2-amino imidazole alkaloids from the marine sponge leucetta chagosensis

Nine new 2-amino imidazole alkaloids belonging to four different groups have been isolated from a Red Sea sponge. The structures of all compounds were elucidated from spectral data, mainly by 1D and 2D NMR techniques, by mass spectra and in case of naamidine A also by chemical transformations. A nudibranch, Notodoris citrina feeding on the L. chagosensis sponge was found to concentrate the new imidazole alkaloids.