Abstract
The enrichment and separation of astragalosides IโIV (AGs IโIV) were studied on eight macroporous resins in the present study. SAโ3 resin offered the best adsorption and desorption capacities for AGs IโIV than other resins. The models of adsorption kinetics were investigated in order to elucidate the mechanism of adsorption. The pseudoโsecondโorder model was the better choice than the pseudoโfirstโorder model to describe the adsorption behavior of AGs IโIV onto SAโ3 resin. The equilibrium experimental data were well fitted to Langmuir and Freundlich isotherms. SAโ3 resin adsorption chromatography tests were carried out to optimize the separation process of AGs IโIV from Radix Astragali extracts. With the optimum parameters for adsorption and desorption, the contents of AGs IโIV were 8.78โ, 11.60โ, 10.52โ and 11.28โfold increased with the recovery yields being 65.88, 90.92, 84.25 and 94.17%, respectively. The preparative enrichment and separation of AGs IโIV from Radix Astragali extracts can be easily and effectively achieved by SAโ3 resin adsorption chromatography. The developed methodology can also be referenced for the separation of other active constituents from herbal materials and manufacture of Radix Astragali products.