Cytotoxic Bisindole Alkaloids from a Marine Sponge Spongosorites sp.

Abstract
Three new bisindole alkaloids of the hamacanthin class (1−3) and one new bisindole alkaloid of the topsentin class (6) were isolated along with known bisindole alkaloids (4, 5, 7−11) from the MeOH extract of a marine sponge Spongosorites sp. by bioactivity-guided fractionation. The planar structures were established on the basis of NMR, MS, and IR spectroscopic analyses. Configurations of compounds 1−4 were derived from 1H NMR data and optical rotation. Compounds 1, 4, 5, and 11 showed moderate to significant cytotoxicity against five human tumor cell lines, and compounds 1−5 showed weak antibacterial activity against clinically isolated methicillin-resistant strains.