Quantitative phenolic profiling and protective effects of grape seed extract on mancozeb-induced cellular and genetic toxicity.

In this study the comprehensive toxic effects of the fungicide mancozeb on Allium cepa L., a widely used non-target model organism, and simultaneously explored the protective potential of grape seed extract (GSE) were studied. A broad set of biological responses was assessed, encompassing physiological parameters (germination rate, root elongation, biomass accumulation), cytogenetic markers [mitotic index (MI), Micronucleus (MN) frequency, chromosomal aberrations(CAs)], biochemical indicators [malondialdehyde (MDA), proline, superoxide dismutase (SOD), catalase (CAT), and chlorophyll levels], as well as anatomical changes in root meristematic tissues. Additionally, Comet assay was applied to detect DNA fragmentation. The experimental design comprised six treatment groups: a negative control irrigated with tap water, two groups administered GSE at concentrations of 465 mg/L and 930 mg/L, a group exposed solely to mancozeb (150 mg/L), and two groups co-treated with mancozeb and each GSE concentration. After the exposure period, root and leaf samples were harvested for comprehensive analyses. The control group exhibited optimal physiological growth and minimal cytogenetic and biochemical stress indicators. Mancozeb treatment, in contrast, significantly elevated the frequency of MN and CAs, increased lipid peroxidation and proline accumulation, and enhanced antioxidant enzyme activities (SOD and CAT), alongside DNA damage and marked anatomical disruptions in meristematic cells. However, the co-application of GSE mitigated these adverse effects across all measured endpoints, with the higher GSE concentration demonstrating superior efficacy. Cell proliferation, which mancozeb application reduced by 36.3% compared to the control, improved by 17.4% in the mancozeb + 930 mg/L GSE applied group. The protective effects of GSE were attributed to its rich phenolic composition, including compounds such as quercetin, resveratrol, and gallic acid, which likely contributed to its antioxidant and cytoprotective properties. In conclusion, mancozeb induced pronounced toxicity in A. cepa at the cellular, biochemical, and anatomical levels, while GSE supplementation effectively ameliorated these toxic impacts. These findings highlight the dual necessity of regulating pesticide application to prevent non-target organism harm and considering natural phytochemical agents like GSE as potential bioprotectants against agrochemical-induced stress.