Comparative Study of Phytonutrient Content and Antioxidant Activity of the Fruit Juices of Watermelon (Citrullus lanatus) and Horned melon (Cucumis metuliferus) http://www.doi.org/10.26538/tjnpr/v7i8.32

Abstract

This study was aimed at determining the vitamin, phytochemical compositions and the antioxidant properties of watermelon and horned melon fruit juices. The analyses were carried out using standard methods. The results obtained showed that the fruits contained vitamins C (0.13 mg/ml and 0.68 mg/ml), A (1.60 and 0.20 mg/ml), B1 (0.0011 and 0.00009 mg/ml), B2 (0.0005 and 0.00011 mg/ml), B3 (6.62 and 0.00007 mg/ml), B9 (0.12 and 0.0021 mg/ml) and E (3.48 and 0.00042 mg/ml) for fruit juice of watermelon and horned melon respectively. From the phytochemical analysis, phytate (0.33%), alkaloids (0.48 mg/ml), Oxalate (3.24 mg/ml) and
tannins (108.79 mg TAE/g) were detected only in the fruit juice of horned melon while flavonoid (3.45 mg/ml) and terpenoids (0.12 mg/ml) were detected only in the fruit juice of watermelon. Others were 0.17 and 0.06 mg/ml phenol, 0.21 and 0.46 mg/ml cardiac glycosides, 0.09 and 0.19 mg/ml saponin for fruit juices of watermelon and horned melon respectively. Horned melon juice showed no antioxidant activity up to a concentration of 100% while the fruit juice of watermelon showed varying activity at different concentrations. The EC50 for scavenging ability on DPPH and inhibition of lipid peroxidation were 40.0 and 76.0% respectively while OD0.5 for reducing power was 45.0 %. These results showed that watermelon juice is richer in phenols and flavonoids than horned melon juice. Therefore, watermelon juice could be used in pharmaceutical preparations.