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Microbial secondary metabolites have a wide range of biological activities due to their structural diversity and have been proved a major source for drug lead compounds. However,the traditional method of a single culture restricts the metabolic pathways of microorganisms and as a result many metabolites cannot be formed. Recently,it has attracted much attention to use various techniques to activate those metabolic pathways restricted by the traditional method to get metabolic products with rich variety of structures. "One strain many compounds" (OSMAC) is a simple and effective approach for activating metabolic pathways and has been successfully applied. This review summarizes the common strategies of the OSMAC approach (altering cultivation parameters, co-cultivation, addition of enzyme inhibitors, etc) and the recent advances of OSMAC combined with genomics scanning. This review also introduces the research of our studies using the OSMAC approach on a fungus Spicaria elegans KLA03 which yielded a series of cytochalasins.

A novel phenazine derivative (1) together with six known compounds (2-7) were isolated by bioassay-guided fractionation from the culture broth of a bacterium, Bacillus sp., collected from a Pacific deep sea sediment sample (depth 5059 m). The structures of these compounds were determined using spectroscopic methods. Their cytotoxic effects on P388 and K562 cell lines were preliminarily examined using the sulforhodamine-B (SRB) assay.

Bioassay-guided fractionation of the EtOAc extract from the fermentation broth of a marine-derived actinomycete Z(2)039-2 led to the isolation of two known indolocarbazole alkaloids, K252c (1) and arcyriaflavin A (2). 1 and 2 exhibited moderate cytotoxic activities against the K562 cell line, and induced apoptotic activities at 10 and 100 microM, respectively. This is the first report on the significant apoptosis inducing effect of indolocarbazole alkaloids against K562 cancer cells.