Hydroxylations and methylations of quercetin, fisetin, and catechin by Streptomyces griseus

Abstract

Preparative-scale biotransformation of quercetin (1), fisetin (7), and (+)-catechin (12) with Streptomyces griseus (ATCC 13273) resulted in the isolation and characterization of nine known hydroxylated and/or methylated (2-6, 8, 9, 11, 13a) metabolites and two previously unknown (10 and 14) metabolites. S. griseus catalyzed aromatic hydroxylations of rings A and B of quercetin and fisetin. Mono- and dimethoxy ring-B metabolites were obtained with all three substrates. Methylation appeared to occur only when catechol functional groups were present. Metabolite structures were established by FABMS, EIMS, and 1D and 2D NMR analysis.