Garlic-mediated green synthesis of ZnO nanoparticles: Characterization, and comparative oral exposure study with bulk zno on body weight, food intake, and hemolytic activity of ZnO in male Albino Rats

Background: Zinc oxide (ZnO) is a widely used industrial material. When reduced to the nanoscale (ZnO NPs), its reactivity and functionality increase but safety concerns arise, particularly after repeated oral exposure. A greener synthesis uses garlic (Allium sativum) extract. Here, ZnO NPs were green-synthesized using garlic extract, characterized by FESEM and UV-Vis, and compared with bulk ZnO (at three dose levels) in male albino rats over 28 days. Body weight, food intake, and ex vivo hemolytic activity were assessed. A separate garlic-only group was included. Results showed that garlic extract neither altered nanoparticulate toxicity nor exhibited a standalone toxic effect.
Objective: This study comparatively evaluated toxicity of bulk ZnO and garlic-synthesized ZnO NPs 
Methodology: ZnO NPs were green-synthesized using Allium sativum (garlic) extract and characterized by UV-Vis spectroscopy and FESEM. Male albino rats were allocated into eight groups: control, garlic extract alone, bulk ZnO at 400, 200, and 100 mg/kg, and ZnO NPs at 400, 200, and 100 mg/kg, administered daily via oral gavage for 28 days. Food intake was recorded daily, and body weight was measured weekly. At the end of the exposure period, ex vivo hemolytic activity of both ZnO forms was evaluated on isolated erythrocytes. Data were analyzed using one-way ANOVA followed by LSD post-hoc test (P ≤ 0.05).
Results: Garlic extract administration (G2) did not produce any observable alteration in feed consumption or body weight. Weekly feed intake was reduced across all groups receiving either bulk or green-synthesized ZnO, with the most pronounced reduction recorded in the high-dose ZnO NPs group (G6), which also exhibited the lowest terminal body weight at week four. Body weight decline was delayed until the fourth week and was confined to groups G3, G6, and G7. In the hemolysis assay, ZnO NPs induced greater erythrocyte lysis than bulk ZnO at every tested concentration, reaching a maximum of 37% versus 26% at the 400 mg dose, with hemolysis demonstrating a clear concentration-dependent relationship.
Conclusion: The present findings demonstrate that repeated oral exposure to ZnO, particularly in its nanoform, induces dose-dependent reductions in feed intake, delayed body weight decline, and concentration-related erythrocyte hemolysis, with the nanoparticulate form eliciting markedly greater toxicity than its bulk counterpart.