Phytochemical Composition and in vitro Antioxidant Activity of Golden Melon (Cucumis melo L.) Seeds for Functional Food Application

Abstract

Aim: Golden melon (Cucumis melo) is an annual herbaceous plant belonging to the family of Cucurbitaceae (Cucurbit). This study was carried out to evaluate the phytochemical composition and in vitro antioxidant activity of golden melon seed extract. Place and Duration of Study: The study was carried out between a period of July and August 2017 at Baking Milling Division, Federal Institute of Industrial Research Oshodi Nigeria.  Methodology: The crude methanolic extracts of the seed were tested for phytochemical and antioxidant activities according to standard analytical procedure. The antioxidant potential of the seed extracts was examined using different assays by determining total phenolic content, total flavonoid content, total antioxidant capacity. The free radical scavenging activities of the extract such as 1,1-diphenyl-2-picrylhydrazyl (DPPH)  radical scavenging activity,  in vitro lipid peroxidation, and nitric oxide (NO) scavenging assay were determined spectrophotometrically. Results: The phytochemical screening of the seed extracts revealed the presence of some secondary metabolites such as alkaloids, phenolic, steroids, flavonoids, terpenoids and cardiac glycosides. The total phenolic content of extract was found to be 29.39 mg/100 g while the amount of total flavonoid content was 20.67 mg/100 g. Scavenging ability was observed to increase in proportion to concentration for all the scavenging assays and at the highest concentration of 100 µg/ml. Total antioxidant capacity assay showed 19.44 mg per 100 g. This high scavenging ability in the seed extracts may be attributed to the presence of phenolic and flavonoids compounds in the extract. The DPPH free radical scavenging activity of 100µg/ml Cucumis melo extract was 75.20% ± 0.72 while the reference standard (Ascorbic acid) was 83.24% ±0.31. Lipid peroxidation inhibition ability of 100 µg/ml Cucumis melo extract was 87.18% ± 0.16 while the standard (ascorbic acid) was 94.96% ± 0.16 at the same concentration. Results obtained from this study showed that the nitric oxide scavenging ability of the extract was 80.50%±0.63 while the standard antioxidant was 85.94% ± 0.54. Conclusion: In all the assays, Cucumis melo extract showed maximum percentage of antioxidant potentials at 100 µg/ml. Additionally, golden melon seed possess appreciable amount of phenols and high antioxidant properties which could be explored and incorporated in functional food applications particularly in baked products.