Solubility and thermodynamic properties of baicalein in water and ethanol mixtures from 283.15 to 328.15 K

Baicalein is a traditional Chinese medicine with multiple pharmacological effects, including anti-inflammatory activity, anti-pathogen activity, antitumor activity and neuroprotective activity. However, due to the limited solubility and poor stability in aqueous solution, its clinical application is greatly compromised. Here, we investigated the solubility and thermodynamic properties of baicalein in a binary system of water and ethanol from 283.15 K to 328.15 K (common temperature in labs and pharmaceutical industry), in order to optimize the extraction and purification process of baicalein. The results showed that the experimental solubility of baicalein increased with the increased ethanol ratio in the binary system and with the rising temperature. Six models, the ideal mixture model, the polynomial empirical equation, the Apelblat equation, the Buchowski–Ksiazczak (λh) equation, the general single model and the combination of Jouyban–Acree and van’t Hoff models, were chosen to correlate with the experimental data. The correlated results of the general single model were in good agreement with the experimentally measured solubility data with root mean square deviations (%) in the range of 0.22–1.06 (Formula presented.) In addition, its thermodynamic property implied that the dissolution process of baicalein under the studied conditions is a non-spontaneous endothermic process.