Diisononyl phthalate down-regulates the expression of antioxidant genes <i>NFE2L2</i> , <i>TXN</i> , and <i>TXNRD2</i> , while diethyl-hexyl terephthalate up-regulates their expression including <i>SOD-1</i>

Phthalates, widely utilised 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 (<i>NFE2L2</i>, <i>SOD1</i>, <i>TXN</i>, and <i>TXNRD2</i>) 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 <i>via</i> 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 48 h. ROS levels also rose by 19-30%, accompanied by down-regulation of <i>NFE2L2</i>, <i>TXN</i>, and <i>TXNRD2</i>.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 <i>SOD1</i>.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.