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 I).Methods:The sensitivity and kinetic model of inhibition of CE and FE on ACE I using N-[3-(2-furyl)-acryloyl]-Phe-Gly-Gly as enzyme substrate for ACE I was evaluated by Michealis Menten approach.The inhibition mechanism was explored from LineweaverBurk 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 I demonstrated positive cooperativity with a Hill's coefficient of 1.89.Conclusions:The study reveals the superior ACE I inhibitory potential of CE over FE and suggest that mixed inhibition pattern of the enzyme might be the underlying mechanism of antihypertensive activity.
ABSTRACT
Objective: To investigate the phenolic compounds composition and the inhibitory activity ofMangifera indica (M. indica) and Mucuna urens (M. urens) seeds extracts against some key enzymes (α-amylase, α-glucosidase and aldose reductase) implicated in the pathology and complications of type 2 diabetes in vitro. Methods: Reverse phase chromatographic quantification of the major flavonoids and phenolic acids in the seeds extracts was carried out using high performance liquid chromatography coupled with diode array detection. The inhibitory activities of the seeds extracts against α-amylase andα-glucosidase were estimated using soluble starch and ρ-nitrophenylglucopyranoside as their respective substrates. Inhibition of aldose reductase activity by the extracts was assayed using partially purified lens homogenate of normal male rat as source of enzyme; inhibition of Fe2+-induced lipid peroxidation by extracts was tested in rat pancreas homogenate.Results:The chromatography result revealed that extracts of both seeds had appreciable levels of some major flavonoids and phenolic acids of pharmacological importance, including gallic acid, chlorogenic acid, caffeic acid, ellagic acid, catechin, rutin, quercitrin, quercetin and kaempferol. Extracts of both seeds effectively inhibited α-amylase, α-glucosidase and aldose reductase activities in a dose-dependent manner, having inhibitory preference for these enzymes in the order of aldose reductase>α-glucosidase>α-amylase. With lower half-maximal inhibitory concentrations (IC50) against α-amylase, α-glucosidase, and aldose reductase, M. indica had stronger inhibitory potency against these enzymes than M. urens. Extracts of both seeds also inhibited Fe2+-induced lipid peroxidation in a dose-dependent pattern, with M. indica being more potent than M. urens.Conclusions:The results obtained provide support for a possible use of M. indica and M. urens seeds in managing hyperglycemia and preventing the complications associated with it in type 2 diabetes.