Diisononyl phthalate down-regulates the expression of antioxidant genes NFE2L2 , TXN , and TXNRD2 , while Diethyl-hexyl terephthalate up-regulates their expression including SOD-1

Phthalates, widely utilized as plasticisers to enhance the flexibility of rigid materials like polyvinyl chloride, are known for their endocrine-disrupting properties and cytotoxic effects. This study investigated the impact of Diisononyl phthalate (DINP) and Diethyl-hexyl terephthalate (DEHT) on human endothelial cells (EA.hy926). The assessment focused on cell viability, reactive oxygen species (ROS) production, and the antioxidant-responsive genes expression (NFE2L2, SOD1, TXN, and TXNRD2) following exposure to varying 1, 10, and 100 µg/mL of DINP or DEHT. Cell viability was determined using MTT and lactate dehydrogenase (LDH) release assays. ROS were measured using the DCFDA assay. Gene expression analysis was conducted via qRT-PCR after 48 h of exposure. Results revealed that DINP 100 µg/mL significantly reduced cell viability at 11 and 17% at 48 and 72 h, respectively; whereas increased LDH release by 69% at 48h. ROS levels also rose by 19-30%, accompanied by down-regulation of NFE2L2, TXN, and TXNRD2. Conversely, DEHT had no adverse effect on cell viability or LDH levels but elevated ROS production (11-14%) and induced up-regulation of antioxidant genes, including SOD1. The findings indicate that DINP exposure could negatively affect the cellular antioxidant response, whereas DEHT leads to up-regulation of antioxidant genes without detrimental effects on viability.