Mechanism-based inactivation of cytochrome P450 2B6 by isopsoralen. (2nd April 2016)

• Record Type: Journal Article
• Authors: Lu, Dan; Ji, Lin; Zheng, Liwei; Cao, Jiaojiao; Peng, Ying; Zheng, Jiang
• Is Part Of: Xenobiotica. Volume 46:Number 4(2016:Apr.)
• Page Start: 335
• Page End: 341
• Publication Date: 2016-04-02
• Subjects: Cytochrome P450 2B6 -- Isopsoralen -- mechanism-based inactivator -- reactive metabolite; Metabolism -- Periodicals; Drugs -- Physiological effect -- Periodicals; Food additives -- Periodicals; Chemicals -- Physiological effect -- Periodicals; Biochemistry -- Periodicals; Pharmaceutical Preparations -- metabolism -- Periodicals; Metabolism -- Periodicals; 574.133
• DOI: 10.3109/00498254.2015.1077403
• Languages: English
• ISSNs: 0049-8254

Abstract

Abstract: 1. Isopsoralen (IPRN) is a major component in many traditional medicinal herbs widely used in Asian countries. The objective of the present study was to investigate the inhibitory effect of IPRN on cytochrome P450 2B6 (CYP2B6) and the mechanism involved in the enzyme inactivation. 2. Pre-incubation of CYP2B6 with IPRN resulted in a time- and concentration-dependent enzyme activity loss. The values of K I and k inact were found to be 7.89 μM and 0.067 min −1, respectively. Ticlopidine exhibited protective effect on the IPRN-induced enzyme inactivation. The estimated partition ratio of the inactivation was 122. The GSH trapping experiments indicate that an epoxide and/or γ -ketoenal intermediate were/was generated in IPRN-fortified microsomal incubations. The synthetic work verified the formation of the reactive intermediate(s). Additionally, CYPs2E1, 2C19, 2B6 and 1A2 were found to be the major enzymes participating in the bioactivation of IPRN. 3. IPRN was characterized as a mechanism-based inactivator of CYP2B6. An IPRN-derived furanoepoxide and/or γ -ketoenal intermediate(s) were/was generated and may be responsible for the inactivation of CYP2B6.