Selective separation of the homologues of baicalin and baicalein from Scutellaria baicalensis Georgi using a recyclable ionic liquid-based liquid-liquid extraction system

Abstract To explore convenient and efficient techniques for the extraction and separation of the active ingredients in medicinal plants is still ongoing. As a new class of molten salt, ionic liquids (ILs) are widely used in the extraction of bioactive compounds from plant resources. In this work, the IL-based biphasic system was developed for the extraction and separation of the homologues of baicalin and baicalein from Scutellaria baicalensis Georgi. The IL-water biphasic system is superior to the other organic solvents-water systems for the extraction and separation of baicalin and baicalein. The phase volume ratio of the IL-water biphasic system was studied, and the other influencing parameters of solid–liquid ratio, extraction temperature, extraction time, and ultrasonic time were optimized through the single factor experiments. The results revealed that the extraction yields were 43.3 mg/g and 14.3 mg/g for baicalin (aqueous phase) and baicalein (IL phase), respectively; and the distribution coefficients were 23.8 and 13.7 for baicalin and baicalein, respectively under the optimized conditions. Finally, the IL can be easily recycled and reused by means of its temperature-responsive characteristic. This study provides a green and efficient method for the selective separation of the homologues in natural plant resources.