New secondary metabolite with cytotoxicity from spawning soft coral Asterospicularia laurae in Taiwan

We have conducted a long-term research on the Taiwanese soft coral Asterospicularia laurae, which resulted in many xenicane-type diterpenoids such as asterolaurins A-M from A. laurae coral tissues during the non-spawning period were isolated. Here, we report a new xenicane diterpenoid, asterolaurin N (1), along with three known xenicane-type monocarbocyclic diterpenes [13-epi-9-desacetylxenicin (2), xeniolide-B 9-acetate (3) and asterolaurin I (4)] from A. laurae during the spawning period. The structures of the new secondary metabolite were established with an extensive spectroscopic analysis. The 1D and 2D nuclear magnetic resonance (NMR) data of the compounds were discussed. We discovered that the C-15 of 1 contains two methyl groups on a carbon bearing an acetyl group, which has not been reported previously. In addition, Compounds 1, 3, and 4 showed selective cytotoxic activity against Molt 4, while 2 exhibited significant cytotoxicity against Molt 4, K562, Sup-T1 and U937 cell lines.