Extraction and purification of flavonoids from radix puerariae

Purpose: To develop an efficient method for the purification of flavonoids from Radix puerariae Methods: Optimal extraction technology was obtained using orthogonal test. Through adsorption and desorption tests, 8 resins with different polarity, diameter, and surface area were studied. Finally, a novel macroporous resin, HPD200A, was applied in the work. Desorption tests were performed in a glass column packed with HPD200A resin, and several parameters of purification were studied. The content of puerarin and flavonoids in the samples were tested by a HPLC and a UV-Vis Spectrophotometer, respectively. Results: Optimum extraction technology was confirmed as follows: extraction time is 1.5 h; ratio of solvent to material 12; and repetition of extraction 3 times. Optimum purification technology was confirmed as follows: decoction is concentrated into 1.05 ~ 1.10 g/ml; 95 % ethanol is added to remove the impurities and the volume ratio is 1.5: 1; the concentration of loading sample is 0.25 g/ml (based on the weight of the crude drug), the volume of loading sample is 2 BV (bed volume). The mobile phases of desorption are water (2BV) and 30 % ethanol (4BV) in succession. The contents of puerarin and flavonoids in the extract were improved greatly after the purification procedure, by up to 32 and 75 %, respectively. Conclusion: This efficient method has potential for purification and preparation of flavonoids in the future.