ARTICLE | doi:10.20944/preprints201608.0145.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: methyl 3,4-dihydroxybenzoate; oxidative stress; apoptosis; neuroprotection; nuclear factor erythroid 2-related factor 2
Online: 15 August 2016 (10:42:05 CEST)
This study investigated the neuroprotective effects of methyl 3,4-dihydroxybenzoate (MDHB) against t-butylhydroperoxide(TBHP) induced oxidative damage in SH-SY5Y (human neuroblastoma cells) and the underlying mechanisms. SH-SY5Y were cultured in DMEM+10% FBS for 24 hours and pretreated with different concentrations of MDHB or N-acetyl-L-cysteine (NAC) for 4 hours prior to the addition of 40 μM TBHP for 24 hours. Cell viability was analyzed using the methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) assays. An annexin V-FITC assay was used to detect cell apoptosis rate. The 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay was used to determine intracellular ROS levels. The activities of antioxidative enzymes (GSH-Px and SOD) were measured using commercially available kits. The oxidative DNA damage marker 8-OHdG was detected using ELISA. Western blotting was used to determine the expression of Bcl-2, Bax, caspase 3, p-Akt and Akt proteins in treated SH-SY5Y cells. Our results showed that MDHB is an effective neuroprotective compound that can mitigate oxidative stress and inhibit apoptosis in SH-SY5Y cells
ARTICLE | doi:10.20944/preprints202305.1551.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: filamentous growth; jasmonic acid carboxyl methyl transferase (JMT); methyl jasmonate (MeJA); pathogenicity; Sporisorium scitamineum; sugarcane smut
Online: 23 May 2023 (03:41:11 CEST)
Sporisorium scitamineum, the basidiomycetous fungus causing sugarcane smut that leads to severe losses in sugarcane quantity and quality, undergoes sexual mating to form dikaryotic hyphae capable of invading the host cane. Therefore, suppressing dikaryotic hyphae formation would potentially be an effective way to prevent host infection by the smut fungus, and the following disease symptom development. The phytohormone methyl jasmonate (MeJA) has been showed to induce plant defense against insects and microbial pathogens. In this study, we verified that exogenous addition of MeJA suppressed dikaryotic hyphae formation under in vitro culture condition, and effective in inhibiting maize smut disease symptom caused by Ustilago maydis. We constructed an Escherichia coli strain expressing plant JMT gene, encoding a jasmonic acid carboxyl methyl transferase that catalyzes conversion from jasmonic acid (JA) to MeJA. By GC-MS we confirmed that the transformed E. coli strain, designated as pJMT strain, was able to produce MeJA in the presence of JA and S-adenosylmethionine (SAM; as methyl donor). Furthermore, the pJMT strain was able to suppress S. scitamineum filamentous growth under in vitro culture condition. It waits to further optimize JMT expression under field condition, in order to utilize the pJMT strain as a biocontrol agent (BCA) of sugarcane smut disease. Overall, our study provides a potentially novel method for controlling crop fungal diseases by boosting phytohormone biosynthesis.
ARTICLE | doi:10.20944/preprints202305.2052.v2
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: methyl-CpG; DNA methylation; gene expression; cell identity
Online: 2 June 2023 (04:15:42 CEST)
Cell identity is determined by chromatin structure and the profiles of gene expression, which are dependent on chromatin accessibility and DNA methylation of regions critical for gene expression, such as enhancers and promoters. These epigenetic modifications are required for mammalian development and are essential for the establishment and the maintenance of the cellular identity. DNA methylation was once thought to be a permanent repressive epigenetic mark, but systematic analysis in various genomic contexts reveals a more dynamic regulation than previously thought. In fact, both active DNA methylation and demethylation occur during cell fate commitment and terminal differentiation. To link methylation signatures of specific genes to their expression profiles, we have determined the methyl-CpG configurations of the promoters of five genes switched on and off during murine postnatal brain differentiation by bisulfite-targeted sequencing. We report here the structure of significant, dynamic and stable methyl-CpG profiles associated with silencing or activation of expression of genes during neural stem cell and brain postnatal differentiation. Strikingly, these methylation cores mark different mouse brain areas and cell types derived from the same areas during differentiation.
ARTICLE | doi:10.20944/preprints202308.1908.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: Bio-magnification; Bio-accumulation; degassing; methyl-mercury; fish physiology
Online: 29 August 2023 (09:01:55 CEST)
Mercury toxicity significantly threatens aquatic ecosystems, particularly impacting fish populations and human well-being. This article exposes the effects of mercury contamination on aquatic life and their habitats. Mercury primarily originates from natural degassing and anthropogenic activities and accumulates in aquatic organisms, most notably in predatory fish, through bio-accumulation and bio-magnification. This bio-accumulation, driven by microbial transformation to methyl-mercury, leads to elevated concentrations in top-level predators. The consequences of mercury exposure on fish physiology are stunted growth, reproductive impairments, and compromised immunity, with potential ramifications for population dynamics and ecosystem resilience. This study delves into specific impacts of mercury on fish, ranging from bone deformities to liver damage, developmental anomalies, neurotoxic effects, and disruptions in reproductive systems. The interplay between ecological, physiological, and human health effects underscores the need for a comprehensive understanding of mercury's underlying mechanisms. Monitoring mercury levels in aquatic systems emerges as a crucial strategy for ensuring fish populations' health and ecosystems' sustainability. Urgent collaborative efforts are imperative to address this global concern, promote harmonious coexistence between human activities and aquatic environments, and secure the availability of safe and nutritious fish for future generations. In conclusion, this article highlights the urgent necessity for targeted interventions and informed decision-making to mitigate the influence of mercury contamination on aquatic ecosystems.
REVIEW | doi:10.20944/preprints202304.0349.v1
Subject: Medicine And Pharmacology, Obstetrics And Gynaecology Keywords: N-methyl-D-aspartate (NMDA) receptors; prenatal exposure; neurotoxic
Online: 14 April 2023 (04:29:05 CEST)
Ketamine is a dissociative anesthetic and antidepressant with several biological targets. Among the many targets, ketamine, notably, has an antagonistic effect on molecular N-methyl-D-aspartate (NMDA) receptors and has been identified as a non-competitive inhibitor of these receptors. Although ketamine has a wide range of therapeutic uses in the clinical setting, it is often used recreationally due to its psychoactive and analgesic effects. Regardless of the indication, prenatal exposure to ketamine has been widely investigated. The misuse of this drug, particularly in pregnant women, has been a point of concern. The neurotoxic potential of ketamine positions it as a danger to a developing fetus. Furthermore, the ability of ketamine to cross the blood-placental barrier poses a threat to the health and maturation processes of the neonate. This paper reviewed published work that explores the mechanisms through which prenatal ketamine exposure can cause altered neurodevelopment, neurobehavior, and the physiological consequences that follow. By exploring investigations using multiple different subjects such as: rodents, non-human primates, and human subjects, this paper develops a full picture of the existing data to generate a strong foundation for improved and informed public health policies.
ARTICLE | doi:10.20944/preprints202112.0166.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: methyl sulfonyl methane; sodium sulfate; laying hen; antioxidant capacity
Online: 10 December 2021 (08:32:41 CET)
The present study was conducted to investigate the comparative effects of organic and inorganic forms of sulfur, methyl sulfonyl methane (MSM) and sodium sulfate (SS), on laying performance, egg quality, ileal morphology, ileal volatile fatty acids, and antioxidant and stress markers in various biological samples in aged laying hens. A total of 144, 73-week-old Lohman Brown-Lite laying hens were randomly assigned to one of three experimental diets: basal diet (CONT), CONT + 0.2% MSM (MSM), and CONT + 0.3% SS (SS). The trial lasted for 12 weeks. MSM and SS groups contained 0.07% of sulfur, either organic or inorganic. Dietary MSM did not affect egg production and feed conversion ratio at 12 weeks compared with the CONT group. Dietary sulfur did not affect egg quality except for Haugh unit at 4 weeks which was lowered (P < 0.05) in the SS group. Compared with the CONT group, higher (P < 0.05) villus height and crypt depth ratio was observed in the SS group. None of dietary sulfur affected the percentages of short-chain fatty acids in the ileum. Total antioxidant capacity of liver increased (P < 0.05) in laying hens fed MSM- and SS-added diets compared with the CONT group. The MSM and SS groups lowered (P < 0.05) malondialdehyde (MDA) concentration in serum samples compared with the CONT. Finally, dietary MSM had the lowest (P < 0.05) MDA concentrations in yolk samples. Taken together, our study showed that dietary organic and inorganic sulfur have positive effects on ileal morphology and antioxidant capacity in laying hens. However, SS-mediated inhibition in laying performance needs to be clarified.
ARTICLE | doi:10.20944/preprints202008.0118.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: Sarcopenia; β-hydroxy-β-methyl butyrate Calcium; Black ginger
Online: 5 August 2020 (09:51:06 CEST)
Muscle mass and strength decrease with aging, but habitual exercise can maintain muscle health. β-Hydroxy-β-methyl butyrate calcium (HMB) and black ginger (BG) are anti-oxidants that have been reported to improve muscle protein metabolism and energy production; these molecules may have synergistic effects. The senescence-accelerated mouse-prone 8 (SAMP8) model is a useful model of muscle aging. Therefore, in this study, we explored how the combination of habitual exercise, HMB, and BG affected muscle aging. We used 28-week-old SAMP8 mice divided into five groups: control, exercise (Ex), Ex+BG, Ex+HMB, and Ex+BG+HMB (Ex+Comb). Mice were required to run on a treadmill for 16 weeks at 5 days per week. In 44-week-old mice, grip strength tests and dissection were conducted. Muscle weight was measured, and the gastrocnemius muscle was subjected to quantitative polymerase chain reaction and immunoblotting. Muscle mass and strength were preserved in the Ex+Comb group, and mitochondrial function was preserved through suppressing oxidative stress. Muscle protein synthesis signaling was improved in the Ex+Comb group. Autophagy and the ubiquitin system were normalized by Ex+Comb treatment. Overall, habitual exercise and HMB plus BG treatment maintained muscle health by suppressing oxidative stress, preserving mitochondrial function, and maintaining muscle protein metabolism in SAMP8 mice.
ARTICLE | doi:10.20944/preprints201608.0128.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: graphene oxide; polyaniline; nanocomposites; adsorbent; methylene blue; methyl orange
Online: 11 August 2016 (11:29:12 CEST)
The present investigation highlights the synthesis of polyaniline (PANI) coated graphene oxide doped with SrTiO3 nanocube nanocomposites through facile in-situ oxidative polymerization method for the efficient removal of carcinogenic dyes, namely, the cationic dye methylene blue (MB) and the anionic dye methyl orange (MO). The synthesised nanocomposites were characterised by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The adsorption efficiencies of graphene oxide (GO), PANI homopolymer and SrTiO3 nanocubes-doped nanocomposites were assessed by monitoring the adsorption of methylene blue and methyl orange dyes from aqueous solution. The adsorption efficiency of nanocomposites doped with SrTiO3 nanocubes were found to be of higher magnitude as compared with undoped nanocomposite. Moreover, the nanocomposite with 2 wt% SrTiO3 with respect to graphene oxide demonstrated excellent adsorption behaviour with 99% and 91% removal of MB and MO respectively, in a very short duration of time.
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: 17α-methyl steroids; long-term metabolites; gas chromatography-mass spectrometry; 17-hydroxymethyl-17-methyl-18-nor; D-ring alteration; doping control; metabolism
Online: 1 March 2021 (13:19:54 CET)
Metandienone and methyltestosterone are orally active anabolic-androgenic steroids with a 17α-methyl structure that are prohibited in sports but are frequently detected in anti-doping analysis. After the previously reported detection of long-term metabolites with a 17ξ-hydroxymethyl-17ξ-methyl-18-nor-5ξ-androst-13-en-3ξ-ol structure in the chlorinated metandienone analog dehydrochloromethyltestosterone (“Oral Turinabol”), in this study we investigated the formation of similar metabolites of metandienone and 17α-methyltestosterone with a rearranged D-ring and a fully reduced A-ring. Using a semi-targeted approach including synthesis of reference compounds, two diastereomeric substances, viz. 17α-hydroxymethyl-17β-methyl-18-nor-5β-androst-13-en-3α-ol and its 5α-analog, were identified following an administration of methyltestosterone. In post-administration urines of metandienone, only the 5β-metabolite was detected. Additionally, 3α,5β-tetrahydro-epi-methyltestosterone was identified in the urines of both administrations besides the classical metabolites included in the screening procedures. Besides their applicability for anti-doping analysis, the results provide new insights on the metabolism of 17α-methyl steroids with respect to the order of reductions in the A-ring, the participation of different enzymes, and alterations of the D-ring.
ARTICLE | doi:10.20944/preprints202305.2008.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: endogenously produced methane; reactive oxygen species; methyl radicals; dimethyl sulfoxide; methyl donors; stable carbon and hydrogen isotope labelling; oxidative stress; antioxidant defense system
Online: 29 May 2023 (10:27:42 CEST)
Methane (CH4), produced endogenously in animals and plants, has recently been suggested to play a role in cellular physiology, potentially influencing the signaling pathways and regulatory mechanisms involved in nitrosative and oxidative stress responses. In addition, it has been proposed that supplementation of CH4 to organisms may be beneficial for the treatment of several diseases, including ischemia, reperfusion injury, and inflammation. However, it is still unclear if and how CH4 is produced in mammalian cells without the help of microorganisms, and how CH4 might be involved in physiological processes in humans. In this study, we provide first proof of the principle that CH4 is formed non-microbially in the human body by applying isotopically labeled methylated sulfur compounds, such as dimethyl sulfoxide (DMSO) and methionine, as carbon precursors to confirm cellular CH4 formation. A volunteer applied isotopically labeled (2H and 13C) DMSO on the skin, orally, and to blood samples. Monitoring of stable isotope values of CH4 convincingly showed the conversion of the methyl groups, as isotopically labeled CH4 was formed during all experiments. Based on these results, we consider several hypotheses about endogenously formed CH4 in humans, including physiological aspects and stress responses involving reactive oxygen species (ROS). While further and broader validation studies are needed, the results may unambiguously serve as a proof of concept for the endoge-nous formation of CH4 in humans by a radical-driven process. Furthermore, these results might encourage follow up studies to decipher the potential physiological role of CH4 and its bioactiv-ity in humans in more detail. Of particular importance is the potential to monitor CH4 as an ox-idative stress biomarker if the observed large variability of CH4 in breath air is an indicator for physiological stress responses and immune reactions. Finally, the potential role of DMSO as a radical scavenger to counteract oxidative stress caused by ROS might be considered in the health sciences. DMSO has already been investigated for many years, but its potential positive role for medical use remained highly uncertain.
ARTICLE | doi:10.20944/preprints201803.0099.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: photocatalyst; titanium dioxide; multi-walled carbon nanotubes; methyl orange; degradation
Online: 14 March 2018 (06:43:53 CET)
In this study, functionalized-MWCNTs with 3-aminopropyltriethoxysilane (APTES) loaded titania nanoparticles (MWCNTs-APTES-TiO2) were prepared to investigate their physicochemical properties and photocatalytic activity for methyl orange (MO) degradation. The TiO2 nanoparticles, functionalized-MNCNT and composite powders were characterized by XRD, raman, and TEM. The results obtained proved that titania (TiO2) nanoparticles was successfully loaded on APTES-MWCNTs. The best photocatalytic degradation of methyl orange solution under UV light irradiation was recorded over MWCNTs-APTES-TiO2 (1:2), with 87% after 180 min. Kinetic analysis indicated that photocatalytic degradation of MO solution by MWCNTs-APTES-TiO2 obeyed second-order kinetic model (R2 > 0.95), supported by half-life equations and graph. The presence of carbon nanotubes accelerated the degradation of methyl orange due to inhibition of electron-hole recombination, the formation of additional hydroxyl radicals and functional groups of the latter had an inhibitory effect on the degradation of methyl orange. This study shows that the MWCNTs-APTES-TiO2 nanocomposites exhibit promising photocatalytic degradation against methyl orange.
Subject: Biology And Life Sciences, Plant Sciences Keywords: hybridization; gene flow; different sunflower forms; imazamox; tribenuron-methyl; ALS gene
Online: 29 June 2021 (11:41:09 CEST)
Weedy sunflower is an invasive plant on the territory of the Republic of Serbia, which causes high yield losses in many crops. During the harvesting of the sunflower crops the dispersal of the seeds occurs, and as a result- the volunteer plants appear next year. Weedy sunflowers originate from volunteer plants that live through a longer period in one place. Spontaneous hybridization of weedy sunflower with other sunflower forms makes them more aggressive. If the volunteer plants originate from the hybrids tolerant to ALS inhibiting herbicides, they can be the carriers of herbicide tolerance genes and thus will not be sensitive to these herbicides. The exchange of the genetic material also enables the transfer of the ALS (AHAS) gene (responsible for the tolerance to the ALS inhibiting herbicides) to the progeny. In this study we have examined the spontaneous hybridization between different sunflower forms (volunteer sunflowers, weedy sunflowers, susceptible and tolerant sunflower hybrids to ALS inhibiting herbicides) in field conditions during three years. The progeny (F1 generation), which was assumed to possess the ALS gene, was tested with the application of the recommended doses of the Express (a.i. tribenuron-methyl) and Pulsar 40 herbicides (a.i. imazamox). The significant percent of the progeny of different forms of sunflowers, survived the herbicide treatment (6-31%). Molecular analysis of the ALS gene sequence in weedy sunflower progeny confirmed gene transfer in two cases at a distance of 30 and 120 m from the gene donor, i.e. tolerant hybrid Sumo 1 PR.
REVIEW | doi:10.20944/preprints202008.0455.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Hedgehog signaling pathway; GLI family; protein arginine methyl transferase; signal transduction
Online: 20 August 2020 (09:58:05 CEST)
The glioma-associated oncogene (GLI) family consists of GLI1, GLI2, and GLI3 in mammals, and is the effector in the Hedgehog signaling pathway. This family has important roles in the development and homeostasis of various tissues. To achieve these roles, the GLI family has widespread outputs. GLI activity is therefore strictly regulated at multiple levels, including via post-translational modifications for context-dependent GLI target gene expression. Conversely, dysregulated GLI activation has strong links with a variety of cancers. The protein arginine methyl transferase (PRMT) family is also associated with embryogenesis, homeostasis, and cancer via epigenetic modifications and signal transduction. In the PRMT family, PRMT1, PRMT5, and PRMT7 reportedly regulate GLI1 and GLI2 activity. PRMT1 methylates GLI1 to upregulate its activity and target gene expression. Cytoplasmic PRMT5 methylates GLI1 and is involved in GLI1 protein stabilization. In contrast, nucleic PRMT5 interacts with MENIN to suppress growth arrest-specific protein 1 expression, which assists Hedgehog ligand binding to Patched, indirectly resulting in downregulated GLI1 activity. PRMT7-mediated GLI2 methylation upregulates its activity through the dissociation of GLI2 and Suppressor of Fused. Therefore, PRMT1, PRMT5, and PRMT7 regulate GLI activity at multiple levels, and PRMT-mediated GLI dysregulation may be involved in cancer formation.
ARTICLE | doi:10.20944/preprints202308.1827.v1
Subject: Biology And Life Sciences, Toxicology Keywords: Pseudomonas syringae; methyl‐accepting chemotaxis protein; Caenorhabditis elegans; receptor protein; nematicidal activity
Online: 29 August 2023 (04:14:35 CEST)
The conventional phytopathogen Pseudomonas syringae has been identified several significant virulence determinants against Caenorhabditis elegans, but their mechanisms of action remain elusive. Here, we report the nematicidal activity and action receptor of a methyl-accepting chemotaxis protein (MCP03) of a wild-type P. syringae MB03 against C. elegans. Purified MCP03 exhibited significant nematicidal toxicity against C. elegans, with a half-lethal concentration of 124.4 μg mL1, and detrimental effects on the growth and brood size of C. elegans. Additionally, MCP03-treated worms showed severe pathological destruction of the intestine and ovary, and depressed wrinkles of the cuticle. Through yeast two-hybrid assays, we identified a subunit of a COP9 signalosome, namely CSN-5, functionated as an action receptor of MCP03. In vitro pull-down and in vivo co-localization assays verified the binding interaction between MCP03 and CSN-5. RNA interference assays confirmed that MCP03 acts on CSN-5 to adversely affect the brood size, growth, and cuticle integrity of C. elegans. Following MCP03 infection, the expression of several genes relative to reproduction, growth, and cuticle formation, such as kgb-1, unc-98, and col-117, were significantly downregulated, which implicated the pathological changes of MCP03-treated nematodes. Thus, this study demonstrates that MCP03 acted on the receptor protein CSN-5 causing lethality and detrimental effects on the fertility, growth, and morphogenesis of C. elegans, which will provide new insights into the signaling pathways and mechanism underlying the nematicidal action of MCP03 towards C. elegans.
ARTICLE | doi:10.20944/preprints202111.0543.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: grafting; polypropylene; gamma rays; methyl methacrylate; N-vinylimidazole; pH-responsiveness; vancomycin; release
Online: 29 November 2021 (15:04:44 CET)
Surface modification of polypropylene (PP) films is achieved using gamma-irradiation-induced grafting to proffer with antimicrobial activity. The copolymer was obtained through a versatile two-step route; pristine PP is exposed to gamma rays and grafted using methyl methacrylate (MMA), then N-vinylimidazole (NVI) is grafted onto the copolymer PP-g-MMA by simultaneous irradiation. The characterization included Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), and physicochemical analysis of swelling and contact angle. The copolymer (PP-g-MMA)-g-NVI was loaded with vancomycin, and the drug released was quantified by UV-vis spectrophotometry at different pH. The surface of (PP-g-MMA)-g-NVI exhibited pH-responsiveness and moderate hydrophilicity, suitable properties for controlled drug release.
ARTICLE | doi:10.20944/preprints202110.0323.v1
Subject: Chemistry And Materials Science, Paper, Wood And Textiles Keywords: Hydrogel; Blended paper; Slow-release fertilizer; Hydroxy Propyl Methyl Cellulose; polyvinyl alcohol
Online: 22 October 2021 (09:48:48 CEST)
In this study, a slow-release urea fertilizer hydrogel was synthesized from hydroxyl propyl methyl cellulose, polyvinyl alcohol and glycerol blends with paper (blended paper) as second layer. The fertilizer hydrogel was characterized by SEM, XRD and FTIR. Its retention in sandy soil, swelling behavior in distilled and tap water as well as slow-release behavior to urea were investigated. The results indicated that the fertilizer had good slow-release properties and ability to retain water in soil. However, the addition of blended paper as a second layer matrix was found to help improve the release properties of the fertilizer. The swelling kinetic of the hydrogel followed the Schott’s Second order model. The release kinetics of urea in water was best described by the Zero order model signifying that the release behavior was independent of fertilizer concentration
ARTICLE | doi:10.20944/preprints201805.0409.v1
Subject: Medicine And Pharmacology, Pathology And Pathobiology Keywords: advanced glycation end products; glyoxal; hypoxanthine/xanthine oxidase; methyl glyoxal; RCS-trapping
Online: 28 May 2018 (13:28:19 CEST)
Advanced Glycation End Products (AGEs) represent a set of substances that contribute directly to the triggering and/or aggravation of pathologies associated with ageing. AGEs are produced by the reaction between reducing sugars (or α-dicarbonyl compounds) proteins and amino acid residues. Current methodologies require an incubation period of 1-3 weeks to generate AGEs. In this study the reaction time for the formation of AGEs (48 and 3 hours) is significantly reduced by coupling and adapting procedures already existing in the literature to the free radical generation system called the hypoxanthine/xanthine oxidase assay. The capacity of different classes and chemical compounds (aminoguanidine, chlorogenic acid, rutin, extracts of Hancornia speciosa Gomes) were evaluated to inhibit the protein glycation process, acting as capturing agents of α-dicarbonyl species. Aminoguanidine, rutin and the leaf extracts of Hancornia speciosa Gomes show a high capacity to act as α-dicarbonyl compound scavengers (RCS-trapping) and resulting in the inhibition of AGEs formation.
ARTICLE | doi:10.20944/preprints202309.1239.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: bio-jet fuel; MoS2 catalyst; zeolite; Brønsted acid sites; hydrodeoxygenation; hydroisomerization; methyl palmitate
Online: 19 September 2023 (05:23:48 CEST)
Series of bifunctional catalysts, MoS2/Al2O3(70 wt.%)-zeolite (30 wt.%) (zeolite – ZSM-5, ZSM-12, ZSM-22 and silica aluminophosphate SAPO-11), were synthesized for hydroconversion of methyl palmitate (10 wt.% in dodecane) in a trickle-bed reactor. Mo loading was about 7 wt.%. Catalyst and supports were characterized by different physical-chemical methods (HRTEM-EDX, SEM-EDX, XRD, N2 physisorption, FTIR spectroscopy). Hydroprocessing was performed at temperature of 250-350°C, hydrogen pressure 3.0-5.0 MPa, liquid hourly space velocity (LHSV) 36 h-1, H2/feed ratio – 600 Nm3/m3. Complete conversion of oxygen-containing compounds was achieved at temperature 310°C in the presence of MoS2/Al2O3-zeolite catalysts, the selectivity for the conversion of methyl palmitate via the ‘direct’ hydrodeoxygenation (HDO) route was over 85%. The yield of iso-alkanes gradually increases in order: MoS2/Al2O3 < MoS2/Al2O3-ZSM-12 < MoS2/Al2O3-ZSM-5 < MoS2/Al2O3-SAPO-11 < MoS2/Al2O3-ZSM-22. The sample MoS2/Al2O3-ZSM-22 demonstrated the highest yield of iso-alkanes (40%). Hydroisomerization activity of the catalysts was in a good correlation with concentration of Brønsted acid sites of synthesized supports.
ARTICLE | doi:10.20944/preprints202304.1122.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: plant cell culture; elicitation; methyl jasmonate; paclitaxel; plant secondary metabolism; C14-hydroxylated taxoids
Online: 28 April 2023 (05:28:39 CEST)
The effects of methyl jasmonate (MeJ) on growth and taxoid formation in the cell culture of Himalayan yew was investigated for elucidate the specifics of the action of phytohormones on dedifferentiated plant cells in vitro. The characteristics of the same suspension culture of Taxus wallichiana was compared in 2017 ("young culture") and in 2022 ("old culture") - 1.5 or 6 years after culture induction, respectively. Cells were grown in flasks and bioreactors, MeJ (100 µM) was added at the exponential growth phase. It was found that cell culture demonstrated good growth (dry weight (DW) accumulation 10–18 g/l, specific growth rate µ = 0.15–0.35 day-1) regardless of "age", cultivation system and MeJ addition. UPLC–ESI-MS analysis showed the presence of C14-hydroxylated taxoids (yunnanxane, taxuyunnanine C, sinenxane C, sinenxane B) in cell biomass in the amounts comparable to plants. The content of C14-OH taxoids during 5 years of cultivation increased by 3-5 times. It was 0.2–1.6 mg/g DW for "young culture” and 0.6-10.1 mg/g for “old culture” depending on cultivation conditions. The ratio of individual compounds changed also: in the "young culture" was predominant yunnanxane, in the "old culture" - sinenxane C. Important that C13-hydroxylated taxoids were found in trace amounts only in the "young culture” (below 0.05 mg/g DW) and were not detected in the "old culture”. The response to MeJ was radically different depending on culture’s «age». In the “young culture”, exogenous MeJ had no effect on the content of C14-OH com-pounds, but significantly (almost 10 times) increased the content of C13-OH compounds. In particular, paclitaxel concentration was elevated up to 0.12–0.19 mg/g DW, which is comparable to its content in the bark of yew trees. By contrast, MeJ added to the "old culture” had minor effect on the synthesis of C13-OH toxoids that appeared in trace amounts only (below 3.5 µg/g DW for paclitaxel) but notably increased the content of C14-OH compounds (1.5–2.0 times in flasks and 5–8 times in bioreactors). These findings suggest that hormonal signaling in dedifferentiated yew cells grown in vitro is different from that in plants and change with culture age. This might be a result of the high level of heterogeneity of cells in vitro and their constant auto-selection for proliferate intensity which leads to predominant formation of C14-OH taxoids versus C13-OH taxoids and modified cell response to exogenous MeJ treatment. These results have both fundamental and practical biotechnological application.
ARTICLE | doi:10.20944/preprints202304.0325.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: agarose; methyl substituent; DSC; NMR; water retention; rheology; gelation hysteresis; gel in ethanol
Online: 13 April 2023 (12:49:48 CEST)
Abstract: Agarose is known to form a homogeneous thermoreversible gel in aqueous medium over a critical polymer concentration. The solid-liquid phase transitions are thermoreversible but depend on the molecular structure of the agarose sample tested. Then, in a first step, the structure was characterised by 1H and 13C NMR in D2O and in DMSO which is a solvent of agarose whatever the temperature. A low yield in methyl substituent on the D-galactose unit was determined. Then, evolution of the 1H NMR spectrum was followed as a function of temperature in increasing and decreasing temperature process from 25 to 80°C. A large thermal hysteresis is obtained and discussed. It helps to interpret rheological behaviour. In fact, NMR signals are related to proton relaxation and especially to proton involved in H-bonds between water and -OH agarose for tightly bound water and agarose/agarose in chain packing. In a second step, water was exchanged against ethanol which is a non solvent of agarose. A stable gel was demonstrated and characterised by rheology to be compared with aqueous behaviour. Bound water playing the role of plasticizer is probably removed and the gel is much stronger (and brittle) in ethanol with a larger thermal stability. It is the first time that such gel is characterised without phase transition when passing from a good-solvent to a non-solvent. This extends the domains of application of agarose.
ARTICLE | doi:10.20944/preprints201805.0222.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: terepinic acids; Stereum sp.; marine microorganism; Undaria pinnatifida; vibralactones; phenylglycine methyl ester method
Online: 16 May 2018 (06:28:36 CEST)
Sterepinic acids A–C (1–3), new carboxylic acids with two primary alcohols, have been isolated from a fungal strain of Stereum sp. OUPS-124D-1 attached to the marine alga Undaria pinnatifida. Dihydro-1,5-secovibralactone (4), a new vibralactone derivative, was isolated from the same fungal metabolites together with known vibralactone A (5), and 1,5-secovibralactone (6). The planar structures of these compounds have been elucidated by spectroscopic analyses using IR, HRFABMS, and NMR spectra. To determine the absolute configuration of the compounds, we used the phenylglycine methyl ester (PGME) method. These compounds exhibited less activity in the cytotoxicity assay against cancer cell lines.
ARTICLE | doi:10.20944/preprints202307.2068.v1
Subject: Physical Sciences, Optics And Photonics Keywords: organosilica glass; europium; ethylene bridge; methyl terminal; structural properties; photoluminescence; elemental composition; spectroscopic ellipsometry
Online: 31 July 2023 (04:36:11 CEST)
Nanoporous films of Eu-doped organosilicate glass (OSG) have been synthesized using sol-gel technology and spin-coating, employing evaporation-induced self-assembly (EISA), on silicon wafers. The Eu doping is achieved by dissolution of Eu(NO3)3·6H2O in the precursor solution. The deposited films are characterized by using Fourier transform infrared (FTIR) spectroscopy, ellipsometric porosimetry (EP), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy. It is observed that Eu doping makes the films more hydrophilic and reduces the pore size and open porosity. The reduction Eu3+ → Eu2+ occurs in the pores of OSG films, which is confirmed by depth profiling XPS. However, Eu3+ still presents on the film’s top surface. Presence of Eu3+ and Eu2+ gives characteristic luminescence emission in the range of 600‒630 nm (Eu3+) and 290‒400 nm (Eu2+). The Eu2+/Eu3+ concentrations ratio depends on CH3 groups concentration in the films. Moreover, concentration of Eu2+ ions in the pores can be reduced by exposure in inductively coupled (ICP) oxygen plasma. The observed shift of the luminescence spectra towards the UV region, in comparison to previously reported Eu-doped organosilicate films, can be attributed to the energy transfer occurring between the host material and Eu2+ ions.
ARTICLE | doi:10.20944/preprints202201.0013.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: hydrophilic sulfonated silica catalyst; Aliquat 336; tetrabutylammonium tetrafluoroborate; transesterification; fatty acid methyl esters, DMSO.
Online: 4 January 2022 (15:24:55 CET)
Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO2-SO3H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Bun4N)](BF4) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of [(Bun4N)](BF4)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.
ARTICLE | doi:10.20944/preprints202305.1022.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: N-methyl piperazine; Dubermatinib; In vitro metabolites; Cyano adducts; GSH conjugate; Xe-nosite reactivity model
Online: 15 May 2023 (10:28:28 CEST)
Dubermatinib (DMB, TP-0903), a benzenesulfonamide, is an inhibitor of the tyrosine kinase AXL, which is a member of the TAM family, and can prevent GAS6-mediated activation of AXL in cancer cells. Patients with previously treated chronic lymphocytic leukemia are being studied in phase I/II clinical trials to determine its antineoplastic potential (CLL). In the current work, the reactive intermediates of DMB were studied using liquid chromatography-mass spectrometry (LC-MS). Human liver microsomes (HLMs) were exposed to dimethylbenzene in a laboratory setting, and the resulting metabolites were collected through protein precipitation. Intense reactivity toward nucleophilic macromolecules was seen in the metabolites of the piperazine and pyrimidine rings in DMB, iminium and 2,5-quinone-imine, respectively. To assess the toxicities of the possibly reactive metabolites, DMB was incubated with HLMs in the presence of 1.0 mM KCN and 1.0 mM glutathione. The DMB metabolites found by LC-MS/MS were seven in vitro phase I metabolites, three cyano adducts, and two GSH conjugates. Phase I in vitro metabolic reactions included N-demethylation, hydroxylation, and dechlorination. The in vitro metabolism of DMB and the metabolites it produces have not been studied before.
ARTICLE | doi:10.20944/preprints202304.0293.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Environment friendly processes; Bayer residue; waste management; bauxite; contaminants; quality control; fatty acid methyl ester
Online: 13 April 2023 (03:42:31 CEST)
Red mud (RM) is a residue obtained from the production of alumina. It contains a high concentration of metal oxides and waste concentrated sodium hydroxide solution (pH = 13). To increase the value of RM, an environmentally friendly process of transesterification using waste cooking oil (WCO), MeOH and concentrated sodium hydroxide solution (CSHS) from aluminum production was proposed. Triglycerides of WCO reacted with MeOH at 60 oC to yield mixtures of fatty acid methyl esters (FAMEs) in the presence of 2.03% (w/w) CSHS/WCO using the CSHS (0.204 mol L-1, predetermined by potentiometric titration) from aluminum production by the Bayer process or with the addition of 0.68% (w/w) fabric softener (3% w/w cetyltrimethylammonium chloride in solution) as a phase transfer (PTA) agent. The addition of PTA to the catalyst resulted in a better yield of the products (greater than 98% yield). A simplified mechanism is presented to account for the experimental results.
ARTICLE | doi:10.20944/preprints201811.0514.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: corn starch; maleic anhydride; lactic acid; methyl acrylate; hydrophobically modified; in-situ solid phase polymerization
Online: 21 November 2018 (05:04:32 CET)
Three kinds of hydrophobic groups grafted starches of maleic anhydride grafted starch (MAH-g-starch), lactic acid grafted starch (LA-g-starch), and methyl acrylate grafted starch (MA-g-starch) were prepared by in-situ solid phase polymerization. The results of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were confirmed successful grafting. The grafting ratios of MAH-g-starch, LA-g-starch and MA-g-starch were 6.50%, 12.45%, and 0.57%, respectively. Influenced by the grafting ratio, LA-g-starch had the best hydrophobic properties and the largest molecular weight, and those for MA-g-starch was the worst. The surfaces of grafted starches were covered with graft polymer, with obvious surface roughness and bond degree of MAH-g-starch and LA-g-starch. The crystalline structure of grafted starches showed some damage, with LA-g-starch exhibiting the greatest decrease in crystallinity, and less of a change for MA-g-starch. Overall, the grafting reaction improved thermoplasticity, with LA-g-starch the most improved, followed by MAH-g-starch, and then MA-g-starch.
ARTICLE | doi:10.20944/preprints202305.1912.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Advanced oxidation process; Core-shell structure; Fenton chemistry; Fe@Fe3O4 interface; Methyl orange decomposition; Oxygen vacancy
Online: 26 May 2023 (10:05:52 CEST)
Iron-based materials are widely applied in Fenton chemistry and they have promising prospects in the processing of wastewater. The composition complexity and rich chemistry of iron and/or oxides, however, hamper the precise understanding on the active sites and the working mechanism which still remain highly controversial. Herein, iron oxides of four different model systems are designed through a conventional precipitation method plus H2 reduction treatment. These systems feature Fe@Fe3O4 with abundant oxygen vacancy, Fe0 and Fe3O4 particles with interface structures, and Fe3O4-dominated nanoparticles of different sizes. These materials are applied in the decomposition of methyl orange as a model reaction to assess the Fenton chemistry. The Fe@Fe3O4 with core-shell structures exhibited significantly higher decomposition activity than the other Fe3O4-rich nanoparticles. A thin Fe3O4 layer formed by auto-oxidation of iron particles when exposing to air can boost the activity as compared with the Fe0 and Fe3O4 particles with interface structures but poor oxygen vacancy. The unique hetero-structure with the co-existence of both metallic iron and oxygen vacancy displayed excellent redox propensity which might account for the superior Fenton activity. This finding provides a new perspective to understand and design highly efficient iron-based Fenton catalysts.
ARTICLE | doi:10.20944/preprints202305.0377.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Environmentally friendly processes; Bayer residue; waste management; basic catalyst, contaminants, red mud, fatty acid methyl ester
Online: 6 May 2023 (05:00:47 CEST)
Red mud (RM) is composed of a waste alkaline solution (pH = 13.3) obtained from the production of alumina. It contains high concentrations of soluble hematite (Fe2O3), goetite (FeOOH), gibisite [Al(OH)3], a boemite (AlOOH), anatase (Tetragonal - TiO2), rutile (Ditetragonal dipyramidal - TiO2), hydrogarnets [Ca3Al2(SiO4)3−x(OH)4x], and perovskite (CaTiO3). It was shown to be an excellent catalytic mixture for biodiesel production. To demonstrate the value of RM, an environmentally friendly process of transesterification in aqueous medium using waste cooking oil (WCO), MeOH and waste alkaline solution (WAS) obtained from aluminum production was proposed. Triglycerides of WCO reacted with MeOH at 60 oC to yield mixtures of fatty acid methyl esters (FAMEs) in the presence of 0.019% (w/w) WAS/WCO using the WAS (0.204 mol L-1, predetermined by potentiometric titration) from aluminum production by the Bayer process. The use of the new catalyst (WAS) resulted in a high yield of the products (greater than 99% yield).
REVIEW | doi:10.20944/preprints202308.1505.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: fatty acids; fatty acid methyl esters; transesterification; epoxidation; catalyst; viscosity; oxidation stability; acidity; biorefinery; sustainability; circular economy
Online: 22 August 2023 (08:11:22 CEST)
The use of biolubricants as an alternative for petroleum-based products has played an important role in the last decade. Thus, due to the encouragement of global policies, which mainly support green chemistry and circular economy, there has been an increasing interest in bio-based products, including biolubricants, from scientific and industrial points of view. Due to the different applications of biolubricants for a wide range of practical uses, the raw materials, production, and characteristics might vary, making this field a continuously changing subject of study by researchers. The aim of this research work was to focus on biolubricant production from vegetable oil crops in a bio-refinery perspective, paying attention to the main raw materials used, the corresponding production methods (with special focus on double transesterification), the role of catalysts and techno-economic studies. Thus, the main factors affecting quality parameters such as viscosity or oxidative stability have been covered, including catalyst addition, reaction temperature or the use of raw materials, reagents or additives were also analyzed. The latest research trends were included, updating previous studies about this matter, considering current conclusions and future research.
ARTICLE | doi:10.20944/preprints202302.0498.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: flavins; 10‐methyl‐isoalloxazine; metal-organic framework (MOF); MIL-53; MOF-5; fluorescence; flavin@MOF; solid solution
Online: 28 February 2023 (03:06:40 CET)
The flavin derivatives 10‐methyl‐isoalloxazine (MIA) and 6-fluoro-10-methyl-isoalloxazine (6F-MIA) were encapsulated in two alternative metal-organic frameworks, (MOFs) MIL53(Al) and MOF5, using a post-synthetic, diffusion-based incorporation into microcrystalline MIL-53 powders and an in-situ approach during the MOF-5 synthesis. The flavin@MOF composites were analyzed by powder X-ray diffractometry (PXRD), N2-sorption studies and time-resolved fluorescence spectroscopy and microscopy. The maximum amount of flavin dye incorporation is 3.9 wt% for MIA@MIL-53(Al) and 1.5 wt% for 6F-MIA@MIL-53(Al), 0.85 wt% for MIA@MOF-5 and 27.6 wt% for 6F-MIA@MOF-5. The emission wavelengths of all flavin@MOF composites mostly correspond to the wavelengths of the flavins in solution. Time-resolved spectroscopy showed that the fluorescence lifetime of flavin@MOF of 2-4.7 ns also corresponds to those in solution but is significantly prolonged compared to the solid flavin dyes with less than 1 ns, thereby confirming the concept of "solid solutions" for dye@MOF composites. The fluorescence quantum yield (ΦF) of the flavin@MOF composites is about half of the solution but is significantly higher compared to the solid flavin dyes. Both the fluorescence lifetime and quantum yield of flavin@MOF decrease with the flavin loading in MIL-53. Theoretical calculations using plane-wave and QM/MM methods are in good correspondence with the experimental results and explain the electronic structures as well as the photoluminescence/photophysical properties of crystalline MIA and the flavin@MOF composites. In the solids flavins π-stacking interactions of the molecules lead to a charge transfer state with low oscillator strength resulting in aggregation-caused quenching (ACQ) with low lifetimes and quantum yields. In the MOF pores the flavin molecules are separated and the computed MIA@MOF structures do not find π-stacking interactions to the pore walls but only weak van-der-Waals contacts which reasons the enhanced fluorescence lifetime and quantum yield of the flavins in the composites compared to their neat solid state. The flexible MOF MIL-53(Al) was optimized essentially to the experimental large-pore form in the guest-free state with QuantumEspresso (QE) and with MIA molecules in the pores the structure contracted to close to the experimental narrow-pore form which was also confirmed by PXRD. In summary, the incorporation of flavins in MOFs yields solid-state materials with enhanced rigidity, stabilized conformation and reduced aggregations of the flavins, leading to increased fluorescence lifetime and quantum yield as controllable photo-luminescent and photo-physical properties.
ARTICLE | doi:10.20944/preprints202107.0025.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Orchid; Protocorm-like bodies; p-Chlorophenoxyisobutyric acid; PCIB; 3-Hydroxy-5-methyl isoxazole; HMI; light emitting diodes
Online: 1 July 2021 (12:28:44 CEST)
Dendrobium okinawense is an endangered epiphytic orchid, and there has been no scientific report so far on its propagation. Protocorm is mass of cell, and protocorm-like bodies (PLBs) look alike protocorm produced by vegetative explants in vitro. Regeneration of PLBs is the most efficient technique for the orchids micro-propagation. We used different light emitting diodes (LEDs) for the efficient PLB organogenesis of D. okinawense. PLBs regenartion under green and red LED surpassed respectively 81.1% and 71.6% in numbers, and respectively 80.8% and 57.8% in fresh weight over white fluorescent light. We manipulated the culture media by different concentrations of PCIB and HMI. PLBs organogenesis promoted by low concentration, it increased respectively 35.9% and 19.3% over control by 0.01 mg/L PCIB and 0.01 ml/L HMI in numbers. Green LED and PCIB independently produced mostly similar numbers of new PLBs. Interestingly, culture media with 0.01 mg/L of PCIB further increased 8.5% of the numbers of PLBs under green LED, whereas the culture media with 0.01 mg/L HMI reduced the number of PLBs under green LED. PLBs culture under green LED with very low concentrations of PCIB manipulated culture media can significantly increase their organogenesis of D. okinawense.
ARTICLE | doi:10.20944/preprints202308.0176.v1
Subject: Chemistry And Materials Science, Electronic, Optical And Magnetic Materials Keywords: Poly(methyl methacrylate); Poly(cyclohexyl methacrylate); Tetraphenylethylene (TPE); Aggregation-induced emission; Density functional theory investigations; Luminescent solar concentrator
Online: 2 August 2023 (10:49:30 CEST)
Fluorophores with a tetraphenylethylene (TPE) core are attracting increasing interest because of their aggregation-induced emission (AIE) behaviour, which makes them particularly suitable when dispersed in thin-layer films. We propose the synthesis and use of a novel TPE fluorophore (hereafter called TPE-BPAN) decorated with two dimethylamino push groups and a 4-biphenylacetonitrile pull moiety. In tetrahydrofuran solutions, TPE-BPAN showed a broad absorption spectrum, and an intense emission is observed when a non-solvent as water is added in amounts of 70% and above. We selected and synthetized five different polymer matrices for TPE-BPAN with decreasing polarity: a) poly(methylmetacrylate) homopolymer (PMMA); b), c), and d) three copolymers of methyl methacrylate and cyclohexyl methacrylate at different compositions (P(MMA-co-CHMA) 75:25, 50:50, 25:75 mol%); e) poly(cyclohexyl methacrylate) homopolymer (PCHMA). The presence of a less polar comonomer as cyclohexyl methacrylate appeared to enhance the emission behaviour of TPE-BPAN, which displayed the highest quantum yield (QY) in P(MMA-co-CHMA) 75:25 in all the range of concentration studied from 0.4 wt.% to 2.0 wt.%. Further reduction in polarity lowered QY to the values of PMMA films; also, lower adhesion to the glass and a marked fragility of the films were observed. Referring to the P(MMA-co-CHMA) 75:25 films, QY values decreased from over 40% at 0.4 wt.% to about 30% at 2.0 wt.%, which is still helpful for energy harvesting applications such as luminescent solar concentrators (LSC). LSC performances were not significantly affected by the matrix's lower polarity and resulted in around one-third of the state-of-the-art due to the lower QY of TPE-BPAN. The theoretical investigation on density functional theory (DFT) clarified the origin of the observed AIE and the role played by the environment in modulating the photophysical behaviour.
ARTICLE | doi:10.20944/preprints202206.0055.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: Sulfonated silica catalyst (SiO2-SO3H); methyl salicylate; green chemistry; methylating agent; deacetylation (acyl nucleophilic substitution); solid acid catalyst
Online: 6 June 2022 (03:45:09 CEST)
SiO2-SO3H, with a surface area of 115 m2/g, pore volume of 0.38 cm3g-1 and 1.32 mmol H+/g, was used as a 20% w/w catalyst for the preparation of methyl salicylate (Wintergreen oil or MS) from acetylsalicylic acid (ASA). A 94% conversion was achieved in a microwave reactor during 40.0 minutes at 120 oC in MeOH. The resulting crude product was purified by flash chromatography. The catalyst could be re-used three times.
ARTICLE | doi:10.20944/preprints202103.0688.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: grape skins; grape seed oil; fatty acid methyl esters; total phenolic content; antioxidant activity; green extraction; circular bioeconomy
Online: 29 March 2021 (12:18:34 CEST)
The aim of this work was the study and evaluation of winery by-products in the framework of circular bioeconomy. Grape seeds and grape skins from Greek traditional Ionian Islands varieties were analyzed in an attempt to provide the appropriate basis for model development of their sustainable exploitation at a local or regional level. The wastes collected directly from the wineries immediately after the vinification process and analyzed by chromatographic and spectroscopic techniques. Also, annual production and yields were estimated. Grape seed oil quality was evaluated based on fatty acid methyl esters (FAMEs) composition. Grape skins phenolic fraction was extracted by an eco-friendly, non-toxic water-glycerol solvent system and were detected qualitatively. Also, total phenolic content (TPC) and antioxidant activity were measured. Based on estimated yields, our results demonstrate that winery by-products have the potential to promote the cyclical bioeconomy in a modern economic growth model that will reduce waste, and environmental costs as they can be reused as whole material in foods, dietary supplements, cosmetic ingredients, food colorants and preservatives.
ARTICLE | doi:10.20944/preprints202208.0110.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: 3-aminopyridin-2(1H)-one derivatives; 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones; antiradical activity; cytoprotective activity
Online: 4 August 2022 (14:12:03 CEST)
Currently, studies are being conducted on the possible role of the cytoprotective effect of biologically active substances in conditions of cerebral hypoxia or cardiomyopathies. At the same time, oxidative stress is considered as one of the important mechanisms of cellular cytotoxicity and a target for the action of cytoprotectors. The aim of this study is to search for derivatives of 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones. The probability of cytoprotective action was assessed by two tests by measuring cell viability (with neutral red dye and MTT test). It was found that some derivatives of 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones under the conditions of our experiment have a pronounced cytoprotective activity, providing better cell survival in vitro, including the MTT test and conditions of blood hyperviscosity. To correlate the obtained results in vitro, molecular docking of the synthesized derivatives was also carried out. The standard drug omeprazole (co-crystallized with the enzyme) was used as a standard. It was shown that all synthesized derivatives of 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones had higher affinity for the selected protein than the standard gastro-cytoprotector omeprazole. The studied derivatives of 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones also fully satisfy Lipinski's rule of thumb of five (RO5), which increases their chances for possible use as orally active drugs with a good ability to absorption and moderate lipophilicity. Thus, the results obtained make it possible to evaluate derivatives of 3-(arylmethyl)-6-methyl-4-phenylpyridin-2(1H)-ones as having a relatively high cytoprotective potential.
ARTICLE | doi:10.20944/preprints201703.0078.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: anodic aluminum oxide (AAO); subwavelength structure (SWS); antireflection; poly-methyl methacrylate (PMMA); dye-sensitized solar cell (DSSC); conversion efficiency
Online: 14 March 2017 (08:46:39 CET)
In this study, a high energy conversion efficient dye-sensitized solar cells (DSSC) was successfully fabricated by attaching a double anti-reflection (AR) layer which is composed of a subwavelength moth-eye structured polymethyl methacrylate (PMMA) film and a polydimethylsiloxane (PDMS) film. The efficiency is up to 6.79%. The moth-eye structured PMMA film was fabricated by using anodic aluminum oxide (AAO) template which is simple, low-cost and scalable. The nano-pattern of AAO template has been precisely reproduced onto PMMA film. The photoanode is composed of Titanium dioxide (TiO2) nanoparticles (NPs) with diameter of 25 nm deposited on the fluorine-doped tin oxide (FTO) glass substrate and the sensitizer N3. The double AR layer can effectively improve the short-circuit current density (JSC) and conversion efficiency from 14.77 to 15.79 mA/cm2 and from 6.26% to 6.79%, respectively.
ARTICLE | doi:10.20944/preprints202001.0182.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: dinoflagellate; Karenia mikimotoi; glycolipids; monogalactosyldiacylglycerol; monogalactosylmonoacylglycerol; polyunsaturated fatty acid methyl ester; Staphylococcus aureus; Escherichia coli; Candida albicans; anti-inflammatory activity
Online: 17 January 2020 (09:18:08 CET)
A New monogalactosyldiacylglycerol (MGDG), a known monogalactosylmonoacylglycerol (MGMG) and a known polyunsaturated fatty acid methyl ester (PUFAME) were isolated from the marine dinoflagellate Karenia mikimotoi. The planar structure of the glycolipids was elucidated using MS and NMR spectroscopic analyses and comparisons to the known glycolipid to confirm its structure. The isolation of PUFAME strongly supports the polyunsaturated fatty acid fragment of these glycolipids. The relative configuration of the sugar was deduced by comparisons of 3JHH values and proton chemical shifts with those of known glycolipids. All isolated compounds MGDG, MGMG and PUFAME (1-3) were evaluated for their antimicrobial and anti-inflammatory activity. All compounds modulated macrophage responses, with compound 3 exhibiting the greatest anti-inflammatory activity.
ARTICLE | doi:10.20944/preprints202101.0607.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: Organic-Inorganic Blends; Poly Methyl-Meth-Acrylate (PMMA); Poly-vinyl-alcohol (PVA); Copper oxide nanoparticles (CuONPs); Optical Characterization; Thermal stability; Surface Morphology.
Online: 29 January 2021 (09:03:22 CET)
We report the synthesis and characterization of Poly Methyl-Meth-Acrylate (PMMA)/Poly vinylalcohol (PVA) polymeric blend doped with different concentrations of Copper oxide (CuO) nanoparticles (NPs). The (PMMA-PVA)/CuO nanocomposite hybrid thin films (wt. % = 0%, 2%, 4%, 8%, and 16%) of CuO NPs are deposited on glass substrates via dip-coating technique. The transmittance (T%), reflectance (R%), the absorption coefficient (α), the optical constants [refractive index (n), extinction coefficient (k)], optical dielectric functions [ɛ',ɛ''] are investigated and interpreted. Tauc, Urbach, Spitzer-Fan, and Drude models are employed to calculate the optical bandgap energy (Eg) and the optoelectronic parameters of the nanocomposite thin films. The refractive index and optical bandgap energy of of (PMMA-PVA) polymeric thin film are found to be (1.5 to 1.85) and 4.101 eV, respectively. Incorporation of specific concentrations of CuO-NPs in (PMMA-PVA) polymeric thin films leads to a noticeable decrease in the optical bandgap energy and to an increase of the refractive index. Moreover, Fourier Transform Infrared Spectroscopy (FTIR) transmittance spectra are measured and analyzed for undoped and doped polymeric thin films to pinpoint the major vibrational modes in the spectral range (500 and 4000 cm-1), as well as, the nature of network bonding in both systems. Thermal stability of thin films is investigated by performing thermogravimetric analysis (TGA). The TGA thermograms confirm that both doped polymeric thin films are thermally stable at temperatures below 110°C which enables them to be attractive for a wide range of optical and optoelectronic applications. Our results indicate that optical, vibrational and thermal properties of both polymeric thin films can be tuned for specific applications by the appropriate corporation of particular concentrations of CuO-NPs.
ARTICLE | doi:10.20944/preprints201911.0061.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: rett syndrome; intrinsically disordered region; phylogenetic profile analysis; post-transcriptional modification; methyl-cpg-binding protein 2; cyclin-dependent kinase-like 5; forkhead box protein g1
Online: 6 November 2019 (10:58:54 CET)
Rett syndrome (RTT), a neurodevelopmental disorder, is mainly caused by mutations in methyl CpG-binding protein 2 (MECP2), which alter the functions of domains to either bind to methylated DNA or interact with a transcriptional co-repressor complex. It has been established that alterations in cyclin-dependent kinase-like 5 (CDKL5) or forkhead box protein G1 (FOXG1) correspond to distinct neurodevelopmental disorders, given that a series of studies have indicated that RTT is also caused by alterations in either one of these genes. We tried to elucidate RTT through evolution and structure assessment of MeCP2, CDKL5, and FOXG1, by focusing on their binding partners and disordered structures. Here, we provide insight into the similarities of the FOXG1 and MECP2 binding partners evolution and function. On the other hand, we suggest that CDKL5 could be a potential candidate for a classical RTT treatment, particularly based on its disordered structure that spans after the catalytic domain to the C-terminus, which shows abundant linear motifs that can bind to molecules with divergent structures of similar affinity. Additionally, we provide insight into the relationship between disordered structure and disease.
ARTICLE | doi:10.20944/preprints201907.0013.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Rett Syndrome; intrinsically disordered region; phylogenetic profile analysis; post-transcriptional modification; methyl-CpG-binding protein 2; cyclin-dependent kinase-like 5; forkhead box protein G1
Online: 1 July 2019 (11:59:56 CEST)
Rett syndrome (RTT) is mainly caused by mutations in methyl CpG-binding protein 2, cyclin-dependent kinase-like 5, or forkhead box protein G1. These RTT-causing proteins harbor an intrinsically disordered region (IDR) whose conformation exhibits spatiotemporal heterogeneity, which not only confer versatility to the protein, but also implicates them in diseases. The IDR generally evolves more rapidly than an ordered structure. In this study, we examined the relationship between pathogenic RTT-associated point mutations in RTT-causing proteins and the evolutionary dynamics of sequence features including structural order–disorder, phosphorylation sites, and evolutionary rates. We also analyzed the molecular properties and evolution of proteins that interact with RTT-causing proteins in terms of phylogenetic profiles, tissue specificity, subcellular localization, expression level, and functions. The results indicate that constrained IDRs may function by forming contacts with other regions in the protein sequence causing pathogenic missense mutations likely to arise in the rapidly evolving IDR and affect molecular networks, leading to disease. The results also provide novel insights into the genetic basis for RTT and the evolution of the neocortex in higher vertebrates.
ARTICLE | doi:10.20944/preprints202309.1706.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: isoxazolidine derivatives; 1,3-dipolar cycloaddition; α-aryl-N-methyl nitrones; Density Functional Theory (DFT); Electron Localization Function (ELF); CDFT indices; docking; molecular dynamics; EGFR; binding energy
Online: 26 September 2023 (04:37:56 CEST)
A series of novel substituted isoxazolidine derivatives was synthesized through 1,3-dipolar cycloaddition reactions of α-aryl-N-methyl nitrones with various ethylene moieties, resulting in the formation of isoxazolidine derivatives. The structures of the synthesized compounds were characterized using spectroscopic methods. The [3+2] cycloaddition (32CA) reactions of α-aryl-N-methyl nitrones with diverse ethylene substituents were computed employing Density Functional Theory (DFT) at the B3LYP/6–31G(d) level, upgrading bond parameters. An investigation of the electron localization function (ELF) unveiled the zwitterionic nature of α-aryl-N-methyl nitrones, devoid of pseudoradical or carbenoid centers. Utilization of CDFT indices enabled the prediction of global electronic flux from the strongly nucleophilic α-aryl-N-methyl nitrones to the varied electrophilic ethylene functionalities. Molecular docking and molecular dynamics simulations were conducted on the isoxazolidine derivatives against the EGFR receptor (PDB: 4ZAU). In silico assessment of the synthesized isoxazolidines involved molecular docking, wherein the compound with the highest docking score was subjected to molecular dynamics simulations. Compound 11a, out of the thirty isoxazolidine derivatives, displayed the most substantial binding energy, yielding a g score of -6.57 kcal/mol. These observations highlighted the functional role of amide NH2 and NO2 in the binding process with the target protein, influencing its activity. Furthermore, prediction of ADME drug-likeness properties was performed to identify a suitable candidate.
ARTICLE | doi:10.20944/preprints202308.0182.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Beetroot (Beta vulgaris); Total Correlation Spectroscopy (TOCSY); Gas Chromatog-raphy-Mass Spectrometry (GC-MS); selective TOCSY; Homonuclear single quantum correlation (HSQC); fatty acid methyl esters (FAME)
Online: 2 August 2023 (10:01:22 CEST)
Abstract: Beetroot (Beta vulgaris L) has been known for being a rich source of phytochemicals, minerals and vitamins. This study presents a model system for how the combination of extrac-tion/chromatography/mass spectrometry and NMR offers an efficient way to profile metabolites in the extracts of a natural product, beetroot . Such combination may lead to the identification of more nutritional or medicinal compounds in natural products, and it is essential for our ongoing investigation to study the selective adsorption/desorption of these metabolites on nanoparticles. The aqueous and organic extracts underwent analyses using UV-vis spectroscopy; GC-MS; LC-MS; 1H, 13C, TOCSY, HSQC, and selective TOCSY NMR experiments. Polar Extract: The two forms of betalain pigment were identified by UV-vis and LC MS. Fourteen amino acids, sucrose, and other compounds among which is riboflavin, were identified by LC-MS. 2D TOCSY showed the spin coupling correlations corresponding to some of these compounds. The HSQC spectrum showed 1H/13C spin correlation in sucrose confirming the high abundance of sucrose in beetroot. Organic Extract: GC-MS data enabled the identification of several compounds including six fatty acid methyl esters (FAME) with higher than, on average, 90% similarity score. Selective TOCSY NMR data showed the spin coupling pattern corresponding to oleic, linoleic, and linolenic fatty acids. 31P NMR spectra indicate that phospholipids exist in both the organic and aqueous phases. Keywords: Beetroot (Beta vulgaris L); Total Correlation Spectroscopy (TOCSY); Gas Chromatog-raphy-Mass Spectrometry (GC-MS); selective TOCSY, Homonuclear single quantum correlation (HSQC); fatty acid methyl esters (FAME).