Antioxidant Activities and Food Value of Five Underutilized Green Leafy Vegetables in South Western Nigeria
Objectives: To determine the food value and antioxidant activities of five underutilized leafy vegetables namely: Bidens pilosa L.-Beggar's ticks/ Cobbler's peg; Celosia trigna L.- Woolflower; Crassocephalum crepidioides (Benth) S. Moore – Fireweed/redflower ragleaf; Launaea taracifolia (L.) Cars- Wide lettuce and Solanun nigrum L. - Black Nightshade/sun berry. Materials and methods: Fresh shoots of the five vegetables were collected from the wild, cleaned and milled. Food values which include proximate, minerals, and vitamin C contents were analyzed following the routine chemical analytical methods of Association of Official Analytical Chemists. 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect and phenolic compounds concentrations of the plants extracts were determined spectrophotometrically. Results: The antioxidant activities and nutrient contents of the five vegetables showed variable trends and considerable high values. Across the vegetables, antioxidant activities ranged from 67.2% (L. taracifolia) to 91.8% (B. pilosa) at a concentration of 1mg/ml of the extracted material. The total phenol contents were between 5953.5k1.5 and 10193.5+0.5 mgi100g. The flavonoid contents varieg from 3438±1.00 to 4974±1.00 mg/100g. Anthocyanin content in mg/100g ranged from 0.385±0.005 to 5.065±0.015 while Proanthocyanidin content varied from 0.125±0.05 to 2.050±0.15 in the extract powder. Crude protein values ranged from 3.5 to 9.16g/100g, Carbohydrate contents varied from 1.09 to 9.43g/100g while ascorbic acid(Vitamin C) compositions ranged from 27.2 to 87.3 mgI100g. Ca content ranges from 31.23 to 54.90 mg/100g, while Fe content varied from 21.25 to 139.75 mg/100g. Conclusion: The vegetables contained appreciable quantities of protein, iron, calcium and vitamin C. The antioxidant activities and phenolic antioxidant contents of the vegetables were also high. The health claims associated with some of these food values and bioactive compounds are noteworthy, thereby underlining the potential role of these underutilized vegetables as functional foods.