GREEN SYNTHESIS OF SILVER NANOPARTICLES USING Cucumis melo L. DIETARY SUPPLEMENT (DIMPLESS®), STANDARDIZATION OF THE SYNTHESIS PROCESS, AND ANTIOXIDANT ACTIVITIES

The green synthesis of metal nanoparticles uses natural extracts as reducing and stabilizer agents, avoiding toxic substances and reducing environmental impacts. This approach is applied in various fields, such as medicine and environmental remediation. Cucumis melo is commonly known as cantaloupe and it is recognized for its nutritional and therapeutic properties, being rich in bioactive compounds such as carotenoids, polyphenols, and antioxidant enzymes. The aim of this study was to produce silver nanoparticles (AgNPs) from the ethanolic extract of the C. melo dietary supplement (Dimpless^®) (EECm) and to evaluate the antioxidant activity of EECm and AgNPs. The AgNPs were obtained via green synthesis and they were identified using UV-Vis spectrophotometric analyses under different conditions (concentrations of EECm and AgNO₃, pH, time, and temperature). After identifying the optimal colloidal surface plasmon resonance profile, antioxidant activity was assessed using the DPPH^• radical scavenging assay. The optimal conditions for AgNPs synthesis were: 1.5 mg/mL extract; 1 mM AgNO₃; pH 10; and 30 minutes at 50°C resulting in a dark brown solution and an extinction spectrum with peaks between 350 and 600 nm, which is consistent with AgNPs formation. EECm at concentration of 1.5 mg/mL did not exhibit significant scavenging activity, and AgNPs exhibited 16.86% antioxidant activity. EECm did not exhibit antioxidant activity; however, when used as a reducing agent for the AgNPs, it exhibited greater antioxidant capacity than that observed for EECm alone. The increase in activity observed for the AgNPs may be associated with the presence of compounds in EECm during the synthesis process, which may remain bound to the surface of nanoparticles, contributing to the formation of a capping layer. In addition, the surface properties of the nanoparticles may promote interactions with radicals present in the reaction medium. It can be concluded that the green synthesis of AgNPs using ethanolic extract of Cucumis melo dietary supplement (Dimpless®) was feasible under the established experimental conditions and even though EECm did not exhibit antioxidant activity, its compounds were capable of reducing the metallic salt for AgNPs formation, which demonstrated greater antioxidant activity, highlighting the potential for future biotechnological applications.

Acknowledgments: This study was supported by the Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES), Grant No. 88887.340172/2026-00