Search Results (59)

Background/Objectives: Atrasentan is a selective endothelin A receptor antagonist (SERA) developed as a potential therapy for chronic renal diseases, including diabetic nephropathy and immunoglobulin A nephropathy. Despite this potential, understanding its metabolic bioactivation is essential for assessing the risks of drug-induced liver injury (DILI). However, the metabolic profile of atrasentan remains poorly characterized, and the mechanisms underlying its potential hepatotoxicity remain underexplored. Therefore, this study aims to investigate the metabolic pathways of atrasentan in human liver microsomes (HLMs) in the presence of nicotinamide adenine dinucleotide phosphate (NADP⁺), uridine diphosphate glucuronic acid (UDPGA), or glutathione (GSH). Methods: A liquid chromatography–high resolution mass spectrometry (LC-HRMS) coupled with a feature-based molecular networking approach was used to characterize metabolites. Characterization of the major metabolites was achieved through cytochrome P450 (P450) phenotyping with human recombinant P450 isoforms. Results: A total of eighteen metabolites were characterized through phase I and II metabolic reactions, including demethylenation, N-dealkylation, O-demethylation, hydroxylation, dehydrogenation, and glucuronidation. Atrasentan acyl glucuronide (M8) was confirmed as the predominant metabolite, and we also putatively annotated a catechol intermediate (M5) and its corresponding GSH conjugate (M15). Characterizing the GSH conjugate (M15) indicates that catechol intermediate (M5) can be further oxidized to a reactive ortho-quinone intermediate, which is subsequently trapped by GSH, suggesting the potential for a bioactivation mechanism. Reaction phenotyping demonstrated that the formation of M5 is catalyzed almost exclusively by the CYP3A subfamily. However, its direct translation to in vivo oxidative stress or covalent protein binding requires further studies. Conclusions: These findings demonstrate that feature-based molecular networking is a valuable strategy for metabolite characterization, underscoring the urgent need for further in vivo metabolism studies to definitively assess hepatotoxic risks associated with these reactive metabolites. Full article

Background/Objectives: Eudesmin is a tetrahydrofurofuranoid lignan known for its diverse pharmacological activities, including anti-tumor, anti-inflammatory, and neuroprotective effects. However, its metabolism has not been well characterized. Methods: This study examined the in vitro metabolism of eudesmin using human and mouse hepatocytes, human liver microsomes, and recombinant drug-metabolizing enzymes. Liquid chromatography–high-resolution mass spectrometry combined with ion identity molecular networking enabled the comprehensive visualization and annotation of eudesmin metabolites. Results: Eudesmin exhibited moderate metabolic stability in human and mouse hepatocytes, with half-lives of 181.0 min and 132.9 min, and intrinsic clearance values of 27.7 mL/min/kg and 154.0 mL/min/kg, respectively. Incubation of eudesmin with human hepatocytes resulted in the formation of 13 metabolites, including five phase I metabolites (M1–M5) and eight phase II conjugates. Phase I metabolism was dominated by O-demethylation of the 3,4-dimethoxyphenyl moieties, yielding mono-O-demethylated (M1 and M2) and di-O-demethylated metabolites (M3 and M4), as well as a hydroxylated metabolite (M5). Enzyme phenotyping, kinetic analyses, and chemical inhibition experiments identified cytochrome P450 2C9 (CYP2C9) as the major contributor to O-demethylation, with additional contributions from CYP2C19, CYP2C8, CYP3A4, and CYP3A5, whereas hydroxylation was mediated primarily by CYP3A4 and CYP3A5. The O-demethylated metabolites subsequently underwent phase II metabolism, forming glucuronide conjugates of M1–M4 and sulfate conjugates of M1–M3, including a disulfate of M3. Uridine 5′-diphospho-glucuronosyltransferase and sulfotransferase screening revealed the involvement of multiple conjugative enzymes, indicating extensive and distributed phase II metabolism. Specifically, di-O-demethylated metabolites and their conjugates were detected in human hepatocytes but not in mouse hepatocytes, suggesting that the sequential O-demethylation pathway is limited in mice. Conclusions: This study characterizes eudesmin metabolism, with CYP2C9-mediated O-demethylation and significant species differences between humans and mice, and provides a basis for its further pharmaceutical development. Full article

Maclekarpine E is a minor alkaloid from Macleaya species with reported in vitro anti-inflammatory activity, but its in vivo metabolism remains unexplored. This study investigated the metabolic fate of maclekarpine E in rats and evaluated the potential pharmacological relevance of its metabolites. Maclekarpine E was orally administered to male Sprague-Dawley rats (250 mg/kg). Plasma, urine and feces were collected and analyzed by UPLC-Q-TOF-MS/MS. CYP phenotyping was performed using recombinant human enzymes. Molecular docking against ABCG2 and ABCC2 was conducted to assess potential interactions of all fecal compounds with these efflux transporters. Network pharmacology was employed to predict potential anti-ulcerative colitis-related targets of the metabolites, generating hypotheses for future experimental validation. Nineteen phase I metabolites were identified. Biotransformations included ring-opening, demethylation and oxidation. All 19 metabolites were detected in feces, nine in plasma and two in urine. No phase II conjugates were observed. CYP2C19 was the only significantly active isoform under the tested conditions, mediating approximately 16.5% substrate depletion (p < 0.05). All 20 fecal compounds bound ABCG2 (ΔG < −5.0 kcal/mol); 19 bound ABCC2. Network pharmacology yielded 57 overlapping targets with ulcerative colitis, enriched in PI3K-Akt and MAPK pathways. This study provides the first comprehensive metabolic profile of maclekarpine E in rats. The compound undergoes CYP2C19-mediated oxidation and is predominantly excreted into feces. Its fecal metabolites are potential ABCG2/ABCC2 substrates and may target UC-associated pathways based on network pharmacology predictions, warranting further experimental validation. Full article

Background/Objectives: Flavonoids are widely used as lead structures in drug discovery, and their pharmacological and metabolic properties are strongly influenced by structural features such as positional isomerism. This study aimed to compare the metabolic profiles and underlying mechanisms of two isoflavone-based positional isomers, ACF-02 (2-(4-hydroxy-3-methoxyphenyl)-6,7-dimethoxy-3-(4-methoxyphenyl)-4H-chromen-4-one) and ACF-03 (2-(3-hydroxy-4-methoxyphenyl)-6,7-dimethoxy-3-(4-methoxyphenyl)-4H-chromen-4-one). Methods: The metabolic pathways of synthetically prepared ACF-02 and ACF-03 were investigated using an in vitro incubation system with human liver microsomes (HLMs) supplemented with an NADPH-regenerating system, followed by liquid chromatography–high-resolution tandem mass spectrometry (LC–HRMS/MS) analysis. Metabolites were identified based on LC–HRMS/MS data and molecular networking-based node connectivity with the parent compounds. Major metabolites were further characterized by CYP phenotyping using recombinant CYP450 isoforms, and the potential for drug–drug interactions of ACF-03 was evaluated using a CYP probe substrate cocktail approach. Results: HLM incubation of ACF-02 and ACF-03 produced both hydroxylated and O-demethylated metabolites, with O-demethylation as the predominant pathway; notably, the most abundant O-demethylated metabolite differed in an isomer-dependent manner, occurring at the B₂ ring for ACF-02 and at the A ring for ACF-03, with distinct CYP isoform involvement. Molecular networking supported the relationships between the parent compounds and their metabolites, and both compounds exhibited relatively high metabolic stability with limited CYP inhibition. Conclusions: Despite differing only in the position of a single methyl substituent, ACF-02 and ACF-03 exhibited distinct isomer-dependent metabolic profiles. These findings demonstrate that even subtle positional isomerism can significantly influence metabolic behavior and should be carefully considered during lead optimization and drug design. Full article

Background/Objectives: Cytochrome P450 (CYP) enzymes are crucial for drug metabolism, yet inter-individual variability in their activity remains a significant clinical challenge. Current phenotyping methods are often impractical or even impossible, particularly in forensic toxicology and vulnerable populations. This proof-of-concept study investigated the feasibility of using in vitro assays with human liver microsomes (HLM) and recombinant CYP enzymes (isoenzymes), combined with untargeted metabolomics, to identify potential endogenous biomarker candidates indicative of CYP phenotype. Methods: This study uses in vitro incubations of HLM and isoenzymes in tandem with targeted and untargeted LC-(HR)MS and metabolomics techniques as well as statistical processing. Results: We demonstrate that HLM and isoenzymes maintain activity in the presence of complex biological matrices (blood/plasma), enabling metabolomic profiling. Untargeted analysis of assays in plasma revealed numerous potential biomarkers, with several showing significant correlations to enzyme activity. Conclusions: While identification remains the major challenge, this approach offers a promising avenue for developing accessible and efficient methods for indirect CYP phenotyping, potentially facilitating investigations in scenarios where traditional approaches are limited. This work provides a foundation for future studies focused on further developing in vitro assays and validating the proposed biomarkers, as well as establishing their utility in clinical and forensic settings. Full article

Background/Objectives: Although several studies have been reported on the modulation of Cytochrome P450 by resveratrol, inconsistencies in the results obtained require further investigation. Here, we report the results of in vivo and in vitro experiments investigating the effect of resveratrol on CYP1A2, which participates in the biotransformation of several drugs used for the treatment of human malignancies. Methods: Male Wistar rats were exposed to resveratrol through diet (1%) for 30 days, and the hepatic CYP1A2 activity and protein concentration were assayed at the end of the treatment. Additionally, the capacity of the phytochemical to interfere with the induction of CYP1A2 by benzo[a]pyrene (50 mg/kg body weight) was also studied. The inhibition of CYP1A2 activity in rat liver microsomal and recombinant human enzymes by resveratrol, as well as its inhibitory kinetics and type of inhibition, were compared. Results: No significant increase in the protein concentration of hepatic CYP1A2 was found in resveratrol-treated rats, but it induces CYP1A2 activity and enhances the induction effect of benzo[a]pyrene. In silico and in vitro experiments demonstrated that resveratrol binds to the active site of human CYP1A2 through hydrophobic interactions with PHE125, PHE226, PHE260, and ALA317, and hydrogen bonds with SER122 and ASP313. It inhibits human recombinant CYP1A2 activity as well as that in rat liver microsomes, with IC₅₀ values of 46 µM and 485 µM, respectively. Resveratrol showed a mixed type of inhibition of recombinant human protein and a competitive inhibition of rat liver microsomal CYP1A. Conclusions: We can conclude that resveratrol is an in vitro inhibitor of CYP1A2, but it increases the benzo[a]pyrene CYP induction effect in vivo. Full article

Hypersensitized P2X3 receptor signaling has been described to play a role in several disorders, including chronic cough. The goal of our in vitro and in vivo studies was to investigate the biotransformation and the influence of CYP3A4 inhibition on the pharmacokinetics of the selective P2X3 antagonist filapixant. Metabolic turnover of filapixant in human liver microsomes and hepatocytes was moderate to high, indicating a complex metabolic pattern with mainly oxidative biotransformation. In recombinant CYP enzymes, depletion of filapixant was observed mainly with CYP3A4 and, to a significantly lesser extent, with CYP1A1, 2D6, 2J2, and 3A5. Drug depletion of [³H]filapixant and metabolite formation in human liver microsomes was significantly inhibited in the presence of strong CYP3A4 inhibitors, whereas other CYP isoform–selective inhibitors showed no or very minor effects. Co-administration of multiple daily doses of 200 mg itraconazole with 80 mg filapixant in humans increased the AUC and C_max of filapixant to 4.01 and 1.89-fold, respectively, indicating that filapixant is a moderately sensitive CYP3A4 substrate. Co-administration of itraconazole also prolonged the half-life of filapixant from 12.1 h to 22.8 h. Overall, changes in AUC, C_max, and half-life indicate that both the bioavailability and elimination of filapixant were affected. Filapixant was well tolerated alone and in combination with itraconazole. Full article

Theaflavins, benzotropolone compounds formed during black tea processing via catechin condensation, have drawn attention for their potential health benefits and diverse biological effects. This study evaluated the inhibitory effects of four theaflavin monomers—theaflavin-3′-gallate, theaflavin-3,3′-digallate, theaflavin-3-gallate, and theaflavin—on eight CYP450 enzymes using pooled human liver microsomes and specific probe substrates, and seven UGT enzymes using human recombinant UGT enzymes and specific probe substrates. Theaflavin-3′-gallate moderately inhibited CYP1A2-catalyzed phenacetin metabolism and CYP2C8-mediated amodiaquine metabolism, with IC₅₀ values of 8.67 μM and 10–20 μM, respectively. Theaflavin-3,3′-digallate exhibited similar effects. Both compounds showed negligible inhibition with other CYP enzymes. In UGT assays, theaflavin-3′-gallate and theaflavin-3,3′-digallate moderately inhibited UGT1A1- and UGT1A3-mediated beta-estradiol glucuronidation (IC₅₀: 1.40–5.22 μM), with weak or no effects on other UGT enzymes. Molecular docking revealed that CYP1A2-theaflavin-3′-gallate and CYP2C8-theaflavin-3,3′-digallate interactions were non-competitive, primarily mediated by hydrogen bonding and π-interactions. UGT1A1-theaflavin interactions suggested non-competitive inhibition, while UGT1A3-theaflavin interactions indicated competitive inhibition. Other enzyme-theaflavin interactions exhibited minimal binding energy differences, implying mixed-type inhibition. These findings highlight the selective inhibitory effects of theaflavins on specific hepatic enzymes, with potential implications for nutrient interactions, particularly for nutrients metabolized by CYP1A2, CYP2C8, UGT1A1, and UGT1A3. Further research is needed to explore the in vivo relevance and assess the dietary implications of theaflavin-rich black tea in nutrition and metabolism. Full article

Aspergillus flavus and its secondary metabolites aflatoxins pose a significant threat to the health of humans, animals, and plants. Therefore, there is an urgent need to control A. flavus contamination. AfverB plays a key role in the aflatoxin gene cluster; however, its function and mechanism in fungal development and virulence remain poorly understood. In this study, we constructed afVerB gene deletion mutants (∆afVerB−1 and ∆afVerB−2) and two CYP domain mutants (afVerB^∆D1 and afVerB^∆D2) through homologous recombination. Phenotype analysis revealed that, via its two CYP domains, AfVerB is deeply involved in fungal morphogenesis and aflatoxin synthesis. Insect and crop colonization models revealed that AfVerB plays a key role in the fungus’s ability to infect hosts, and stress experiments discovered that AfVerB plays a significant role in the response to various environmental stresses, which explains why AfVerB is a key factor in fungal infection to some extent. RT-qPCR analysis demonstrated that AfVerB performs its bio-function through corresponding regulatory factors. We ultimately discovered that AfVerB is deeply involved in cell membrane stress stability, thereby participating in the regulation of fungal drug resistance (sensitive to AMB and resistant to VOR in this study). The CYP domain of AfVerB, particularly its second CYP domain, is crucial for the execution of its biological functions. This study elucidated the regulatory mechanisms by which AfVerB regulates fungal pathogenicity and aflatoxin biosynthesis, providing potential strategies for controlling A. flavus and its aflatoxin contamination. Full article

Background/Objectives: Perillyl alcohol (POH), a monoterpene natural product derived from the essential oils of plants such as perilla (Perilla frutescens), is currently in phase I and II clinical trials as a chemotherapeutic agent. In this study, we investigated the effect of POH on cytochrome P450 (CYP) activity for evaluating POH–drug interaction potential. Methods: The investigation was conducted using pooled human liver microsomes (HLMs), recombinant CYP3A4 (rCYP3A4) enzymes, and human pluripotent stem cell-derived hepatic organoids (hHOs) employing liquid chromatography-tandem mass spectrometry. Results: POH inhibited the activities of CYP2A6 and CYP2B6 with K_i of 6.35 and 3.78 μM, respectively, whereas it stimulated CYP3A4 activity in pooled HLMs incubated with midazolam (MDZ). In a direct CYP inhibition assay using HLMs, activities of CYP2C9, CYP2C19, and CYP2E1 were also inhibited by POH, with IC₅₀ values greater than 50 μM, but those of CYP1A2, CYP2C8, CYP2D6, and CYP3A4 (testosterone) were not significantly inhibited. In pooled HLMs, the V_max/K_m value of 1′-hydroxy MDZ, but not that of 4-hydroxy MDZ, was increased 2.7-fold by 100 μM POH compared with that in the absence of POH. Moreover, stimulation of MDZ 1′-hydroxylation by CYP3A4 was observed in hHOs and rCYP3A4 with cytochrome b₅ but not rCYP3A4 without cytochrome b₅. Furthermore, activation of CYP3A4-mediated metabolism by POH was observed in HLMs incubated with fimasartan but not atorvastatin, buspirone, donepezil, nifedipine, or tadalafil, suggesting a substrate-dependent activation of CYP3A4 by POH. Conclusions: POH inhibits CYP2A6 and CYP2B6, but it activates CYP3A4. These findings underscore the need for further evaluation of the interactions of clinical drugs with POH. Full article

Activin is a dimeric growth factor with diverse biological activities in vertebrates. This study aimed to investigate the regulatory role of the activin signaling pathway in the ovary of the endangered, cultured sturgeon species Acipenser sinensis. One activinβA subunit was identified, with a full-length complementary DNA (cDNA) sequence of 1572 base pairs. Multiple sequence alignment suggested that ActivinβA shared high sequence identities with its counterparts in four other sturgeon species. Phylogenetic analysis indicated the conserved evolution of ActivinβA among vertebrates from mammals to fish species. Transcripts of activinβA were distributed ubiquitously in the liver, kidney, intestine, ovary, midbrain, hypothalamus, and pituitary, with the highest transcription found in the pituitary. In Chinese sturgeon ovarian cells, in vitro human recombinant Activin A incubation stimulated the activin system-related gene transcriptions of activinβA, follistatin, its receptors -activinRIIA and activinRIIB, and drosophila mothers against decapentaplegic proteins (smads) smad2, smad3, and smad4. Ovary development-related mRNA levels of cyp19a1a and aromatase receptors of erα and erβ were enhanced by Activin A or human chorionic gonadotropin (hCG) incubation. Furthermore, 15 IU/mL hCG treatment increased the transcription levels of activinβA, follistatin, activinRIIA, and smad2. This suggested that the activin system was functional for the regulation of ovary development in Chinese sturgeon, possibly under the regulation of gonadotropin, by recruiting activinβA, follistatin, activinRIIA, and smad2. These results were helpful for the molecular exploration of activin signaling in fish species, as well as the ovarian maturation regulation of A. sinensis. Full article

[2,3-diamino-N-(4-(benzo[d]thiazol-2-yl)phenyl)propanamide], named as ETN101, is a novel therapeutic agent for hepatocellular carcinoma. In vitro studies examined ETN101 metabolites in human, mouse, rat, dog, and monkey hepatocytes and identified the drug-metabolizing enzymes involved using cDNA-expressed human recombinant cytochrome P450s (CYPs), carboxylesterases (CESs), N-acetyltransferase (NAT) 1, and human liver cytosol. ETN101 showed similar metabolic stability across hepatocytes from five species, with particularly comparable stability in humans, rats, and monkeys. Its half-life was 75.0 min in humans, 68.9 in rats, 73.1 in monkeys, 120.4 in mice, and 112.7 in dogs. Thirty-four ETN101 metabolites, including the major metabolite M1, were identified using liquid chromatography–high-resolution mass spectrometry. ETN101 was primarily metabolized to M1 and CYP1A2 is exclusively responsible for M1 metabolism. Both NAT1 and NAT2 were responsible for the N-acetylation of M1 to M2. ETN101 remained stable in human CESs. In conclusion, this study provides comprehensive insights into the metabolic characteristics of ETN101, valuable for its toxicological and clinical development. Full article

The objective of the study was to evaluate the profile and diagnostic significance of serum autoantibodies in infertile patients with premature ovarian insufficiency (POI). The pilot study included 26 patients of reproductive age with POI and diminished ovarian reserve who received complex treatment using new surgical technologies (Group 1) and 18 patients without POI (Group 2). The profile of serum autoantibodies, including anti-ovarian antibodies, antibodies against thyroid peroxidase (TPO), steroidogenic enzymes, and steroid and gonadotropic hormones, was studied using modified ELISAs and human recombinant steroidogenic enzymes (CYP11A1, CYP19A1, CYP21A2). Patients in Group 1 had higher levels of IgG autoantibodies against steroidogenic enzymes, estradiol, progesterone, and TPO than those in Group 2. Tests for IgG antibodies against CYP11A1, CYP19A1, and CYP21A2 exhibited high sensitivity (65.4–76.9%), specificity (83.3–89.9%), and AUC values (0.842–0.910) for POI, the highest in the first test. Three-antibodies panel screening showed higher diagnostic accuracy (84.1% versus 75–79.6%). The levels of these antibodies correlated with menstrual irregularities and a decrease in the antral follicle count. Thus, antibodies against CYP11A1, CYP19A1, and CYP21A2 have a high diagnostic value for POI. Three-antibody panel screening may improve the accuracy of POI diagnosis and be useful for identifying high-risk groups, early stages of the disease, and predicting POI progression. Full article

Hydroxy-α-sanshool (HAS) is the predominant active compound in Zanthoxylum bungeanum Maxim (ZBM). Our present work was aimed to explore the in vitro metabolism characteristics, and in vivo pharmacokinetic (PK) profile of HAS. Plasma (human), liver microsomes, and hepatocytes (human, monkey, dog, mouse, and rat) were collected for HAS metabolism studies in vitro and HAS elimination rates in liver microsomes and hepatocytes of different species were investigated. In addition, five recombinant human CYP enzymes were used to identify CYP isoforms of HAS. Finally, the PK properties of HAS in rats in vivo were studied by oral administration (p.o.). The results showed that HAS stably metabolized in human and rat liver microsomes and human hepatocytes, and the binding of HAS to human plasma proteins was nonspecific; HAS has strong inhibitory effects on CYP2C9 and CYP2D6 of human liver microsomes. In addition, in vivo PK study, HAS is rapidly absorbed in rats after oral administration. In conclusion, the in vivo and in vitro metabolic studies of HAS in this study provide data support for its further development and application, and the metabolic profiles of different species can be used as a reference for its safety evaluation. Full article

Several studies utilizing Rhodiola rosea, which contains a complex mixture of phytochemicals, reported some positive drug-drug interaction (DDI) findings based on in vitro CYP450’s enzyme inhibition, MAO-A and MAO-B inhibition, and preclinical pharmacokinetic studies in either rats or rabbits. However, variation in and multiplicity of constituents present in Rhodiola products is a cause for concern for accurately evaluating drug-drug interaction (DDI) risk. In this report, we examined the effects of bioengineered, nature-identical salidroside on the inhibition potential of salidroside on CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 utilizing human liver microsomes, the induction potential of salidroside on CYP1A2, CYP2B6 and CYP3A4 in cryopreserved human hepatocytes, the inhibitory potential of salidroside against recombinant human MAO-A and MAO-B, and the OATP human uptake transport inhibitory potential of salidroside using transfected HEK293-OATP1B1 and OATP1B3 cells. The results demonstrate that the bioengineered salidroside at a concentration exceeding the predicted plasma concentrations of <2 µM (based on 60 mg PO) shows no risk for drug-drug interaction due to CYP450, MAO enzymes, or OATP drug transport proteins. Our current studies further support the safe use of salidroside in combination with other drugs cleared by CYP or MAO metabolism or OATP-mediated disposition. Full article