Ethanolic extracts of seeds of Parinari curatellifolia exhibit potent antioxidant properties: A possible mechanism of its antidiabetic action

Abstract

The present study sought to evaluate the antioxidative property of seed of Parinari curatellifolia (P. curatellifolia) that has been previously reported to attenuate high glucose level in type 2 diabetes. The amount of antioxidant agents such as phenols, flavonoids, vitamin C and glutathione were determined in the ethanolic extracts of the seed. In addition, the possible antioxidant mechanisms of the extracts were assessed by measuring their reducing property, iron (II) chelating ability and their ability to scavenge 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radicals. In addition, the ability of the extracts to prevent deoxyribose degradation and inhibits lipid peroxidation in the brain, liver, heart and pancrease were also determined. The results show that the seed contains phenols (9.4 ± 0.89 mg gallic acid equivalent), flavonoids (1.57 ± 0.17 mg quercetin equivalent), vitamin C (46.82 mg/g of seed) and glutathione (24.22 µg/g of seed). Furthermore, P. curatellifoliasignificantly scavenged DPPH radicals, reduced Fe3+ and chelated Fe2+ in a dose dependent manner. Likewise, P. curatellifolia caused a marked reduction in the degradation of deoxyribose induced by Fe2+, H2O2 or both. However, the seed inhibited peroxidation of cerebral, hepatic and cardiac but not pancreatic lipids subjected to either iron or sodium nitroprusside oxidative assaults. Taken together, we conclude that since type-2 diabetes is intrinsically linked with oxidative stress,P. curatellifolia possibly exerts its antidiabetic action using a combination of mechanisms and its antioxidant potency possibly play a major role in ameliorating secondary complications resulting from oxidative damage in diabetes. Key words: Parinari curatellifolia, diabetes, antioxidant, oxidative stress, lipid peroxidation.