Sinularosides A and B, Bioactive 9,11-Secosteroidal Glycosides from the South China Sea Soft Coral Sinularia humilis Ofwegen

Two new 9,11-secosteroidal glycosides, namely, sinularosides A and B (1, 2), together with the known pregnene glycoside 3 beta(beta-xylopyranosyloxy)-5 alpha-pregna-20-ene (3), were isolated from the South China Sea soft coral Sinularia humilis Ofwegen. The structures of these compounds were elucidated by a combination of detailed spectroscopic analyses, chemical methods, and comparison with reported data. This is the first report of 9,11-secosteroidal glycosides from a soft coral and from nature. In in vitro bioassays, the new compounds exhibited potent antimicrobial activities and showed no growth inhibition activity against the tumor cells HepG2 and Caco-2.