Protective Effects of Aloe vera Gel Extract Against Cytotoxic, Genotoxic, and Physiological Damage Induced by Nitric Acid in Allium cepa Cells

This study was conducted using the Allium cepa L. test system to determine the possible physiological and cytogenetic effects of Aloe vera L. (ALV) leaf gel extract against the toxicity induced by nitric acid (HNO₃), a strong oxidizing agent. In terms of germination percentage, the ALV1 (10%) and ALV2 (20%) groups exhibited results similar to the control group. However, the marked decrease in germination percentage observed following HNO₃ exposure was significantly improved in the HNO₃ALV1 (10%) and HNO₃ALV2 (20%) combination groups, indicating the mitigating role of Aloe vera gel in suppressing toxic effects. Furthermore, compared with the HNO₃-treated group, significant increases in root length and fresh weight were observed in the HNO₃ALV1 (10%) and HNO₃ALV2 (20%) groups. With respect to the mitotic index (MI), the HNO₃ALV1 (10%) group showed a higher MI value than the HNO₃ALV2 (20%) group, suggesting that increasing the concentration of Aloe vera gel may exert an inhibitory effect on mitotic activity. Similarly, the frequency of chromosomal abnormalities and micronucleus. MN was lower in the HNO₃ALV1 (10%) group compared to the HNO₃ALV2 (20%) group. Nonetheless, both combinations significantly reduced MN formation and chromosomal abnormalities compared to HNO₃ treatment alone, indicating a protective and antigenotoxic effect. In conclusion, the findings demonstrate that Aloe vera gel extract, when applied at appropriate concentrations, has the potential to act as a bioprotective agent by alleviating HNO₃-induced genotoxicity and physiological impairments in Allium cepa root meristem cells.