When antioxidant defences collapse: Gen-X induced oxidative stress in Procambarus clarkii hepatopancreas and gills

Gen-X was introduced as safer alternative to PFOA. Although its short-chain structure reduces bioaccumulation potential, it may mimic some legacy PFAS toxic effects. Its mobility in freshwater ecosystems and persistence raise concerns about biota. This study investigates whether sub-chronic Gen-X exposure induces oxidative stress in hepatopancreas and gills of Procambarus clarkii , maintained for 28 days at three environmentally relevant Gen-X concentrations (0.5, 1, 10 µg/L), plus a control tank. Chemical analyses (pooled samples) revealed dose-dependent accumulation in tissues, mainly in hepatopancreas. Oxidative biomarkers indicated cellular damage, including lipid peroxidation in the hepatopancreas at 1 µg/L and protein and lipid oxidation in both organs at 10 µg/L. Enzymatic assays (N=10) revealed tissue-specific responses. In the hepatopancreas, SODs activity was inhibited at the two highest doses, suggesting enzyme impairment, while it was activated in gills. In both organs, Se-GPxs exhibited a biphasic response, with increase at low exposure and decrease at high, coinciding with macromolecular injury. Catalase was inhibited at 0.5 µg/L in hepatopancreas and activated at 1 µg/L in gills, indicating compartment-specific detoxification. Results demonstrate that Gen-X disrupts redox homeostasis in P. clarkii through differential antioxidant modulation, with enzyme inhibition marking critical thresholds beyond which defences fail and oxidative damage occurs.