Mobola plum seed methanolic extracts exhibit mixed type inhibition of angiotensin Ⅰ-converting enzyme in vitro

Abstract

Objective: To explore the possible inhibitory potentials and mechanism by Mobola plum (Parinari curatellifolia) seeds crude methanol (CE) and flavonoid-rich (FE) extracts on angiotensin-1-converting enzyme (ACE â ). Methods: The sensitivity and kinetic model of inhibition of CE and FE on ACE â using N-[3-(2-furyl)-acryloyl]-Phe-Gly-Gly as enzyme substrate for ACE â was evaluated by Michealis Menten approach. The inhibition mechanism was explored from Lineweaver–Burk model and IC50 was determined from Cheng–Prusoff empirical analysis. Results: The IC50 of CE and FE were 13.54 and 39.38 μg/mL, respectively. Both extracts exhibited mixed type inhibition with the inhibitory constant (Ki) of CE was between 0.38 and 0.37 μg/mL while that of FE showed a two-fold increase (1.62 μg/mL and 0.28 μg/mL). FE on ACE â demonstrated positive cooperativity with a Hill's coefficient of 1.89. Conclusions: The study reveals the superior ACE â inhibitory potential of CE over FE and suggest that mixed inhibition pattern of the enzyme might be the underlying mechanism of antihypertensive activity. Keywords: Angiotensin converting enzyme, Blood pressure, FAPGG, Mixed type inhibition, Parinari curatellifolia