Bioactive staurosporine derivatives from the Streptomyces sp. NB-A13.

Six new (1–6) and nine known (7–15) staurosporine derivatives were isolated from the rice solid fermentation of the marine-derived Streptomyces sp. NB-A13. Compound 7 exhibited stronger inhibitory activity against SW-620 cell lines than the positive control staurosporine (25.10 nM), with IC50 values of 9.99 nM. Moreover, compounds 1–5, 8–13 and 15 also showed significant cytotoxicities with IC50 values ranging from 0.02 to 16.60 μM.