Antitrypanosomal pyridoacridine alkaloids from the Australian ascidian Polysyncraton echinatum

Bioassay-guided fractionation of the crude CH₂Cl₂/MeOH extract from the Australian ascidian Polysyncraton echinatum led to the isolation of a new pyridoacridine alkaloid, 12-deoxyascididemin (1), along with two known analogues, ascididemin (2) and eilatin (3). The structure of 1 was determined following extensive analysis of 1D/2D NMR and MS data. Biological evaluation showed that compounds 1-3 are potent antitrypanosomal agents with IC₅₀ values of 0.077, 0.032, and 1.33 μM against Trypanosoma brucei brucei, respectively.