Patterns of chemical diversity in the marine ascidian Phallusia spp.: anti-tumor activity and metabolic pathway inhibiting steroid biosynthesis.

The complex nature of marine biodiversity is partially responsible for the lack of studies in Indian ascidian species, which often target a small number of novel biomolecules. We performed untargeted metabolomics using gas chromatography-mass spectrometry (GC-MS) in two invasive ascidian species to investigate the inter-specific chemical diversity of Phallusia nigra and P. arabica in search of drug-like properties and metabolic pathways. The chemical profiling of individual ascidian species was obtained using GC-MS, and the metabolites were determined by searching in NIST library and literature data. The principal component analysis of GC-MS mass spectral variables showed a clear discrimination of these two ascidian species based on the chemical composition and taxonomy. The metabolites, lipids, macrolides, and steroids contributed strongly to the discrimination of these two species. Results of this study confirmed that GC-MS-based chemical profiling could be utilized as a tool for chemotaxonomic classification of ascidian species. The extract of P. nigra showed promising anti-tumor activity against HT29 colon cancer 35 µM and MCF7-breast cancer (34.76 µM) cells compared to P. arabica. Of the more than 70 metabolites measured, 18 metabolites that mapped various pathways linked to three metabolic pathways being impacted and altered in steroid biosynthesis, primary bile acid biosynthesis, and steroid hormone biosynthesis were observed to have changed significantly (p > 0.004, FDR < 0.01). Also, higher expression of this pathway was associated with more significant cytotoxicity in breast and colon carcinoma cells.