Screening immunomodulatory Q-markers in Astragali Radix based on UHPLC-QTOF-MS analysis and spectrum-effect relationship.

Astragali Radix (AR) is one of the famous traditional Chinese medicines (TCMs) for boosting immunity, whereas the quality markers (Q-markers) of AR have not been clearly researched. The immunomodulatory activities of the bioactive extractions and components were evaluated by NO inhibition rate; phagocytic index; IL-10, TNF-α, IL-1β, and IL-6 cytokines in RAW264.7 cells; and the relative proliferation rate of spleen cells. The total saponins (TS) and the grade 2 (Xiaoxuan, XX) of AR showed the strongest immunomodulatory activities. At the concentration of 40 μg/mL, the TS increased spleen cells proliferation by 48.0% and upregulated the level of IL-1β and IL-6. Cytokines in the XX-treated group were at least 1.6 times higher than the control group. A total of 190 common peaks were detected in AR by ultrahigh-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS). The multivariate statistical analyses revealed that 41 compounds were positively correlated with immune responses, and bioactive compounds were verified by using RAW264.7 cell assay. Subsequently, the contents of six compounds in different commercial grades were determined, and the results showed the same trend in contents and activities. Finally, calycosin-7-O-β-D-glucoside, astragaloside IV, astragaloside II, astragaloside I, isomucronulatol-7-O-glucoside, and 9,10-dimethoxypterocarpan-3-O-glucoside were screened out as immunomodulatory Q-markers of AR.