Purification of procyanidins from Kunlun Chrysanthemum by macroporous resins combined with silica gel and evaluation of antioxidant activities in vitro.

The objective of the present study was to evaluate an efficient purifying process of Kunlun Chrysanthemum procyanidins (KCPC) by combination of AB-8 macroporous adsorption resin and silica gel column through adsorption and desorption experiments under static and dynamic status with the purity of procyanidins and the antioxidant activity as indexes respectively. The optimum parameters for adsorption by AB-8 resin were as follows: Sample concentration 1mg/mL, pH6, injecting velocity 2 bed volume (BV) /h, with 3 BV 70% ethanol as eluting solvent, and elution flow rate 2BV /h. One cycle after treatment using AB-8 resin, the purity of KCPC obviously enhanced 3 times compared with that of not prepurified, that is from 22.68 to 63.76%. The optimum parameters for adsorption by silica gel column were as follows: The concentration of procyanidins in a sample solution of 1.2mg/mL (pH 6) with a speed of 2BV/h. Concentration for desorption, with 5 BV of 80% ethanol as an eluent at a flow rate of 2 BV/h. After one-run treatment with silica gel column, the purity of KCPC increased from 63.76 to 81.97%. The antioxidant activities of the purified KCPC in vitro were further investigated. The results indicated that the purification method of combination of AB-8 resin and silica gel column was superior to AB-8 adsorption resin used alone in term of antioxidant activities. Moreover, the 1,1-diphenyl-2-picrylhydrazyl (DPPH•) scavenging ability, the scavenging activity of hydroxyl radicals and the reducing ability appeared to be dose-dependent of KCPC. The novel purification method of combination of AB-8 resin and silica gel column will offer a promising way to purify KCPC for wider application.