Antibacterial activity of nano zinc oxide green-synthesised from <i>Gardenia thailandica</i> triveng. Leaves against <i>Pseudomonas aeruginosa</i> clinical isolates: in vitro and in vivo study

Abstract

The increasing emergence of bacterial resistance is a challenge for the research community, thus novel antibacterial agents should be developed. Metal nanoparticles are promising antibacterial agents and could solve the problem of antibiotic resistance. Herein, we used <i>Gardenia thailandica</i> methanol extract (GTME) to biogenically synthesise zinc oxide nanoparticles (ZnO-NPs). The characterisation of ZnO-NPs was performed by UV spectroscopy, FTIR, scanning and transmission electron microscopes, dynamic light scattering, and X-ray diffraction. The antibacterial activity of ZnO-NPs was studied both <i>in vitro</i> and <i>in vivo</i> against <i>Pseudomonas aeruginosa</i> clinical isolates. Its minimum inhibitory concentration values ranged from 2 to 64 µg/mL, and it significantly decreased the membrane integrity and resulted in a significant increase in the inner and outer membrane permeability. Also, the ZnO-NPs treated cells possessed a distorted and deformed shape when examined by scanning electron microscope. The <i>in vivo</i> study (biochemical parameters and histological investigation) was conducted and it revealed a protective effect of ZnO-NPs against the deleterious influences of <i>P. aeruginosa</i> bacteria on lung, liver, and kidney tissues. LC-ESI-MS/MS revealed a phytochemical tentative identification of 57 compounds for the first time. We propose that GTME is a useful source for ZnO-NPs which has a promising antibacterial activity.