Cytotoxic and PPARs transcriptional activities of sterols from the Vietnamese soft coral Lobophytum laevigatum.

A new unusual sterol, named lobophytosterol (1), and five known metabolites (2-6) were isolated from the methanol extract of the soft coral Lobophytum laevigatum. Their chemical structures were elucidated by extensive spectroscopic analysis and comparison with those reported in the literature. The absolute stereochemistry of 1 was determined using a modified Mosher's method. Compounds 1-3 showed cytotoxic activity against HCT-116 cells with IC(50) values of 3.2, 6.9 and 18.1 μM, respectively. Compound 1 additionally displayed cytotoxic effects on A549 and HL-60 cells with IC(50) values of 4.5 and 5.6 μM, respectively. Treatment of these cells with compound 1 resulted in an induction of apoptosis evident by chromatin condensation in treated cells. Besides, compounds 2, 4, and 6 significantly upregulated PPARs transcriptional activity dose-dependently in Hep-G2 cells. Taken together, these data suggest that compound 1 might inhibit the growth of the cancer cells by the induction of apoptosis, and compounds 2, 4, and 6 might act as specific agonists for PPARα, PPARδ, and PPARγ and may therefore regulate cellular glucose, lipid, and cholesterol metabolism.