Analysis of nutritional and antioxidant potential of three traditional leafy vegetables for food security and human wellbeing

Consumption of traditional leafy vegetables (TLVs) is important for ensuring food and nutritional security. Traditional leafy vegetables are rich in both macro and micro nutritional components such as proteins, fat, minerals and vitamins, antioxidant pigments, phytochemicals and several other bioactive metabolites. It is therefore important to bio-prospect the nutritional components and antioxidant potential of the locally available leafy vegetables. The aim of this study was to quantify the nutritional, antioxidative components and antioxidant activity of three TLVs namely Spilanthes acmella (L.) L., Eryngium foetidum L., and Cissus quadrangularis L. Methods such as Association of Official Analytical Collaboration (AOAC), Anthrone, Lowry's, colorimetric assays, 1,1, diphenyl-2-picryl hydrazine (DPPH) scavenging assay were used for the estimation of proximate components, water soluble carbohydrate, protein, other bioactive compounds and antioxidant activity respectively. We observed variations in the proximate, antioxidative components and antioxidant activities of the three TLVs and their extracts. Results revealed that crude fiber was highest in the leaves of C. quadrangularis (9.34%) followed by S. acmella (8.42%) and E. foetidum (0.62%). The total crude protein content was highest in S. acmella (110.19 mg/g) as compared to C. quadrangularis (9.88 mg/g) and E. foetidum (81.34 mg/g). The moisture content was found to be highest in E. foetidum (85.66%) followed by S. acmella (82.32%) and C. quadrangularis (56.64 %). Elevated water-soluble carbohydrate was found in E. foetidum (53.41 mg/g). Analysis of antioxidative components revealed that E. foetidum presented the highest concentration of chlorophyll a, chlorophyll b and carotenoids whereas C. quadrangularis exhibited least concentrations. Highest concentration of ascorbic acid and dehydroascorbic acid quantity was observed in C. quadrangularis (6.54 mM/g FW and 12.11 mM/g FW respectively). This study further observed that, S. acmella possesses a higher quantity of polyphenols and flavonoids (27.46 mg GAE/g DW and 14.07 mg QE/g DW respectively) than the other two species. The methanolic extract of the plants shows significant antioxidant activity. Among the three plants, C. quadrangularis showed the highest antioxidant activity with an IC₅₀ value of 1.097 mg/ml in the DPPH assay. The results of the study revealed the nutritional and antioxidant potential of the three traditional leafy vegetables. The supplementation of the diets with such traditional crops and their promotion will promote good health and wellbeing among the people.