Apoptosis and cytotoxicity caused by ethoxyquin salts in human lymphocytes in vitro

Cytotoxicity of four salts of ethoxyquin (EQ; 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline), an antioxidant used in various food products (mainly in animal feeds), was studied: ethoxyquin ascorbate, ethoxyquin hexanoate, ethoxyquin salicylate and ethoxyquin salt of Trolox C (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid). This study is part of the research aimed at searching for new potential preservatives, which was undertaken due to many unfavourable side-effects observed in animals fed with EQ containing feeds and in people working with it. In this study the trypan blue exclusion assay was used to study the viability of human cultured lymphocytes after 24-h treatment with the tested compounds, and the TUNEL method was applied to detect apoptotic DNA fragmentation. All the compounds tested decreased cell viability when they were used at the two highest concentrations: 250 and 500 μM. Significantly increased numbers of apoptotic cells were observed after treatments with ethoxyquin ascorbate, ethoxyquin hexanoate and ethoxyquin salicylate.