New beta-carboline alkaloids from the Andaman Sea sponge Dragmacidon sp

Chemical investigation of the hithertho undescribed sponge Dragmacidon sp. from the Andaman Sea afforded two new beta-carboline alkaloids, which were named dragmacidonamines A (1) and B (2). The structures of the new compounds were unambiguously established on the basis of NMR spectroscopic (1H, 13C, COSY, 1H detected direct, and long-range 13C-1H correlations) and mass spectrometric (EI and ESIMS) data. The 3-carboxylic-beta-carboline moiety and the thiomethylated imidazolinium unit as found in dragmacidonamines are very rarely encountered in nature