Abstract: In the present study, three aqueous extraction techniques, water bath extraction, direct heating extraction and microwave-assisted extraction were compared to determine the most suitable one for maximum extraction yield of water-soluble flavonoids from Angelica keiskei Koidzumi leaves. The water bath extraction method provided maximum extraction of water-soluble flavonoids and the optimal extraction conditions were heating at 95 ℃ for 10 min. Further investigations were carried to explore the purification of the resulting crude extract under various conditions of macroporous resin type, sample loading amount, and elution solvent (ethanol) pH, ethanol concentration and elution volume. HP-20 type resin was found to have higher adsorption and desorption capacities for flavonoids and the optimal conditions for purifying water-soluble flavonoids from Angelica keiskei Koidzumi leaves using the resin were determined as follows: 40 mL of crude extract sample at 2.445 mg/mL were loaded onto HP-20 type resin and then desorbed with 8 BV of 70% acidified ethanol (pH 2), resulting in a purification factor of approximately 6.8.

Key words: Angelica keiskei Koidzumi, water-soluble flavonoids, macroporous resin, water extraction, purification