Inhibitory activity of Urena lobata leaf extract on alpha-amylase and alpha-glucosidase: in vitro and in silico approach
Abstract Objectives 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 this study to examine the anti-diabetic potential of U. lobata leaf extract through inhibition of α-amylase and α-glucosidase. Methods 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. Results U. lobata leaf extract showed inhibitory activity on α-glucosidase and α-amylase with the IC50 value was 43.73 and 83.73 μg/mL, respectively, meanwhile, acarbose as standard has IC50 value at 1.14 and 0.08 μg/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. Conclusions Ethanolic extract of U. lobata showed inhibition activity on α-glucosidase stronger than on α-amylase as antidiabetic.