Contrast between African seeds and vegetables: Identification of their high antioxidant capacity

Abstract

Eleme O. Obinna, Okonkwo Chima and Okpokpor Jefferson

The antioxidant capacity of 2 African seeds and 8 vegetables were analyzed using ferric reducing antioxidant power assay (FRAP assay) after water and acetone extractions. The contents of ascorbic acid, phenolics and flavonoids were determined and their correlations with FRAP value were investigated. The results showed that Vernonia amygdalina was stronger (4.84 mM/100 g dry weight (DW)) than other vegetables analyzed in antioxidant capacity based on total FRAP values. Baphia nitida was the lowest in total FRAP value (1.26 mM/100 g DW). Treculia africana seed was higher than Telfairia occidentalis seed in total FRAP value. T. occidentalis leaf had antioxidant capacity than its corresponding seed. All water extracts were higher in FRAP value than the acetone extracts. FRAP value was significantly correlated with the contents of ascorbic acid, phenolics, or flavonoids in water extracts and with flavonoids in acetone extract, in which ascorbic acid and flavonoids contributed most in the water extracts based on multivariate regression analysis. In conclusion, the different African seeds and vegetables were remarkably different in antioxidant capacity.