Chemical Investigation of the Indonesian Tunicate and Evaluation of the Effects Against of the Novel Alkaloids Polyaurines A and B.

A deep study of the metabolic content of the tunicate , collected from Indonesian coast, afforded the isolation of two novel alkaloids, polyaurines A () and B (), along with two new -substituted benzoyl derivatives ( and ) and four known compounds (-). The structural elucidation of the new secondary metabolites was assigned by 1D, 2D NMR, and HRESIMS techniques. Computational studies resulted a useful tool to unambiguously determine in polyaurine B the presence of rarely found 1,2,4-thiadiazole ring. The effects of polyaurines A and B on mammalian cells growth and on the viability of different blood-dwelling (phylum: Platyhelminthes) stages, as well as egg production, were evaluated. Both compounds resulted not cytotoxic; interestingly some of the eggs produced by polyaurine A-treated adult pairs in vitro are smaller, deformed, and/or fragmented; therefore, polyaurine A could represent an interesting bioactive natural molecule to be further investigated.