New sesquiterpene hydroquinones from the Caribbean sponge Aka coralliphagum

Four new sulfated sesquiterpene hydroquinones siphonodictyals E1–E4 (1–4) and cyclosiphonodictyol A (5) were isolated from a sample of the Caribbean sponge Aka coralliphagum collected off the coast of San Salvador in the Bahamas. The structures of the new compounds were elucidated on the basis of mass spectrometric and NMR spectroscopic analysis. Compounds 1–4 are derivatives of siphonodictyal E (9). Siphonodictyal E4 (4) exhibited mild antiproliferation activity against L929 mouse fibroblast, KB-31 epidermoid carcinoma, and MCF-7 breast cancer cell lines, while siphondictyal E3 (3) and cyclosiphonodictyol A (5) showed moderate activity against Gram-positive bacteria.