Efficient Extraction of Bioactive Flavonoids from Ginkgo biloba Leaves Using Deep Eutectic Solvent/Water Mixture as Green Media

Deep eutectic solvent (DES)/water mixture as alternative extraction solvent was proposed for the efficient extraction of Ginkgo flavonoids from Ginkgo biloba leaves. Fifty DESs were prepared and investigated for the extraction of Ginkgo flavonoids. Compared with the present most efficient extraction solvent (70 % ethanol in water), three DESs, choline chloride/1,3-butanediol (ChCl/B), choline chloride/levulinic acid (ChCl/LA1), and 1,2-propanediol/levulinic acid (P/LA1), gave obviously higher extraction yields. The extraction process was further optimized systematically. The optimized extraction conditions were as follows: ChCl/LA1 containing 40 % (w/w) water was used as the solvent to extract Ginkgo flavonoids at a solvent to solid ratio of 10:1 (v/w) with stirring at 50 degrees C and 150 rpm for 15 min. Under the optimal conditions, 99.87 % of Ginkgo flavonoids could be extracted from the Ginkgo biloba leaves powder at a time. Furthermore, the recovery of Ginkgo flavonoids in the DES extraction solution was efficiently achieved using macroporous resin AB-8, which gave a recovery yield of 93.7 %. The DES-based extraction combined with macroporous resin recovery developed in this work can be an efficient alternative method for the extraction and separation of Ginkgo flavonoids from Ginkgo biloba leaves.