13-Epi-9-Deacetylxenicin Derivatives from a Taiwanese Soft Coral Asterospicularia laurae and Treir Cytotoxic Activity

摘要

The xenicane-type diterpene 13-epi-9-deacetylxenicin (1) was isolated from polar extract of the soft coral Asterospicularia laurae. The structure of 13-epi-9-deacetylxenicin was determined by X-ray diffraction analysis, and the absoulte configuration was determined using the modified Mosher′s method. Eleven acylation products of 13-epi-9-deacetylxenicin were prepared: 13-epi-9-O-p-anisoylxenicin (2), 13-epi-9-O-2-furoylxenicin (3), 13-epi-9-O-2-thiophenecarbonylxenicin (4), 13-epi-9-O-2-benzoylxenicin (5), 13-epi-9-O-p-toluoylxenicin (6), 13-epi-9-O-4-chlorobenzoylxenicin (7), 13-epi-9-O-4-fluorobenzoylxenicin (8), 13-epi-9-O-4-propylbenzoylxenicin (9), 13-epi-9-O-4-nitrobenzoylxenicin (10), and 13-epi-9-O-cinnamoylxenicin (11) are new compounds, and one known compound, 13-epixenicin (12). The structures of the new metabolites were determined on the basis of extensive spectroscopic analysis, particularly mass spectroscopy and 2D NMR (1H–1H COSY, HMQC, HMBC, and NOESY) spectroscopy. The in vitro cytotoxic activities of the twelve compounds were evaluated against Molt4, K562, U937, and SUP-T1 human tumor cell lines.