However, the biological mechanisms underlying translational failure need to be examined to ensure future myostatin inhibitor development endeavors do not meet with the same fate. Here, we explore the biology which could explain the failed translation of myostatin inhibitors in the treatment of DMD.
ARTICLE | doi:10.20944/preprints202106.0528.v1
Subject: Life Sciences, Biochemistry Keywords: ACE-inhibition; antioxidant potential; processed cheddar cheese; water soluble extract; ethanol soluble extract
Online: 22 June 2021 (07:45:25 CEST)
The purpose of this study was to develop an in-vitro digestion protocol to evaluate the antioxidant potential of the peptides found in processed cheddar cheese using digestion enzymes. We studied first antioxidant and angiotensin converting enzyme (ACE) inhibition and antioxidant activities of processed cheddar cheese with the addition of spices e.g. cumin, clove and black pepper made from buffalo milk and ripened for 9 months. Then we conducted an in vitro digestion of processed cheddar cheese by gastric and duodenal enzymes. Freeze dried water (WSE) and ethanol soluble fractions (ESE) of processed cheddar cheese were also monitored for their ACE inhibition activity and antioxidant activities. In our preliminary experiments, different levels of spices (cumin, clove and black pepper) were tested into cheese matrix and only one level 0.2g/100g (0.2%) on the basis of cheese weight was considered good concerning sensory evaluation. Significant increase in ACE-inhibition (%) of processed Cheddar cheese as well as its WSE and ESE was obtained. Lower IC50 values were found after duodenal phase digestion compared to oral phase digestion.
ARTICLE | doi:10.20944/preprints202103.0596.v1
Subject: Biology, Anatomy & Morphology Keywords: postharvest treatment; jasmonate; metabolite profiling; lipid metabolism; Solanum lycopersicum; ethylene inhibition; fruit quality
Online: 24 March 2021 (16:12:21 CET)
Application of exogenous jasmonate can stimulate the production of ethylene, carotenoids and aroma compounds, resulting in the acceleration of fruit ripening. These alterations improve fruit quality and make fruit desirable for human consumption, but overripening of a fruit results in large losses of fruit crops. In order to overcome this problem, 1-methylcyclopropene was ap-plied to the fruits due to its capacity to block the receptors of ethylene, resulting in the sup-pressed of fruit ripening. In this study, treatments only with 1-methylcyclopropene, and with both 1-methylcyclopropene and methyl jasmonate was conducted to observe if an exogenous methyl jasmonate can improve the levels of metabolites in their fruits with ethylene receptors blocked. Fruits were analyzed at 4, 10 and 21 day after harvest (DAH) and compared with the no treated fruits. The postharvest treatments affected primary metabolites (sugars, organic acids, amino acids and fatty acids) and secondary metabolites (carotenoids, tocopherols and phytoster-ols). However, the lipid metabolism of the tomato was the most impacted by the exogenous jasmonate. Fatty acids, carotenoids, tocopherols and phytosterols showed a delay in their pro-duction at 4 and 10 DAH. In contrast, at 21 DAH these non-polar metabolites exhibited an im-portant improvement in their accumulation.
ARTICLE | doi:10.20944/preprints202012.0289.v1
Subject: Life Sciences, Biochemistry Keywords: remdesivir; perturbation of nucleotide pools; inhibition of RNA and DNA synthesis; CTP synthase
Online: 11 December 2020 (15:57:14 CET)
Remdesivir (RDV) has garnered much hope for its moderate anti-COVID-19 effects, but its limited amelioration of survival in hospitalized patient causes a huge controversy over the applicability of RDV to COVID-19 treatment. Developing strategies to improve its antivirus efficacy is urgently required. As anticipated, RDV exhibits similar behavior with other nucleotide analogs to disrupt the metabolism of natural endogenous ribonucleotides (RNs) and deoxyribonucleotides (dRNs). Alterations in endogenous RNs and dRNs play a critical role in virus replication as well as other key cellular functions. Thus elucidation of the disturbances of RDV on RNs and dRNs could help to understand its exact mechanism of action. Here, the metabolic profiling determined by liquid chromatography–mass spectrometry method showed a general increase in the abundance of nucleotides and a more than 2-fold increase for specific nucleotides. However, the variation of pyrimidine ribonucleotides was relative slight or even contrary, resulting in obvious imbalance between purine and pyrimidine ribonucleotides, which implied the obstacle of RDV to pyrimidine synthesis and could further block the transcription and replication of viral RNA. Additionally, the extreme disequilibrium between cytidine triphosphate (CTP) and cytidine monophosphate might result from the inhibition of CTP synthase and provide a metabolic target for the treatment of COVID-19 infection. Since nucleotides metabolism pathways are vulnerable to nucleotide analogues and are liable to be the regulation targets, it is promising to enhance the efficacy of RDV through co-administration with CTP synthase inhibitors or de novo pyrimidine synthesis inhibitors to exacerbate the imbalance of nucleotide pools.
ARTICLE | doi:10.20944/preprints202012.0032.v1
Subject: Biology, Anatomy & Morphology Keywords: Colorectal cancer; Dehydrodiisoeugenol (DEH); Autophagy inhibition; Endoplasmic reticulum (ER) stress; anti-cancer agent
Online: 1 December 2020 (14:57:00 CET)
Dehydrodiisoeugenol (DEH), a novel lignan component extracted from the Nutmeg seeds, displays noticeable anti-inflammatory and anti-allergic effects in digestive system diseases. However, the mechanism of its anti-cancer activity in gastrointestinal cancer is still to be investigated. Here, the anti-cancer effect of DEH to human colorectal cancer and its underlying mechanism were evaluated. The DEH treatment arrests the cell cycle of colorectal cancer cells at G1/S phase, which leading to a significant cell growth inhibition. Moreover, it can induce strong cellular autophagy and the autophagy would be inhibited through autophagic inhibitors with reducing EDH-induced inhibition of cell growth in colorectal cancer cells. Further studies indicated that DEH can also induce endoplasmic reticulum (ER) stress, and could subsequently stimulating autophagy through activating PERK/eIF2α and IRE1α/XBP-1s/CHOP pathways. Knockdown of PERK or IRE1α can significantly decrease the DEH-induced autophagy and retrieve cell viability in cells treated with DEH. What’s more, DEH exhibits significant anti-cancer activities through CDX- and PDX-model as well. Taken together, our studies strongly suggest that DEH might be a potential anti-cancer agent against colorectal cancer via activating ER stress-induced autophagy inhibition.
ARTICLE | doi:10.20944/preprints202004.0161.v2
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: COVID-19; docking; drug repurposing; natural products; in silico drug design; viral replication inhibition
Online: 1 June 2020 (02:42:54 CEST)
We use state-of-the-art computer-aided drug design (CADD) techniques to identify prospective inhibitors of the main protease enzyme, 3CLpro of the SARS-CoV-2 virus causing COVID-19. From our screening of over one million compounds including approved drugs, investigational drugs, natural products, and organic compounds, and a rescreening protocol incorporating enzyme dynamics via ensemble docking, we have been able to identify a range of prospective 3CLpro inhibitors. Importantly, some of the identified compounds had previously been reported to exhibit inhibitory activities against the 3CLpro enzyme of the closely related SARS-CoV virus. The top- ranking compounds are characterized by the presence of multiple bi- and monocyclic rings, many of them being heterocycles and aromatic, which are flexibly linked allowing the ligands to adapt to the geometry of the 3CLpro substrate site and involve a high amount of functional groups enabling hydrogen bond formation with surrounding amino acid residues, including the catalytic dyad residues H41 and C145. Among the top binding compounds we identified several tyrosine kinase inhibitors, which include a bioflavonoid, the group of natural products that binds best to 3CLpro. Another class of compounds that decently binds to the SARS-CoV-2 main protease are steroid hormones, which thus may be endogenous inhibitors and might provide an explanation for the age-dependent severity of COVID-19. Many of the compounds identified by our work show a considerably stronger binding than found for reference compounds with in vitro demonstrated 3CLpro inhibition and anticoronavirus activity. The compounds determined in this work thus represent a good starting point for the design of inhibitors of SARS-CoV-2 replication.
ARTICLE | doi:10.20944/preprints201901.0062.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: small molecule; ligand; receptor; docking; molecular dynamics; DNA repair; inhibition; PCNA; ADME; toxicology
Online: 8 January 2019 (11:10:26 CET)
Natural and synthetic small molecules from the NCI Developmental Therapeutics Program (DTP) were employed in molecular dynamics-based docking with DNA repair proteins whose RNA-Seq based expression was associated with overall cancer survival (OS) after adjustment for the PCNA metagene. The compounds employed were required to elicit a sensitive response (vs. resistance) in more than half of the cell lines tested for each cancer. Methodological approaches included peptide sequence alignments and homology modeling for 3D protein structure determination, ligand preparation, docking, toxicity and ADME prediction. Docking was performed for unique lists of DNA repair proteins which predict OS for AML, cancers of the breast, lung, colon, and ovaries, GBM, melanoma, and renal papillary cancer. Results indicate hundreds of drug-like and lead-like ligands with best-pose binding energies less than -6 kcal/mol. Ligand solubility for the top 20 drug-like hits approached lower bounds, while lipophilicity was acceptable. Most ligands were also blood-brain barrier permeable with high intestinal absorption rates. While the majority of ligands lacked positive prediction for Herg channel blockage and Ames carcinogenicity, there was considerable variation for predicted fathead minnow, honey bee, and Tetrahymena pyriformis toxicity. The computational results suggest the potential for new targets and mechanisms of repair inhibition and can be directly employed for in vitro and in vivo confirmatory laboratory experiments to identify new targets of therapy for cancer survival.
ARTICLE | doi:10.20944/preprints201807.0351.v1
Subject: Materials Science, General Materials Science Keywords: electrochemical sensor; inhibition bacteria sensor array; immobilization of bacteria; water pollution; pattern recognition
Online: 19 July 2018 (11:51:41 CEST)
The development of a novel and simple inhibition biosensor array for detection of water pollutants based on immobilized bacteria is the main goal of this work. A series of electrochemical measurements (i.e. cyclic voltammograms) were carried out on screen-printed gold electrodes with three types of bacteria, namely Escherichia coli, Shewanella oneidensis, and Methylococcus capsulatus, immobilized via poly L-lysine. For comparison purposes, similar measurements were carried out on bacteria samples in solutions,; also optical measurements (fluorescence microscopy, optical density, and flow cytometry) were performed on the same bacteria in both liquid and immobilized forms. The study of the effect of heavy metal ions (lead), pesticides (atrazine) and petrochemicals (hexane) on DC electrochemical characteristics of immobilized bacteria revealed a possibility of pattern recognition of the above inhibition agents in aquatic environment.
Subject: Keywords: hearing loss; aging; hyperactivity; excitability; loss of inhibition; neurophysiology; auditory perception; neural plasticity; speech processing
Online: 15 April 2021 (13:34:54 CEST)
Many aging adults experience some form of hearing problems that may arise from auditory peripheral damage. However, it has been increasingly acknowledged that hearing loss is not only a dysfunction of the auditory periphery but results from changes within the entire auditory system, from periphery to cortex. Damage to the auditory periphery is associated with an increase in neural activity at various stages throughout the auditory pathway. Here, we review neurophysiological evidence of hyperactivity, auditory perceptual difficulties that may result from hyperactivity, and outline open conceptual and methodological questions related to the study of hyperactivity. We suggest that hyperactivity alters all aspects of hearing – including spectral, temporal, spatial hearing – and, in turn, impairs speech comprehension when background sound is present. By focusing on the perceptual consequences of hyperactivity and the potential challenges of investigating hyperactivity in humans, we hope to bring animal and human electrophysiologists closer together to better understand hearing problems in older adulthood.
ARTICLE | doi:10.20944/preprints201911.0039.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: heart failure; Sacubitril/valsartan; Neprilysin inhibition; reduced ejection fraction; echocardiography; Nt-Pro-BNP; hemodynamic; remodeling
Online: 4 November 2019 (11:20:22 CET)
Background: Sacubitril/valsartan has been shown to be superior to enalapril in reducing the risks of death and hospitalization for heart failure (HF). However the effect on cardiac performance remains unknown. We sought to evaluate the effects of sacubitril/valsartan on clinical, bioumoral and echocardiographic parameters in patients with HFrEF. Methods: Sacubitril/valsartan was administered to 205 HFrEF patients. Results: Among 230 patients (mean age 59 ± 10 years, 46% with ischemic heart disease) 205 (89%) completed the study. After a follow–up of 10.49 (2.93±18.44) months, the percentage of patients in NYHA class III changed from 40% to 17% (p<0.001). Median N–Type natriuretic peptide (Nt-proBNP) decreased from 1865 ± 2318 to 1514 ± 2205 pg/mL, (p=0.01). Furosemide dose reduced from 131.3 ± 154.5 to 120 ± 142.5 (p=0.047). Ejection fraction (from 27± 5.9% to 30 ± 7.7% (p<0.001) and E/A ratio (from 1.67 ± 1.21 to 1.42 ± 1.12 (p=0.002)) improved. Moderate to severe mitral regurgitation (from 30.1% to 17.4%; p=0.002) and tricuspid velocity decreased from 2.8 ± 0.55 m/sec to 2.64 ± 0.59 m/sec (p<0.014). CONCLUSIONS: Sacubitril/valsartan induce “hemodynamic reverse remodeling” and in association with Nt-proBNP concentrations lowering improve NYHA class despite a diuretic dose reduction.
ARTICLE | doi:10.20944/preprints201711.0196.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: carbohydrate starvation; non-structural carbohydrate; photosynthesis; photosynthesis inhibition; respiration; relative growth rate; structure; diurnal variation
Online: 30 November 2017 (08:48:58 CET)
Predicting the growth response of seedlings from the environmental responses of photosynthesis and metabolism may be improved by considering the dynamics of non-structural carbohydrate, NSC, over a diurnal cycle. Attenuation of growth metabolism when NSC content is low could explain why some NSC is conserved through the night. A dynamic model, incorporating diurnal variation in NSC, was developed to simulate growth of seedlings hour-by-hour. I compared predictions of this model to published growth and NSC data for seedlings that varied according to temperature, light, day length, or CO2. Prolonged-darkness experiments showed a temperature dependent upper limit on the respiration capacity. Respiration was attenuated as NSC was depleted. Furthermore, when NSC was high at dawn, inhibition of photosynthesis could attenuate the accumulation of NSC under low temperature, or high light, or high CO2. These concepts were used to simulate plant metabolism and growth rates and diurnal variation of NSC in tomato seedlings under two light levels and various temperatures. Comparison of other results using the same model parameters showed the dynamic model could predict results for starch and starch-less plants, and when growth was affected by CO2 enrichment and day length.
ARTICLE | doi:10.20944/preprints202111.0184.v2
Subject: Life Sciences, Virology Keywords: baloxavir marboxil; H5N1 highly pathogenic avian influenza virus; viral replication; inhibition; lung inflammation; combination therapy; oseltamivir
Online: 12 January 2022 (13:18:58 CET)
Human infections caused by the H5 highly pathogenic avian influenza virus (HPAIV) sporadically threaten public health. The susceptibility of HPAIVs to baloxavir acid (BXA), a new class of inhibitors for the influenza virus cap-dependent endonuclease, has been confirmed in vitro, but it has not yet been fully characterized. Here, the efficacy of BXA against HPAIVs, including recent H5N8 variants, was assessed in vitro. The antiviral efficacy of baloxavir marboxil (BXM) in H5N1 virus-infected mice was also investigated. BXA exhibited similar in vitro activities against H5N1, H5N6, and H5N8 variants tested in comparison with seasonal and other zoonotic strains. Compared with oseltamivir phosphate (OSP), BXM monotherapy in mice infected with the H5N1 HPAIV clinical isolate, the A/Hong Kong/483/1997 strain, also caused a significant reduction in viral titers in the lungs, brains, and kidneys, thereby preventing acute lung inflammation and reducing mortality. Furthermore, compared with BXM or OSP monotherapy, combination treatments with BXM and OSP using a 48-hour delayed treatment model showed a more potent effect on viral replication in the organs, accompanied by improved survival. In conclusion, BXM has a potent antiviral efficacy against H5 HPAIV infections.
ARTICLE | doi:10.20944/preprints201906.0301.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: tumor blood vessel; Tumor Angiogenic Inhibition Triggered Necrosis (TAITN); CXCR4 antagonist; oral squamous cell carcinoma; hypoxia
Online: 28 June 2019 (15:18:43 CEST)
CXCR4 is a chemokine receptor crucial in tumor progression, although the angiogenic role of CXCR4 in oral squamous cell carcinoma (OSCC) has not been investigated. Here we show that CXCR4 is crucial for tumor angiogenesis thereby supports tumor survival in OSCC. Immunohistochemistry on human clinical specimens revealed that CXCR4 and a tumor vasculature marker CD34 were co-distributed in tumor vessels in human OSCC specimens. To ask the effects of CXCR4 inhibition, we treated the OSCC-xenografted mice with AMD3100, so-called plerixafor, an antagonist of CXCR4. Notably, we found a unique pathophysiological structure defined as Tumor Angiogenic Inhibition Triggered Necrosis (TAITN) induced by the CXCR4 antagonism. Treatment with AMD3100 increased necrotic area with the induction of hypoxia-inducible factor-1α in the xenografted tumors, suggesting that AMD3100-induced TAITN was involved in hypoxia and ischemia. Taken together, we demonstrated that CXCR4 plays a crucial role in tumor angiogenesis required for OSCC progression, whereas TAITN induced by CXCR4 antagonism could be an effective anti-angiogenic therapeutic strategy in OSCC treatment.
ARTICLE | doi:10.20944/preprints201811.0330.v1
Subject: Chemistry, Medicinal Chemistry Keywords: hyperpigmentation; tyrosinase inhibitors; 3-(2,4-dihydroxyphenyl)propionic acid; structure-activity relationship study; B16-F10 cellular melanogenesis inhibition
Online: 14 November 2018 (09:59:45 CET)
Compounds with tyrosinase inhibitory efficacy could be effective as depigmenting agents. Although a large number of natural and synthetic tyrosinase inhibitors have been reported, few of them are used as skin-whitening agents due to poor activity and safety concerns. 3-(2,4-Dihydroxyphenyl)propionic acid (DPPA), a naturally occurring compound isolated from Ficus carica, was previously discovered as a moderate tyrosinase inhibitor. In this study, the structure-activity relationship study of DPPA was conducted. Compound 3g, with the 2,4-resorcinol subunit and terminal hydrophobic di-butylamino group, was identified with low nanomolar enzymatic IC50 value. Additionally, compound 3g could effectively reduce melanin levels in B16-F10 melanoma cells treated with α-melanocyte-stimulating hormone (α-MSH) without affecting cell viability and proliferation. All these results indicated that compound 3g could be considered as a promising candidate for the treatment of diseases associated with hyperpigmentation.
REVIEW | doi:10.20944/preprints201802.0070.v1
Subject: Earth Sciences, Environmental Sciences Keywords: microbial sulphide oxidation, corrosion, mine waste and water remediation, biofilm development, inhibition of Acid mine and rock draiange
Online: 8 February 2018 (15:35:56 CET)
Abstract: Measures to counteract AMD generation need to start at the mineral surface, inhibiting mineral-oxidizing, acidophilic microbes. Laboratory and long-term field tests with pyrite-containing mining wastes, where Carbonaceous Phosphate Mining Waste (CPMW) was added, resulted in low acidity, and near neutral drainage. The effect was reproducible, nd confirmed by several independent research groups. This was shown to involve an organic coating, likely a biofilm. The biofilm formation was confirmed when CPMW was added to lignite coal waste with an initial pH of 1. Forty five days after the addition, the coal waste was dominated by heterotrophic microorganisms in biofilms. A review of the scientific literature supports that CPMW has physical and chemical characteristics which are capable of inducing a strong inhibitory effect on sulphide oxidation by forming an organic coating over the mineral surface. CPMW characteristics appear to provide the cornerstone of a new technology for the reduction of sulphide oxidation in mine wastes. An hypothesis for testing this technology is presented which could result in an economical and sustainable approach to mine waste and water management.
ARTICLE | doi:10.20944/preprints202002.0134.v1
Subject: Life Sciences, Biochemistry Keywords: autophagy; autophagonizer; target identification of label-free compound; target validation; autophagic flux; autophagy inhibition; lysosomal integrity function of Hsp70
Online: 11 February 2020 (09:03:51 CET)
Manipulating autophagy is a promising strategy for treating cancer as several autophagy inhibitors shown to induce autophagic cell death. One of these, autophagonizer (APZ), induces apoptosis-independent cell death by binding an unknown target via an unknown mechanism. To identify APZ targets we used a label-free drug affinity responsive target stability (DARTS) approach with a liquid chromatography/tandem mass spectrometry (LC-MS/MS) readout. Of 35 protein interactors, we identified Hsp70 as a key target protein of unmodified APZ in autophagy. Either APZ treatment or Hsp70 inhibition attenuates integrity of lysosomes, which leads to autophagic cell death exhibiting an excellent synergism with a clinical drug, temozolomide, in vitro, in vivo, and orthotropic glioma xenograft model. These findings demonstrate the potential of APZ to induce autophagic cell death and its development to combinational chemotherapeutic agent for glioma treatment. Collectively, our study demonstrated that APZ, a new autophagy inhibitor, can be used as a potent antitumor drug candidate to get over unassailable glioma and revealed a novel function of Hsp70 in lysosomal integrity regulation of autophagy.
ARTICLE | doi:10.20944/preprints202010.0274.v1
Subject: Life Sciences, Biochemistry Keywords: protein aggregation; inhibition of amyloid fibril formation; antioxidants; polyphenols; cystatin C; NAC and vitamin C; amyloid fibrils; stefin B aggregation; TEM
Online: 13 October 2020 (10:49:14 CEST)
We compare the effect on amyloid fibril formation by two homologous proteins from the family of cystatins, human stefin B (stB) and cystatin C (cysC) in presence of 3 polyphenols: curcumin, resveratrol and quercetin and 2 non-phenolic anti-oxidants: vitamin C (VitC) and N-acetyl cystein (NAC). Some of the experimental data have already been presented, here we compare, further discuss and highlight the results. The amyloid fibril formation was followed by ThT fluorescence and transmission electron microscopy. Inhibitory effects on amyloid fibrillation reaction depended on anti-oxidant class and concentration. The fact that different effect of polyphenols was observed with the two cystatins; Cur acted inhibitory on stB but not on cysC fibril formation, could be explained if the 3 polyphenols would not bind to the same binding site in the fibrils core. Other differences are pointed out and discussed. Synergistic effects of VitC and chosen polyphenols on amyloid fibrilllation of human stB have been explored and are reported here for the first time.
ARTICLE | doi:10.20944/preprints201912.0184.v1
Subject: Chemistry, Medicinal Chemistry Keywords: sponge; quorum sensing; quorum sensing inhibition; N-acyl homoserine lactone; Sarcotragus spinosulus; 3-Br-N-methyltyramine; 5,6-dibromo-N,N-dimethyltryptamine
Online: 13 December 2019 (12:12:54 CET)
Marine sponges, a well documented prolific source of natural products, harbors numerous microbial communities believed to possess N-acyl homoserine lactones (AHLs) mediated Quorum sensing (QS) as one of the mechanisms of interaction. Bacteria and eukaryotic organisms are known to produce molecules that can interfere with QS signaling, thus affecting microbial genetic regulation and function. In the present study, we established the potential for production of both QS signal molecules as well as QS interfering molecules (QSI) in the same sponge species Sarcotragus spinosulus. A total of eighteen saturated acyl chain AHLs were identified along with six putative unsaturated acyl chain AHLs. Bioassay guided purification led to the isolation of two brominated metabolites with QS-interfering activity. The structures of these compounds were elucidated by comparative spectral analysis of 1HNMR and HR-MS data and was identified as 3-Br-N-methyltyramine (1) and 5,6-dibromo-N,N-dimethyltryptamine (2). The QSI activity of compounds 1 and 2 were evaluated using reporter gene assays for long- and short-chain signals (E. coli pSB1075 and E. coli pSB401) and was confirmed by measuring dose dependent inhibition of proteolytic activity and pyocyanin production in P. aeruginosa PAO1. The obtained results showed the co-existence of QS and QSI in S. spinosulus, a complex network which may mediate the orchestrated function of the microbiome within the sponge holobiont.
ARTICLE | doi:10.20944/preprints201806.0092.v1
Subject: Life Sciences, Other Keywords: Neuroscience; basal ganglia; cortical layers; cerebellum; habenula; inhibition; predictions; dopamine; serotonin; acetylcholine; opioids; mirror neurons; place cells; language; imagery; working memory
Online: 7 June 2018 (06:02:29 CEST)
Understanding brain function is one of the most important open problems in science today. At present, there is no concrete theory for how the brain works. Here, a theory is presented that provides a detailed mechanistic biological account of the brain’s capacities. Brain function is managed by a response (R) process that is structurally similar to the immune response, and shows anatomical and molecular specificity. Different R process stages utilize different cortical layers, hippocampus fields, basal ganglia paths, GABAergic interneurons, cerebellum paths, and molecular agents such as dopamine, serotonin and opioids. We show how the R process supports hierarchical action sequences, language and thought. The theory is supported by a large body of experimental evidence in many modalities, and accounts for virtually all of the major facts known about the brain at the system level.
REVIEW | doi:10.20944/preprints201707.0019.v1
Subject: Chemistry, Medicinal Chemistry Keywords: affective disorders; alzheimer’s disease; l-Deprenyl (Selegiline); donepezil; galantamine; value; inhibitor constant; mechanism-based inhibition; multitarget-directed ligand (MTDL); rasagiline; rivastigmine
Online: 11 July 2017 (05:58:53 CEST)
The actions of many drugs involve enzyme inhibition. This is exemplified by the inhibitors of monoamine oxidases (MAO) and the cholinsterases (ChE) that have been used for several pharmacological purposes. This review describes key principles and approaches for the reliable determination of enzyme activities and inhibition as well as some of the methods that are in current use for such studies with these two enzymes. Their applicability and potential pitfalls arising from their inappropriate use are discussed. Since inhibitor potency is frequently assessed in terms of the quantity necessary to give 50% inhibition (the IC50 value), the relationships between this and the mode of inhibition is also considered, in terms of the misleading information that it may provide. Incorporation of more than one functionality into the same molecule to give a multi-target-directed ligands (MTDLs) requires careful assessment to ensure that the specific target effects are not significantly altered and that the kinetic behaviour remains as favourable with the MTDL as it does with the individual components. Such factors will be considered in terms of recently developed MTDLs that combine MAO and ChE inhibitory functions.
ARTICLE | doi:10.20944/preprints201608.0162.v1
Subject: Life Sciences, Microbiology Keywords: bacterial ghosts (BGs); Vibrio parahaemolyticus; chemically induced lysis; minimum inhibition concentration (MIC); sodium hydroxide (NaOH); lipopolysaccharides (LPS); endotoxic activity; macrophages; cytotoxicity; cytokine
Online: 17 August 2016 (10:26:00 CEST)
Acellular bacterial ghosts (BGs) are empty non-living bacterial cell envelopes, commonly generated by controlled expression of the cloned lysis gene E of bacteriophage PhiX174. In this study, Vibrio parahaemolyticus ghosts (VPGs) were generated by chemically induced lysis and the method is based on minimum inhibitory concentration (MIC) of sodium hydroxide (NaOH), acetic acid, boric acid, citric acid, maleic acid, hydrochloric acid and sulfuric acid. The MIC values of the respective chemicals were 3.125, 6.25, < 50.0, 25.0, 6.25, 1.56 and 0.781 mg/ml. Except boric acid, the lysis efficiency was reached more than 99.99% at 5 min after treatment of all chemicals. Among those chemicals, NaOH-induced VPGs showed completely DNA-free that was confirmed by quantitative real-time PCR. Besides, lipopolysaccharides (LPS) extracted from the NaOH-induced VPGs showed no distinctive band on SDS-PAGE gel after silver staining. On the other hand, LPS extracted from wild-type bacterial cells as well as the organic acids-induced VPGs showed triple major bands and LPS extracted from the inorganic acids-induced VPGs showed double bands. It suggests that some surface structures in LPS of the NaOH-induced VPGs may be lost, weakened or modified by the MIC of NaOH. Nevertheless, Limulus amoebocyte lysate assay revealed that there is no significant difference in endotoxic activity between the NaOH-induced VPGs and wild-type bacterial cells. Macrophages exposed to the NaOH-induced VPGs at 0.5 × 106 CFU/mL showed cell viability of 97.9%, however the MIC of NaOH did not reduce the cytotoxic effect of wild-type bacterial cells. Like Escherichia coli LPS, the NaOH-induced VPGs are an excellent activator of pro-inflammatory cytokines (IL-1β and iNOS), anti-inflammatory cytokine (IL-10) and dual activities (IL-6) in the stimulated macrophage cells. On the other hand, the induction of TNF-α mRNA was remarkable in the macrophages exposed with wild-type cells. Scanning electron microscopy showed the formation of trans-membrane lysis tunnel structures in the NaOH-induced VPGs. SDS-PAGE and agarose gel electrophoresis also confirmed that cytoplasmic proteins and genomic DNA released from the VPGs to culture medium through the lysis tunnel structures. Taken together, all these results indicated that the NaOH-induced VPGs show the potency of safe, economical and effective inactivated bacterial vaccine candidate.
ARTICLE | doi:10.20944/preprints202012.0414.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: galantamine; curcumin; in vivo AChE inhibition; acute toxicity in mice; antioxidant activity; malondialdehide levels; glutathione levels; brain homogenate; complete blood count; biochemical serum parameters
Online: 16 December 2020 (13:45:10 CET)
The acetylcholinesterase (AChE) inhibitors are the main drugs for symptomatic treatment of neurodegenerative disorders like Alzheimer’s disease. A recently designed, synthesized and tested hybrid compound between the AChE inhibitor galantamine (GAL) and the antioxidant polyphenol curcumin (CU) showed high AChE inhibition in vitro. Here, we describe tests for acute and short-term toxicity in mice as well as antioxidant tests on brain homogenates measured the levels of malondialdehide (MDA) and glutathione (GSH). Haematological and serum biochemical analyses were also performed. In the acute toxicity tests, the novel AChE inhibitor given orally in mice showed LD50 of 49 mg/kg. The short-term administration of 2.5 and 5 mg/kg did not show toxicity. In the ex vivo tests, the GAL-CU hybrid performed better than GAL and CU themselves. In a dose of 5 mg/kg, it demonstrates 25% reduction in AChE activity, 28% and 73% increase in the levels of MDA and GSH, respectively. No significant changes in blood biochemical data were observed. The GAL-CU hybrid is a novel non-toxic AChE inhibitor with high antioxidant activity which makes it a perspective multitarget drug candidate for treatment of Alzheimer’s disease.
ARTICLE | doi:10.20944/preprints201912.0399.v1
Subject: Life Sciences, Microbiology Keywords: natural product; actinobacteria; quorum sensing inhibition (QSI); biosynthetic gene clusters (BGCs); global natural product social networking (GNPS); cyclic dipeptides (2,5-diketopiperazines, DKPs); LC-HRMS
Online: 31 December 2019 (02:59:59 CET)
Streptomyces, being one of the most promising genera due to its ability to synthesize a variety of bioactive secondary metabolites of pharmaceutical interest, here studied in relation to its genomic and metabolomic potential. Coinciding with the increase in sequenced data, mining of bacterial genomes for biosynthetic gene clusters (BGCs) has become a routine component of natural product discovery. Herein, we describe the isolation and characterization of a Streptomyces tendae VITAKN with quorum sensing inhibitory activity (QSI) that was isolated from southern coastal parts of India. The nearly complete genome consists of 8,621,231bp with a GC content of 72.2%. Utilizing the BiG-SCAPE-CORASON platform, a sequence similarity network predicted from this strain was evaluated through sequence similarity analysis with the MIBiG database and existing 3,365 BGCs predicted by antiSMASH analysis of publicly available complete Streptomyces genomes. Crude extract analyzed on LC-HRMS/MS and Global Natural Product Social Molecular Networking (GNPS) online workflow using dereplication resulted in the identification of cyclic dipeptides (2,5-diketopiperazines, DKPs) in the extract, which are known to possess QSI activity. Our results highlight the potential use of genomic mining coupled with LC-HRMS/MS and bionformatic tools (GNPS) as a potent approach for metabolome studies in discovering novel QSI lead compounds. This study also provides the biosynthetic diversity of these BGCs and an assessment of the predicted chemical space yet to be discovered.
ARTICLE | doi:10.20944/preprints201805.0137.v1
Subject: Life Sciences, Other Keywords: neuroscience; thalamus; basal ganglia; cortical layers; hippocampus; cerebellum; habenula; claustrum; amygdala; inhibition; predictions; automaticity; dopamine; serotonin; acetylcholine; opioids; oxytocin; crh; glucocorticoids; cannabinoids; orexin; melanin-concentrating hormone; mirror neuron; place cells; grid cells; language; imagery; working memory; attention; consciousness; emotions
Online: 9 May 2018 (05:35:51 CEST)
Understanding brain function is one of the most important problems in human history. At present, there is no concrete theory for how the brain works. Here, a theory is presented that provides a detailed mechanistic biological account of the brain's capacities, including motor control, functional states, language, and thinking. Brain function is managed by a well-defined response (R) process that is generally similar to the process underlying the immune system. The R process is strongly reflected in the brain's anatomy, physiology, and external interactions. Different R process stages are supported by distinct excitatory networks located in different cortical layers, hippocampal fields, and bagal ganglia paths, by distinct coordination networks comprised of GABAergic interneurons, and by distinct molecular agents. The roles of norepinephrine, serotonin, dopamine and acetylcholine is to promote the alert, planning, goal-setting and execution R process modes, respectively. Opioids and oxytocin promote termination by success, failure, fight or run, while glucocorticoids and cannabinoids suppress acute responses to protect cells. The R process has two instances occurring at different time scales. The millisecond-scale Quax process implements the execution of hierarchical sequences of movements and thoughts, in which the selection of the next action is determined via interaction between top-down predictions and sensory inputs. The slower Need process controls the satisfaction of internal and external needs. The theory differs from the existing standard accounts in many of the major topics (e.g., the basal ganglia, dopamine, language), and shows how cognition results from biological processes.