The cyto-genotoxic potential of dibutyl phthalate promotes DNA damage and cellular stress with altered DNA repair gene expression in Madin-Darby Bovine Kidney (MDBK) cells

Dibutyl phthalate (DBP) is a widely used plasticizer and endocrine-disrupting chemical frequently detected in polyvinyl chloride (PVC) consumer products and environmental matrices. Although there is growing evidence of its toxicological effects, data on its cyto-genotoxic potential and the resulting molecular responses in bovine renal epithelial cells are limited. The present study investigated the cytotoxic, genotoxic, and chromosomal destabilizing effects of DBP in Madin-Darby Bovine Kidney (MDBK) cells and examined the transcriptional responses of the DNA damage-associated genes OGG1 and HPRT1 . MTT assay was used to determine cell viability after exposing cells to different DBP concentrations ranging from 5 to 200 µM. Cells were then treated with 25, 50 and 75 µM DBP for the alkaline comet assay, micronucleus assay and quantitative real-time PCR analysis, based on the estimated LC₅₀ value. DBP induced a concentration-dependent reduction in cell viability, with an LC₅₀ of 50 µM after 24 h of exposure. Significant dose-dependent increases ( p < 0.05) were observed in DNA damage index, comet tail DNA percentage, and genomic instability index. Similarly, micronucleus and binucleated cell frequencies, and cytostasis increased significantly, whereas cytokinesis-block proliferation index (CBPI) decreased with increasing DBP concentration. The highest tested concentration (75 µM) elicited cyto-genotoxic responses comparable to the positive control group. Gene expression analysis showed that both OGG1 (5.33-fold) and HPRT1 (6.57-fold) were elevated, with higher DBP concentrations leading to increased gene expression. These findings highlight that DBP induces concentration-dependent cyto-genotoxicity and transcriptional alterations in MDBK cells, underscoring the need for safer plasticizer alternatives.