ARTICLE | doi:10.20944/preprints201908.0102.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Curcumin; diferuloylmethane; E100; CYP19A1; Aromatase; estrogen synthase; cytochrome P450.
Online: 8 August 2019 (11:25:51 CEST)
Turmeric is a popular ingredient in the cuisine of many Asian countries. Turmeric is known for its use in Chinese and Ayurvedic medicine and comes from the roots of the Curcuma longa. Turmeric is rich in curcuminoids, including curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Curcumin has potent anti-inflammatory and anti-carcinogenic activities. Since many anti-cancer drugs target enzymes from the steroidogenic pathway, we tested the bioactivity of curcuminoids on cytochrome P450 CYP17A1, CYP21A2, and CYP19A1 enzyme activities. Curcuminoids were extracted from turmeric with organic solvents. We conducted a cell-based assay for CYP17A1 and CYP21A2 activities using human adrenal cell line NCI-H295R. 3H-pregnenolone was used for CYP17A1 assays, and 3H-17alpha-hydroxyprogesterone was used as a substrate for CYP21A2. Curcuminoids were added at different concentrations and incubated for 24h. Steroids were separated by thin layer chromatography and analyzed by phosphorimager analysis. For CYP19A1 activity, an in vitro assay using endoplasmic reticulum from JEG3 were used with 3H-androstenedione as the substrate. Curcuminoids were incubated for 1h, and the formation of 3H-water from the androstenedione breakdown was measured by scintillation counting. When using 10 µg/ml of curcuminoids, both the 17-hydroxylase as well as 17,20 lyase activities of CYP17A1 were reduced significantly. On the other hand, CYP21A2 activity was only reduced to ~50% control. Furthermore, CYP19A1 activity was reduced to ~20% of control when using 1-100 µg/ml of curcuminoids in a dose-dependent manner. No effect on the activity of 5alpha reductase for the conversion of androstenedione to androstanedione was observed. Molecular docking studies confirmed that curcumin could dock into the active sites of CYP17A1, CYP19A1 as well as CYP21A2. In CYP17A1 and CYP19A1, curcumin docked within 2.5 Å of central heme while in CYP21A2 the distance from heme was 3.4 Å, which is still in the same range or lower than distances of bound steroid substrates. These studies show that curcuminoids may potentially cause inhibition of steroid metabolism, especially at higher dosages. The activities of CYP17A1 and CYP19A1 were inhibited by curcuminoids, which indicate potential anti-carcinogenic effects in case of prostate cancer as well as breast cancer, which can be targeted by inhibition of steroidogenesis. Also, the recent popularity of turmeric powder/curcumin as a dilatory supplement needs further evaluation for the effect of curcuminoids on steroid metabolism. Curcuminoids present in curcumin may affect activities of multiple steroid metabolizing cytochrome P450 enzymes. Computational docking suggests curcumin binds into the active sites of steroid metabolizing P450s and may serve as a model for lead discovery. Molecular structure of curcuminoids could be modified to generate better lead compounds with inhibitory effects on CYP17A1 and CYP19A1 for potential drugs against prostate cancer and breast cancer.
REVIEW | doi:10.20944/preprints202202.0255.v1
Subject: Chemistry, Other Keywords: cytochrome P450 monooxygenase; peroxygenase; peroxidase; protein engineering; oxidation; hydroxylation; epoxidation; sulfoxidation; dual-functional small molecule
Online: 21 February 2022 (14:17:19 CET)
Cytochrome P450 monooxygenases (P450s) are promising versatile oxidative biocatalysts. However, the practical use of P450s in vitro is limited by their dependence on the co-enzyme NAD(P)H and the complex electron transport system. Using H2O2 simplifies the catalytic cycle of P450s; however, most P450s are inactive in the presence of H2O2. By mimicking the molecular structure and catalytic mechanism of natural peroxygenases and peroxidases, an artificial P450 peroxygenase system has been designed with the assistance of a dual-functional small molecule (DFSM). DFSMs, such as N-(ω-imidazolyl fatty acyl)-l-amino acids, use an acyl amino acid as an anchoring group to bind the enzyme, and the imidazolyl group at the other end functions as a general acid-base catalyst in the activation of H2O2. In combination with protein engineering, the DFSM-facilitated P450 peroxygenase system has been used in various oxidation reactions of non-native substrates, such as alkene epoxidation, thioanisole sulfoxidation, and alkanes and aromatic hydroxylation, which showed unique activities, and regio- and enantioselectivities when compared with native P450s. Moreover, the DFSM-facilitated P450 peroxygenase system can switch to the peroxidase mode by mechanism-guided protein engineering. In this short review, the design, mechanism, evolution, application, and perspective of these novel non-natural P450 peroxygenases for the oxidation of non-native substrates are discussed.
ARTICLE | doi:10.20944/preprints202205.0021.v1
Subject: Life Sciences, Biochemistry Keywords: Anopheles gambiae; Cameroon; Malaria; Pyrethroids; Resistance Escalation; Cytochrome P450s
Online: 5 May 2022 (05:07:43 CEST)
(1) Background: Malaria remains a global public health problem. Unfortunately, the resistance of malaria vectors to insecticides commonly used threatens disease control and elimination efforts. Molecular mechanisms helping some malaria vectors to now survive to greater doses of insecticides remains poorly understood. Here, we elucidated the pattern of resistance escalation in the main malaria vector Anopheles gambiae in a pesticide-driven agricultural hotspot in Cameroon and its impact on vector control tools; (2) Methods: Larval stages and indoor blood-fed females (F0) were collected in Mangoum in May and November and forced to lay eggs; the emerging mosquitoes were used for WHO tube, synergist and cone tests. Molecular identification was done using SINE PCR whereas TaqMan-based PCR was used for genotyping of L1014F/S and N1575Y kdr and the G119S-ACE1 resistance markers. Transcription profile of candidate resistance genes was performed using qRT-PCR methods. Characterization of the breeding water and soil from Mangoum was also performed using HPLC technique; (3) Results: An. gambiae s.s. was the only species in Mangoum with 4.10 % infection with Plasmodium. These mosquitoes were resistant to all the four classes of insecticides with mortality rates <7% for pyrethroids and DDT and <54% for carbamates and organophophates. This population also exhibited high resistance intensity to pyrethroids (permethrin, alpha-cypermethrin and deltamethrin) after exposure to 5X and 10X discriminating doses and Synergist assays with PBO revealed only a partial recovery of susceptibility to permethrin, alpha-cypermethrin and deltamethrin. Only PBO-based nets (Olyset plus and permaNet 3.0) and Royal Guard showed an optimal efficacy. A high amount of alpha-cypermethrin was detected in breeding sites (5.16 fold LOD) suggesting ongoing selection from agricultural pesticides. The 1014F-kdr allele was fixed (100%) whereas the 1575Y-kdr (37.5%) and the 119S Ace-1R (51.1%) are moderately present. Elevated expression of P450s respectively in permethrin and deltamethrin resistant mosquitoes [CYP6M2 (10 and 34-fold), CYP6Z1(17 and 29-fold), CYP6Z2 (13 and 65-fold), CYP9K1 (13 and 87-fold)] supports their role in the observed resistance besides other mechanisms including chemosensory genes as SAP1 (28 and 13-fold), SAP2 (5 and 5-fold),SAP3 (24 and 8-fold) and cuticular genes as CYP4G16 (6 and 8-fold) and CYP4G17 (5 and 27-fold). However, these candidate genes were not associated with resistance escalation as expression level did not differ significantly between 1x, 5x and 10x surviving mosquitoes. (4) Conclusions: Intensive and multiple resistance is being selected in malaria vectors from pesticide-based agricultural hotspot of Cameroon leading to loss of efficacy of pyrethroid-only nets. Further studies are needed to decipher the molecular basis underlying such resistance escalation to better assess its impact on control interventions.
ARTICLE | doi:10.20944/preprints202004.0221.v1
Subject: Life Sciences, Biochemistry Keywords: Cancer; cytochrome c; drug delivery; Lewis Lung Carcinoma; nanoprecipitation
Online: 14 April 2020 (14:27:15 CEST)
The delivery of Cytochrome c (Cyt c) to the cytosol stimulates apoptosis in cells were its release from mitochondria and apoptosis induction is inhibited. We developed a drug delivery system consisting of Cyt c nanoparticles decorated with folate-poly(ethylene glycol)-poly(lactic-co-glycolic acid)-thiol (FA-PEG-PLGA-SH) to deliver Cyt c into cancer cells and test their targeting in the Lewis Lung Carcinoma (LLC) mouse model. Cyt c-PLGA-PEG-FA nanoparticles (NPs) of 253 ± 55 and 354 ± 11 nm were obtained by Cyt c nanoprecipitation, followed by surface decoration with the co-polymer SH-PLGA-PEG-FA, and compared to a nanoparticle-free formulation. Overexpression of FA in LLC cells and internalization of Cyt c-PLGA-PEG-FA nanoparticles (NPs) was confirmed by confocal microscopy. Caspase activation assays show NPs retain 88-96% Cyt c activity. The NP formulations were more efficient in decreasing LLC cell viability than the NP-free formulation, with IC50: 49.2 to 70.1 μg/ml versus 129.5 μg/ml, respectively. Our NP system is thrice as selective towards cancerous than normal cells. In-vivo studies using tagged nanoparticles show accumulation in mouse LLC tumor 5 min post-injection. In conclusion, our NP delivery system for Cyt c shows superiority over the NP-free formulation and reaches a folic acid-overexpressing tumor in an immune-competent animal model.
Subject: Medicine & Pharmacology, Allergology Keywords: Mitochondria; cytochrome c oxidase; COX4-1; COX4-2; HIF-1α
Online: 10 February 2021 (10:58:33 CET)
Cytochrome-c-oxidase (COX) subunit 4 (COX4) plays important roles in the function, assembly and regulation of COX (mitochondrial respiratory complex 4), the terminal electron acceptor of the oxidative phosphorylation (OXPHOS) system. The principal COX4 isoform, COX4-1, is expressed in all tissues, whereas COX4-2 is mainly expressed in the lungs, or under hypoxia and other stress conditions. We have previously described a patient with a COX4-1 defect with a relatively mild presentation compared to other primary COX deficiencies, and hypothesized that this could be the result of compensatory upregulation of COX4-2. To this end, COX4-1 was downregulated by shRNAs in human foreskin fibroblasts (HFF), and compared to patient's cells. COX4-1, COX4-2 and HIF-1α were detected by immunocytochemistry. The mRNA transcripts of both COX4 isoforms and HIF-1 target genes were carried out by RT-qPCR. COX activity and OXPHOS function were measured by enzymatic and oxygen consumption assays, respectively. Pathways were analyzed by CEL-Seq2 and by RT-qPCR. We demonstrate elevated COX4-2 levels in the COX4-1-deficient cells with a concomitant HIF-1α stabilization, nuclear localization and upregulated hypoxia and glycolysis pathways. We suggest that COX4-2 and HIF-1α has the are upregulated, also in normoxia as a compensatory mechanism in COX4-1 deficiency.
ARTICLE | doi:10.20944/preprints202011.0294.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Cytochrome oxidase; NADH dehydrogenase; F. hepatica; F. gigantica; COX; CYTB
Online: 10 November 2020 (09:12:31 CET)
Mitochondria is a cellular source of energy, playing an essential role in cellular stress induced by environmental stimuli. The genetic diversity of mitochondrial genes involved in oxidative phosphorylation affects the production of cellular energy and regional adaptation to various ecological (climatic) pressures influencing amino acid sequences (variants of protein). However, a little is known about the combined effect of protein changes on cell-level metabolic alterations in simultaneous exposure to various environmental conditions, including mitochondrial dysfunction and oxidative stress induction. Present study was designed to address this issue by analyzing the mitochondrial proteins in Fasciola species including Cytochrome C oxidase (COX1, COX2, COX3 and CYTB) and NADH dehydrogenase (ND1, ND2, ND3, ND4, ND5 and ND6). Mitochondrial proteins were used for a detailed computational investigation using available standard bioinformatics tools to explore structural and functional relationships. Our analysis shows that the mitochondrial protein family of Fasciola species are extensively diversified in all species studied, showing an extending role in various biological processes The results showed that the protein of COX1 of F. hepatica, F. gigantica and F. jacksoni consist of 510, 513 and 517 amino acids respectively. The alignment of proteins showed that these proteins are conserved in the same regions at ten positions in COX and CYTB proteins while at twelve locations in NADH. Three dimensional structure of COX, CYTB and NADH proteins were compared and the differences in additional conserved and binding sites in COX and CYTB proteins as compared to NADH were found in three Fasciola species. These results, based on the amino acid diversity pattern, were used to identify sites in the enzyme and the variations in mitochondrial proteins among Fasciola species. This study provides valuable information for future experimental studies including identification of therapeutics, diagnostics and immunoprophylactic interests with novel mitochondrial proteins.
Subject: Life Sciences, Biochemistry Keywords: adlay; adlay bran oil; cytochrome P450; food-drug interactions; rats
Online: 10 September 2019 (03:16:30 CEST)
Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) contains various phytonutrients for treating many diseases in Asia. To investigate whether orally administered of adlay bran oil (ABO) can cause drug interactions, the effects of ABO on the pharmacokinetics of five cytochrome P450 (CYP) probe drugs were evaluated. Rats were given a single oral dose (2.5 mL/kg BW) of ABO 1 h before administration of a drug cocktail either orally or intravenously, and blood was collected at various time points. A single oral dose of ABO administration did not affect the pharmacokinetics of five probe drugs when given as a drug cocktail intravenously. However, ABO increased plasma theophylline, dextromethorphan, and diltiazem when co-administered an oral drug cocktail. After 7-days of feeding with an ABO-containing diet, plasma concentrations of theophylline and chlorzoxazone were increased after oral administration of drug cocktail. The major CYP enzyme activities in liver and intestinal were not affected by ABO treatment. Results from this study indicate that a single oral dose or short-term administration of ABO may increase plasma drug concentrations when ABO is given concomitantly with drugs. ABO is likely to enhance intestinal drug absorption. Therefore, caution is needed to avoid food-drug interactions between ABO and co-administered drugs.
ARTICLE | doi:10.20944/preprints201804.0082.v2
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Resveratrol; TRAIL; apoptosis; lung cancer cells; NF-κB; Cytochrome c
Online: 13 August 2018 (06:18:03 CEST)
Aims TRAIL is a promising anticancer agent that has the potential to sensitize a wide variety of cancer or transformed cells by inducing apoptosis. However, resistance to TRAIL is a growing concern. Current manuscript aimed to employing combination treatment to investigate resveratrol induced TRAIL sensitization in NSCLC. Method A549 and HCC-15 cells were used in experimental design. Cell viability was determined by morphological image, crystal violet staining and MTT assay. Apoptosis was evaluated by LDH assay, Annexin V and DAPI staining. Autophagy and apoptosis indicator protein were examined by western blotting. TEM and puncta assay were carried out to evaluate the autophagy. MTP and ROS activity were evaluated by JC-1 and H2DCFDA staining. Findings Resveratrol is a polyphenolic compound capable of activation of tumor suppressor p53 and its pro-apoptotic modulator PUMA. Herein, we showed the p53-independent apoptosis by decrease the expression of phosphorylated Akt-mediated suppression of NF-κB that is also substantiated with the downregulation of anti-apoptotic factors Bcl-2 and Bcl-xl in NSCLC, resulting in an attenuation of TRAIL resistance in combined treatment. Furthermore, apoptosis was induced in TRAIL-resistant lung cancer cells with a co-treatment of resveratrol and TRAIL assessed by the loss of MMP, ROS generations which resulting the translocation of cytochrome c from the mitochondria into the cytosol due to mitochondrial dysfunction. Moreover, autophagy flux was not affected by resveratrol-induced TRAIL-mediated apoptosis in NSCLC. Significance Overall, targeting the NF-κB (p65) pathway via resveratrol attenuates TRAIL resistance and induces TRAIL-mediated apoptosis which could be the effective TRAIL-based cancer therapy regimen.
ARTICLE | doi:10.20944/preprints202201.0328.v1
Subject: Life Sciences, Biochemistry Keywords: cytochrome oxidase; thyroid hormones; steroid hormones; Bile Acids Binding Site; regulation
Online: 21 January 2022 (13:36:04 CET)
Thyroid hormones regulate tissue metabolism establishing an energy balance in the cell, in particular by affecting oxidative phosphorylation. Their long-term impact is mainly associated with changes in gene expression, while the short-term effects may differ in mechanism. Our work is devoted to short-term effects of hormones T2, T3, and T4 on mitochondrial cytochrome c oxidase (CcO) mediated by a direct contact with the enzyme. The data obtained indicate the existence of two separate sites of CcO interaction with thyroid hormones differing in location, affinity and specificity to hormone binding. It is shown that T3 and T4 but not T2 inhibit oxidase activity of CcO in solution and on membrane preparations with Кi≈100–200 M. In solution, T3 and T4 compete in a 1:1 ratio with the detergent dodecyl-maltoside for binding to the enzyme. Peroxidase and catalase partial activities of CcO are not sensitive to hormones while electron transfer from heme a to the oxidized binuclear center is affected. We believe that T3 and T4 are ligands of the Bile Acid Binding Site found in the 3D structure of CсO by Ferguson-Miller’s group, and hormone induced inhibition is associated with dysfunction of the K- proton channel. Similar conclusion we made recently with regard to steroid-like compounds. It is found that T2, T3, and T4 inhibit superoxide generation by oxidized CcO in the presence of excess Н2О2. Inhibition is characterized by Ki values of 0.3 – 5 M and apparently affects the formation of О2• at the protein surface. The second binding site for thyroid hormones presumably coincides with the point of tight T2 binding on the Va subunit described in the literature.
ARTICLE | doi:10.20944/preprints202112.0144.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: 21-hydroxylase deficiency; congenital adrenal hyperplasia; CYP21A2; functional characterization; Cytochrome P450
Online: 9 December 2021 (08:34:16 CET)
Deficiency of Cytochrome P450 Steroid 21-hydroxylase (CYP21A2) represents 90% of cases in congenital adrenal hyperplasia (CAH), an autosomal recessive disease caused by defects in cortisol biosynthesis. Computational prediction along with functional studies are often the only way to classify variants to understand the links to disease-causing effects. Here we investigated the pathogenicity of uncharacterized variants in the CYP21A2 gene reported in the Brazilian and Portuguese populations. Physicochemical alterations, residue conservation, and effect on protein structure were accessed by computational analysis. The enzymatic performance was obtained by functional assay with the wild-type and mutant CYP21A2 proteins expressed in HEK293 cells. Computational analysis showed that p.W202R, p.E352V, and p.R484L have severely impaired the protein structure, while p.P35L, p.L199P, and p.P433L have moderate effects. The p.W202R, p.E352V, p.P433L, and p.R484L variants showed residual 21OH activity consistent with the simple virilizing phenotype. The p.P35L and p.L199P variants showed partial 21OH efficiency associated with the non-classical phenotype. Additionally, p.W202R, p.E352V and p.R484L also modified the protein expression level. We have determined how the selected CYP21A2 gene mutations affect the 21OH activity through structural and activity alteration contributing to the future diagnosis and management of 21OH deficiency.
ARTICLE | doi:10.20944/preprints202109.0487.v1
Subject: Physical Sciences, Applied Physics Keywords: near-infrared spectroscopy; brain; BOLD signal; breath holding; cytochrome C oxidase
Online: 29 September 2021 (10:50:12 CEST)
A major limitation of near-infrared spectroscopy (NIRS) is its high sensitivity to the scalp and low sensitivity to the brain of adult humans. In the present work we use multi-distance hyperspectral NIRS (hNIRS) to investigate the optimal source-detector distances, range of wavelengths, and analysis techniques to separate cerebral responses to 30-s breath holds (BHs) from the responses in the superficial tissue layer in healthy adult humans. We observed significant responses to BHs in the scalp hemodynamics. Cerebral responses to BHs were detected in the cytochrome C oxidase redox (rCCO) at 4 cm without using data from the short-distance channel. Using the data from the 1 cm channel in the two-layer regression algorithm showed that hemodynamic and rCCO responses also occurred at 3cm. We found that the waveband 700-900 nm was optimal for the detection of cerebral responses to BHs in adults.
Subject: Life Sciences, Other Keywords: epigallocatechin-3-gallate; acetaminophen; cytochrome P-450; bioactivation; apoptosis; autophagy; hepatotoxicity
Online: 28 July 2019 (16:45:51 CEST)
Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol in green tea. In this study, the effects of dietary EGCG on oxidative stress and the metabolism and toxicity of acetaminophen in liver were investigated. Rats were fed the diets with (0.54 %) or without EGCG supplementation for four weeks and were then intraperitoneally injected with acetaminophen (1g/kg). Results showed EGCG lowered hepatic oxidative stress and cytochrome P450 (CYP) 1A2, 2E1, and 3A, and UDP-glucurosyltransferase activities prior to acetaminophen injection. After acetaminophen challenge, the elevations in plasma alanine aminotransferase activity and histological changes in liver were ameliorated by EGCG treatment. EGCG reduced acetaminophen-induced apoptosis by increasing the Bax/Bcl2 ratio in liver. EGCG mildly increased autophagy by increasing the LC3B II/I ratio. Lower hepatic acetaminophen-glutathione and acetaminophen-protein adducts contents were observed after EGCG treatment. EGCG increased glutathione peroxidase and NAD(P)H quinone 1 oxidoreductase activities and reduced organic anion-transporting polypeptides 1a1 expression in liver after acetaminophen treatment. Our results indicate that EGCG may lower oxidative stress and reduce the metabolism and toxicity of acetaminophen. The reductions in CYP-mediated acetaminophen bioactivation and uptake transporter, as well as enhanced antioxidant enzyme activity, may limit the accumulation of toxic products in liver and thus lower hepatotoxicity
ARTICLE | doi:10.20944/preprints202206.0243.v1
Subject: Life Sciences, Other Keywords: Insecticide resistance; Anopheles gambiae; Anopheles coluzzii; Cytochrome P450; Gluthathi-one-S-Transferases
Online: 17 June 2022 (03:31:08 CEST)
Background: Insecticide resistance in Anopheles gambiae s.l. is a major challenge for malaria vector control in Nigeria. Both target-site insensitivity and metabolic resistance have been im-plicated in resistance process, with the latter receiving little attention in Nigeria. Therefore, we investigated metabolic enzyme activities in Anopheles gambiae s.l populations resistant to Del-tamethrin and Diethyldichlorotriethylethane (DDT) in South-West Nigeria. Methods: Anopheles larvae were collected from Ibadan, Oyo and Badagry, Lagos. Adults were exposed to Deltamethrin and DDT using WHO method. Cohorts of populations were further exposed to Pyperonil Butoxide (PBO) and Deltamethrin. Insecticide-exposed and unexposed co-horts were examined for metabolic enzyme activities. Results were compared between exposed and unexposed samples ANOVA (P<0.05). Results: Mosquitoes were identified as An. gambiae (89%, Ibadan; 0%, Badagry) and An. coluzzii (11%, Ibadan; 100%, Badagry). The populations showed varied level of resistance to Deltamethrin (26%, Ibadan; 71%, Badagry) and DDT (2%, Ibadan; 44%, Badagry). Mortality to Deltamethrin in-creased from 26% to 64% (Ibadan) and 71% to 84% (Badagry) when populations were pre-exposed to PBO. Biochemical analysis revealed significant high levels (P<0.05) of cytochrome P450 and GST in exposed samples. Conclusions: Cytochrome P450 and GST are involved in Deltamethrin and DDT resistance in Anopheles gambiae s.l populations in South-West Nigeria.
ARTICLE | doi:10.20944/preprints202208.0317.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: Cytochrome P450; POR; Congenital adrenal hyperplasia; metabolic disorders; CYP3A4; protein stability; drug metabolism
Online: 17 August 2022 (10:02:51 CEST)
Cytochrome P450 oxidoreductase (POR) is the redox partner of steroid and drug-metabolizing cytochromes P450 located in the endoplasmic reticulum. Mutations in POR cause a broad range of metabolic disorders. The POR variant rs17853284 (P228L) identified by genome sequencing has been linked to lower testosterone levels and reduced P450 activities. We expressed POR wild type and the P228L variant in bacteria, purified the proteins, and performed protein stability and catalytic functional studies. Variant P228L affected the stability of the protein as evidenced by lower unfolding temperatures and higher sensitivity to urea denaturation. A significant reduction of small molecule metabolism was observed with POR P228L while activities of CYP3A4 were reduced by 25%, and activities of CYP3A5, and CYP2C9 were reduced by more than 40% compared to WT POR. The 17,20 lyase activity of CYP17A1 responsible for production of main androgen precursor dehydroepiandrosterone, was reduced to 27% of WT in presence of P228L variant of POR. Based on in silico and in vitro studies we predict that the change of proline to leucine may change the rigidity of the protein, causing conformational changes in POR, leading to altered electron transfer to redox partners. A single amino acid change can affect protein stability and cause a severe reduction in POR activity. Molecular characterization of individual POR mutations is crucial for a better understanding of the impact on different redox partners of POR.
ARTICLE | doi:10.20944/preprints202105.0739.v1
Subject: Life Sciences, Biochemistry Keywords: Protein Unfolding 2; Cytochrome c’ 3; Small-Angle Neutron Scattering 4; Open-bundle structure
Online: 31 May 2021 (10:59:40 CEST)
The open-bundle structure of cytochrome c’ as an unfolding intermediate was determined by small-angle neutron scattering experiment (SANS). The four-α-helix bundle structure of Cyt c’ at neutral pH was transited to an open-bundle structure (at pD ~13), which is a joint-clubs consisting of four clubs (α-helices) connected by short loops. The compactly folded structure of Cyt c’ (radius of gyration, Rg = 18 Å for the Cyt c’ dimer) at neutral or mildly alkaline pD transitioned to a remarkably larger “open-bundle” structure at pD ~13 (Rg = 25 Å for the Cyt c’ monomer). Cyt c’ adopts an unstructured random coil structure at pD = 1.7 (Rg = 25 Å for the Cyt c’ monomer). Numerical partial scattering function analysis (joint-clubs) and ab initio modelling gave structures similar to the “open-bundle”, which retains the α-helices but loses the bundle structure.
REVIEW | doi:10.20944/preprints201812.0032.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: cannabis; cannabinoids; THC; CBD, drug-drug interactions; pharmacokinetic; cytochrome P450; UDP- glucuronosyltransferases; glucoprotein-P
Online: 3 December 2018 (16:07:43 CET)
Endocannbinoids system (ECS) engrossed a considerable interest as potential therapeutic targets in various carcinomas and cancer related conditions alongside with neurodegenerative diseases. Cannabinoids are implemented in several physiological processes such as appetite stimulation, energy balance, pain modulation and the control of chemotherapy induced nausea and vomiting (CINV). However, pharmacokinetics and pharmacodynamics interactions could be perceived in drug combinations, so in this short review we tried to shed the light over the potential drug interactions of medicinal cannabis. Hitherto, few data have been provided to the healthcare practitioners about the drug-drug interactions of cannabinoids with other prescription medications. In general, cannabinoids are usually well tolerated, but the bidirectional effects may be expected with concomitant administered agents via affected membrane transporters (glycoprotein p, breast cancer resistance proteins) and metabolizing enzymes (Cytochrome P450 and UDP- glucuronosyltransferases). The caveats should be undertaken to closely monitor the responses of cannabis users with certain drugs to guard their safety, especially for the elderly and people with chronic diseases or kidney and liver conditions.
REVIEW | doi:10.20944/preprints202103.0143.v1
Subject: Medicine & Pharmacology, Allergology Keywords: antioxidants; alcohol metabolism; hepatoprotective; anti-ALD; mitochondrial dysfunction; mitochondria-targeted; oxidative stress; and cytochrome P450 2E1
Online: 4 March 2021 (09:13:05 CET)
Oxidative stress initiates and facilitates the disruption of the structural integrity of hepatic mitochondria, which leads to steatosis, steatohepatitis, fibrosis, and cirrhosis. It is now evident that mitochondrial dysfunction could be responsible for alcoholic liver disease (ALD). The challenge in treating ALD has been the limited availability of hepatoprotective agents and the lack of highly efficient delivery systems. Recent studies have shown that mitochondria-targeted therapies could address mitochondrial dysfunction (MD), which may greatly improve hepatoprotection and ALD treatment. This mini-review discusses the potential role of mitochondria-targeted antioxidants (MTAs) in the maintenance of hepatocellular integrity. This report also considers the mechanism of liver injury induced by alcohol and the progression of ALD from a mitochondrial oxidative damage perspective as well as the possible mechanistic actions of hepatoprotective antioxidants. Preliminary studies suggest the prospect of MTAs as anti-ALD and hepatoprotective agents.
ARTICLE | doi:10.20944/preprints201705.0166.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: constitutive androstene receptor; cytochrome P450, fibrosis; gender difference; high-fat-cholesterol (HFC) diet; necrosis; stroke-prone spontaneously hypertensive 5/Dmcr rats; sulfotransferase, pregnane X receptor; UGP-glucuronosyltransferase
Online: 23 May 2017 (07:54:46 CEST)
During middle age, women are less susceptible to nonalcoholic steatohepatitis (NASH) than men. Thus, we investigated the underlying molecular mechanisms behind these sexual differences using an established rat model of NASH. Mature female and male stroke-prone spontaneously hypertensive 5/Dmcr rats were fed control or high-fat-cholesterol (HFC) diets for 2, 8, and 14 weeks. Although HFC-induced hepatic fibrosis was markedly less severe in females than in males, only minor gender differences were observed in expression levels of cytochrome P450 enzymes (CYP)7A1, CYP8B1 CYP27A1, and CYP7B1, and multidrug resistance-associated protein 3, and bile salt export pump, which are involved in fibrosis-related bile acid (BA) kinetics. However, the BA detoxification-related enzymes UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT) 2A1, and the nuclear receptors constitutive androstene receptor (CAR) and pregnane X receptor (PXR), were strongly suppressed in HFC fed males, and were only slightly changed in HFC-diet fed females. Expression levels of the farnesoid X receptor and its small heterodimer partner were similarly regulated in a gender-dependent fashion following HFC feeding. Hence, the pronounced female resistance to HFC-induced liver damage likely reflects sustained expression of the nuclear receptors CAR and PXR and the BA detoxification enzymes UGT and SULT.