Green synthesis of iron oxide nanoparticles using <i>Justicia adhatoda</i> leaf extract and evaluating their <i>in vitro</i> antibacterial, antioxidant, anti-angiogenic, and anticancer activities

In this study, we report an eco-friendly green synthesis of iron oxide nanoparticles (IONPs) using Justicia adhatoda leaf extract. The leaf extract rich in polyphenols, flavonoids, alkaloids, and tannins serves dual roles, acting both as a natural capping/stabilizing agent and potentially imparting intrinsic antimicrobial, antioxidant, and anticancer properties. Characterization by XRD confirmed crystallinity; DLS revealed an average particle size of 77 nm, and zeta potential value was found to be −30.4 mV. The IONPs exhibited stronger antimicrobial activity against Gram-positive bacteria (highest zone of inhibition ∼9 mm) than Gram-negative strains (∼2.3 mm). Antioxidant evaluation showed an IC50 of 146 ± 0.3 µg/mL, and anti-angiogenic testing demonstrated the inhibition of new of blood vessel formation compared to control in CAM assay. The IONPs also exhibited cytotoxicity in vitro against A375 human melanoma cells (IC50 = 63.85 ± 0.2 µg/mL) and SK-N-SH neuroblastoma cells (IC50 = 61.06 ± 0.2 µg/mL). Collectively, these findings highlight the green-synthesized IONPs using J. adhatoda leaf extract offer a sustainable nanoplatform with promising antimicrobial, antioxidant, anti-angiogenic, and anticancer potential.