Synthesis and characterization of ZnO nanomaterial from Cassia sieberiana and determination of its anti-inflammatory, antioxidant and antimicrobial activities

Utilization of plant extracts for the synthesis of nanomaterials is a green technology that is safe to the environment. In the current study, zinc oxide nanoparticles (ZnO NPs) was synthesised using the methanolic root bark extract of Cassia sieberiana as capping and stabilizing agents for the first time. The ZnO NPs were then characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), UV–Vis spectroscopy, transmission electronic microscopy (TEM) and energy dispersive X-ray (EDX). Anti-inflammatory and antioxidant activity of the nanoparticles were analyzed by egg albumin (EA) denaturation assay and DPPH free radical scavenging assay respectively. The agar well diffusion method was also used to access the antimicrobial activity of the ZnO NPs against S. aureus (gram-positive), E. coli (gram-negative), S. typhi (gram-negative) and C. albicans (yeast). Saponins, anthracenosides, triterpenes and polyphenols were the phytochemicals present in the plant extract. The average particle size (TEM) determined was 12.9 ± 3.1 nm with spherical shapes. ZnO NPs demonstrated good antioxidant activity (IC50 = 0.480 ± 0.018 mg mL−1) and dose-dependently inhibited the heat-induced denaturation of egg albumin (IC50 = 0.676 ± 0.000 mg mL−1). In general, the synthesized ZnO NPs showed a positive anti-microbial activity against the selected microbes. The ZnO NPs showed a significant zone of inhibition for S. typhi (20.0 mm), S. aureus (24.0 mm), whereas the zone of inhibition was less for E. coli (13.7 mm) and C. albicans (11.7 mm) at 25 mg/mL. The green synthesized ZnO NPs may be used as an effective drug delivery system.