The phenolic and alkaloid profiles of Solanum erianthum and Solanum torvum modulated their biological properties

Solanum erianthum D. Don. and S. torvum Swartz of the family Solanaceae have been extensively used for both food and pharmaceutical purposes. In this study, a metabolomic approach was used to compare the phytochemical composition and biological activity of the different plant parts of both species. The inhibitory activity against important enzymes (i.e., cholinesterases, tyrosinase, α-amylase and α-glucosidase), antimicrobial and antifungal potentials, in vitro antioxidant activity, as well as the phenolic and alkaloid profiles of the fruit, leaf and stem bark extracts of both species were studied. The results showed that the stem barks were characterized by the highest amounts of total phenolics (on average: 12.6 mg/g), whilst the S. erianthum leaves were the best source of total alkaloids (2.1 mg/g). Overall, the stem bark extracts of both species were found to be a good source of antioxidant compounds. All the extracts were effective against acetylcholinesterase and tyrosinase, while only the leaf extracts of both plants were a good source of butyrylcholinesterase inhibitors. The extracts have significant anti-microbial and anti-fungal potentials. A modest anti-diabetic effect was measured for α-amylase and α-glucosidase. Strong correlations (p <0.01) were found between the bioactives and the biological activities. Therefore, this study showed the potential of untargeted metabolomics to investigate the bioactive profile of plant extracts, thus providing discrimination between S. erianthum and S. torvum.