Lissodendrins A and B: 2-Aminoimidazole Alkaloids from the Marine Sponge Lissodendoryx (Acanthodoryx) fibrosa

Chemical investigation of the Indonesian sponge Lissodendoryx (Acanthodoryx) fibrosa yielded the new 2-amino-imidazole alkaloids lissodendrins A (1) and B (2). Their structures were unambiguously determined by extensive NMR spectroscopic (H-1, C-13, ROESY and long-range HMBC) studies and mass spectrometric (HRESIMS/MS) data. Lissodendrins A (1) and B (2) possess unprecedented skeletons with the latter compound bearing a (p-hydroxyphenyl) glyoxal moiety, which is rarely encountered in natural products. A plausible biosynthetic pathway for these new metabolites is proposed.