Gephyyamycin and cysrabelomycin, two new angucyclinone derivatives from the sp. HN-A124.

Gephyyamycin () owned the rare 3,12a-epoxybenz[]anthracene ring system, and cysrabelomycin () possessed an acetylated cysteine group, two new angucyclinone derivatives were isolated from the rice solid fermentation of the marine-derived sp. HN-A124, an actinobacterium isolated from the marine sediments collected from Hainan Province, China. Their structures were elucidated on the basis of MS, NMR spectroscopic, X-ray diffration data analyses and quantum chemical calculations of the electronic circular dichroism (ECD) spectra. Compound appeared to show moderate cytotoxicity against human prostate cancer PC3 and human ovarian carcinoma A2780 cell lines with IC values of 19.39 and 10.23 μM, respectively; on the other hand, compound also exhibited moderate antibacterial activities against and with an MIC value of 20.0 and 20 μM, respectively.