In vitro Kinetic of Inhibition of Lipase, Antioxidant Activity, Glucose Entrapment and Polyphenolic Content of Solanum linnaeanum

Abstract

Decoction as traditionally used and methanol extract of a commonly consumed vegetable Solanum linnaeanum (SL) was evaluated for any antioxidant potential (Ferric reducing power (FRAP) assay, nitric oxide, DPPH, and xanthine oxidase inhibitory activity). The inhibitory effect of SL against α-amylase, α-glucosidase and pancreatic lipase activity was studied and the type of inhibition was established by the Lineweaver-Burk plot in vitro. The entrapment ability in decreasing glucose movement in an in vitro model was also investigated. The total phenolic, flavonoid, anthocyanin and tannin content were determined. The aqueous extract (IC50=0.20 µg/ mL) was more active against pancreatic lipase than the methanol extract (IC50=0.40 µg/ mL) and the positive control Orlistat® (IC50=0.35 µg/ mL). An uncompetitive type of inhibition as indicated by a reduction in Vmax and Km was recorded. Methanol extract demonstrated a more efficient DPPH scavenging potential. The FRAP of the methanolic extract was 102.708±1.36 mM trolox equivalent (TE)/mg extract. Decoction extracts showed no significant difference (p>0.05) on glucose entrapment capacities (33.3 %) when compared to the positive control (Arabic gum). Phytochemical screening of SL indicated the presence of phenols (152.80±1.40 (GAE) [g/mL]) and flavonoids (4.34±0.16 Rutin equivalent[μg/mL]) in the methanol extract only and absence of tannin and anthocyanin in both methanol and aqueous extracts. This study is the first attempt to establish valuable baseline data on SL bioactivity. The results can be further exploited for the development of new therapeutic dietary approach for the management of diabetes and obesity.