Inhibitory activity of Urena lobata leaf extract on dipeptidyl peptidase-4 (DPP-4): Is it different in vitro and in vivo?

Abstract

This study was aimed to compare the anti diabetic effect of Urena lobata leaf extract through DPP-4 inhibitory activity by in vitro and in vivo. Urena lobata leaf was extracted in ethanol and hot water to evaluate its activity on DPP-4 both of in vitro and in vivo. In vitro test using Gly-pro-p-nitroanilide (GPPN) as substrate of DPP-4 and the reactions product of them was observed by microplate reader at λ=405 nm furthermore the IC50 value was determined. In vivo study utilize an animal model of diabetes with 2 control groups and 6 test groups (n=4), in which DPP-4 level, GLP-1 level and AUC of blood glucose were examined after extract administration. The in vitro DPP-4 inhibitory activity of ethanolic extract of U. lobata is higher than water extract with the IC50 value of 1654, 64 and 6489, 88 μg/ml respectively. However, the water extract of U. lobata exhibits stronger decrease DPP-4 level (60–70%) compared to ethanolic extract (40–60%) in vivo study as well as the AUC of blood glucose were reduced by 50–60% and 20–50%, respectively. Meanwhile, GLP-1 level could be retained more by the water extract of U. lobata administration (3–7 fold) compared to ethanolic extract (25 fold) due to the reducing of DPP-4 activity.