α-Tocopherols from the Formosan Soft Coral Lobophytum crassum

In our screening of marine organisms for bioactive metabolites we have obtained two new alpha-tocopherols, designated as crassumtocopherols A (1) and B (2), from the Formosan soft coral Lobophytum crassum. The structures of 1 and 2 were determined on the basis of comprehensive NMR and HR-ESI-MS analyses. The cytotoxicity of 1, 2, natural vitamin E, and synthetic vitamin E against cancer cell lines and antiviral activity against human cytomegalovirus were evaluated in vitro. Compounds 1 and 2 exhibited moderate cytotoxicity against P-388 (mouse lymphocytic leukemia) cell lines with IC50 of 3.2 and 2.7 mu g mL(-1), respectively. In addition, compound 2 also displayed moderate cytotoxicity against HT-29 (human colon adenocarcinoma) with an IC50 of 3.9 mu g mL(-1). However, natural vitamin E and synthetic vitamin E were not cytotoxic to the selected cancer cell lines and the results for inhibition of antiviral activity against human cytomegalovirus are all negative at a concentration of 1 mu g mL(-1).