Monanchomycalin C, a new pentacyclic guanidine alkaloid from the far-eastern marine sponge Monanchora pulchra

Abstract

A new pentacyclic guanidine alkaloid, monanchomycalin C (1), along with the earlier known ptilomycalin A (2), were isolated from the Far-Eastern marine sponge Monanchora pulchra. The structure of 1 was elucidated using 1D and 2D NMR spectroscopic and mass spectrometric data. Compounds 1 and 2 exhibited cytotoxic activities against human breast cancer MDA-MB-231 cells with IC 50 values of 8.2 μM and 4.3 μM, respectively.