Chemical Investigation of the Indonesian Tunicate <i>Polycarpa aurata</i> and Evaluation of the Effects Against <i>Schistosoma mansoni</i> of the Novel Alkaloids Polyaurines A and B

Abstract

A deep study of the metabolic content of the tunicate Polycarpa aurata, collected from Indonesian coast, afforded the isolation of two novel alkaloids, polyaurines A (1) and B (2), along with two new p-substituted benzoyl derivatives (3 and 4) and four known compounds (5−8). 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 Schistosoma mansoni (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.

Keywords

• natural products
• ascidians
• <i>Polycarpa aurata</i>
• 1,2,4-thiadiazole alkaloids
• <i>Schistoma mansoni</i>