Tug of war between clozapine and CYP450 inducers: A case report.

The management of schizoaffective disorder bipolar type often involves a combination of pharmacotherapy and psychotherapy. Clozapine, an effective antipsychotic for treatment-resistant schizophrenia, and oxcarbazepine, a mood stabilizer, is a commonly prescribed medication. We present a case report of a 56-year-old male with schizoaffective disorder bipolar type who experienced subtherapeutic clozapine levels despite dose adjustments, leading to deteriorating symptoms. Oxcarbazepine, a weak CYP450 inducer, likely contributed to the subtherapeutic levels. Additionally, the pharmacogenetic analysis revealed a CYP1A2 *1F/*1F genotype, indicating normal activity with a potential for decreased serum levels and adverse events in the presence of inducers. The patient was eventually stabilized on a regimen of lithium, paliperidone, and quetiapine, avoiding oxcarbazepine. This case highlights the importance of considering individual patient factors, including pharmacogenetics when managing treatment-resistant patients. Monitoring serum clozapine levels and assessing enzyme activity before initiating therapy may help optimize treatment outcomes and minimize adverse events.

The impact of freeze-dried Baiyedancong-Oolong tea aqueous extract containing bioactive compounds on the activities of CYP450 enzymes, the transport capabilities of P-gp and OATs, and transcription levels in mice.

In this study, (-)-epigallocatechin gallate (EGCG) and caffeine extracted from freeze-dried autumn Baiyedancong Oolong tea (FBOT) were orally administered to mice for 7 consecutive days to explore the effects of BOT and its bioactive compounds on the activities and transcription levels of CYP450 enzymes, intestinal effluence transporter P-gp, and renal ingestion Organic Anion Transporters (OATs). Concurrently, EGCG and caffeine enhanced the activities of CYP3A, CYP2E1, and CYP2C37 in the liver of mice, while impairing the transport capabilities of P-gp and OATs. Reduced levels of MDR1 encoding P-gp transcription in the small intestine and renal OAT1 and OAT3 revealed that transcription was involved in the regulation of CYP450, P-gp, and OATs. The reduced transcription level of liver CYP2E1 suggested that CYP2E1 activity may have been elevated due to alternative mechanisms, but not through transcription. The absorption, metabolism, and excretion of drugs may be influenced by the daily consumption or high-dose administration of BOT and its related products, in which EGCG and caffeine may make great contributions.

Cytochrome P450 CYP6AE70 Confers Resistance to Multiple Insecticides in a Lepidopteran Pest, Spodoptera exigua.

Cytochrome P450 monooxygenases are associated with the detoxification of xenobiotics, and overexpression of P450 genes has been proven to be associated with insecticide resistance in insect species. Our previous study has revealed that multiple CYP6AE genes were significantly overexpressed in a resistant strain of Spodoptera exigua, and among these genes, CYP6AE70 was particularly highly expressed. However, the functional roles of the CYP6AE genes in insecticide resistance remain unknown in this pest. Here, we investigate the relationship between the CYP6AE genes and insecticide resistance by focusing on CYP6AE70. The expression of CYP6AE70 was increased after exposure to chlorpyrifos, cypermethrin, and deltamethrin. Ectopic overexpression of P450 in transgenic flies by the GAL4/UAS system dramatically enhanced the tolerance to these three insecticides. Furthermore, the recombinant CYP6AE70 was functionally expressed in Sf9 cells, and metabolic assays revealed that the recombinant P450 protein could efficiently metabolize chlorpyrifos, cypermethrin, and deltamethrin. Finally, molecular modeling and docking also showed that this P450 protein were tightly bound to the three insecticides. These results determine that the upregulation of CYP6AE genes results in resistance to multiple insecticides in S. exigua. This study improves our understanding of P450-mediated insecticide resistance and will help us to design more effective resistance management for pest control.

Magical role of Iron nanoparticles for enhancement of thermal efficiency and gene regulation of fish in response to multiple stresses.

The present study addresses the challenges of uncontrolled temperature and pollution in aquatic environments, with a focus on fish ability to tolerate high temperatures. The investigation aimed to determine the role of iron nanoparticles (Fe-NPs) in enhancing the thermal tolerance of Pangasianodon hypophthalmus exposed to high-temperature stress, arsenic (As), and ammonia (NH3) toxicity. Fe-NPs were synthesized using green approaches, specifically from fish gill waste. The dietary Fe-NPs were formulated and administered at 10, 15, and 20 mg kg⁻1 of feed. Notably, Fe-NPs at 15 mg kg⁻1 of diet significantly reduced the critical thermal minimum (CTmin) to 14.44±0.21 °C and the lethal thermal minimum (LTmin) to 13.46±0.15 °C, compared to the control and other treatment groups. Conversely, when Fe-NPs at 15 mg kg⁻1 were administered with or without exposure to stressors (As+NH3+T), the critical thermal maximum (CTmax) increased to 47.59±0.16°C, and the lethal thermal maximum (LTmax) increased to 48.60±0.37 °C, both significantly higher than the control and other groups. A strong correlation was observed between LTmin and CTmin (R2 = 0.90) and between CTmax and LTmax (R2 = 0.98). Furthermore, dietary Fe-NPs at 15 mg kg⁻1 significantly upregulated the expression of several stress-related genes, including HSP70, iNOS, Caspase-3a, CYP450, MT, cat, sod, gpx, TNFα, IL, TLR, and Ig. The enhanced thermal tolerance (LTmin and LTmax) can be attributed to these gene regulations, suggesting the mechanistic involvement of Fe-NPs in improving thermal resilience. Overall, the findings demonstrate that dietary supplementation with Fe-NPs, particularly at 15 mg kg⁻1, improves thermal tolerance and stress response in P. hypophthalmus by enhancing gene expression and overall thermal efficiency under stressor conditions.

Antidepressants as new endocrine disruptors? - transcriptomic profiling in gonads of Mytilus trossulus exposed to norfluoxetine.

In this study an impact of norfluoxetine (NFLU) on Mytilus trossulus gonads was investigated focusing on sex-related differences in hormonal changes, gene expression, and transcriptomic profiling. Sex-specific differences in gonadal serotonin levels were found. NFLU stimulates serotonin synthesis and/or transport in female gonads, potentially accelerating oocyte maturation and gamete release. In males, NFLU decreases serotonin level what likely leads to impeding sperm maturation and thus spawning delay. Transcriptomic analyses highlighted the presence of NFLU-induced changes in gene expression related to gametogenesis and neurotransmission. In females, NFLU upregulated genes associated with oocyte development and downregulated those involved in sperm maturation. NFLU-treated males exhibited mixed effects in their genes in relation to spermatogenesis. Additionally, sex-related differences in the expression of the CYP450 genes responsible for detoxification were found. Overall, norfluoxetine acts as an endocrine-disrupting chemical and impacts gonadal serotonin levels and gene expression, potentially disrupting reproductive success of M. trossulus.

First insight into the formation of transformation products of a biopesticide guvermectin in rat and its health risk.

Guvermectin is a new chemical isolated from the microbial metabolites and is registered as a novel plant growth regulator. However, the biotransformation behavior and toxicity of guvermectin to mammals remain unclear and have unknown implications for consumers or occupationally exposed persons. Therefore, we investigated the biotransformation of guvermectin in vivo and in vitro, its effects on CYP450s activities, and its oral toxicity in rats. The results showed that guvermectin could be rapidly absorbed when administered orally and eliminated rapidly in the serum, with a half-life of 6.3 h. Four phase І metabolism products of guvermectin in the serum were screened and identified using UPLC-QTOF/MS. Two products, adenine and psicofuramine, were confirmed using reference standards. Hydrolysis and oxidation reactions were the main transformation pathways. Oral toxicity tests in rats showed that guvermectin exhibited light toxicity to rats (LC50 > 5000 mg/kg b.w.). However, an in vitro probe drug experiment revealed that guvermectin could induce CYP2D6 activity, and a lower concentration of guvermectin exhibited a stronger effect on CYP2D6 than higher concentration (1.38-fold). Molecular docking studies implied that guvermectin was an antagonist of CYP1A2, CYP2C9, and CYP3A4. These findings provided a better understanding of the environmental and human health risks associated with guvermectin and promote its rational use. However, the potential risk of endocrine disruption can not be ignored due to the presence of nucleoside-like metabolites.

A Comprehensive Review of Schizophrenia and Antipsychotic Metabolism as a Predictor of Treatment Response.

Some patients with schizophrenia fail to respond to standard antipsychotics and are considered treatment-resistant. In these cases, clozapine is the only antipsychotic with proven efficacy, but its use is complicated by severe adverse effects, complex monitoring requirements, and non-response. Variation within the CYP450 enzymes CYP1A2, CYP2D6, CYP3A4, and CYP2C19 has been linked to the differential metabolism of antipsychotics. Testing for CYP450 single nucleotide polymorphisms may be a useful predictor of treatment resistance and could inform pharmacogenetic recommendations to identify potential treatment non-responders. Nonetheless, it remains uncertain whether differential antipsychotic metabolism is directly related to treatment efficacy. This comprehensive narrative review endeavours to delve into the molecular and genetic basis of schizophrenia, and discuss the current treatments available. In particular, we aim to examine the aetiology of treatment resistance in schizophrenia through available literature and discuss current challenges within the field.

Electrochemical Probing of Human Liver Subcellular S9 Fractions for Drug Metabolite Synthesis.

Human liver subcellular fractions, including liver microsomes (HLM), liver cytosol fractions, and S9 fractions, are extensively utilized in in vitro assays to predict liver metabolism. The S9 fractions are supernatants of human liver homogenates that contain both microsomes and cytosol, which include most cytochrome P450 (CYP) enzymes and soluble phase II enzymes such as glucuronosyltransferases and sulfotransferases. This study reports on the direct electrochemistry and biocatalytic features of redox-active enzymes in S9 fractions for the first time. We investigated the electrochemical properties of S9 films by immobilizing them onto a high-purity graphite (HPG) electrode and performing cyclic voltammetry under anaerobic (Ar-saturated) and aerobic (O2-saturated) conditions. The heterogeneous electron transfer rate between the S9 film and the HPG electrode was found to be 14 ± 3 s-1, with a formal potential of -0.451 V vs. Ag/AgCl reference electrode, which confirmed the electrochemical activation of the FAD/FMN cofactor containing CYP450-reductase (CPR) as the electron receiver from the electrode. The S9 films have also demonstrated catalytic oxygen reduction under aerobic conditions, identical to HLM films attached to similar electrodes. Additionally, we investigated CYP activity in the S9 biofilm for phase I metabolism using diclofenac hydroxylation as a probe reaction and identified metabolic products using liquid chromatography-mass spectrometry (LC-MS). Investigating the feasibility of utilizing liver S9 fractions in such electrochemical assays offers significant advantages for pharmacological and toxicological evaluations of new drugs in development while providing valuable insights for the development of efficient biosensor and bioreactor platforms.

Identification of three novel P450 enzymes involved in the oxidative modification of a newly discovered fusicoccane diterpene.

Fusicoccane (FC)-type diterpenoids are a class of diterpenoids characterized by a unique 5-8-5 ring system and exhibit diverse biological activities. Recently, we identified a novel FC-type diterpene synthase MgMS, which produces a myrothec-15(17)-en-7-ol (1) hydrocarbon skeleton, however, its tailoring congeners have not been elucidated. Here, we discovered two additional gene clusters Bn and Np, each encoding a highly homologous terpene synthase to MgMS but distinct tailoring enzymes. Heterologous expression of the terpene synthases BnMS and NpMS yielded the same product as MgMS. Subsequent introduction of three P450 enzymes MgP450, BnP450 and NpP450 from individual gene clusters resulted in four new FC-type diterpenoids 2-5. Notably, MgP450 serves as the first enzyme responsible for hydroxylation of the C19 methyl group, whereas NpP450 functions as a multifunctional P450 enzyme involved in the oxidations at C5, C6, and C19 positions of the 5-8-5 tricyclic skeleton. C5 oxidation of the hydrocarbon skeleton 1 led to broadening of the NMR signals and incomplete spectra, which was resolved by high-temperature NMR spectral analysis.

Bioinformatics Analysis of the Genome of Rhodococcus rhodochrous IEGM 1362, an (-)-Isopulegol Biotransformer.

A genome of Rhodococcus rhodochrous IEGM 1362 was sequenced and annotated. This strain can transform monoterpene alcohol (-)-isopulegol with the formation of two novel pharmacologically promising metabolites. Nine genes encoding cytochrome P450, presumably involved in (-)-isopulegol transformation, were found in the genome of R. rhodochrous IEGM 1362. Primers and PCR conditions for their detection were selected. The obtained data can be used for the further investigation of genes encoding enzymes involved in monoterpene biotransformation.

Computational simulations uncover enantioselective metabolism of chiral triazole fungicides by human CYP450 enzymes: A case study of tebuconazole.

Tebuconazole (TEB), a prominent chiral triazole fungicide, has been extensively utilized for plant pathogen control globally. Despite experimental evidence of TEB metabolism in mammals, the enantioselectivity in the biotransformation of R- and S-TEB enantiomers by specific CYP450s remains elusive. In this work, integrated in silico simulations were employed to unveil the binding interactions and enantioselective metabolic fate of TEB enantiomers within human CYP1A2, 2B6, 2E1, and 3A4. Molecular dynamics (MD) simulations clearly delineated the binding specificity of R- and S-TEB to the four CYP450s, crucially determining their differences in metabolic activity and enantioselectivity. The primary driving force for robust ligand binding was identified as van der Waals interactions with CYP450s, particularly involving the hydrophobic residues. Mechanistic insights derived from quantum mechanics/molecular mechanics (QM/MM) calculations established C2-methyl hydroxylation as the predominant route of R-/S-TEB metabolism, while C6-hydroxylation and triazol epoxidation were deemed kinetically infeasible pathways. Specifically, the resulting hydroxy-R-TEB metabolite primarily originates from R-TEB biotransformation by 1A2, 2E1 and 3A4, whereas hydroxy-S-TEB is preferentially produced by 2B6. These findings significantly contribute to our comprehension of the binding specificity and enantioselective metabolic fate of chiral TEB by CYP450s, potentially informing further research on human health risk assessment associated with TEB exposure.

Cadmium causes spleen toxicity in chickens by regulating mitochondrial unfolded protein response and nuclear receptors response.

Cadmium (Cd) is a heavy metal that pollutes the environment and threatens human and animal health via the food chain. The spleen is one of the target organs affected by Cd toxicity. However, the mechanism of Cd toxicity is not fully understood. In this study, 80 chicks were allocated into 4 groups (n = 20) and exposed to different doses of CdCl2 (0 mg/kg, 35 mg/kg, 70 mg/kg and 140 mg/kg) for 90 d. The pathological changes in the spleen, mitochondrial dynamics-related factors, cytochrome P450 (CYP450) enzyme system contents, activities, transcription levels, nuclear receptors (NRs) response molecule levels, and mitochondrial unfolded protein-related factors were detected. The findings indicate that exposure to Cd significantly leads to spleen injury. In Cd groups, the total contents of CYP450 and cytochrome b5 (Cyt b5) increased, and the activities of the CYP450 enzyme system (APND, ERND, AH, and NCR) changed. The NRs response was induced, and the gene levels of AHR/CAR and corresponding CYP450 isoforms (CYP1B1, CYP1A5, CYP1A1, CYP2C18, CYP2D6 and CYP3A4) were found altered. The study found that Cd exposure altered the mRNA expression levels of mitochondrial dynamics-related factors, such as OPA1, Fis1, MFF, Mfn1, and Mfn2, breaking mitochondrial fusion and cleavage and ultimately leading to mitochondrial dysfunction. Changes were detected in the gene levels of several mitochondrial unfolded protein response (mtUPR)-related factors, namely (SIRT1, PGC-1α, NRF1, TFAM, SOD2, and HtrA2). Cd also altered the gene levels of mitochondrial function-related factors (VDAC1, Cyt-C, COA6, PRDX3, RAF and SIRT3). It is showed that Cd can initiate the NRs response, influence the homeostasis of the CPY450 enzyme system, trigger the mtUPR, impair mitochondrial function, and ultimately lead to Cd toxicity in the spleen of chickens.

Fumonisin B1 induces endoplasmic reticulum damage and inflammation by activating the NXR response and disrupting the normal CYP450 system, leading to liver damage in juvenile quail.

Fumonisin B1 (FB1) is a mycotoxin affecting animal health through the food chain and has been closely associated with several diseases such as pulmonary edema in pigs and diarrhea in poultry. FB1 is mainly metabolized in the liver. Although a few studies have shown that FB1 causes liver damage, the molecular mechanism of liver damage is unclear. This study aimed to evaluate the role of liver damage, nuclear xenobiotic receptor (NXR) response and cytochrome P450 (CYP450)-mediated defense response during FB1 exposure. A total of 120 young quails were equally divided into two groups (control and FB1 groups). The quails in the control group were fed on a normal diet, while those in the FB1 group were fed on a quail diet containing 30 mg/kg for 42 days. Histopathological and ultrastructural changes in the liver, biochemical parameters, inflammatory factors, endoplasmic reticulum (ER) factors, NXR response and CYP450 cluster system and other related genes were examined at 14 days, 28 days and 42 days. The results showed that FB1 exposure impaired the metabolic function and caused liver injury. FB1 caused ER stress and decreased adenosine triphosphatease activity, induced the expression of inflammation-related genes such as interleukin 6 and nuclear factor kappa-B, and promoted inflammation. In addition, FB1 disrupted the expression of multiple CYP450 isoforms by activating nuclear xenobiotic receptors (NXRs). The present study confirms that FB1 exposure disturbs the homeostasis of cytochrome P450 systems (CYP450s) in quail liver by activating NXR responses and thereby causing liver damage. This study's findings provide insight into the molecular mechanisms of FB1-induced hepatotoxicity.

Pharmacogenetics of Calcineurin inhibitors in kidney transplant recipients: the African gap. A narrative review.

Calcineurin inhibitors (CNIs) are the mainstay of immunosuppression in kidney transplantation. Interpatient variability in the disposition of calcineurin inhibitors is a well-researched phenomenon and has a well-established genetic contribution. There is great diversity in the makeup of African genomes, but very little is known about the pharmacogenetics of CNIs and transplant outcomes. This review focuses on genetic variants of calcineurin inhibitors' metabolizing enzymes (CYP3A4, CYP3A5), related molecules (POR, PPARA) and membrane transporters involved in the metabolism of calcineurin inhibitors. Given the genetic diversity across the African continent, it is imperative to generate pharmacogenetic data, especially in the era of personalized medicine and emphasizes the need for studies specific to African populations. The study of allelic variants in populations where they have greater frequencies will help answer questions regarding their impact. We aim to fill the knowledge gaps by reviewing existing research and highlighting areas where African research can contribute.

Research on the pharmacogenetics of calcineurin inhibitors in kidney transplant recipients is truly wanting in data from the African continent. Given Africa's vast genetic diversity, it is necessary to intensify efforts to generate data from Africa in this field.

Brassica napus cytochrome P450 superfamily: Origin from parental species and involvement in diseases resistance, abiotic stresses tolerance, and seed quality traits.

Cytochromes P450 monooxygenases (CYP450s) constitute the largest enzymic protein family that is widely present in plants, animals, and microorganisms, participate in numerous metabolic pathways, and play diverse roles in development, metabolism, and defense. Rapeseed (Brassica napus) is an important oil crop worldwide and have many versions of reference genome. However, there is no systemically comparative genome-wide analysis of CYP450 family genes in rapeseed and its parental species B. rapa and B. oleracea. In this study, we identified 765, 293 and 437 CYP450 genes in B. napus, B. rapa and B. oleracea, respectively, which were unevenly located in A01-A10 and/or C01-C09 chromosomes in corresponding species. Phylogenetic relationship analysis indicated that 1745 CYP450 proteins from three Brassica species and Arabidopsis were divided into 4 groups. Whole genome duplication (WGD) or segmental duplication resulted in gene expansion of CYP450 family in three Brassica species. There were 33-83 SSR loci in CYP450 genes of three Brassica species, and numerous transcription factor binding sites were identified in their promoters. A total of 459-777 miRNAs were predicted to target 174-426 CYP450 genes in three Brassica species. Based on transcriptome data, BnCYP450s, BrCYP450s and BoCYP450s were differentially expressed in various tissues. There existed numerous BnCYP450 DEGs in response to pathogens and abiotic stresses. Besides, many BnCYP450 DEGs were involved in the regulation of important traits, such as seed germination, seed ALA content, and yellow-seed. The qRT-PCR experiment confirmed the transcriptome analysis results by validating two representative Sclerotinia-responsive BnCYP450 DEGs as an example. Three BnCYP450s genes (CYP707A1, CYP81F1, CYP81H1) might be regulated by seed-specific transcription factors BnTT1 and BnbZIP67 to participate in the development and metabolism of seed coat and embryo by undertaking related metabolic reactions.

Combined transcriptome and metabolome analysis identifies triterpenoid-induced defense responses in Myzus persicae Sülzer-infested peach.

The defense response of peach (Prunus persica) to insect attack involves changes in gene expression and metabolites. Piercing/sucking insects such as green peach aphid cause direct damage by obtaining phloem nutrients and indirect damage by spreading plant viruses. To investigate the response of peach trees to aphids, the leaf transcriptome and metabolome of two genotypes with different sensitivities to green peach aphid (GPA, Myzus persicae) were studied. The transcriptome analysis of infected peach leaves showed two different response patterns. The gene expression of aphid-susceptible peach plants infected by aphids was more similar to that of the control plants, while the gene expression of aphid-resistant peach plants infected by aphids showed strongly induced changes in gene expression compared with the response in the control plants. Furthermore, gene transcripts in defense-related pathways, including plant-pathogen interaction, MAPK signaling, and several metabolic pathways, were more strongly enriched upon aphid infestation. Untargeted secondary metabolite profiling confirmed that aphid treatment induced larger changes in aphid-resistant peaches than in aphid-susceptible peaches. Consistent with transcriptomic alterations, nine triterpenoids showed extremely significant GPA-induced accumulation in aphid-resistant peaches, whereas triterpenoid abundance remained predominantly unchanged or undetected in aphid- susceptible peaches. Furthermore, some types of transcription factors (including WRKYs, ERFs, NACs, etc.) were more strongly induced upon GPA infestation in aphid-resistant peaches but not in aphid-susceptible peaches. Aphid feeding-dependent transcriptome and metabolite profiles provide the foundation for understanding the molecular mechanisms underlying the response of peach to aphid infestation. These results suggested that accumulation of specialized triterpenoids and the corresponding pathway transcripts may play a key role in peach GPA resistance.

Chromosomal-level genome assembly of Hylurgus ligniperda: insights into host adaptation and environmental tolerance.

BACKGROUND: Hylurgus ligniperda (Coleoptera: Curculionidae) is a worldwide forest quarantine pest. It is widely distributed, has many host tree species, and possesses strong adaptability. To explore its environmental adaptability and the related molecular mechanisms, we conducted chromosome-level genome sequencing and analyzed the transcriptome under different environmental factors, identifying key expressed genes. RESULTS: We employed PacBio, Illumina, and Hi-C sequencing techniques to assemble a 520 Mb chromosomal-level genome of H. ligniperda, obtaining an N50 of 39.97 Mb across 138 scaffolds. A total of 10,765 protein-coding genes were annotated after repeat masking. Fourteen chromosomes were identified, among which Hyli14 was determined to be the sex chromosome. Survival statistics were tested over various growth periods under high temperature and low humidity conditions. The maximum survival period of adults reached 292 days at 25 °C, 65% relative humidity. In comparison, the maximum survival period was 14 days under 35 °C, 65% relative humidity, and 106 days under 25°C, 40% relative humidity. This indicated that environmental stress conditions significantly reduced adults' survival period. We further conducted transcriptome analysis to screen for potentially influential differentially expressed genes, such as CYP450 and Histone. Subsequently, we performed gene family analysis to gain insights into their functions and interactions, such as CYP450 and Histone. CYP450 genes affected the detoxification metabolism of enzymes in the Cytochrome P450 pathway to adapt to different environments. Histone genes are involved in insect hormone biosynthesis and longevity-regulating pathways in H. ligniperda to adapt to environmental stress. CONCLUSIONS: The genome at the chromosome level of H. ligniperda was assembled for the first time. The mortality of H. ligniperda increased significantly at 35 ℃, 65% RH, and 25 ℃, 40% RH. CYP450 and Histone genes played an important role in response to environmental stress. This genome offers a substantial genetic resource for investigating the molecular mechanisms behind beetle invasion and spread.

Living systematic review and meta-analysis of plasma-concentrations of antipsychotic drugs in carriers and non-carriers of variant CYP450 genotypes: Living systematic review protocol.

Introduction: Carriers of variant alleles of genes that encode liver CYP450 and UGT enzymes may experience abnormal plasma levels of antipsychotics and, consequently, worse efficacy or tolerability. Although pharmacogenomics is a rapidly developing field, current guidelines often rely on limited, underpowered evidence. We have previously demonstrated that meta-analysis is a viable strategy for overcoming this problem. Here, we propose a project that will expand our previous work and create a living systematic review and meta-analysis of drug plasma level differences between carriers and non-carriers of variant genotype-predicted phenotypes for every pharmacokinetic drug-gene interaction relevant to commonly used antipsychotic drugs. Protocol: First, a baseline systematic review and meta-analysis will be conducted by searching for observational pharmacogenomics-pharmacokinetic studies. Data on dose-adjusted drug plasma levels will be extracted, and participants will be grouped based on their genotype for each drug-gene pair separately. Differences in plasma drug levels between different phenotypes will be compared using a random-effect ratio-of-means meta-analysis. The risk of bias will be assessed using ROBINS-I, and the certainty of evidence will be assessed using GRADE. Following the establishment of baseline results, the literature search will be re-run at least once every six months, and the baseline data will be updated and re-evaluated as new evidence is published. A freely available website will be designated to present up-to-date results and conclusions. Discussion: This systematic review will provide evidence-based results that are continuously updated with evidence as it emerges in the rapidly developing field of pharmacogenomics. These results may help psychiatrists in their decision-making, as clinicians are becoming increasingly aware of the patients' genetic data as testing becomes more widespread and cheaper. In addition, the results may serve as a scientific basis for the development of evidence-based pharmacogenomics algorithms for personalized dosing of antipsychotics to mitigate potentially harmful drug-gene interactions.

Systematic Review of Naturally Derived Substances That Act as Inhibitors of the Nicotine Metabolizing Enzyme Cytochrome P450 2A6.

Tobacco smoking has been highlighted as a major health challenge in modern societies. Despite not causing death directly, smoking has been associated with several health issues, such as cardiovascular diseases, respiratory disorders, and several cancer types. Moreover, exposure to nicotine during pregnancy has been associated with adverse neurological disorders in babies. Nicotine Replacement Therapy (NRT) is the most common strategy employed for smoking cessation, but despite its widespread use, NRT presents with low success and adherence rates. This is attributed partially to the rate of nicotine metabolism by cytochrome P450 2A6 (CYP2A6) in each individual. Nicotine addiction is correlated with the high rate of its metabolism, and thus, novel strategies need to be implemented in NRT protocols. Naturally derived products are a cost-efficient and rich source for potential inhibitors, with the main advantages being their abundance and ease of isolation. This systematic review aims to summarize the natural products that have been identified as CYP2A6 inhibitors, validated through in vitro and/or in vivo assays, and could be implemented as nicotine metabolism inhibitors. The scope is to present the different compounds and highlight their possible implementation in NRT strategies. Additionally, this information would provide valuable insight regarding CYP2A6 inhibitors, that can be utilized in drug development via the use of in silico methodologies and machine-learning models to identify new potential lead compounds for optimization and implementation in NRT regimes.

Probe substrates assay estimates the effect of polyphyllin H on the activity of cytochrome P450 enzymes in human liver microsomes.

Cytochrome P450 enzymes (CYPs) play a crucial role in phase I metabolic reactions. The activity of CYPs would affect therapeutic efficacy and may even induce toxicity. Given the complex components of traditional Chinese medicine, it is important to understand the effect of active ingredients on CYPs activity to guide their prescription. This study aimed to evaluate the effect of polyphyllin H on the activity of CYPs major isoforms providing a reference for the clinical prescription of polyphyllin H and its source herbs. The effects of polyphyllin H were evaluated in pooled human liver microsomes using probe substrates of CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 to determine their activities. The Lineweaver-Burk was used to model the inhibition, and a time-dependent inhibition experiment was performed to understand the characteristics of the inhibition. Polyphyllin H significantly suppressed the activity of CYP1A2, 2D6, and 3A4 with IC50 values of 6.44, 13.88, and 4.52 µM, respectively. The inhibition of CYP1A2 and 2D6 was best fitted with a competitive model, yielding the inhibition constant (Ki) values of 3.18 and 6.77 µM, respectively. The inhibition of CYP3A4 was fitted with the non-competitive model with the Ki value of 2.38 µM. Moreover, the inhibition of CYP3A4 was revealed to be time-dependent with the inhibition parameters inhibition constant (KI) and inactivation rate constant (Kinact) values of 2.26 µM-1 and 0.045 min-1. Polyphyllin H acted as a competitive inhibitor of CYP1A2 and 2D6 and a non-competitive and time-dependent inhibitor of CYP3A4.