||In order to discover bioactive secondary metabolites, we continued the chemical investigation of the ethyl acetate extract of a Formosan soft coral Lobophytum varium, collected from the Jihui Fishing Port, Taitung, Taiwan in 2013. This study further led to the isolation of ten natural products, including one new lobane-type diterpenoid lobovarol L (1) and five new prenyleudesmane-type diterpenoids lobovarols M─Q (2─6), along with four known compounds: lobatrienolide (7), loba-8,10,13(15)-triene-|
14,17,18-triol 14-acetate (8), loba-8,10,13(15)-triene-14,17,18-triol 14,17-diacetate (9), lobovarol I (10). The chemical structures of compounds 1─10 were elucidated on the basis of spectroscopic methods (IR, MS, 1D and 2D NMR), and by comparison of the spectroscopic data with the related known diterpenoids.
The cytotoxicity of compounds 1─10 against P388 (mouse lymphocytic leukemia), DLD-1 (human colon adenocarcinoma), CCD-966SK (human skin fibroblast) cell lines were evaluated. The results showed that compounds 2 exhibited cytotoxicity against CCD-966SK cell line with an IC50 value of 15.5 μg/mL. In anti-inflammatory assay, none of compounds show significant anti-inflammatory activity by inhibiting superoxide anion generation and elastase release in fMLF/CB-stimulated human neutrophils at 1 μM .