Microbial hydroxylation and methylation of genistein by Streptomycetes

Streptomyces griseus (ATCC 10137) and Streptomyces catenulae (ATCC 23893) were used to convert genistein-5,7,4'-trihydroxyisoflavone (1)-a major isoflavone found in soybeans, into five metabolites, four of which were previously unknown. These were 5,7,3',4'-tetrahydroxy-8-methylisoflavone (5), 5,7,3',4'-tetrahydroxy-8-methylisoflavanone (4), 5,7,4'-trihydroxy-3'-methoxyisoflavone (5), 5,7,8,3',4'-pentahydroxyisoflavone (7), and the known compound, 5,7-dihydroxy-3',4'-dimethoxyisoflavone (6). Identities of these metabolites were established by HRFABMS and 1D and 2D NMR correlation spectroscopy.