The chemical and chemo-ecological studies on Weizhou nudibranch Glossodoris atromarginata.

A detailed chemical investigation of the nudibranch Glossodoris atromarginata collected from Weizhou Island, South China Sea, yielded a new spongian-type diterpene 1, together with the four known-related compounds 2-5. The structure of the new compound 1 was elucidated by the detailed spectroscopic analysis, the comparison of the spectroscopic data with the known diterpene isoagatholactone, and the 13 C chemical shift calculation. In addition, evidence for the absolute stereochemistry of the known compound 2 was, for the first time, provided by the application of time-dependent density functional theory electronic circular dichroism calculation.