Anti-diabetic potential of Urena lobata leaf extract through inhibition of dipeptidyl peptidase IV activity

To evaluate the anti-diabetic potential of leaf extract from Urena lobata (U. lobata) through dipeptidyl peptidase IV (DPP-IV) inhibitory activity. U. lobata leaf was extracted in hot water and ethanol. The activity of DPP-IV inhibitor was tested by in vitro study using gly-pro-p-nitroanilide as substrat of DPP-IV and vildagliptin, as standard reference. A product of the reactions between gly-pro-p-nitroanilide and DPP-IV, was observed by microplate readers with λ = 405 nm. All data were expressed as mean ± SD and the IC50 value was determined by non linear regression curve fit. Active substances in leaf extract of U. lobata was analyzed by liquid chromatography-mass spectrometry. DPP-IV inhibitory activity of active compounds was evaluated in silico using docking server. The ethanolic extract of U. lobata showed stronger DPP-IV inhibitor activity than water extract with the IC50 values of 1 654.64 and 6 489.88 μg/mL, respectively. Vildagliptin, based on standard reference for DPP-IV inhibitor activity, has IC50 value of 57.44 μg/mL. Based on in silico analysis, mangiferin, stigmasterol and β-sitosterol in U. lobata extract have a strong inhibitory activity on DPP-IV. The results showed that DPP-IV inhibitory activity of U. lobata is related to its active compounds such as mangiferin, stigmasterol and β-sitosterol.