In vitro toxicity of surfactants in U937 cells: cell membrane integrity and mitochondrial function.

Surface-active agents are components of many drugs and cosmetics. In order to examine their cytotoxic and membrane-toxic potential, various surfactants were examined in U937 cells using the tetrazolium reduction assay EZ4U, a modified XTT test, and the arachidonic acid release test (AART). EZ4U measures the ability of living cells to reduce a colorless tetrazolium salt to an orange water-soluble formazan derivative by mitochondrial dehydrogenases. [3H]arachidonic acid ([3H]AA) is rapidly incorporated into cell membrane phospholipids. Due to membrane disintegration or enzymatic catalysis, it is released into the cell culture medium and can be measured by scintillation technique. The results after 24-hour-exposure are as follow (CC50 microg/ml; RC50 microg/ml): benzalkonium chloride (0.6), Cremophor A25 (1.4; 5.9), sodium cetearyl sulfate (1.6; 19.9), Brij78 (1.6; 7.7), TEGO betaine E (3.0; 19.3), TEGO betaine CKD (4.1; 20.2), TEGO betaine L7 (7.5; 20.0), sodium dodecyl sulfate (7.5; 39.0), Triton X-100 (8.9; 110), polysorbate 80 (48.1; 491), soybean lecithin (7920; 19940).