Watermelon white rind is thrown to the environment as agro waste producing ecological and environmental problems. The present study is an attempt to evaluate the medicinal properties of the rind to generate valuable health-promoting products. Aqueous and ethanolic extracts were prepared and screened for antibacterial activity against three pathogenic bacterial strains: two Gram-negative bacteria (E. coli and Salmonella sp.) and one Gram-positive bacteria (Staphylococcus aureus). Both ethanolic and aqueous extracts of watermelon white rind have antagonistic effect against E. coli and Salmonella sp., While Staphylococcus aureus was resistant to both extracts. The diameters of inhibition zone of ethanolic and aqueous extracts against E. coli were 5.75±0.96 mm and 3.00±0.82 mm, respectively. Whereas, the diameters were 8.50±0.58 mm and 4.25±0.96 mm against Salmonella sp., respectively. GC-MS analysis revealed the existence of methionine, L-aspartic acid, glycyl-D-asparagine, 9cis-retinoic acid, stearic acid allyl ester and ascorbic acid permethyl. These active compounds contributed definitely to the antibacterial activity of ethanolic and aqueous extracts against the used pathogenic bacteria. As a result, the white rind could be properly handled and utilized to maximize the safe waste management.

Cantaloupe refers to the Cucumis melo species in the Cucurbitaceae family. Seeds are solid by-product generated in large quantity. Regulation of agricultural by-products as a source of bioactive compounds could minimize environmental hazard. For that reason, cantaloupe seeds were evaluated for its antioxidant and antibacterial activities. The current study included the proximate analysis of the seeds that had protein content 20.8%, crude fiber 33.1%, moisture 8% and fat 24.6%. Characterization of bioactive constituents by GC-MS analysis revealed the existence of methionine (60.17%), 4-aminoheptanedioic acid (4.75%), 9-cis-retinoic acid (34.12%) and stearic acid allyl ester (0.96%). Data revealed that total phenolic and flavonoid contents of cantaloupe seeds had range of 50.5 mg GAE/100 g dry weight and 6.43 mg QE/100 g dry weight, respectively. Total antioxidant activity valued 272.6 mg AAE/100 g dry weight. Ferric reducing antioxidant power increased relative to increase the extract concentration which indicated high reducing ability of cantaloupe seeds. Ethanolic extract of cantaloupe seeds had mild inhibition activity against E. coli and Salmonella sp., while Staphylococcus aureus was resistant to the ethanolic extract. Aqueous extract did not show any antagonistic effect against the three pathogenic bacterial strains. Inclusion of phytochemical bioactive compounds and methionine as sulphur-containing amino acid in cantaloupe seeds may contribute to the apparent antibacterial activity against Gram-negative bacteria. Results ensured that cantaloupe seeds possessed nutritional, antibacterial and antioxidant properties.