Phytochemical, Vitamin and Antioxidant Assessments of the Stems and Leaves of Four Commonly Consumed Vegetables in Nigeria

Background and Objectives: Nutrient composition of vegetables is critical for diet supplementation and disease management in phytomedicine. This study analyzed phytochemical and vitamin contents and antioxidant potentials of methanolic extracts of leaves and stems from Ocimum gratissimum (OG), Telfairia occidentalis (TO), Vernonia amygdalina (VA) and Gongronema latifolium (GL) in Abia State, Nigeria. Materials and Methods: This study analyzed phytochemicals, antioxidants and vitamins using standard analytical methods. Moreover, 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power were assessed using photometric assays. Results: Phytochemical analyses showed the highest concentrations in phenolic contents of the leaf extracts and flavonoid contents of the stem extracts of OG (6.16 ±0.02 mg/100 g and 5.40 ±0.01 mg/100 mg, respectively). The 2,2-diphenyl-1-picrylhydrazyl assay indicated that the leaf extracts of TO and OG were consistently higher for scavenging activities at 100, 200 and 400 µg/ml concentrations, respectively. In contrast, stem extracts of VA and GL were higher at similar concentrations. The ferric reducing antioxidant power results demonstrated the highest values in the leaves and stems of OG (1.55 ±0.02 and 0.77 ±0.24 µm/fe(II)/l, respectively). Vitamin A and C compositions (mg/100 g) in the stem extracts were higher than those in the leaves; whereas, their leaf extracts included higher compositions of vitamin E (mg/100 g). Conclusions: This study suggests conscious incorporation of stems and leaves as vegetables in diets to boost diet and supplement biological antioxidant defenses against oxidative stress-induced diseases, developing SDGs two(2) and three(3) with focusing on malnutrition and promoting health and well-being of all ages.