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Rendić SP, Crouch RD, Guengerich FP. Roles of selected non-P450 human oxidoreductase enzymes in protective and toxic effects of chemicals: review and compilation of reactions. Arch Toxicol 2022; 96:2145-2246. [PMID: 35648190 PMCID: PMC9159052 DOI: 10.1007/s00204-022-03304-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/26/2022] [Indexed: 12/17/2022]
Abstract
This is an overview of the metabolic reactions of drugs, natural products, physiological compounds, and other (general) chemicals catalyzed by flavin monooxygenase (FMO), monoamine oxidase (MAO), NAD(P)H quinone oxidoreductase (NQO), and molybdenum hydroxylase enzymes (aldehyde oxidase (AOX) and xanthine oxidoreductase (XOR)), including roles as substrates, inducers, and inhibitors of the enzymes. The metabolism and bioactivation of selected examples of each group (i.e., drugs, “general chemicals,” natural products, and physiological compounds) are discussed. We identified a higher fraction of bioactivation reactions for FMO enzymes compared to other enzymes, predominately involving drugs and general chemicals. With MAO enzymes, physiological compounds predominate as substrates, and some products lead to unwanted side effects or illness. AOX and XOR enzymes are molybdenum hydroxylases that catalyze the oxidation of various heteroaromatic rings and aldehydes and the reduction of a number of different functional groups. While neither of these two enzymes contributes substantially to the metabolism of currently marketed drugs, AOX has become a frequently encountered route of metabolism among drug discovery programs in the past 10–15 years. XOR has even less of a role in the metabolism of clinical drugs and preclinical drug candidates than AOX, likely due to narrower substrate specificity.
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Affiliation(s)
| | - Rachel D Crouch
- College of Pharmacy and Health Sciences, Lipscomb University, Nashville, TN, 37204, USA
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA
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Jones BC, Srivastava A, Colclough N, Wilson J, Reddy VP, Amberntsson S, Li D. An Investigation into the Prediction of in Vivo Clearance for a Range of Flavin-containing Monooxygenase Substrates. Drug Metab Dispos 2017; 45:1060-1067. [PMID: 28784689 DOI: 10.1124/dmd.117.077396] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/04/2017] [Indexed: 11/22/2022] Open
Abstract
Flavin-containing monooxygenases (FMO) are metabolic enzymes mediating the oxygenation of nucleophilic atoms such as nitrogen, sulfur, phosphorus, and selenium. These enzymes share similar properties to the cytochrome P450 system but can be differentiated through heat inactivation and selective substrate inhibition by methimazole. This study investigated 10 compounds with varying degrees of FMO involvement to determine the nature of the correlation between human in vitro and in vivo unbound intrinsic clearance. To confirm and quantify the extent of FMO involvement six of the compounds were investigated in human liver microsomal (HLM) in vitro assays using heat inactivation and methimazole substrate inhibition. Under these conditions FMO contribution varied from 21% (imipramine) to 96% (itopride). Human hepatocyte and HLM intrinsic clearance (CLint) data were scaled using standard methods to determine the predicted unbound intrinsic clearance (predicted CLint u) for each compound. This was compared with observed unbound intrinsic clearance (observed CLint u) values back calculated from human pharmacokinetic studies. A good correlation was observed between the predicted and observed CLint u using hepatocytes (R2 = 0.69), with 8 of the 10 compounds investigated within or close to a factor of 2. For HLM the in vitro-in vivo correlation was maintained (R2 = 0.84) but the accuracy was reduced with only 3 out of 10 compounds falling within, or close to, twofold. This study demonstrates that human hepatocytes and HLM can be used with standard scaling approaches to predict the human in vivo clearance for FMO substrates.
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Affiliation(s)
- Barry C Jones
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Abhishek Srivastava
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Nicola Colclough
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Joanne Wilson
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Venkatesh Pilla Reddy
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Sara Amberntsson
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
| | - Danxi Li
- Oncology IMED, Astrazeneca, Cambridge, United Kingdom (B.C.J., N.C., J.W., V.P.R.), DSM Astrazeneca, Cambridge, United Kingdom (A.S.); DSM Astrazeneca, Gothenburg, Sweden (S.A.); and Pharmaron, Beijing, China (D.L.)
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