Quality Evaluation of Astragali Radix based on DPPH Radical Scavenging Activity and Chemical Analysis

Objective To assess the quality of Astragali Radix from different areas based on the biological evaluation and chemical analysis. Methods The bioassay method of 1,1-diphenyl- 2-picryl-hydrazyl (DPPH) radical scavenging activity for Astragali Radix was established. The parameters of DPPH assay including sample extraction time, reaction time, repeatability, and stability were detected. Furthermore, a method of HPLC-MS was developed to simultaneously determine calycosin-7-O-glucoside, ononin, formononetin, and astragaloside IV in Astragali Radix samples. And the total flavonoids and total saponins were detected by spectrophotometry. The relationship between DPPH evaluation and chemical analysis was studied by Pearson correlation analysis. Results Twelve batches of Astragali Radix from different origins showed a wide range of DPPH radical scavenging activities (IC50 = 1.395-9.894 mu g/mL). Based on DPPH assay, Sample 10 derived from Inner Mongolia Autonomous Region (IC50 = 1.395 mu g/mL) showed the best quality of all samples. Chemical analysis showed that different compounds selected as indices would cause different results for quality evaluation. Pearson correlation analysis revealed that the contents of total flavonoids (P = 0.032), calycosin-7-glucoside (P = 0.035), and astragaloside IV (P = 0.010) were positively correlated with DPPH radical scavenging activity. Conclusion Except for chemical analysis, DPPH radical scavenging activity can be used as a good alternative to assess and control the quality of Astragali Radix.