Metabolism of Sesamin by Cytochrome P450 in Human Liver Microsomes

Abstract

ABSTRACT:Metabolism of sesamin by cytochrome P450 (P450) was examined using yeast expression system and human liver microsomes. Saccharomyces cerevisiae cells expressing each of human P450 isoforms (CYP1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) were cultivated with sesamin, and monocatechol metabolite was observed in most of P450s. Kinetic analysis using the microsomal fractions of the recombinant S. cerevisiae cells revealed that CYP2C19 had the largest k cat /K m value. Based on the kinetic data and average contents of the P450 isoforms in the human liver, the putative contribution of P450s for sesamin metabolism was large in the order of CYP2C9, 1A2, 2C19, and 2D6. A good correlation was observed between sesamin catecholization activity and CYP2C9-specific activity in in vitro studies using 10 individual human liver microsomes, strongly suggesting that CYP2C9 is the most important P450 isoform for sesamin catecholization in human liver. Inhibition studies using each anti-P450 isoform-specific antibody confirmed that CYP2C9 was the most important, and the secondary most important P450 was CYP1A2. We also examined the inhibitory effect of sesamin for P450 isoform-specific activities and found a mechanism-based inhibition of CYP2C9 by sesamin. In contrast, no mechanism-based inhibition by sesamin was observed in CYP1A2-specific activity. Our findings strongly suggest that further studies are needed to reveal the interaction between sesamin and therapeutic drugs mainly metabolized by CYP2C9.

Comparison of Metabolism of Sesamin and Episesamin by Drug-Metabolizing Enzymes in Human Liver

“…Thus, P450s would be essential for the metabolism of both sesamin and episesamin. We demonstrated previously that sesamin was catecholized in human liver microsomes predominantly by CYP2C9, and sesamin was a mechanism-based inhibitor of CYP2C9 (Yasuda et al, 2010). Furthermore, we also demonstrated the speciesspecific differences in sesamin metabolism between humans and rats (Yasuda et al, 2011).…”

“…at ASPET Journals on May 12, 2018 dmd.aspetjournals.org CYP2C9 was much larger than that of CYP1A2 (Yasuda et al, 2010). Table 1 shows the comparison of kinetic parameters of CYP2C9 and CYP1A2 between sesamin and episesamin.…”

“…Relative intensities (percentages) of major ion fragments of the authentic standard of episesamin and its metabolites were as follows: episesamin: m/z 319 ( Episesamin Metabolism by Recombinant Human P450s. In our previous study (Yasuda et al, 2010), we revealed that some P450 enzyme had the sesamin catecholization activity, and their activity was high in order of CYP2C19, CYP2D6, CYP2C9, and CYP1A2, although CYP2C9 was the most important in human liver. In this study, we examined the episesamin catecholization by P450 enzymes including these P450s.…”

“…Figure 1A shows the HPLC profiles of sesamin (a) or episesamin (b) and their metabolites in human liver microsomes. As described previously (Yasuda et al, 2010), sesamin was converted to one metabolite: sesamin monocatechol. Meanwhile, episesamin was converted to two metabolites designated M1 and M2 (Fig.…”

Biotransformation of (-)-Camphor by Salmonella typhimurium OY1002/2A6 Expressing Human CYP2A6 and NADPH-P450 Reductase

“…In particular, CYP3A4 metabolizes a large number of drugs, and is the most essential P450 isoform in drug metabolism 14 . Reproducing the biokinetics of drug metabolism by using S. typhimurium OY1002/3A4 and the methods described in this study may further elucidate the biological mechanisms of human metabolism.…”