scholarly journals Atropselective Oxidation of 2,2’,3,3’,4,6’-Hexachlorobiphenyl (PCB 132) to Hydroxylated Metabolites by Human Liver Microsomes and Its Implications for PCB 132 Neurotoxicity

2018 ◽  
Author(s):  
Eric Uwimana ◽  
Brianna Cagle ◽  
Coby Yeung ◽  
Xueshu Li ◽  
Eric V. Patterson ◽  
...  
Keyword(s):  
Individual Differences ◽  
Human Liver ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Limited Information ◽  
Cellular Targets ◽  
Dopaminergic Cells ◽  
Single Donor ◽  
Metabolite Profiles ◽  
Arene Oxide

ABSTRACTPolychlorinated biphenyls (PCBs) have been associated with neurodevelopmental disorders. Several neurotoxic congeners display axial chirality and atropselectively affect cellular targets implicated in PCB neurotoxicity. Only limited information is available regarding the atropselective metabolism of these congeners in humans and their atropselective effects on neurotoxic outcomes. Here we investigate the hypothesis that the oxidation of 2,2’,3,3’,4,6’-hexachlorobiphenyl (PCB 132) by human liver microsomes (HLMs) and their effects on dopaminergic cells in culture are atropselective. Racemic PCB 132 was incubated with pooled or single donor HLMs, and levels and enantiomeric fractions of PCB 132 and its metabolites were determined gas chromatographically. The major metabolite was either 2,2’,3,4,4’,6’-hexachlorobiphenyl-3’-ol (3’-140), a 1,2-shift product, or 2,2’,3,3’,4,6’-hexachlorobiphenyl-5’-ol (5’-132). The PCB 132 metabolite profiles displayed inter-individual differences and depended on the PCB 132 atropisomer. Computational studies demonstrated that 3’-140 is formed via a 3,4-arene oxide intermediate. The second eluting atropisomer of PCB 132, first eluting atropisomer of 3’-140, and second eluting atropisomer of 5’-132 were enriched in all HLM incubations. Enantiomeric fractions of the PCB 132 metabolites differed only slightly between the single donor HLM preparations investigated. Reactive oxygen species and levels of dopamine and its metabolites were not significantly altered after a 24 h exposure of dopaminergic cells to pure PCB 132 atropisomers. These findings suggest that there are inter-individual differences in the atropselective biotransformation of PCB 132 to its metabolites in humans; however, the resulting atropisomeric enrichment of PCB 132 is unlikely to affect neurotoxic outcomes associated with the endpoints investigated in the study.

scholarly journals Atropselective Oxidation of 2,2′,3,3′,4,6′-Hexachlorobiphenyl (PCB 132) to Hydroxylated Metabolites by Human Liver Microsomes and Its Implications for PCB 132 Neurotoxicity

2019 ◽  
Vol 171 (2) ◽  
pp. 406-420 ◽  
Author(s):  
Eric Uwimana ◽  
Brianna Cagle ◽  
Coby Yeung ◽  
Xueshu Li ◽  
Eric V Patterson ◽  
...  
Keyword(s):  
Human Liver ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Limited Information ◽  
Interindividual Differences ◽  
Cellular Targets ◽  
Dopaminergic Cells ◽  
Single Donor ◽  
Metabolite Profiles ◽  
Arene Oxide

AbstractPolychlorinated biphenyls (PCBs) have been associated with neurodevelopmental disorders. Several neurotoxic congeners display axial chirality and atropselectively affect cellular targets implicated in PCB neurotoxicity. Only limited information is available regarding the atropselective metabolism of these congeners in humans and their atropselective effects on neurotoxic outcomes. Here we investigate the hypothesis that the oxidation of 2,2′,3,3′,4,6′-hexachlorobiphenyl (PCB 132) by human liver microsomes (HLMs) and their effects on dopaminergic cells in culture are atropselective. Racemic PCB 132 was incubated with pooled or single donor HLMs, and levels and enantiomeric fractions of PCB 132 and its metabolites were determined gas chromatographically. The major metabolite was either 2,2′,3,4,4′,6′-hexachlorobiphenyl-3′-ol (3′-140), a 1,2-shift product, or 2,2′,3,3′,4,6′-hexachlorobiphenyl-5′-ol (5′-132). The PCB 132 metabolite profiles displayed interindividual differences and depended on the PCB 132 atropisomer. Computational studies suggested that 3′-140 is formed via a 3,4-arene oxide intermediate. The second eluting atropisomer of PCB 132, first eluting atropisomer of 3′-140, and second eluting atropisomer of 5′-132 were enriched in all HLM incubations. Enantiomeric fractions of the PCB 132 metabolites differed only slightly between the single donor HLM preparations investigated. Reactive oxygen species and levels of dopamine and its metabolites were not significantly altered after a 24 h exposure of dopaminergic cells to pure PCB 132 atropisomers. These findings suggest that there are interindividual differences in the atropselective biotransformation of PCB 132 to its metabolites in humans; however, the resulting atropisomeric enrichment of PCB 132 is unlikely to affect neurotoxic outcomes associated with the endpoints investigated in the study.

scholarly journals Utilization of Human Liver Microsomes to Explain Individual Differences in Paclitaxel Metabolism by CYP2C8 and CYP3A4

2005 ◽  
Vol 97 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Ryoko Taniguchi ◽  
Toshio Kumai ◽  
Naoki Matsumoto ◽  
Minoru Watanabe ◽  
Koji Kamio ◽  
...  
Keyword(s):  
Individual Differences ◽  
Human Liver ◽  
Liver Microsomes ◽  
Human Liver Microsomes

scholarly journals In vitro biotransformation of pyrrolizidine alkaloids in different species: part II—identification and quantitative assessment of the metabolite profile of six structurally different pyrrolizidine alkaloids

2020 ◽  
Vol 94 (11) ◽  
pp. 3759-3774
Author(s):  
Ina Geburek ◽  
Dieter Schrenk ◽  
Anja These
Keyword(s):  
Human Liver ◽  
Pyrrolizidine Alkaloids ◽  
High Resolution Mass Spectrometry ◽  
Liver Microsomes ◽  
Metabolite Profile ◽  
Human Liver Microsomes ◽  
Rat Liver Microsomes ◽  
Metabolite Profiles ◽  
Fragmentation Patterns

Abstract Pyrrolizidine alkaloids (PA) exert their toxic effects only after bioactivation. Although their toxicity has already been studied and metabolic pathways including important metabolites were described, the quantification of the latter revealed a large unknown portion of the metabolized PA. In this study, the qualitative and quantitative metabolite profiles of structurally different PAs in rat and human liver microsomes were investigated. Between five metabolites for europine and up to 48 metabolites for lasiocarpine were detected. Proposals for the chemical structure of each metabolite were derived based on fragmentation patterns using high-resolution mass spectrometry. The metabolite profiles of the diester PAs showed a relatively good agreement between both species. The metabolic reactions were summarized into three groups: dehydrogenation, oxygenation, and shortening of necic acid(s). While dehydrogenation of the necine base is considered as bioactivation, both other routes are considered as detoxification steps. The most abundant changes found for open chained diesters were dealkylations, while the major metabolic pathway for cyclic diesters was oxygenation especially at the nitrogen atom. In addition, all diester PAs formed several dehydrogenation products, via the insertion of a second double bond in the necine base, including the formation of glutathione conjugates. In rat liver microsomes, all investigated PAs formed dehydropyrrolizidine metabolites with the highest amount formed by lasiocarpine, whereas in human liver microsomes, these metabolites could only be detected for diesters. Our findings demonstrate that an extensive analysis of PA metabolism can provide the basis for a better understanding of PA toxicity and support future risk assessment.

Deactivation of anti-cancer drug letrozole to a carbinol metabolite by polymorphic cytochrome P450 2A6 in human liver microsomes

Xenobiotica ◽  
2009 ◽  
Vol 00 (00) ◽  
pp. 090901052053001-8
Author(s):  
K. Murai ◽  
H. Yamazaki ◽  
K. Nakagawa ◽  
R. Kawai ◽  
T. Kamataki
Keyword(s):  
Cytochrome P450 ◽  
Human Liver ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Cancer Drug ◽  
Anti Cancer ◽  
Cytochrome P450 2A6

Selegiline Metabolism and Cytochrome P450 Enzymes:In vitro Study in Human Liver Microsomes*

2000 ◽  
Vol 86 (5) ◽  
pp. 215-221 ◽  
Author(s):  
Paivi Taavitsainen ◽  
Markku Anttila ◽  
Leena Nyman ◽  
Hari Karnani ◽  
Jarmo S. Salonen ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Human Liver ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Vitro Study

scholarly journals Nontargeted Metabolomics by High-Resolution Mass Spectrometry to Study the In Vitro Metabolism of a Dual Inverse Agonist of Estrogen-Related Receptors β and γ, DN203368

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 776
Author(s):  
Sin-Eun Kim ◽  
Seung-Bae Ji ◽  
Euihyeon Kim ◽  
Minseon Jeong ◽  
Jina Kim ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Human Liver ◽  
High Resolution Mass Spectrometry ◽  
Liver Microsomes ◽  
Human Liver Microsomes ◽  
Rat Liver Microsomes ◽  
High Resolution Mass ◽  
Resolution Mass

DN203368 ((E)-3-[1-(4-[4-isopropylpiperazine-1-yl]phenyl) 3-methyl-2-phenylbut-1-en-1-yl] phenol) is a 4-hydroxy tamoxifen analog that is a dual inverse agonist of estrogen-related receptor β/γ (ERRβ/γ). ERRγ is an orphan nuclear receptor that plays an important role in development and homeostasis and holds potential as a novel therapeutic target in metabolic diseases such as diabetes mellitus, obesity, and cancer. ERRβ is also one of the orphan nuclear receptors critical for many biological processes, such as development. We investigated the in vitro metabolism of DN203368 by conventional and metabolomic approaches using high-resolution mass spectrometry. The compound (100 μM) was incubated with rat and human liver microsomes in the presence of NADPH. In the metabolomic approach, the m/z value and retention time information obtained from the sample and heat-inactivated control group were statistically evaluated using principal component analysis and orthogonal partial least-squares discriminant analysis. Significant features responsible for group separation were then identified using tandem mass spectra. Seven metabolites of DN203368 were identified in rat liver microsomes and the metabolic pathways include hydroxylation (M1-3), N-oxidation (M4), N-deisopropylation (M5), N,N-dealkylation (M6), and oxidation and dehydrogenation (M7). Only five metabolites (M2, M3, and M5-M7) were detected in human liver microsomes. In the conventional approach using extracted ion monitoring for values of mass increase or decrease by known metabolic reactions, only five metabolites (M1-M5) were found in rat liver microsomes, whereas three metabolites (M2, M3, and M5) were found in human liver microsomes. This study revealed that nontargeted metabolomics combined with high-resolution mass spectrometry and multivariate analysis could be a more efficient tool for drug metabolite identification than the conventional approach. These results might also be useful for understanding the pharmacokinetics and metabolism of DN203368 in animals and humans.

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