Abstract:

This study aimed to determine the equilibrium solubility and oil/water partition coefficients of quercetin and its
ester derivative. The equilibrium solutions of quercetin and its ethyl acetate derivative in various media were detected by
high performance liquid chromatogram (HPLC); and the shake flask-HPLC method was applied to determine the partition
coefficients of quercetin and its ethyl acetate derivative in n-octanol-water-buffer solutions of different pH values. The
equilibrium solubility of querctin and its ethyl acetate derivative was 23.02 and 10.23 μg/mL in water at 37 ℃, and the
equilibrium solubility of querctin increased with increasing pH of the buffer solution, but no remarkable change was
observed for its ethyl acetate derivative. The partition coefficients of quercetin and its ethyl acetate derivative in n-octanolwater-
buffer solutions of different pH were 1.819 and 3.696, respectively. The esterification modification of quercetin
improved its lipid solubility.

Key words: querctin, ethyl acetate derivative of quercetin, equilibrium solubility, apparent oil/water partition coefficient