Bioactive staurosporine derivatives from the Streptomyces sp. NB-A13

Abstract 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. The structures of the new staurosporine derivatives were established by extensive spectroscopic data interpretation. The absolute configurations of 1 and 2 were assigned by quantum chemical calculations of the electronic circular dichroism (ECD) spectra. All of these compounds were screened for their cytotoxic activities against PC-3 and SW-620 cell lines. Compound 7 exhibited stronger inhibitory activity against SW-620 cell lines than the positive control staurosporine (25.10 nM), with IC 50 values of 9.99 nM. Moreover, compounds 1 – 5 , 8 – 13 and 15 also showed significant cytotoxicities with IC 50 values ranging from 0.02 to 16.60 μM, while 6 exhibited no cytotoxic potency. Additionally, compounds 1 – 7 were also tested for enzyme inhibition activities of Protein kinase C theta (PKC-θ), and showed activity with IC 50 values ranging from 0.06 to 9.43 μM except for compound 6 , which has no inhibition activity.