Phytochemical Analysis and in vitro Antioxidant Activity of Fractions of Methanol Extract of Polyalthia longifolia var. Pendula Leaf

Abstract

This study was aimed to determine the antioxidant capacity of various fractions of crude methanol extract of Polyalthia longifolia leaves. The various fractions were obtained by successive liquid-liquid partitioning of the crude methanol extract into n-hexane, chloroform and ethyl acetate. The flavonoid and phenolic contents as well as the 2, 2- diphenyl-1-picrylhydrazyl scavenging activity and total reducing power of the crude methanol extract of Polyalthia longifolia leaves and its fractions were analyzed using standard methods. From the results obtained, ethyl acetate fraction had the highest flavonoid (571.30 mgQE/g) and phenolic (278.45 mgGAE/g) contents and the lowest IC50 values for 2, 2- diphenyl-1-picrylhydrazyl scavenging activity (˂ 1 µg/ml) and total reducing power (0.24 µg/ml). However, the water soluble fraction showed least values for flavonoid content (7.22 mgQE/g), phenolic content (48.66 mgGAE/g) and highest IC50 values for 2, 2- diphenyl-1-picrylhydrazyl scavenging activity (505.87 µg/ml) and total reducing power (47.99 µg/ml). The flavonoid content, phenolic content and total reducing power were in the order; ethyl acetate fraction > chloroform fraction > methanol extract > n-Hexane fraction > water soluble fraction. However, the inhibition of 2, 2- diphenyl-1-picrylhydrazyl free radical followed the order; ethyl acetate fraction > methanol extract > chloroform fraction > n-Hexane fraction > water soluble fraction. In general, the antioxidant activity of the ethyl acetate fraction was the most outstanding when compared with the crude methanol extract and other fractions. Having established the presence of significant concentrations of pharmaceutically important phytochemicals in the fractions of the methanol extract of the leaves especially the ethyl acetate, more evidence based studies such as analysis of specific chemical composition and in-vivo pharmacological potential of each fraction is imperative in order to expound more on the medicinal usability of the various fractions of the leaves.