A new, rare trinor-dolabellane diterpenoid, sangiangol A (1), and one new dolabellane diterpenoid, sangiangol B (2), together with known cembranes and dolabellanes (3-8), were isolated from the ethyl acetate layer of an extract of an Indonesian marine soft coral, Anthelia sp. Compounds 1-8 exhibited moderate cytotoxicity against an NBT-T2 cell line (0.5-10 µg/mL). The structures of the new compounds were determined by analyzing their spectra and a molecular modelling study. A possible biosynthetic pathway for sangiangols A (1) and B (2) is presented. Cytotoxicity requires two epoxide rings or a chlorine atom, as in 4 (stolonidiol) and 5 (clavinflol B).
Keywords: NMR; cytotoxicity; dolabellane; molecular modelling; soft coral.