IN VITRO ANTIOXIDANT AND FREE RADICAL SCAVENGING POTENTIAL OF METHANOLIC EXTRACTS OF UVARIA CHAMAE LEAVES AND ROOTS

Nwokolo Lorreta Nwakaego,Ene Martin Chukwugekwu,Ezechukwu Ifunanya Ngozi,Onyekwelu Kenechukwu Chibuike,Ezeh Richard Chukwunonye,Adilieje Chioma Marylyn

doi:10.22159/ijpps.2019v11i1.29330

Abstract

Objective: This study investigated the in vitro antioxidant and free radical potentials of methanol extracts of Uvaria chamae leaves and roots.Methods: Fresh Uvaria chamae leaves and roots were air dried, pulverized and extracted using methanol. Phytochemical, total phenolic, flavonoids, antioxidant and tannin contents, DPPH, hydroxyl, and superoxide radical scavenging properties of the extracts were determined using standard methods.Results: In vitro antioxidant potentials revealed that methanol extract of Uvaria chamae leaves contains vitamin A (4871±79.21 I. U) and vitamin C (1.72±0.02%) while the root extract contains vitamin A (673.28±0.00I. U) and vitamin C (1.66±0.01%). Both extracts had equal contents of vitamin E (8.83±0.04 mg/100g). The leaf extract scavenged 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in a concentration dependent manner with the correlation coefficient (R2) of 0.839 and effective concentration (EC50) of 31.19 µg/ml, while the root extract scavenged DPPH with R2 of0.778 and EC50 of 14.00 µg/ml. The leaf and root extracts scavenged superoxide radical and hydroxyl radical with EC50 of 5.93 µg/ml and 719.45 µg/ml; 107.89 µg/ml and 912.01 µg/ml respectively compared to the EC50 of ascorbic standard (30.27 µg/ml) and EC50 of vitamin E standard (106.66µg/ml) respectively. The leaf extract showed significantly higher (p<0.05) anti radical power (ARP) of superoxide (0.17) compared to the root extract (0.0014) and the root extract showed significantly higher (p<0.05) ARP of DPPH (0.071) compared to the leaf extract (0.032).Conclusion: The leaves and roots of Uvaria chamae are rich in natural antioxidants that can be exploited in the treatment of diseases related to oxidative stress.

Highlights

There are several types of antioxidants; natural antioxidants, which are obtained entirely from natural sources and the synthetic antioxidants which are created from chemical processes
Reactive oxygen species (ROS) are highly reactive molecules possessing one or more unpaired electrons generated in living systems in the presence of molecular oxygen
The qualitative phytochemical composition of Uvaria chamae leaves and roots showed that proteins, carbohydrates, and tannins were present in higher amount in the leaves while in roots, they were moderately present except tannin that was in trace amount

Summary

Introduction

There are several types of antioxidants; natural antioxidants, which are obtained entirely from natural sources and the synthetic antioxidants which are created from chemical processes. Antioxidants are nature's way of protecting the body and cells from damaging free radicals [1]. Reactive oxygen species (ROS) are highly reactive molecules possessing one or more unpaired electrons generated in living systems in the presence of molecular oxygen. Mitochondria are the major site of free radical/ROS production in the body through oxidative phosphorylation resulting in the formation of ROS as a by-product of electron transfer reactions. Other endogenous sources of cellular ROS includes the phagocytic cells such as neutrophils, eosinophils and macrophages which generate ROS during the oxidative burst; the peroxisomes which produces hydrogen peroxide under physiological conditions and the cytochrome P450 enzymes which by oxidizing unsaturated fatty acids reduces molecular oxygen to superoxide anion radical and hydrogen peroxide [2,3,4]

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