Drug metabolism and transport mediated the hepatotoxicity of Pleuropterus multiflorus root: a review.

Pleuropterus multiflorus root (PMR, Polygoni Multiflori Radix) is an herbal medicine widely used in East Asia, particularly China. However, the potential hepatotoxicity has hindered its rational and safe application of PMR in clinical practice. Recently, the hepatotoxic study of PMR have made great progress, especially drug metabolism and transport-mediated liver injury. In this review, we summarized the advancement of drug metabolism and transport regluated hepatic injury of PMR, pointed out the key role of drug metabolizing enzymes and transporters in regulating hepatic injury of PMR, and emphasized the main hepatotoxic substances, toxicity promoter, and hepatic toxic substance-toxicity promoter interactions in PMR. On this basis, the clinical prospect of preventing and treating hepatic injury of PMR from the perspective of metabolism and transporter was discussed, to provide a useful reference and theoretical basis for the prevention and treatment of hepatic injury of PMR.

Generation and application of CES1-knockout Tet-Off-regulated CYP3A4 and UGT1A1-expressing Caco-2 cells.

Caco-2 cells, a human colorectal adenocarcinoma cell line, are widely used to model small intestinal epithelial cells in the drug development process because they can predict drug absorption with high accuracy. However, Caco-2 cells have several issues. First, Caco-2 cells have little expression of cytochrome P450 3A4 (CYP3A4), which is a major drug-metabolizing enzyme in the human intestine. We previously developed Caco-2 cells whose expression of CYP3A4 can be controlled using doxycycline (Dox) (CYP3A4-Caco-2 cells) (Ichikawa et al., Sci. Rep, 2021). However, since the Tet-On system was used to regulate CYP3A4 expression in these cells, there was concern about drug-drug interactions. The second issue is that in the human small intestine, carboxylesterase 2 (CES2) is more highly expressed than carboxylesterase 1 (CES1), while in Caco-2 cells CES1 is more highly expressed. The third issue is the low level expression of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1), a phase II drug-metabolizing enzyme. In this study, we used genome-editing technology to establish CES1-knockout Caco-2 cells whose CYP3A4 and UGT1A1 expression can be regulated by the Tet-Off system. These cell lines would be useful in pharmaceutical researches, including intestinal toxicological studies, as an in vitro model for orally administered drugs.

Systemic messenger RNA replacement therapy is effective in a novel clinically relevant model of acute intermittent porphyria developed in non-human primates.

OBJECTIVE: Acute intermittent porphyria (AIP) is a rare metabolic disorder caused by haploinsufficiency of hepatic porphobilinogen deaminase (PBGD), the third enzyme of the heme biosynthesis. Individuals with AIP experience neurovisceral attacks closely associated with hepatic overproduction of potentially neurotoxic heme precursors. DESIGN: We replicated AIP in non-human primates (NHPs) through selective knockdown of the hepatic PBGD gene and evaluated the safety and therapeutic efficacy of human PBGD (hPBGD) mRNA rescue. RESULTS: Intrahepatic administration of a recombinant adeno-associated viral vector containing short hairpin RNA against endogenous PBGD mRNA resulted in sustained PBGD activity inhibition in liver tissue for up to 7 months postinjection. The administration of porphyrinogenic drugs to NHPs induced hepatic heme synthesis, elevated urinary porphyrin precursors and reproduced acute attack symptoms in patients with AIP, including pain, motor disturbances and increased brain GABAergic activity. The model also recapitulated functional anomalies associated with AIP, such as reduced brain perfusion and cerebral glucose uptake, disturbances in hepatic TCA cycle, one-carbon metabolism, drug biotransformation, lipidomic profile and abnormal mitochondrial respiratory chain activity. Additionally, repeated systemic administrations of hPBGD mRNA in this AIP NHP model restored hepatic PBGD levels and activity, providing successful protection against acute attacks, metabolic changes in the liver and CNS disturbances. This approach demonstrated better efficacy than the current standards of care for AIP. CONCLUSION: This novel model significantly expands our understanding of AIP at the molecular, biochemical and clinical levels and confirms the safety and translatability of multiple systemic administration of hPBGD mRNA as a potential aetiological AIP treatment.

Distinct cellular uptake patterns of two anticancer unsymmetrical bisacridines and their metabolic transformation in tumor cells.

Unsymmetrical bisacridines (UAs) represent a novel class of anticancer agents. Their high cytotoxicity towards multiple human cancer cell lines and inhibition of human tumor xenograft growth in nude mice signal their potential for cancer treatment. Therefore, the mechanism of their strong biological activity is broadly investigated. Here, we explore the efflux and metabolism of UAs, as both strongly contribute to the development of drug resistance in cancer cells. We tested two highly cytotoxic UAs, C-2028 and C-2045, as well as their glucuronic acid and glutathione conjugates in human cancer cell lines (HepG2 and LS174T). As a point of reference for cell-based systems, we examined the rate of UA metabolic conversion in cell-free systems. A multiple reaction monitoring (MRM)-mass spectrometry (MS) method was developed in the present study for analysis of UAs and their metabolic conversion in complex biological matrices. Individual analytes were identified by several features: their retention time, mass-to-charge ratio and unique fragmentation pattern. The rate of UA uptake and metabolic transformation was monitored for 24 h in cell extracts and cell culture medium. Both UAs were rapidly internalized by cells. However, C-2028 was gradually accumulated, while C-2045 was eventually released from cells during treatment. UAs demonstrated limited metabolic conversion in cells. The glucuronic acid conjugate was excreted, whereas the glutathione conjugate was deposited in cancer cells. Our results obtained from cell-free and cell-based systems, using a uniform MRM-MS method, will provide valuable insight into the mechanism of UA biological activity in diverse biological models.

Drug Metabolizing Enzymes: An Exclusive Guide into Latest Research in Pharmaco-genetic Dynamics in Arab Countries.

Drug metabolizing enzymes play a crucial role in the pharmacokinetics and pharmacodynamics of therapeutic drugs, influencing their efficacy and safety. This review explores the impact of genetic polymorphisms in drug-metabolizing genes on drug response within Arab populations. We examine the genetic diversity specific to Arab countries, focusing on the variations in key drug-metabolizing enzymes such as CYP450, GST, and UGT families. The review highlights recent research on polymorphisms in these genes and their implications for drug metabolism, including variations in allele frequencies and their effects on therapeutic outcomes. Additionally, the paper discusses how these genetic variations contribute to the variability in drug response and adverse drug reactions among individuals in Arab populations. By synthesizing current findings, this review aims to provide a comprehensive understanding of the pharmacogenetic landscape in Arab countries and offer insights into personalized medicine approaches tailored to genetic profiles. The findings underscore the importance of incorporating pharmacogenetic data into clinical practice to enhance drug efficacy and minimize adverse effects, ultimately paving the way for more effective and individualized treatment strategies in the region.

Physiological and behavioural implications of the portosystemic shunt in C57Bl/6J mice.

A significant fraction of the popular inbred C57Bl/6J mice show structural and biochemical features of the congenital portosystemic shunt (PSS). How this hepatic abnormality affects physiological and behavioural parameters has not been explored in detail. Here, we confirmed the frequent occurrence of the PSS in C57Bl/6J mice by three different methods. We screened a cohort of 119 C57Bl/6J mice for total bile acids (TBA) in plasma, identified 11 animals (9.2%) with high TBA (>11 µm; 171.1 ± 76.8 µm), and confirmed PSS presence in that subset by magnetic resonance angiography and 1H-magnetic resonance spectroscopy of brain metabolites in the hippocampal area. In addition to the high glutamine and low myo-inositol levels, we detected lower levels of several neurotransmitters and metabolites in the hippocampus, higher brain weight and volume, as well as enhanced brain glucose utilisation in the PSS mice. We also observed differences in peripheral organ weights, haematological cell counts and clinical chemistry parameters in C57Bl/6J mice with and without PSS. Animals with PSS were slightly hyperlocomotive, had better balance on the rotarod, showed altered gait properties, and displayed attenuated fear memory in the fear conditioning test. Furthermore, we revealed a significant alteration of the pharmacokinetic profile of diazepam in C57Bl/6J mice with PSS. Our data support previous reports of hepatic disturbances and demonstrate an altered neurobiological phenotype in C57Bl/6J mice with PSS. Such congenital differences between inbred C57Bl/6J littermates may significantly distort experimental outcomes of pharmacological, behavioural and genetic studies. KEY POINTS: A significant proportion of C57Bl/6J mice, an inbred strain popular in preclinical research, have congenital portosystemic shunts (PSS) that allow venous blood to enter systemic circulation bypassing the liver. In this study, we extended existing knowledge of PSS consequences, particularly with respect to the effects on brain structure and function. We demonstrated that C57Bl/6J mice with PSS differ from their normal counterparts in brain size and contents of several neuroactive substances, as well as in peripheral organ weights, rate of glucose utilisation, blood cell counts and blood clinical chemistry parameters. C57Bl/6J mice with PSS showed altered locomotor behaviour, performed worse in a memory test and had abnormal blood pharmacokinetics of a benzodiazepine drug after a single administration. PSS presence may significantly complicate the interpretation of experiments in C57Bl/6J mice; therefore, we propose that before their use in biomedical studies, these mice should be screened with a simple blood test.

Disposition of Oral Nalbuphine and Its Metabolites in Healthy Subjects and Subjects with Hepatic Impairment: Preliminary Modeling Results Using a Continuous Intestinal Absorption Model with Enterohepatic Recirculation.

Nalbuphine (NAL) is a mixed κ-agonist/µ-antagonist opioid with extensive first-pass metabolism. A phase 1 open-label study was conducted to characterize the pharmacokinetics (PKs) of NAL and select metabolites following single oral doses of NAL extended-release tablets in subjects with mild, moderate, and severe hepatic impairment (Child-Pugh A, B, and C, respectively) compared to healthy matched subjects. NAL exposures were similar for subjects with mild hepatic impairment as compared to healthy subjects and nearly three-fold and eight-fold higher in subjects with moderate and severe hepatic impairment, respectively. Datasets obtained for healthy, moderate, and severe hepatic impaired groups were modeled with a mechanistic model that incorporated NAL hepatic metabolism and enterohepatic recycling of NAL and its glucuronidated metabolites. The mechanistic model includes a continuous intestinal absorption model linked to semi-physiological liver-gallbladder-compartmental PK models based on partial differential equations (termed the PDE-EHR model). In vitro studies indicated that cytochromes P450 CYP2C9 and CYP2C19 are the major CYPs involved in NAL oxidation, with glucuronidation mainly catalyzed by UGT1A8 and UGT2B7 isozymes. Complex formation and elimination kinetics of NAL and four main metabolites was well predicted by PDE-EHR. The model is expected to improve predictions of drug interactions and complex drug disposition.

The effect of gene polymorphism on ticagrelor metabolism: an in vitro study of 22 CYP3A4 variants in Chinese Han population.

Background: Ticagrelor is a novel oral antiplatelet agent which can selectively inhibit P2Y12 receptor. Bleeding and dyspnea are common adverse reactions of ticagrelor in clinic. The side effects of ticagrelor are correlated with the plasma concentration of ticagrelor. Objective: This study aimed to evaluate the catalytic characteristics of 22 CYP3A4 alleles identified in the Chinese Han population on the metabolism of ticagrelor in vitro, focusing on the effect of CYP3A4 polymorphism on ticagrelor metabolism. Methods: In this study, insect cells were used to express 22 CYP3A4 variants, which were then incubated with 1-50 µM ticagrelor at 37 °C for 30 minutes to obtain the metabolite (AR-C124910XX). AR-C124910XX was detected by UHPLC-MS/MS to calculate the kinetic parameters, including Km, Vmax and CLint. Results: Compared to the wild-type, most CYP3A4 alleles exhibited significant differences in intrinsic clearance. The intrinsic clearance of CYP3A4*11, *18 and *33 was much higher than that of wild-type; four variants exhibited similar intrinsic clearance values as the wild-type enzyme; The remaining 14 variants showed significantly reduced intrinsic clearance values, ranging from 1.48% to 75.11% of the wild-type; CYP3A4*30 displayed weak or no activity. Conclusion: This study conducted a comprehensive assessment of the effect of CYP3A4 variants on ticagrelor's metabolism. The results suggested that there is allele-specific activity towards ticagrelor in vitro. These findings can provide some insights and predictions for treatment strategies and risk assessments associated with ticagrelor in clinical practice.

IL-17A activates JAK/STAT signaling to affect drug metabolizing enzymes and transporters in HepaRG cells.

The founding family member, Interleukin (IL)-17A, is commonly known as IL-17 and has garnered increasingly attention for proinflammatory functions in autoimmune disorders. Although the effects of IL-17A on hepatic important drug-metabolizing enzymes and transporters (DMETs) expression still remain unclear, it is critical to ascertain owing to the well-established alterations of the drug disposition capacity of the liver occurring during immune imbalance. The present study was designed to explore the effects and mechanisms of IL-17A on DMETs mRNA and protein expression in HepaRG cells by real-time quantitative reverse transcription polymerase chain reaction and Western blot, respectively. It is discovered that IL-17A can inhibit most DMETs mRNA expression (drug-metabolizing enzymes of CYP1A2, CYP3A4, CYP2C9, CYP2C19, GSTA1 and UGT1A1 and transporters of NTCP, OCT1, OATP1B1, BCRP and MDR1) as well as the protein expression of CYP3A4 and CYP2C19, via the janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) signaling pathway. Thus, abnormal regulation of DMETs in IL-17A-mediated immune disorders such as psoriasis may cause alterations in pharmacokinetic processes and may occasionally result in unexpected drug-drug interactions (DDIs) in clinical practice.

Preclinical characterization of a water-soluble low-impact ampakine prodrug, CX1942 and its active moiety, CX1763.

Aim: AMPA-glutamate receptor (AMPAR) dysfunction mediates multiple neurological/neuropsychiatric disorders. Ampakines bind AMPARs and allosterically enhance glutamate-elicited currents. This report describes the activity of the water-soluble ampakine CX1942 prodrug and the active moiety CX1763.Results: CX1763 and CX1942 enhance synaptic transmission in hippocampi of rats. CX1763 increases attention in the 5CSRTT in rats and reduces amphetamine-induced hyperactivity in mice. CX1942 potently reverses opioid-induced respiratory depression in rats. CX1942/CX1763 was effective at 2.5-10 mg/kg. CX1763 lacked epileptogenicity up to 1500 mg/kg in rats.Conclusion: These data document that CX1942 and CX1763 are active and without prominent side effects in multiple pre-clinical assays. CX1942 could serve as a prodrug for CX1763 with the advantage of high water solubility as in an intravenous formulation.

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CYP3A-Mediated Carbon-Carbon Bond Cleavages in Drug Metabolism.

Cytochrome P450 enzymes (P450s) play a critical role in drug metabolism, with the CYP3A subfamily being responsible for the biotransformation of over 50% of marked drugs. While CYP3A enzymes are known for their extensive catalytic versatility, one intriguing and less understood function is the ability to mediate carbon-carbon (C-C) bond cleavage. These uncommon reactions can lead to unusual metabolites and potentially influence drug safety and efficacy. This review focuses on examining examples of C-C bond cleavage catalyzed by CYP3A, exploring the mechanisms, physiological significance, and implications for drug metabolism. Additionally, examples of CYP3A-mediated ring expansion via C-C bond cleavages are included in this review. This work will enhance our understanding of CYP3A-catalyzed C-C bond cleavages and their mechanisms by carefully examining and analyzing these case studies. It may also guide future research in drug metabolism and drug design, improving drug safety and efficacy in clinical practice.

UGT2B10 is the Major UDP-Glucuronosyltransferase 2B Isoform Involved in the Metabolism of Lamotrigine and is Implicated in the Drug-Drug Interaction with Valproic Acid.

Lamotrigine is a phenyltriazine anticonvulsant that is primarily metabolized by phase II UDP-glucuronosyltransferases (UGT) to a quaternary N2-glucuronide, which accounts for ~ 90% of the excreted dose in humans. While there is consensus that UGT1A4 plays a predominant role in the formation of the N2-glucuronide, there is compelling evidence in the literature to suggest that the metabolism of lamotrigine is catalyzed by another UGT isoform. However, the exact identity of the UGT isoform that contribute to the formation of this glucuronide remains uncertain. In this study, we harnessed a robust reaction phenotyping strategy to delineate the identities and its associated fraction metabolized (fm) of the UGTs involved in lamotrigine N2-glucuronidation. Foremost, human recombinant UGT mapping experiments revealed that the N2-glucuronide is catalyzed by multiple UGT isoforms. (i.e., UGT1A1, 1A3, 1A4, 1A9, 2B4, 2B7, and 2B10). Thereafter, scaling the apparent intrinsic clearances obtained from the enzyme kinetic experiments with our in-house liver-derived relative expression factors (REF) and relative activity factors (RAF) revealed that, in addition to UGT1A4, UGT2B10 was involved in the N2-glucuronidation of lamotrigine. This was further confirmed via chemical inhibition in human liver microsomes with the UGT1A4-selective inhibitor hecogenin and the UGT2B10-selective inhibitor desloratadine. By integrating various orthogonal approaches (i.e., REF- and RAF-scaling, and chemical inhibition), we quantitatively determined that the fm for UGT1A4 and UGT2B10 ranged from 0.42 - 0.64 and 0.32 - 0.57, respectively. Finally, we also provided nascent evidence that the pharmacokinetic interaction between lamotrigine and valproic acid likely arose from the in vivo inhibition of its UGT2B10-mediated pathway.

Emerging Pharmacotherapies for Obesity: A Systematic Review.

The history of anti-obesity pharmacotherapies is marked by disappointments, often entangled with societal pressure promoting weight loss and the conviction that excess body weight signifies a lack of willpower. However, categories of emerging pharmacotherapies generate hope to reduce obesity rates. This systematic review of phase 2 and phase 3 trials in adults with overweight/obesity investigates the effect of novel weight loss pharmacotherapies, compared to placebo/control or Food and Drug Administration-approved weight loss medication, through searching Medline, Embase, and ClinicalTrials.gov (2012-2024). We identified 53 phase 3 and phase 2 trials, with 36 emerging anti-obesity drugs or combinations thereof and four withdrawn or terminated trials. Oral semaglutide 50 mg is the only medication that has completed a phase 3 trial. There are 14 ongoing phase 3 trials on glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) (ecnoglutide, orforglipron, TG103), GLP-1 RA/amylin agonist (CagriSema), GLP-1/glucagon RAs (mazdutide, survodutide), GLP-1/glucose-dependent insulinotropic polypeptide and glucagon RA (retatrutide), dapagliflozin, and the combination sibutramine/topiramate. Completed phase 2 trials on incretin-based therapies showed a mean percent weight loss of 7.4-24.2%. Almost half of the drugs undergoing phase 2 trials were incretin analogs. The obesity drug pipeline is expanding rapidly, with the most promising results reported with incretin analogs. Data on mortality and obesity-related complications, such as cardio-renal-metabolic events, are needed. Moreover, long-term follow-up data on the safety and efficacy of weight maintenance with novel obesity pharmacotherapies, along with studies focused on under-represented populations, cost-effectiveness assessments, and drug availability, are needed to bridge the care gap for patients with obesity. Significance Statement Obesity is the epidemic of the 21st century. Except for the newer injectable medications, drugs with suboptimal efficacy have been available in the clinician's armamentarium. However, emerging alternatives of novel agents and combinations populate the obesity therapeutic pipeline. This systematic review identifies the state and mechanism of action of emerging pharmacotherapies undergoing or having completed phase 2 and phase 3 clinical trials. The information provided herein furthers the understanding of obesity management, implying direct clinical implications and stimulating research initiatives.

Functional significance of CYP2B6 gene rare allelic variants identified in Japanese individuals.

Cytochrome P450 2B6 (CYP2B6) catalyzes the metabolism of many drugs, including efavirenz and propofol. Genetic polymorphisms in CYP2B6 alter its enzymatic activity and substantially affect its pharmacokinetics. High-frequency variants, such as CYP2B6*6, are associated with the risk of developing side effects due to reduced CYP2B6 activity. However, the impact of rare alterations on enzyme function remains unknown, and some of these variants may significantly decrease the CYP2B6 activity. Therefore, in this study, we evaluated in vitro the functional alterations in 29 missense variants of the CYP2B6 gene identified in 8,380 Japanese individuals. Wild-type CYP2B6 and 29 rare CYP2B6 variants were transiently expressed in mammalian cells. The expression levels of variant CYP2B6 proteins in the microsomal fractions extracted from 293FT cells were assessed using western blotting and reduced-carbon monoxide difference spectroscopy, and a specific peak at 450 nm was detected in the wild-type and 19 variants. Furthermore, kinetic parameters were determined by assaying the reactions with efavirenz and propofol and quantifying the metabolite concentrations. We found that 12 variants had significantly lower or abolished enzymatic activity with both the substrates. In silico three-dimensional docking and molecular-dynamics simulations suggested that these functional changes were due to conformational changes in essential regions, such as the heme-binding site and ligand channels involved in transporting substrates to the active site. These findings have implications for predicting the plasma concentrations of CYP2B6 substrates and controlling their side effects.

The simultaneous inhibition of SLC6A19 and BCRP transporters leads to an increase of indoxyl sulfate (a uremic toxin) in plasma and kidney.

SLC6A19 inhibitors are being studied as therapeutic agents for Phenylketonuria. In this work, a potent SLC6A19 inhibitor (RA836) elevated rat kidney uremic toxin indoxyl sulfate (IDS) levels by intensity (arbitrary unit) of 13.7{plus minus}7.7 compared to vehicle 0.3{plus minus}0.1 (P=0.01) as determined by tissue mass spectrometry imaging (tMSI) analysis. We hypothesized that increased plasma and kidney levels of IDS could be caused by the simultaneous inhibition of both Slc6a19 and a kidney IDS transporter responsible for excretion of IDS into urine. To test this, we first confirmed the formation of IDS through tryptophan metabolism by feeding rats a Trp-free diet. Inhibiting Slc6a19 with RA836 led to increased IDS in these rats. Next, RA836 and its key metabolites were evaluated in vitro for inhibiting kidney transporters OAT1, OAT3 and BCRP. RA836 inhibits BCRP with an IC50 of 0.045 µM but shows no significant inhibition of OAT1 or OAT3. Finally, RA836 analogs with either potent or no inhibition of SLC6A19 and/or BCRP were synthesized and administered to rats fed a normal diet. Plasma and kidney samples were collected to quantify IDS using LC-MS. Neither a SLC6A19 inactive but potent BCRP inhibitor nor a SLC6A19 active but weak BCRP inhibitor raised IDS levels, while compounds inhibiting both transporters caused IDS accumulation in rat plasma and kidney, supporting the hypothesis that rat Bcrp contributes to the excretion of IDS. In summary, we identified that inhibiting Slc6a19 increases IDS formation, while simultaneously inhibiting Bcrp results in IDS accumulation in the kidney and plasma. Significance Statement This is the first publication to decipher the mechanism for accumulation of IDS (a uremic toxin) in rats via inhibition of both Slc6a19 and Bcrp. Specifically, inhibition of Slc6a19 in the GI track increases IDS formation and inhibition of Bcrp in the kidney blocks IDS excretion. Therefore, we should avoid inhibiting both SLC6A19 and BCRP simultaneously in humans to prevent accumulation of IDS, a known risk factor for cardiovascular disease, psychic anxiety, and mortality in chronic kidney disease patients.

Adipocyte maturation impacts daunorubicin disposition and metabolism.

INTRODUCTION: Acute lymphoblastic leukaemia (ALL) is the most common type of childhood leukaemia with effective chemotherapeutic treatment. However, obesity has been associated with higher ALL chemoresistance rates and lower event-free survival rates. The molecular mechanism of how obesity promotes chemotherapy resistance is not well delineated. OBJECTIVES: This study evaluated the effect of adipocyte maturation on sequestration and metabolism of chemotherapeutic drug daunorubicin (DNR). METHODS: Using targeted LC-MS/MS multi-analyte assay, DNR sequestration and metabolism were studied in human preadipocyte and adipocyte cell lines, where expressions of DNR-metabolizing enzymes aldo-keto reductases (AKR) and carbonyl reductases (CBR) were also evaluated. In addition, to identify the most DNR-metabolizing AKR/CBR isoforms, recombinant human AKR and CBR enzymes were subject to DNR metabolism. The results were further validated by AKR-, CBR-specific inhibitors. RESULTS: This report shows that adipocyte maturation upregulates expressions of AKR and CBR enzymes (by 4- to 60- folds, p < .05), which is positively associated with enhanced sequestration and metabolism of DNR in adipocytes compared to preadipocytes (by ~30%, p < .05). In particular, adipocyte maturation upregulates AKR1C3 and CBR1, which are the predominate metabolic enzyme isoforms responsible for DNR biotransformation to its metabolites. CONCLUSION: Fat is an expandable tissue that can sequester and detoxify DNR when stimulated by obesity, likely through the upregulation of DNR-metabolizing enzymes AKR1C3 and CBR1. Our data partially explains why obese ALL patients may be more likely to become chemoresistant towards DNR, and provides evidence for potential clinical investigation targeting obesity to reduce DNR chemoresistance.

Altered Levels of Gene Expression of Drug Metabolism Enzymes in Rat Brain Following Kainic Acid Treatment.

Objectives: Previous studies have shown that gene expressions can be regulated in the hippocampus of rats after seizures induced by kainic acid (KA). The aim of this study was to examine the potential regulatory impact of KA administration on gene expression levels of enzymes responsible for drug metabolism in rat hippocampal tissue. Materials and Methods: Rats received intraperitoneal injections of KA and saline at a dose of 10 mg/kg. Behavioral changes were observed in experimental animals following the administration of KA. Four hours after receiving treatments, all rats were decapitated, and the brains were removed. Hippocampal tissues were used for total RNA isolation, and cDNA synthesis was performed by reverse transcription polymerase chain reaction (PCR). Gene expression levels of enzymes responsible for drug metabolism were determined by quantitative PCR using the RT2 Profiler PCR Array Rat Drug Metabolism PCR array system containing the relevant primers for a total of 84 genes. The gene expression levels of drug-metabolizing enzymes were quantified using the comparative Ct (2-ΔΔ(delta delta)Ct) method. The Student's t-test was used for data analysis. Results: Our results indicate that KA treatment caused significant changes in the gene expression levels of metallothionein 3, glucose phosphate isomerase, adenosine triphosphate-binding cassette protein C1, cytochrome P450 enzymes (Cyp2c6v1, Cyp3a23/3a1, Cyp2c7), glutathione peroxidase 1, 4, and 5, glutamic acid decarboxylase 1 and 2, paraoxonase 2, carbohydrate sulfotransferase 1, glutathione S-transferases (Gsta3, Gstm1, Gstm4), microsomal glutathione S-transferase 3, carboxylesterase 2C, fatty acid amide hydrolase, pyruvate kinase-muscle, arachidonate 5-lipoxygenase, apolipoprotein E, cytochrome b5 reductase 5, xanthine dehydrogenase, N-acetyltransferase 1, glucokinase regulator, hexokinase 2, myristoylated alanine rich protein kinase C substrate, and stannin in the hippocampus compared with the control (p < 0.05). Conclusion: As a conclusion, it can be said that the seizure activity triggered by KA has the potential to change the gene expression levels of the enzymes responsible for drug metabolism in the hippocampus of rats.

Evolution, Structure, and Drug-Metabolising Activity of Mammalian Prenylcysteine Oxidases.

Prenylcysteine oxidases (PCYOXs) metabolize prenylated cysteines produced by protein degradation. They utilize oxygen as co-substrate to produce free cysteine, an aldehyde, and hydrogen peroxide through the unusual oxidation of a thioether bond. In this study, we explore the evolution, structure, and mechanism of the two mammalian PCYOXs. A gene duplication event in jawed vertebrates originated these two paralogs. Both enzymes are active on farnesyl- and geranylgeranylcysteine, but inactive on molecules with shorter prenyl groups. Kinetics experiments outline a mechanism where flavin reduction and re-oxidation occur rapidly without any detectable intermediates, with the overall reaction rate limited by product release. The experimentally determined three-dimensional structure of PCYOX1 reveals long and wide tunnels leading from the surface to the flavin. They allow the isoprene substrate to curl up within the protein and position its reactive cysteine group close to the flavin. A hydrophobic patch on the surface mediates membrane association, enabling direct substrate and product exchange with the lipid bilayer. Leveraging established knowledge on flavoenzyme inhibition, we designed sub-micromolar PCYOX inhibitors. Additionally, we discovered that PCYOXs bind and slowly degrade salisirab, an anti-RAS compound. This activity suggests potential and previously unknown roles of PCYOXs in drug metabolism.

Effects of compound probiotics on pharmacokinetics of CYP450s probe drugs in rats.

Compound probiotics have been widely used and commonly co-administered with other drugs for treating various chronic illnesses, yet their effects on drug pharmacokinetics remain underexplored. This study elucidated the impact of VSL#3 on the metabolism of probe drugs for cytochrome P450 enzymes (CYP450s), specifically omeprazole, tolbutamide, midazolam, metoprolol, phenacetin and chlorzoxazone. Male Wistar rats were administered with drinking water containing VSL#3 or not for 14 days and then intragastrically administered a CYP450s probe cocktail; This was done to investigate the host CYP450s metabolic phenotype. Stool, liver/jejunum and serum samples were collected for 16S rRNA sequencing, RNA sequencing, and bile acid profiling. The results indicated significant differences in both alpha and beta diversity of intestinal microbial composition between the probiotic and vehicle groups in rats. In the probiotic group, the bioavailability of omeprazole increased by 269.9%, whereas those of tolbutamide and chlorpropamide decreased by 28.1% and 27.4%, respectively. The liver and jejunum exhibited 1,417 and 4,004 differentially expressed genes, respectively, between the two groups. In the probiotic group, most of CYP450s genes were upregulated in the liver but downregulated in the jejunum. The expression of genes encoding metabolic enzymes and drug transporters also changed. The serum conjugated bile acids in the probiotic group were significantly reduced. Shorter duodenal villi and longer ileal villi were found in the probiotic group. In summary, VSL#3 administration altered the gut microbiota, host drug-processing gene expression, and the intestinal structure in rats, which could be reasons for pharmacokinetic changes. Significance Statement This study focused on the effects of the probiotic VSL#3 on the pharmacokinetic profile of CYP450s probe drugs and the expression of host drug metabolism genes. Compared with previous studies, the current study provides a comprehensive explanation for the host drug metabolism profile modified by probiotics, here combined with the bile acid profile and histopathological analysis.