Three novel cytotoxic and antifungal alkaloids, nortopsentins A (1), B (2), and C (3), along with two known compounds, topsentin (4) and bromotopsentin (5), were isolated from the Caribbean deep-sea sponge Spongosorites ruetzleri. The structures of the nortopsentins were established mainly on the basis of NMR spectroscopic data. The unique imidazolediylbis [indole] skeleton of the nortopsentins demonstrates a new condensation process in tryptophan metabolism. The nortopsentins exhibited in vitro cytotoxicity against P388 cells and antifungal activity against Candida albicans. © 1991, American Chemical Society. All rights reserved.