Example 13
The hemolysis assay was previously described by G. Ruiz-Gomez, et al., J. Med. Chem. (2009) 52: 6042-6052. Prior to the assay, the optimum concentration of Normal Human Serum (NHS) needed to achieve 100% lysis of rabbit erythrocytes (RE) is determined by titration. In the assay, NHS (Complement Technology) is diluted in GVB0 Buffer (0.1% gelatin, 5 mM Veronal, 145 mM NaCl, 0.025% NaN3, pH 7.3, Complement Technology) plus 10 mM Mg-EGTA and incubated with test compound at various concentrations for 15 minutes at 37° C. RE (Complement Technology) freshly suspended in GVB0 plus 10 mM Mg-EGTA are added to a final concentration of 1×108 cells/mL and reactions are incubated for 30 minutes at 37° C. Positive control reactions (100% lysis) consist of GVB0 plus 10 mM Mg-EGTA with NHS and RE but without test compound; negative control reactions (0% lysis) consist of GVB0 plus 10 mM Mg-EGTA with RE only. Samples are centrifuged at 2000 g for 3 minutes and supernatants collected. Absorbance at 405 nm (A405) is recorded using a microplate spectrophotometer. IC50 values are calculated by nonlinear regression from the percentage of hemolysis as a function of test compound concentration.