Hyrtimomines A-C, new heteroaromatic alkaloids from a sponge Hyrtios sp.

Three new alkaloids, hyrtimomines A-C (1-3), were isolated from an Okinawan marine sponge Hyrtios sp. The structures of 1-3 were elucidated on the basis of spectroscopic analysis and application of a phenylglycine methyl ester (PGME) method. Hyrtimomines A (1) and B (2) are heteroaromatic alkaloids possessing a fused hexacyclic 6/5/6/6/7/5 ring system, while hyrtimomine C (3) is an alkaloid consisting of hydroxyindole and azepino-hydroxyindole moieties. Hyrtimomine A (1) exhibited cytotoxicity against KB and L1210 cells.