Ingenine E, a new cytotoxic β-carboline alkaloid from the Indonesian sponge Acanthostrongylophora ingens.

A new β-carboline alkaloid ingenine E (4), along with three known metabolites annomontine (1), acanthomine A (2), and 1,2,3,4-tetrahydronorharman-1-one (3) were isolated from the Indonesian marine sponge Acanthostrongylophora ingens. Their structure characterization was unequivocally carried out using one- and two-dimensional NMR spectroscopy, as well as high-resolution mass spectrometry. The cytotoxic activity of the isolated compounds was evaluated toward MCF7, A549, HCT116, PC12, and Hela cancer cell lines. Ingenine E (4) exhibited cytotoxic activity against MCF7, HCT116, and A549 cell lines with IC50 values of 3.5, 0.67, and 2.15 μg/ml.