Total phenolics, vitamin C and free radical scavenging capacities of some Nigerian fruits

Abstract

Aqueous extracts of selected fruits were assessed to ascertain if, there is a correlation between the natural antioxidants in the fruits and their antioxidant capacities using four in-vitro assay methods. Total phenol, flavonoids, vitamin C, 2,2-diphenyl-1-picrylhydrazyl [DPPH], 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) [ABTS] , radical scavenging abilities, ferric reducing antioxidant property [FRAP], and iron II chelating ability were determined in the fruit extracts. Guava and shaddock contained the highest amount of total phenol (364.00±5.66mg/100g GAE) and flavonoids (83.64±5.15mg/100g) respectively. Watermelon and pawpaw had the lowest value for total phenol (14.1±2.83mg/100g GAE) and flavonoids (3.64±0.00mg/100g). Vitamin C content was highest in Guava (5.65±1.37mg/g), watermelon had the lowest amount (0.33±0.28mg/g). Shaddock and guava had the highest value for DPPH (63.78±5.89%) and ABTS scavenging ability (0.0042±0.00005mmol/g) respectively. Watermelon and lime had the lowest value for DPPH (11.22±0.45%) and ABTS scavenging ability (0.00079±0.000083mmol/g) respectively. FRAP was highest in Guava (20.54±0.02mg/g). Pawpaw had the highest value for iron chelation (41.35±1.36%), while watermelon and apple had the lowest value for FRAP (1.11±0.55mg/g) and iron chelation (11.54±0.00%) respectively. Total phenol, Flavonoid and vitamin C correlated positively with FRAP, ABTS and DPPH assays. Guava, shaddock and pawpaw possess significant antioxidant and radical scavenging abilities which correlated positively with the antioxidants.