Department of Applied Biological Science, Nihon University, Kanagawa, Fujisawa, 252-8510, Japan.
The microsome of yeast cells overexpressing CYP81E1, a cytochrome P450 cDNA recently cloned from licorice (Glycyrrhiza echinata L., Fabaceae), catalyzed the hydroxylation of isoflavones, daidzein and formononetin, to yield 2'-hydroxyisoflavones, 2'-hydroxydaidzein, and 2'-hydroxyformononetin, respectively. The chemical structures of the reaction products were confirmed by mass spectrometric analysis. Genistein also yielded a putative 2'-hydroxylated product, but flavanones and cinnamic acid derivatives were not used as substrates for the reaction with the recombinant yeast microsome. CYP81E1 protein was thus demonstrated for the first time to be isoflavone 2'-hydroxylase involved in the biosynthesis of isoflavonoid-derived antimicrobial compounds of legumes. Copyright 1998 Academic Press.