INHIBITION OF ANGIOTENSIN-I CONVERTING ENZYME ACTIVITY AND FE2+- INDUCED OXIDATIVE STRESS BY PHENOLIC RICH EXTRACTS FROM PLANTAIN (Musa paradisiaca) PEELS

Abstract

Plantain (Musa paradisiaca) fruits are processed before consumption, leaving a massive quantity of peels as waste. The present study was designed to evaluate the antioxidant potentials, and their interaction with key enzyme relevant to hypertension (Angiotensin –I converting enzyme). The unripe (UPP), ripe (RPP) and over- ripe (OPP) peels were obtained from their plantain fruits and extracted with methanol–1M HCl solution (1:1 v/v).Then, the total phenolic content, ferric reducing antioxidant power (FRAP),1,1-diphenyl-1-picryl-hydrazyl (DPPH),and 2’,2’-azino-bis (3-ethylbenzazoline-6-sulphonic acid (ABTS) radicals scavenging assay, and reducing properties were determined as the antioxidant indices. The abilities of the extracts to prevent lipid peroxidation in rat heart using thiobarbituric reactive species (TBARS) and the interaction of the extract with Angiotensin-I converting enzyme (ACE) were also determined. The results showed that UPP had significantly (P < 0.05) higher phenolic contents [total phenol (64mg. GAE/g), total flavonoid (26.36mg. QUE/g)] as well as higher antioxidant activities than both RPP and OPP. Furthermore, all the plantain peels exhibited inhibitory effect on ACE, with the UPP (EC50 = 2.70μg/ml) having the strongest inhibitory activity. The results of the Gas chromatography-partial characterization,carried out indicated the presence of notable phenolic compounds; such as, astragalin, isoquercetin, p-coumaric, quercetin, rutin, cathechin, procathechuic, and cavarol, in all the plantain peel samples studied.The results obtained suggest that the plantain (M. paradisiaca) peels can be used as (Nutraceutical) natural source of phenolic compounds with health protective potentials in the management of hypertension.