Monoindole alkaloids from a marine sponge Mycale fibrexilis

► Eleven monoindol alkaloids were obtained from a marine sponge Mycale fibrexilis. ► Herein, we first report the chemical investigation on M. fibrexilis. ► The emergence of monoindole alkaloids is less common in the family Mycalidae. ► Monoindole alkaloids were useful as chemotaxonomic markers for the family Mycalidae.