Cytogenotoxic and Molecular Interaction Profile of Iohexol in SH-SY5Y Human Neuroblastoma Cells: An In Vitro and In Silico Approach.

Iohexol, a nonionic and low-osmolality iodinated contrast agent, is widely used in medical imaging applications. Although it is generally considered safe, its potential cytotoxic and genotoxic effects on neuronal cells have not been sufficiently elucidated. In this study, the cytotoxic, genotoxic, and oxidative stress-related effects of iohexol on the SH-SY5Y human neuroblastoma cell line were evaluated by both in vitro and in silico approaches. SH-SY5Y neuroblastoma cells were exposed to increasing concentrations of iohexol in the range of 1.5-150 mg I/mL for 24 h. Cell viability was evaluated by the CCK-8 (Cell Counting Kit-8) method, and DNA damage was analyzed by alkaline comet assay. Morphological changes were examined by phase contrast microscopy. In addition, possible interactions of the iohexol molecule with double-stranded DNA (B-DNA) and the human thioredoxin reductase I (TrxR1) enzyme were investigated by molecular docking analyses. Iohexol significantly decreased cell viability with increasing concentrations; especially significant cytotoxicity was detected at concentrations ≥ 75 mg I/mL. Morphological analyses revealed cellular stress indicators such as cell rounding, shrinkage, and detachment from the surface. The comet assay revealed a mild but significant genotoxic potential at high concentrations (75 and 150 mg I/mL), indicated by an increased frequency of cells with DNA damage (Damaged Cell Index), but not in the overall severity of DNA damage (Genetic Damage Index). Molecular docking results revealed that iohexol showed weak binding affinity with B-DNA (-3.9 kcal/mol) but a moderate interaction potential with the TrxR1 enzyme (-5.99 kcal/mol). This suggests that the observed toxicity may be mediated through indirect mechanisms, such as oxidative stress, rather than direct DNA interaction. In conclusion, this study demonstrates that high concentrations of iohexol induce both cytotoxic and mild genotoxic effects in a neuronal cell model. The findings suggest that the safety profile of this contrast agent should be carefully evaluated, highlighting the importance of dose adjustment in clinical applications.