Experimental solubility measurement and determination of preferential solvation of quercetin as a natural antioxidant agent in binary mixtures of water and 2-propanol by Kirkwood-Buff method

Flavonoids are the most abundant bioactive polyphenolic compounds having a plant origin and the most important property of them is their antioxidant activity. Since the knowledge of the solubility of bioactive materials in various solvents is very important for pharmaceutical researches and industrial applications, in this work, the solubility of natural flavonoid quercetin has been measured quantitatively. This study has been performed in binary solvent mixtures containing water and 2-propanol (0-100% v/v), at constant temperature 25 °C by using the saturation technique. From solubility data, the preferential solvation parameters of this flavonoid were determined by the reverse Kirkwood-Buff integral method in different compositions of the solvent mixture studied. The results show that the flavonoid solubility increases with increasing percentage of organic solvent and also in high compositions of the organic solvent, solvation extent of this compound become more than water-rich region. Finally, the results obtained have been discussed based on solvent-solute interactions.