Binding of new aminopropan-2-ol compounds to bovine serum albumin, α1-acid glycoprotein and rat serum using equilibrium dialysis and LC/MS/MS

Background: The binding of three new aminopropan-2-ol compounds briefly called 2F109, ANBL and TWo8 with potential cardiovascular activity to bovine serum albumin (BSA), alpha 1-acid glycoprotein (AGP) and to rat serum was studied. The chemical structures of these compounds are related to carvedilol. They possess an antiarrhythmic and hypotensive activity, and beta- and alpha-adrenolytic mechanism of action. All analogues are weak bases with pKa values 8.65, 8.85 and 8.26 for 2F109, ANBL and TWo8, respectively, and they possess lipophilic character (log P> 1.9584). Methods: The extent of protein binding was determined using equilibrium dialysis in the range 2.5 - 900 mu M, and 2.5-300 mu M for binding of investigated compounds to BSA and AGP, respectively, and the quantitative measurement was done by LC/BSI-MS/MS assay. Results: The studied compounds bound to a single class of binding sites on BSA which was characterized by low affinity (K-d for 2F109 = 8.49 x 10(-5) M, for ANBL = 1.92 x 10(-5) M, and for TWo8 = 1.71 x 10(-5) M) and low capacity (n = 0.53 for 2F109, 0.132 for ANBL and 0.13 for TW08). The binding of 2F109, ANBL and TWo8 to AGP revealed one class of binding sites, with moderate affinity (K-d for 2F109 =4.67 x 10(-6) M, for ANBL = 3.48 x 10-5 M, and for TWo8 = 1.13 x 10(-5) M) and higher capacity (n = 2.21 for 2F109, 2.76 for ANBL and 2.28 for TWo8). Conclusion: The obtained data indicate that 2F109, ANBL and TWo8 moderately bind to BSA (34.2 - 71.2%) with low capacity (K-a = 6.21 x 10(3)-7.61 x 10(3) M-1) and strongly bind to AGP (71.5 - 85.5%) with moderate affinity (K-a= 7.94 x 10(4)-4.73 x 10(5)M(-1)).