Abstract
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. Key words: Antioxidant capacity, ascorbic acid, flavonoids, phenolics, African seeds and vegetables.
Highlights
Natural antioxidants, in fruits and vegetables have gained increasing interest among consumers and the scientific community because epidemiological studies have indicated that frequent consumption of natural antioxidants is associated with a lower risk of cardiovascular disease and cancer (Temple, 2000).These antioxidants are a class of compounds thought to prevent certain types of chemical damages caused by an excess of free radicals-charged molecules that are generated by a variety of sources including pesticides, smoking, radiation and exhaust fumes
The measurements were conducted in triplicate and the results reported as mean ± standard deviation (SD) values
All water extracts were higher in ferric reducing antioxidant power (FRAP) value than the acetone extracts among all the vegetables analyzed in this study
Summary
In fruits and vegetables have gained increasing interest among consumers and the scientific community because epidemiological studies have indicated that frequent consumption of natural antioxidants is associated with a lower risk of cardiovascular disease and cancer (Temple, 2000). These antioxidants are a class of compounds thought to prevent certain types of chemical damages caused by an excess of free radicals-charged molecules that are generated by a variety of sources including pesticides, smoking, radiation and exhaust fumes. These antioxidants are effective in scavenging various free radicals, inhibiting initiation of chained reactions by binding to metal ions (Peschel et al., 2006).
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