GREEN SYNTHESIS CHARACTERIZATION AND ANTIOXIDANTS EFFECT OF ZINC OXIDE NANOPARTICLES FROM RAWULVOFIA VOMITORIA EXTRACTS IN CADMIUM TREATED ALBINO RATS

ABSTRACT Heavy metals, particularly cadmium, pose significant health risks due to their toxic effects on humans and animals. Cadmium toxicity causes kidney damage, bone demineralization, and cancer, leading to oxidative stress and inflammation. This study aims to synthesize and characterize zinc oxide nanoparticles (ZnO NPs) from Rauvolfia vomitoria extracts and evaluate their antioxidant effects in albino rats exposed to cadmium. Rauvolfia vomitoria leaves and bark extracts (RVLE and RVBE) were prepared by ethanol/water extraction, yielding 59.2 g of RVLE per 1000 g of dried powder. RVLE-based ZnO NPs (RVLE-ZnNPs) were synthesized by dissolving zinc nitrate in water, followed by gradual addition of the RVLE extract under continuous stirring, with UV-visible spectroscopy confirming nanoparticle formation. ZnO NPs were characterized by UV-visible spectrometry, SEM, EDX, zeta potential analysis, XRD, and FTIR. Forty male albino rats (200 ± 20 g) were divided into eight groups, each receiving varying treatments, including cadmium alone or in combination with ZnO NPs or extracts. After 28 days of treatment, blood samples and organ tissues were collected for biochemical and cadmium analysis using ICP-OES. Oxidative stress biomarkers (SOD, GPx, MDA, CAT, GSH) were measured using standard laboratory method, and cadmium concentration in tissues were analyzed.. Data were analyzed using ANOVA with Tukey's HSD post hoc test, considering p < 0.05 as statistically significant. Characterization confirmed successful synthesis of ZnO NPs with distinctive UV peaks, indicating stable nanoparticles. SEM analysis showed spherical nanoparticles with a mean size of 45 ± 5 nm. EDX confirmed elemental zinc presence, while zeta potential measured at -25.3 mV indicated nanoparticle stability. XRD patterns confirmed high crystallinity, and FTIR detected functional groups from the RVLE involved in nanoparticle synthesis. Antioxidant assays revealed elevated MDA in the Cd-only group (2.73 ± 0.10 nmol/mg protein), indicating oxidative stress, while RVLE-ZnNPs and RVBE-ZnNPs groups showed significantly lower MDA levels (1.35 ± 0.07 nmol/mg and 1.41 ± 0.09 nmol/mg). SOD and GPx activities were significantly higher in treated groups, with the RVLE-ZnNPs group showing the highest SOD activity (89.3 ± 2.1 U/mg) and GPx activity (85.2 ± 1.9 U/mg), in comparison to the Cd-only group (SOD: 50.2 ± 1.8 U/mg; GPx: 47.5 ± 1.6 U/mg). Cadmium tissue accumulation was notably high in the liver (1.25 ± 0.09 µg/g) and kidneys (1.70 ± 0.10 µg/g) in the Cd group, but was reduced to near undetectable levels with RV NPs treatment (liver: 0.01 ± 0.00 µg/g; kidneys: 0.01 ± 0.00 µg/g). The green-synthesized ZnO NPs from Rauvolfia vomitoria showed significant potential in mitigating cadmium-induced oxidative damage in albino rats, attributed to their antioxidant activity. The reduction in oxidative stress markers and Cd accumulation in tissues supports the protective effects of RVLE-ZnNPs and RVBE-ZnNPs, suggesting that Rauvolfia vomitoria-derived ZnO NPs may serve as effective agents for managing cadmium toxicity, warranting further investigation for potential therapeutic applications.