Comparative Study on Antioxidant Potentials of Some Leafy Vegetables Consumed Widely in India

The antioxidant activities with respect to the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH)‐radical scavenging activity and reducing activity were assessed and compared for seven edible leafy vegetables (Enhydra fluctuans, Glinus oppositifolius, Amaranthus sp.1, Amaranthus sp.2, Amaranthus spinosus, Ipomoea aquatica and Corchorus sp.) widely consumed in India, especially West Bengal state. Phytochemical analysis of these vegetables revealed the presence of phenolics (gallic acid equivalents 2.87–61.85 mg/g), flavonoids (quercetin equivalents 2.75–406.98 mg/g) and tannins (tannic acid equivalents 7.39–32.52 mg/g). Two of the samples, E. fluctuans and Corchorus sp. exhibited remarkable DPPH radical scavenging activities (>70%) with significant IC₅₀ values of 65.04 and 128.95 μg/mL, respectively. Extracts of these two species were also found to possess significant Fe³⁺‐reducing activities. The constituents of the extracts were separated by thin layer chromatography (TLC) and the positions of the antioxidative active fractions were determined using TLC bioautography followed by spraying with DPPH solution. The study suggested E. fluctuans and Corchorus sp. to be potential sources of antioxidative compounds. PRACTICAL APPLICATIONS: Concerns regarding the use of synthetic antioxidants as preservatives in the food industry, because of their toxicity and harmful health hazards, have resulted in the limitation of their usage in the food industry. This has necessitated urgent search for novel antioxidative compounds of natural origin for use as food supplements as well as preservatives in the food industry. Many of the fruits and vegetables consumed daily possess significant antioxidant activities and are good sources of natural antioxidative compounds. The selected seven leafy vegetables, all of which are widely consumed in India, were studied with respect to their relative antioxidative potentials. Accordingly, E. fluctuans followed by Corchorus sp. were found to have the best potential as sources of natural antioxidative compounds for uses in nutraceutical and food industry.