Phenolic Content and Antioxidant Activity of Extracts of 12 Melon (Cucumis melo) Peel Powders Prepared from Commercial Melons

Melons are a diverse group of fresh, dessert fruits that includes orange flesh cantaloupe, green flesh honeydew, and mixed hybrid melons. As part of an effort to discover potential health benefits of fruit and vegetable peels that are considered to be byproducts of food processing, we determined the total phenolic content and antioxidative activities of methanolic extracts of the powdered peels of the following commercial melon (Cucumis melo) varieties sold at retail markets in California that were imported from Mexico and Honduras: nonorganic Canary, Charentias, Hani Gold, Vine ripened, and Santa Claus; and organic Ambrosia, Cantaloupe, Galia, Goddess, Ham, Honeydew, and Tuscan. The total phenolic content (in mg gallic acid equivalents/g extract) ranged from 0.69 (Tuscan) to 2.96 (Galia) or 4.3-fold variation from lowest to highest value. The antioxidative activity (in mg ascorbic acid equivalents/mL extract) ranged from 0.13 (organic Tuscan) to 0.26 (organic Galia). Similar results were observed using the ABTS antioxidative assay. The content of the phenolic and flavonoid compounds 3-hydroxybenzoic acid, chlorogenic acid, neochlorogenic acid, isovanillic acid, apigenin-7-alpha-glucoside, luteolin-7-o-glucoside, and quercetin-3-galactoside in three melon flesh samples (nonorganic and organic Galia from Honduras and organic Galia from Mexico and two peel samples (Mexican organic peel and flesh) were analyzed using HPLC. The results suggest that the peel from the Honduran Galia melon with the highest antioxidative activity merits further study to investigate potential health properties. Potential nutritional and health benefits of melon peels, Seeds, and their bioactive compounds are discussed. Practical ApplicationThe peel from the Honduran Galia melon variety merits further study for potential health benefits, including antioxidative, anticholesterol, and antidiabetic activities, and stimulation of thyroid function, as reported for peels from other melon varieties, as well as antibiotic activities against pathogenic bacteria, protozoa, and viruses.