Cyclopentenone Derivatives and Polyhydroxylated Steroids from the Soft Coral Sinularia acuta

Four new polyhydroxylated steroids, 1 – 4 , and the racemic form of cyclopentenone 9 , together with four known steroids, 5 – 8 , one known cyclopentenone derivative, 10 , and one known butenolide derivative, 11 , were isolated from the soft coral Sinularia acuta collected from Weizhou Island of Guangxi Province, P. R. China. Their structures were elucidated on the basis of spectroscopic analyses and by comparison of the corresponding data with those previously reported. The cytotoxicities of the isolates 1 – 11 in vitro against the selected tumor cell lines HL‐60, HeLa, and K562 were evaluated. Compounds 2 and 5 showed potent cytotoxicities against HL‐60 cell lines with IC₅₀ values of 7.3 and 9.9 μM , respectively. Compounds 5 and 6 showed moderate activities against K562 cell lines with IC₅₀ values of 10.9 and 11.7 μM , respectively, while compounds 1, 2 , and 6 showed weak activities against HeLa cell lines with respective IC₅₀ values of 44.8, 27.1, and 18.2 μM . This is the first report on chemical and bioactivity research of S. acuta.