Green Synthesis and Characterization of AgNPs of Martynia annua Fruit Extract: Evaluation for Their Antioxidant and Antibacterial Activities

Abstract

Background: Green synthesis of silver nanoparticles using plant extracts offers an eco-friendly and cost-effective alternative to conventional methods, utilizing phytochemicals for enhanced biological activity. Martynia annua shows strong potential in this approach due to its rich bioactive compounds and proven antimicrobial, antioxidant, and therapeutic properties. Aim: The study aimed to synthesize silver nanoparticles of Martynia annua fruit extract (MAF-AgNPs) and evaluate their antioxidant and antibacterial potential along with physicochemical characterization. Study Design: An experimental laboratory-based study involving green synthesis, nanoparticle characterization and in-vitro antioxidant and antibacterial evaluation. Place and Duration of Study: Department of Zoology, University of Rajasthan, Jaipur, India, during 2023–2025. Methodology: Fresh fruits of Martynia annua were collected from in and around Jaipur city and extract was prepared in methanol & water (3:1) solution. The fruit extract was used for green synthesis of silver nanoparticles where plant phytochemicals acted as reducing and stabilizing agents. The synthesized nanoparticles were characterized using UV–Visible spectroscopy, FTIR, XRD and FE-SEM techniques. Antioxidant activity was evaluated using DPPH, ABTS and FRAP assays while antibacterial activity was assessed by the Kirby–Bauer disc diffusion method against E. coli, P. aeruginosa and B. subtilis. Results: The extract yield was 6.21 ± 0.28 g and nanoparticle yield was 2.9 ± 0.2 mg. A characteristic UV–Visible peak at 432 nm confirmed nanoparticle formation. The synthesized nanoparticles exhibited concentration-dependent antioxidant activity in DPPH, ABTS and FRAP assays. Significant antibacterial activity was observed with zones of inhibition of 20.0 mm against E. coli, 13.33 mm against P. aeruginosa and 12.0 mm against B. subtilis. FE-SEM analysis showed particle sizes ranging from 15 to 51.91 nm while XRD confirmed their crystalline nature with an average size of 7.2 nm. Conclusion: The green synthesized MAF-AgNPs showed notable antioxidant and antibacterial activities supported by stable physicochemical properties. The findings highlight Martynia annua fruit as a promising and eco-friendly source for nanoparticle synthesis with potential biomedical applications.