The known compound ascididemin (1) and two novel octacyclic aromatic alkaloids, eudistones A (2) and B (3), were isolated from the Seychelles tunicate Eudistoma sp. The structures of 2 and 3, which possess a unique carbon skeleton, were elucidated by extensive NMR analysis and chemical interconversion. The relative configuration was determined by comparison of NMR coupling constants with those predicted by molecular modeling. © 1991, American Chemical Society. All rights reserved.