Investigation on Hansen solubility parameter, solvent effect and thermodynamic properties of 3-methylflavone-8-carboxylic acid dissolved in different solvents

Abstract

In this work, the dissolution behavior of a novel pharmacological factor, 3-methylflavone-8-carboxylic acid (MFCA) in different solvents was studied. Firstly, the solubility of MFCA in ten mono-solvents (acetonitrile, tetrahydrofuran, acetone, N,N-dimethylformamide, methyl acetate, ethyl acetate, butyl acetate, methanol, ethanol and isobutanol) and three binary solvents (N,N-dimethylformamide + acetonitrile, tetrahydrofuran + acetonitrile, methyl acetate + acetonitrile) at different temperatures (273.15–323.15 K) was determined by static equilibrium-high performance liquid chromatography. The experimental results showed that the solubility of MFCA increased with increasing temperature in tested solvents, and the solubility of MFCA in N,N-dimethylformamide was maximal. The Hansen solubility parameter was used to research the dissolution behavior of MFCA. Meanwhile, the solvent effect was discussed by KAT-LSER model in ten mono-solvents, and it was found that the hydrogen bond basicity and nonspecific dipolarity/polarizability were favorable to the dissolution of MFCA. In addition, modified Apelblat model, λh model, CNIBS/R-K model and Jouyban-Acree model were used to analyze the correlation and evaluate the applicability for the experimental solubility data of MFCA. The calculated data showed that modified Apelblat model and CNIBS/R-K model are the best models for mono and binary solvents, respectively. Finally, the dissolution thermodynamic properties of MFCA were studied by van't Hoff analysis, indicating that the dissolution of MFCA was an endothermic and entropic driven process. To sum up, these experimental results could provide pretty reference for purification and crystallization optimization of MFCA, and realize the industrial large-scale production of various drugs such as diuretic.