The effects of biogenic and abiogenic disulphides on endothelial cells in culture: Comparison of three methods of viability assessment

Effects of biogenic and abiogenic disulfides on viability of human umbilical vein endothelial cells in culture were studied using three methods: inclusion of neutral red (NR) into cells, quantification of intracellular ATP, and modifications of the Mosmann method (1983), the essence of which consists in reduction of tetrazolim salts—MTT and MTS—by cells (Mosmann, 1983). 2,2′-Dithio-bis(N,N-diethyl)dietanamine (DS) was used as an abiogenic sulfide. As for biogenic disulfides, we used oxydized glutathione (GSSG) and garlic oil (GO), the major component of which is diallyl disulfide (DADS). It has been established that DS and GO have a compatible cytotoxic effect (ES₅₀ amounts to ～0.6 mM), whereas GSSG at a concentration up to 1 mM had no effect on the viability of endothelial cells. It has been demonstrated for the first time that DS and GO can serve as mediators of plasma-membrane oxidoreductase activity, with tetrazolium salts being used as the substrate, which may cause a false-negative effect. In this connection, Mosmann’s method has serious limitations in evaluating the effect of disulfides on cell viability, although it can be used when studying the mechanism of their action.