Antifouling and cytotoxic constituents from the South China Sea sponge Acanthella cavernosa

A bioassay-guided chemical investigation of the South China Sea sponge Acanthella cavemosa resulted in the isolation of eight new diterpenoids, kalihinols M-T (1-8), together with seven known analogues (9-15). These compounds featured a trans-decalin ring bearing a tetrahydrofuran or a tetrahydropyran ring at C-7. Compounds 1 and 2, with a formamide functionality beared at C-4, extended the structure breadth of this diterpenoid family. The absolute stereostructures of 1-14 were determined by a combination of 2D NMR and CD spectroscopic analysis and single crystal X-ray diffraction. Compounds 1 and 2 were confirmed to have the configurations of 4S, 55, whereas 3-14 were determined as 4R, 5R. Compounds 3-14 displayed significant antifouling activity against the barnacle Balanus amphitrite larvae, and the cytotoxic activities of 3-14 were evaluated against the H1299, A549, PC3, CT-26, and HCT-116 cancer cell lines. (C) 2012 Elsevier Ltd. All rights reserved.