Anti-Cryptococcal and Nitric Oxide Synthase Inhibitory Imidazole Alkaloids from the Calcareous Sponge Leucetta cf chagosensis

Antifungal imidazole alkaloids were isolated from the Egyptian Red Sea sponge Leucetta cf chagosensis using HPLC. These compounds were the previously reported naamidine A, B, D and G and the unreported symmetric imidazole alkaloid naamine D. Naamine D possesses moderate antifungal and nitric oxide synthase inhibitory activity. The structure of naamine D was determined using 1D and 2D NMR experiments including 1H–15N HMBC and high resolution mass spectrometry.