Possible effects of counterions on biological activities of anionic surfactants

The aggressiveness in terms of apogenic and necrotic activities of lysine-d erived anionic surfactants towards a mammalian cell line (U937) were studie d. We used (NNepsilon)-N-alpha-dioctanoyl lysine as the model surfactant wi th lysine, tris, Na+ or Li+ as counterions. The aggressiveness of the diffe rent surfactants was assessed as the concentrations leading to apoptosis or necrosis after the cells were incubated in the presence of surfactants and then cultivated in their absence. Used in the same conditions, acetates as sociated with the same cations, had no effects on the cells. Our results sh ow that the aggressiveness of the surfactants depended on the nature of the counterions: it was high when surfactants were associated with small count erions, and low with large counterions. (C) 2001 Elsevier Science Inc. All rights reserved.