A novel combined process for extracting, separating and recovering flavonoids from flos sophorae immaturus

The hydrotropic characteristic of ionic liquids can be used to recover bio-molecules from aqueous media and ionic liquid based-aqueous biphasic systems have been extensively applied to the separation and purification of value-added compounds. According to the hydrotropy effect and the phase separation ability, n-1,3-dibutylimidazolium propionate was chosen from several imidazolium carboxylate ionic liquids to carry out the novel combined process integrating extracting, separating and recovering flavonoids from flos sophorae immaturus with the aid of aqueous biphasic systems. The optimum separation conditions derived from the response surface analysis were potassium citrate concentration 26.12%, pH 9.83 and temperature 41.89 °C, with the predicted extraction efficiency 100.27% and measured one 99.68%. The flavonoids in the ionic liquid-rich phase were precipitated out and recovered by the dilution of using pure water as an anti-solvent and the cooling of refrigerator, producing the maximum recovery rate 82% or so and establishing the appropriate dilution ratio 5 in the involved recovery systems. The extracts presented good scavenging activity, namely, 62% on the 2, 2-diphenyl-1-picrylhydrazyl radical and 85% on the hydroxyl radical from the well-known Fenton reaction when the sample concentration was approximately 0.125 mg/mL, elucidating the combined process efficient and feasible.