Cytotoxic Steroids from the Vietnamese Soft Coral Sinularia leptoclados

Fifteen steroids, including two new compounds, leptosteroid (1) and 5,6 beta-epoxygorgosterol (2), were isolated and structurally elucidated from the Vietnamese soft coral Sinularia leptoclados. Their cytotoxic effect against a panel of eight human cancer cell lines was evaluated using sulforhodamine B (SRB) method. Significant cytotoxicity against hepatoma cancer (HepG2, IC50=21.13 +/- 0.70 mu M) and colon adenocarcinoma (SW480, IC50=28.65 +/- 1.53 mu M) cell lines were observed for 1 and against acute leukemia (HL-60, IC50=20.53 +/- 2.26 mu M) and SW480 (IC50=26.61 +/- 1.59 mu M for ergost-5-en-3 beta,7 beta-diol (8). In addition, 3 beta,7 beta-dihydroxyergosta-5,24(28)-diene (13) showed significant cytotoxic activity on all tested cell lines with IC50 values ranging from 13.45 +/- 1.81 to 29.01 +/- 3.21 mu M.