In order to discover bioactive secondary metabolites, we have investigated the chemical constituents from the organic extracts of the soft coral Lobophytum varium, which was collected from Jihui Fish Port, Taitung, Taiwan. This study led to the isolation of twelve natural compounds, including five new lobane diterpenes [1], lobovarols A–E (1–4), and an eudesmane derivative [2] lobovarol E (5), along with seven known compounds 6–12. The structures and relative configurations of all metabolites had been established by detailed spectroscopic analyses including 1D and 2D NMR (COSY, HSQC, HMBC and NOESY) data in association with MS experiments. The anti-inflammatory activities of compounds 1–12 on neutrophil pro-inflammatory responses were evaluated by measuring their ability in suppressing fMLP/CB-induced superoxide anion (O2− •) generation and elastase release in human neutrophils. From the results, 17,18-epoxyloba-8,10,13(15)-trien-16-ol (11) [3] showed significant inhibition (45.3 ± 4.1 %) toward elastase release generation at 10 μM.
[1] Raju BL, Subbaraju GV, Rao CB, Trimurtulu G. J Nat Prod 1993, 56: 961–966.
[2] Matthée GF, Körrig GM, Wright AD. J Nat Prod 1998, 61: 237–240.
[3] Dunlop RW, Wells R. Aust J Chem 1979, 32: 1345–1351.