Antimicrobial Terpenoids from South China Sea Soft Coral sp.

Chemical investigation of the South China Sea soft coral sp. afforded 13 structurally diverse terpenoids, including three new neolemnane sesquiterpene lineolemnene, E-G (-); a new aristolane-type sesquiterpenoid, 2-acetoxy-aristolane (); four new decalin-type bicyclic diterpenes, named biofloranate A-D (-); a new serrulatane, named euplexaurene D (); and a new aromadendrane-type diterpenoid cneorubin K (), together with three known related compounds (-). The structures of the new compounds were elucidated by NMR spectroscopy, the Mosher's method, and ECD analysis. Compounds - were tested in a wide panel of biological assays. Lineolemnene J () showed weak cytotoxicity against the CCRF-CEM cancer cell line. The isolated new diterpenes, except euplexaurene D (), demonstrated moderate antimicrobial activity against and with a MIC of 4-64 μg/mL. Compound exhibited a mild inhibitory effect against influenza A H1N1 virus (IC = 5.9 µM).