Postharvest UV - C treatment positively affects the bioactive components, antioxidant, antidiabetic and inhibition of Fe²⁺ - induced lipid peroxidation properties of <i>Gongronema latifolia</i> leaf extracts

Abstract

This research work is to investigate the effect of radiating Gongronema latifolium leaves with UV-C light on the bioactive component, antioxidant, antidiabetic and Fe²⁺ induced lipid peroxidative inhibitory capacity of the leaves. The leaves were freshly harvested and divided into 3 parts; one part was treated with UV-C lamp at 210 nm for 10 minutes (UV-C 10), the second part for 20 minutes (UV-C 20) while the last part was not treated. The aqueous extracts of G. latifolium were used for the analysis. The UV-C 20 sample had a higher level of total phenolics (6.10 mgGAE/g) and total flavonoids (0.64 mgQE/g). However, the untreated sample showed a significantly (p ˂ 0.05) higher value of ascorbic acid than the treated samples. There was increase in the scavenging and inhibiting abilities of G. latifolium when irradiated with UV-C. The UV-C 20 sample exhibited a higher and significant (p ˂ 0.05) DPPH scavenging and metal chelating abilities as well as higher inhibitory effect on α-amylase, α-glucosidase enzyme and Fe²⁺ induced lipid peroxidation in vitro. The UV-C irradiated leaves could be used therapeutically for the correction of stress induced diseases.

Keywords: Gongronema latifolium, UV-C, phenolic, ascorbic acid, total flavonoid, DPPH scavenging activity, α-amylase, α-glucosidase enzyme