Plant-mediated ZnO nanoparticles using Allophylus concanicus: Synthesis, characterization, and in vitro biological evaluation

Abstract

This study reports the green synthesis of zinc oxide nanoparticles (ZnONPs) using Allophylus concanicus leaf extract (Ac-ZnONPs) via an eco-friendly co-precipitation method. Nanoparticle formation was confirmed by a color change and a UV–Visible absorption peak at 354​​​​​​ ​nm. FE-SEM revealed spherical nanoparticles averaging 33.14​​​​​​ ​nm, with EDX confirming Zn, O, and C. FTIR indicated phenolic and flavonoid functional groups involved in reduction and capping. PXRD patterns matched the hexagonal wurtzite ZnO phase (ICDD No. 01–070–8072), with calculated lattice parameters a= 3.26 A˚ and c= 5.22​​​​​​ A˚. Zeta potential of –18.4​​​​​​​ mV suggested moderate colloidal stability. Biological evaluations demonstrated strong antibacterial activity (MICs of 1.25 µg/mL for Gram-positive and 5​​​​​​​ µg/mL for Gram-negative bacteria), likely due to ROS generation and membrane disruption. Ac-ZnONPs exhibited excellent antioxidant activity (93.26 % DPPH scavenging at 200​​​​​​​ µg/mL) and notable anti-inflammatory activity (IC₅₀ of 15.92 ± 0.56​​​​​​​ µg/mL, comparable to diclofenac sodium). Moderate antidiabetic activity was observed (IC₅₀ values of 20.27 ± 0.39​​​​​​​ µg/mL for α-amylase and 18.18 ± 0.39​​​​​​​ µg/mL for α-glucosidase). These findings highlight the multifunctional bioactivity of Ac-ZnONPs, supporting their potential for diverse biomedical applications and offering a sustainable route for plant-based ZnO nanomaterials.