Isolation of three new naturally occurring compounds from the culture of Micromonospora sp P1068

Bioassay guided isolation of an antibacterial extract prepared from the fermentation broth of a Micromonospora sp. P1068 led to the isolation of eight compounds identified as (3R) 3,4',7-trihydroxy-isoflavanone ( 1), 3-hydroxydehydrodaidzein, daidzein ( 2), 3-methyl-1H-indole-2- carboxylic acid ( 3), 1H- indole-3-carboxaldehyde (4), 3-(p-hydroxyphenyl)-N-methylpropionamide, N-methylphloretamide ( 5), phenyl acetic acid ( 6), 2-hydroxy phenyl acetic acid ( 7) and 4-hydroxy-5-methoxy-benzoic acid ( 8). Compounds 1 and 5 were found to be novel chemical entities while 3 was isolated from a natural source for the first time. All compounds were evaluated for their antimicrobial activities against a panel of clinically significant microorganisms. Compound 4 was active against Staphylococcus aureus ( MIC, 32 mu g/ml), Enterococcus faecium (MIC, 32 mu g/ml) and Escherichia coli (MIC, 64 mu g/ml).