Phytochemical and in vitro total antioxidant capacity analyses of peel extracts of different cultivars of Cucumis melo and Citrullus lanatus

Context: Cucumis melo Linn. (Cucurbitaceae) and Citrullus lanatus Thunb. (Cucurbitaceae) are desert vegetables popular for their nutritional value and year round availability. The pulp and seeds of these plants are used for dietary purposes or as medications for certain ailments in the folk medicinal system. Peels of the fruit are either wasted or used as feed of grazing animals. Objective: A detailed investigation regarding the chemical constituents and antioxidative analyses of the peel extract of fully ripened fruits from different cultivars of the two vegetables was carried out here for the first time. Materials and methods: Chemical constituents of the peel extracts of C. melo and C. lanatus cultivars in methanol, 1-butanol, chloroform and n-hexane were analysed by gas chromatography-mass spectrometry (GC-MS) and the antioxidative properties were evaluated using standard in vitro antioxidative assays. Results: The results demonstrated large variation in the chemical constituents of the extracts including alkanes, saturated and unsaturated fatty acids and their esters, cyclic ketones, aldehydes, phenolic compounds and anthocyanin derivatives. Total phenolic content ranged from 2.96-0.85 mg/L gallic acid equivalents for different extracts. Discussion and conclusion: Employing GC-MS analyses and standard in vitro antioxidative assays, the data presented here clearly demonstrate the potency of C. melo and C. lanatus extracts as antioxidant and radical scavenger plants which may be used as good sources of natural antioxidants. The peels of both the plants can be added to the diet at various stages to compensate food shortage and dietary deficiency problems of living beings.