Khat (Catha edulis) Leaf Extract-Based Zinc Oxide Nanoparticles and Evaluation of Their Antibacterial Activity

Abstract

In this study, we used khat (Catha edulis) leaf extract as a reducing and stabilizing agent for the biosynthesis of zinc oxide nanoparticles (ZnO NPs). The rapid color change of the solution to pale yellow and UV-visible absorption peak at 322 nm confirmed the initial formation of ZnO NPs. FTIR spectrum analysis revealed the contribution of khat leaf extract to the bioreduction of Zn2+ ions to ZnO NPs. The FTIR spectrum for the stretching vibration of ZnO at 480 cm-1 also confirms the formation of ZnO NPs. The XRD spectrum showed the crystallinity and the hexagonal wurtzite structure of ZnO NPs. The size of the synthesized ZnO NPs calculated using the Debye-Scherrer formula was found to be equal to 17 nm. Antibacterial efficacy of green-produced zinc oxide nanoparticles against Gram-positive and Gram-negative microorganisms was tested. It has the greatest inhibition zone (23 mm) against E. coli, but the least activity was against S. pneumoniae (15 mm).