A new isoflavone derivative from Streptomyces sp. YIM GS3536

A new natural product named 7-O-methyl-8-chlorogenistein (1) was isolated together with eight known isoflavones, 8-chlorogenistein (2), kakkatin (3), 7-O-methyl genistein (4), genistein (5), daidzein (6), glycitin (7), genistin (8), and daidzin (9), from the metabolites of Streptomyces strain YIM GS3536, which was isolated from soil sample collected from Yunnan Province, China. We report the unambiguous assignments of the 1H and 13C NMR spectra of the new compound 7-O-methyl-8-chlorogenistein (1). Compound 1 exhibited appreciable cytotoxicity against human melanoma cell lines (B16) and human leukemia cell lines (HL60) with IC50 values of 17.5 and 19.2 μM, respectively. The MIC values of 1 for Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Candida albicans were in the range of 23–35 μM.