Study of dissolution and transfer processes of new bioactive thiazolo[4,5-d]pyrimidine derivatives in modeling biological systems

•Solubility of 3 new bioactive compounds was measured in buffers and 1-octanol.•Solubility data were correlated with the modified Apelblat and van’t Hoff equations.•Partition coefficients in 1-octanol/buffer 7.4 system of compounds were determined.•Thermodynamic functions of dissolution and partition were discussed. New thiazolo[4,5-d]pyrimidine derivatives were synthesized as potential antifungal agents. The amorphous nature of the obtained compounds was verified by DSC and PXRD. The kinetic and equilibrium solubilities of the derivatives were studied by the shake-flask method in pharmaceutically relevant solvents: buffer pH 2.0, buffer pH 7.4 and 1-octanol. It has been found that within the temperature range of (293.15–313.15) K the solubility of the compounds does not exceed 5 10-4 mol·L-1 in aqueous solvents and 6 10-2 mol·L-1 in alcohol. The solubility values were correlated by van’t Hoff and modified Apelblat equations. Based on the partition coefficients in the system 1-octanol/ buffer pH 7.4 the lipophilicity of the compounds have been estimated. The thermodynamic functions of dissolution and partition for the compounds studied in the solvents selected were calculated. It has been established that the transfer process of compounds from the aqueous phase to the organic is endothermic and entropy-controlled. The efficiency of the some computer’s programs to predict partition coefficients has been tested using experimental data. It was shown that the in vitro antifungal activity of the studied compounds increases with growth solubility in aqueous solvents.