Two major isoflavone glycosides [calycosin 7-O-β-D-glucopyranoside （1） and ononin （2）] and their aglycones [calycosin （3） and formononetin （4）] were simultaneously quantified with HPLC/DAD method. Two unknown compounds were identified as calycosin 7-O-β-D-glucopyranoside-6＇＂-O-malonate （U1） and formononetin 7-O-β-D-glucopymnoside-6＇＂-O-malonate （U2）, respectively, with LC/MS^n. Raw Radix astragli were shown to have higher contents of isoflavone glycosides （1, 2）, but lower contents of aglycones （3, 4） than the processed herbal materials. After being moistened with water and stored up for 24 h at 35 ℃, the glycosides and their m_alonates were almost completely transformed to their corresponding aglycones. The different contents of the isoflavone glycosides and their aglycones in raw and processed Radix astragali materials might be due to enzymolysis of the glycosides during processing.
Radix Astragali （Huangqi） is one of the most valuable traditional Chinese medicinal herbs. It is used in the traditional Chinese medicine to reinforce ＇qi＇, and it has immunostimulant, tonic, and antioxidant activities. There are many different sources of Huangqi in the market. In this study, the quality of Huangqi was evaluated by the measurement of four flavonoids, calycosin-7-O-β-D-glucopyranoside, ononin, calycosin and formononetin with HPLC-UV, as well as astragaloside IV with HPLC-ELSD. Samples included different plant species, different places of cultivation, different ages of plants, different seasons of collection and different commercial specifications. The results showed that the contents of isoflavonoids and astragaloside IV varied significantly in different sources. Our study provided useful information for the quality evaluation of Radix Astragali.
