Effects of 1,3,4-thiadiazolium derivatives on MDR cell parameters.

The experimental conditions are described in the Materials and Methods, sections 2.5.1 and 2.9. The efficiency of each mesoionic derivative to inhibit the efflux of fluorescent substrates was determined by flow cytometry, relatively to controls (either parental cells, or the same transfected cells fully inhibited with reference inhibitors). The EC50 values (μM) were determined by using increasing derivatives concentrations, up to 50 μM, and calculated as derivatives concentrations producing half-maximal inhibition of drug efflux. The IG50 values (μM) were obtained by MTT assays upon treatment for 72 h with mesoionic derivatives at 0–100 μM; they were calculated as derivatives concentrations producing half-maximal inhibition of growth.
aIG50 obtained with resistant transfected cells
bIG50obtained with control, sensitive, cells; n.d. not determined
Effects of 1,3,4-thiadiazolium derivatives on MDR cell parameters.