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. (C) 2000 Elsevier Science Ltd.