Anti-Inflammatory Lobane and Prenyleudesmane Diterpenoids from the Soft Coral Lobophytum varium.

New lobane-based diterpenoids lobovarols A-D ( 1 - 4 ) and a prenyleudesmane-type diterpenoid lobovarol E ( 5 ) along with seven known related diterpenoids ( 6 - 12 ) were isolated from the ethyl acetate extract of a Taiwanese soft coral Lobophytum varium . Their structures were identified on the basis of multiple spectroscopic analyses and spectral comparison. The absolute configuration at C-16 of the known compound 11 is reported herein for the first time. The anti-inflammatory activities of compounds 1 - 12 were assessed by measuring their inhibitory effect on N -formyl-methionyl-leucyl-phenyl-alanine/cytochalasin B (fMLP/CB)-induced superoxide anion generation and elastase release in human neutrophils. Metabolites 2 , 5 , and 11 were found to show moderate inhibitory activity on the generation of superoxide anion, while compounds 5 , 8 , 11 , and 12 could effectively suppress elastase release in fMLP/CB-stimulated human neutrophil cells at 10 μM. All of the isolated diterpenoids did not exhibit cytotoxic activity (IC ₅₀ > 50 μM) towards a limited panel of cancer cell lines.
Competing Interests: The authors declare no conflict of interest.