Alkaloids from the sponge Monanchora unguifera.

The bioassay-guided fractionation of the cytotoxic crude gum obtained from the Caribbean sponge Monanchora unguifera led to the isolation and characterization of the new compounds batzelladine J (1) and crambescidic acid (2) in addition to known guanidine alkaloids ptilomycalin A (3a), ptilocaulin (4), and isoptilocaulin (5). The structures of the compounds were elucidated by interpretation of the 1D and 2D NMR experiments. The chemotaxonomic implications of these findings are discussed.