Hydrocotyle javanica Thunb and chitosan functionalized zinc oxide nanocomposites for enhanced antioxidant and antibacterial applications

BELLAI & HUI: ANTI-ICTERIC EFFECT OF A. SPINOSUS L. THROUGH PKC PATHWAY MODULATION

Abstract

Plant-mediated nanoparticle synthesis has gained attention due to the growing demand for eco– friendly and biocompatible materials. Hydrocotyle javanica (H. javanica), an ethnomedicinal herb rich in flavonoids, phenolics, and sesquiterpenes, remains underexplored for such applications. This study reports the green synthesis of zinc oxide nanoparticles (ZnO NPs) using H. javanica extract coated with chitosan (ZnO-HJ-CS), which was characterized through XRD, FTIR, zeta potential and particle size distribution (PSD), and subsequently evaluated for antioxidant (DPPH, SOD, NOD and OH assays) and antimicrobial activities (against E. coli, S. aureus, S. pneumoniae, S. epidermidis, and B. subtilis). XRD analysis of ZnO-HJ-CS demonstrated a hexagonal wurzite structure, consistent with the ZnO standard reference (JCPDS No. 01-079-2205). FTIR spectra exhibited broadening and shifting of peaks along the O-H, C=C, and
C-O stretches. SEM analysis revealed an irregular, roughened surface morphology. Compared to pure ZnO, the PSD shifted to 702 nm, with a zeta potential of -15.1 mV. ZnO-HJ-CS exhibited antioxidant activity with IC₅₀ values of 34.3, 74.5,
27.3 and 63.6 µg/mL in the respective assay, while exhibiting pronounced antibacterial activity against E. coli (IC₅₀ values of 53.31 µg/mL) and S. aureus (57.52 µg/mL) among all the tested bacterial strains.