A benzyl-α-pyrone metabolite, streptpyrone A (1), was obtained together with three known isoflavonoids, daidzein-7-O-α-l-rhamnoside (2), genistein-7-O-α-l-rhamnoside (3), and daidzein (4), from the culture broth of an Indonesian actinomycete Streptomyces sp. TPU1401A. The structure of 1, elucidated based on its spectroscopic data, has been reported as a synthetic compound. However, this is the first report of the isolation of 1 as a metabolite of microbial origin. Strain TPU1401A exhibited the ability to transform the isoflavone aglycones 4 and genistein (5) into the 7-O-glycosides 2 and 3, respectively. Compounds 2 and 3 promoted the growth of strain TPU1401A more effectively than compounds 4 and 5. These results suggest that strain TPU1401A utilizes isoflavone glycosides to promote growth by transforming isoflavones through microbial glycosidation.
Keywords: Indonesian actinomycete; Streptomyces sp. TPU1401A; Streptpyrone A; isoflavonoid; microbial transformation.