Avaliação comparativa de biomarcadores da biologia redox no fígado de fêmeas de zebrafish expostas ao metilparabeno e ao ácido 4-hidroxibenzóico

Abstract

Parabens have been widely used in industrial, cosmetic, and food products due to their effectiveness in preventing microbial contamination and preserving products. However, the increasing use of these compounds has raised concerns about their impact on animal, human, and environmental health. Although parabens are frequently detected in various aquatic environments, understanding their systemic effects on aquatic organisms remains limited. This study used adult female zebrafish (Danio rerio) as an animal model to evaluate the ecotoxicological effects of subacute exposure to methylparaben (MeP), one of the most commonly used and detected parabens, as well as 4-hydroxybenzoic acid (4-HB), its primary metabolite. After exposing the females to environmentally relevant concentrations of MeP and 4-HB (1.0 and 10.0 µg/L) for seven days, multiple biomarkers in the liver were assessed, including biometric parameters, the hepatosomatic index, redox imbalance, and oxidative stress. Biometric data and the hepatosomatic index showed no significant alterations after the short exposure period. However, antioxidant activity was affected, with a significant increase in reactive oxygen species (ROS) production in all groups exposed to both parabens. Animals exposed to MeP and 4-HB exhibited a reduction in the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), with more pronounced reductions associated with 4-HB, especially at the higher concentration. Conversely, total thiol (T-SH) levels, an antioxidant capacity biomarker, and the activity of glutathione-S-transferase (GST) showed no significant changes compared to the control group. Lipid peroxidation, evaluated through malondialdehyde (MDA) levels, significantly increased in groups exposed to 4-HB and the higher concentration of MeP, indicating oxidative damage to cell membranes. On the other hand, the increase in total protein levels in 4-HB-treated groups suggests possible adaptive responses by the organism. Our findings support previous studies showing that MeP induces redox imbalance and oxidative 9 damage. However, for the first time, we demonstrate that exposure to 4-HB results in greater hepatic toxicity compared to MeP, with more pronounced effects on the reduction of antioxidant defenses and the increase in lipid peroxidation. The results indicate that 4HB had a more significant impact on the liver of female zebrafish compared to MeP. These findings suggest that subacute exposure to both parabens, especially 4-HB, has a greater impact on redox homeostasis and possibly hepatic metabolism in fish, highlighting the need for further investigations into the ecotoxicological effects of 4-HB exposure. Given that 4HB is a common metabolite of various parent parabens and has been ubiquitously detected in the environment and aquatic organisms, further research is crucial.