The antioxidant butylated hydroxyanisole potentiates the toxic effects of propylparaben in cultured mammalian cells

• Butylated hydroxyanisole and propylparaben in mixture induce greater cytotoxicity than individual exposure to the compounds.
• Concurrent exposure of Vero cells to butylated hydroxyanisole and propylparaben causes enhanced oxidative DNA damage.
• Cross-talk between TGFβ and ATM pathways regulates the cell response to butylated hydroxyanisole-propylparaben mixture.

Butylated hydroxyanisole and propylparaben are phenolic preservatives commonly used in food, pharmaceutical and personal care products. Both chemicals have been subjected to extensive toxicological studies, due to the growing concern regarding their possible impacts on environmental and human health. However, the cytotoxicity and underlying mechanisms of co-exposure to these compounds have not been explored. In this study, a set of relevant cytotoxicity endpoints including cell viability and proliferation, oxidative stress, DNA damage and gene expression changes were analyzed to assess whether the antioxidant butylated hydroxyanisole could prevent the pro-oxidant effects caused by propylparaben in Vero cells.We demonstrated that binary mixtures of both chemicals induce greater cytotoxic effects than those reported after single exposure to each compound. Simultaneous treatment with butylated hydroxyanisole and propylparaben caused G0/G1 cell cycle arrest as a result of enhanced generation of oxidative stress and DNA double strand breaks. DNA microarray analysis revealed that a cross-talk between transforming growth factor beta (TGFβ) and ataxia-telangiectasia mutated kinase (ATM) pathways regulates the response of Vero cells to the tested compounds in binary mixture. Our findings indicate that butylated hydroxyanisole potentiates the pro-oxidant effects of propylparaben in cultured mammalian cells and provide useful information for their safety assessment.