The green synthesis of metal nanoparticles using plant-based phytochemicals has emerged as a sustainable alternative to conventional physical and chemical approaches, offering eco-friendly, cost-effective, and scalable solutions. Pterocarpus marsupium, a medicinally significant plant, contains diverse phytoconstituents such as flavonoids, phenolics, and terpenoids, which act as natural reducing and capping agents in nanoparticle synthesis. This comparative review investigates and evaluates the synthesis, physicochemical characterization, and biomedical applications of gold (AuNPs), silver (AgNPs), zinc (ZnNPs), and copper (CuONPs) nanoparticles derived from P. marsupium bark extract. Characterization techniques including UV-Visible spectroscopy, FTIR, SEM, and XRD revealed unique structural and morphological features of the nanoparticles. The AuNPs displayed SPR at ~535 nm, indicating effective formation and stability. AgNPs and CuONPs showed peaks around 435 nm and 442 nm, respectively, while ZnNPs showed characteristic absorption near 370 nm. FTIR spectra confirmed the presence of phytochemicals responsible for bioreduction and stabilization. Biologically, AuNPs demonstrated potent anticancer activity against oral squamous cell carcinoma (OSCC), attributed to ROS generation and mitochondrial apoptosis pathways. AgNPs exhibited significant antioxidant and cytotoxic effects on ovarian cancer cells, while CuONPs were most effective against Gram-positive and Gram-negative bacteria. Although ZnNPs have been less explored in the reviewed studies, they are widely recognised for their antibacterial and antioxidant properties. This study highlights the multifunctionality and therapeutic potential of phyto-synthesised metal nanoparticles, with a particular emphasis on P. marsupium as a valuable green nanofactory for biomedical applications.

Pterocarpus marsupium, green synthesis, nanoparticles, anticancer, antioxidant, antimicrobial activity, FTIR, UV-Vis, phytochemicals.