Inhibitory activity of Urena lobata leaf extract on alpha-amylase and alpha-glucosidase: in vitro and in silico approach.

Abstract

In food ingestion, alpha-glucosidase (α-glucosidase) and alpha-amylase (α-amylase) are enzymes that are responsible to convert a carbohydrate into glucose. Inhibition of both enzyme activities can prolong absorption of glucose in intestine and reduce post-prandial increase of blood glucose concentration, thus, it is beneficial for type-2 diabetes treatment. Traditionally, Urena lobata (U.lobata) has been used to manage diabetes, but the scientific proof of this claim remains scarce. Therefore, the objective of thisstudy to examine the anti-diabetic potential of U.lobata leaf extract through inhibition of α-amylase and α-glucosidase. U.lobata leaf extract was obtained through extraction process using ethanol and the chemical compounds in the extract were analyzed by liquid chromatography-mass spectra (LC-MS). The inhibitory activity of U.lobata on α-glucosidase and α-amylase was evaluated by in silico using docking server, whereas in vitro enzymatic assays were using para-nitrophenyl-α-d-glucopyranoside (α-NPG) and starch as substrates. The data were presented as mean±SD and the IC50 value was calculated using SPSS. U.lobata leaf extract showed inhibitory activity on α-glucosidase and α-amylase with the IC50 value was 43.73 and 83.73μg/mL, respectively, meanwhile, acarbose as standard has IC50 value at 1.14 and 0.08μg/mL. Molecular docking study indicated β-sitosterol and stigmasterol from U.lobata extract have a huge inhibitory activity both on α-amylase and α-glucosidase based on inhibition constant (Ki) value. Ethanolic extract of U.lobata showed inhibition activity on α-glucosidase stronger than on α-amylase as antidiabetic.