Cytotoxic and Apoptotic Effects of Sultamicillin and Cefuroxime Axetil and Their Potential Transformation Products in RTG-2 Fish Gonad Cells.

Sultamicillin and cefuroxime axetil are orally administered prodrugs that have been detected in aquatic environments, yet limited information is available regarding the cellular responses associated with their exposure in fish models. This study evaluated cytotoxic and apoptosis-related cellular responses following in vitro exposure to sultamicillin and cefuroxime axetil in the rainbow trout gonad cell line (RTG-2). Cell viability was assessed after 48 h exposure to concentrations ranging from 3.125 to 100 µM using the WST-1 assay, and IC50 values were determined. The calculated IC50 values were 22.80 ± 1.72 µM for sultamicillin and 31.33 ± 0.95 µM for cefuroxime axetil. Apoptosis-related responses were evaluated by Western blot analysis of p53 and BCL2 proteins. Exposure under the present experimental conditions was associated with increased p53 expression and decreased BCL2 expression, indicating activation of apoptosis-related pathways. Molecular docking analysis predicted stable interactions of both compounds with p53 and BCL2, with sultamicillin exhibiting stronger predicted binding affinities than cefuroxime axetil. Overall, the findings demonstrate that exposure to sultamicillin and cefuroxime axetil under the present in vitro conditions is associated with reduced cell viability and apoptosis-related protein alterations in RTG-2 cells. Because both compounds are prodrugs that may undergo hydrolysis or transformation during incubation, the observed biological responses should be interpreted as effects associated with the exposure conditions rather than as evidence of the intrinsic toxicity of the intact parent compounds. These findings provide baseline information for future mechanistic studies and environmental risk assessment of antibiotic-related contaminants in aquatic ecosystems.