Potent in vitro antimalarial activity of metacycloprodigiosin isolated from Streptomyces spectabilis BCC 4785

Bioassay-guided fractionation of the extract from the fermentation broth of Streptomyces spectabilis BCC 4785 led to the isolation of three principle antimalarial agents, metacycloprodigiosin, bafilomycin A, and spectinabilin. Metacycloprodigiosin exhibited potent in vitro activity against Plasmodium falciparum K1, with a 50% inhibitory concentration of 0.0050 +/- 0.0010 mug/ml, while its cytotoxicity was much weaker.