Introduction:: In recent years, the green synthesis of gold nanoparticles (AuNPs) using plant-based extracts has emerged as an eco-friendly, cost-effective, and sustainable alternative to conventional chemical synthesis. Among various plant sources, guava (Psidium guajava) leaves are rich in bioactive phytochemicals and serve as a natural reservoir of reducing and stabilizing agents for nanoparticle fabrication. Methods:: Gold nanoparticles were synthesized using an aqueous extract of Indian red guava leaves. Phytoconstituents such as polyphenols, flavonoids, and vitamin C were employed to reduce gold ions (Au³⁺) to stable AuNPs, eliminating the need for toxic chemicals and adhering to the principles of green chemistry. The synthesized nanoparticles were characterized using UV–Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM). Results:: The biosynthesized AuNPs exhibited notable antioxidant properties, as demonstrated by their effective scavenging of DPPH free radicals, indicating potential in mitigating oxidative stress. Antimicrobial assays revealed broad-spectrum activity against both Gram-positive and Gramnegative bacterial strains. Biocompatibility was confirmed by MTT assays, which showed minimal cytotoxicity at lower concentrations. Further in vivo toxicity assessment using zebrafish embryos revealed minimal adverse effects across tested concentrations. Discussion:: These findings underscore the multifunctional nature of guava leaf-mediated AuNPs, which exhibit strong antioxidant and antimicrobial activity, excellent biocompatibility, and low cytotoxicity. The biogenic synthesis route not only improves the functional properties of AuNPs but also aligns with environmental sustainability goals by valorizing agricultural by-products and biobased economy. Conclusion:: This study validates the use of guava leaf extract as a green, sustainable, and efficient medium for the synthesis of AuNPs. The resulting nanoparticles hold significant potential for biomedical applications, including drug delivery, wound healing, and antimicrobial therapies. This green approach supports the broader goals of sustainable nanotechnology and circular economy practices.
Balasamy et al. (Sun,) studied this question.