Redox-dependent cytoprotection by zerumbone via Nrf2-Keap1 mediated restoration of antioxidant and apoptotic balance in Mancozeb-exposed cells.
Mancozeb (MZB), a widely used fungicide, induces oxidative stress-mediated cytotoxicity through excessive reactive oxygen species (ROS) generation. Present study evaluated the cytoprotective potential of zerumbone (Zer), a bioactive sesquiterpenoid, against MZB-induced toxicity in Vero cells. Dose-response and time-course assays determined the EC50 of MZB and a non-cytotoxic dose of Zer. Pre-treatment with Zer (10 μM, 18 h) significantly improved cell viability (66 ± 7%) following MZB exposure (22 μM, 6 h) and markedly reduced intracellular ROS levels. Zer attenuated MZB-induced DNA damage, lowering genotoxicity from 44 ± 6% to 23 ± 12% (p < 0.05), and significantly reduced apoptotic and necrotic cell death. Expression of apoptosis (Bax, Bcl-2, caspase-3, -8, -9), antioxidant (Nrf2, Keap1, catalase, HO-1, NQO1, SOD, GPx, PHD2) and inflammation-related (p53, Akt) markers was analysed and validated by western blotting to characterize molecular responses to Zer pre-treatment. Dysregulated expression of apoptosis and antioxidant markers, including caspase-3, catalase and GPx, was restored by Zer. Additionally, Zer normalized MZB-elevated Nrf2 levels while inducing its regulatory partners Keap1, NQO1 and HO-1. Overall, zerumbone confers substantial protection against MZB-induced oxidative injury by restoring redox balance, reducing genotoxic stress and preventing cell death, highlighting its therapeutic potential against fungicide-induced toxicity.