Presentation Type
Poster Presentation
Abstract
Aldehyde oxidase (AO) is an enzyme that metabolizes drugs containing aromatic azaheterocycles. Small thiol-containing molecules have been reported to inactivate AO. Clopidogrel is an antiplatelet agent used to treat cardiovascular diseases. Clopidogrel is a prodrug that is bioactivated in vivo by cytochrome P450 enzymes CYP3A4 and CYP2C19 into a thiol metabolite. Our research aims to explore whether the clopidogrel thiol metabolite can inhibit AO, leading to potential drug-drug interactions when co-administered with other drugs that are metabolized by AO. In order to determine whether the prodrug clopidogrel and/or its thiol metabolite inhibit AO, O6-benzylguanine (AO substrate) was incubated with human liver S9 (AO and cytochrome P450 enzyme source) in the presence and absence of clopidogrel or the clopidogrel thiol metabolite. AO activity was then determined by measuring formation of 8-oxo-benzylguanine via LC-MS/MS. An unknown concentration (≤ 250 uM) of the thiol metabolite produced 50-65% inhibition of AO activity, whereas 50 uM clopidogrel produced only 15-20% inhibition, regardless of the presence of NADPH (co-factor required for cytochrome P450-mediated conversion of clopidogrel to the thiol metabolite). In addition, the AO inhibition observed in the presence of the thiol metabolite was concentration-dependent. These preliminary studies indicate that the thiol metabolite of clopidogrel may inhibit AO, but additional experiments are required to confirm these data. Importantly, the clinical relevance of these findings will be highly dependent on the concentrations of thiol metabolite achieved in patients treated with clopidogrel relative to the concentrations required to inhibit AO.
Faculty Mentor
Rachel Crouch
Recommended Citation
Crouch, Rachel; Kamal, Merna; and Woldeamanuel, Hilina, "Investigation of Aldehyde Oxidase Inhibition by Clopidogrel and its Thiol Metabolite" (2025). Student Scholar Symposium. 80.
https://digitalcollections.lipscomb.edu/student_scholars_symposium/2025/Full_schedule/80
Included in
Enzymes and Coenzymes Commons, Other Pharmacy and Pharmaceutical Sciences Commons, Pharmacology Commons
Investigation of Aldehyde Oxidase Inhibition by Clopidogrel and its Thiol Metabolite
Aldehyde oxidase (AO) is an enzyme that metabolizes drugs containing aromatic azaheterocycles. Small thiol-containing molecules have been reported to inactivate AO. Clopidogrel is an antiplatelet agent used to treat cardiovascular diseases. Clopidogrel is a prodrug that is bioactivated in vivo by cytochrome P450 enzymes CYP3A4 and CYP2C19 into a thiol metabolite. Our research aims to explore whether the clopidogrel thiol metabolite can inhibit AO, leading to potential drug-drug interactions when co-administered with other drugs that are metabolized by AO. In order to determine whether the prodrug clopidogrel and/or its thiol metabolite inhibit AO, O6-benzylguanine (AO substrate) was incubated with human liver S9 (AO and cytochrome P450 enzyme source) in the presence and absence of clopidogrel or the clopidogrel thiol metabolite. AO activity was then determined by measuring formation of 8-oxo-benzylguanine via LC-MS/MS. An unknown concentration (≤ 250 uM) of the thiol metabolite produced 50-65% inhibition of AO activity, whereas 50 uM clopidogrel produced only 15-20% inhibition, regardless of the presence of NADPH (co-factor required for cytochrome P450-mediated conversion of clopidogrel to the thiol metabolite). In addition, the AO inhibition observed in the presence of the thiol metabolite was concentration-dependent. These preliminary studies indicate that the thiol metabolite of clopidogrel may inhibit AO, but additional experiments are required to confirm these data. Importantly, the clinical relevance of these findings will be highly dependent on the concentrations of thiol metabolite achieved in patients treated with clopidogrel relative to the concentrations required to inhibit AO.