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

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