| In our country, Chinese herb resources are abundant, which are important source of natural antioxidant components. Our Chinese medicine theory is characterized by using Chinese prescriptions. However, traditional Chinese herb pairs are the basic units of Chinese formulars and the intermediate points between single herbs and multi-herb recipes, and it often presents the synergistic effect, which means that the antioxidant effect of the herb pairs was better than that of single herbs.In our previous study, it was found that the antioxidant activity was significantly increased when Huangqi was combined with Shengma. At present, many studies have been carried out on the components and the pharmacological activity of the two single herbs, but the study on the antioxidant effect and chemical constituents of the Huangqi and Shengma herb pair was fewer. In our study, the antioxidant ability and the changes of components when Huangqi and Shengma combined was measured, and the total flavonoids of two herbs were isolated using column chromatography to discuss the mechanism of the synergistic antioxidant activity preliminarily. Recults are as follows:1,In our study, the vitro antioxidant assay (DPPH and ABTS radical scavenging assay, FRAP assay) was applied to evaluate the antioxidant capacity of Huangqi and Shengma herb pair. It was found that the antioxidant ability of Huangqi and Shengma herb pair was significantly higher than that of single herbs, and the degree of synergistic effect was affected by the mode of combining. Besides, the content of polyphenol and flavonoid changed after Huangqi was combined with Shengma, which may be one of the reasons bringing about synergistic antioxidant effect.2,The antioxidant ability and the synergistic antioxidant effect of different samples extracted by ethanol at different concentrations and adding different metallic ions when was extracted was also studied. It was found that the sample of PM presented the best synergistic effect in DPPH radical scavenging assay when was extracted by ethanol with the concentration of 70%, however, when the sample of PM was extracted by absolute ethanol, it performed the best synergistic effect in ABTS radical scavenging ability. However, the sample of EM presented the best synergistic antioxidant effect when was extracted by ethanol with the concentration of 30%. What's more, the samples of PM and EM presented synergistic effect in the assay of determinating the total phenolic and flavonoid contents if they were extracted by water and ethanol. But the rate of increasing of EM was higher than that of PM if they were extracted by ethanol. So we selected ethanol as the extraction solvent to study the mechanism of the synergistic effect existing in the sample of EM. In addition, the significant synergistic antioxidant effect was not found when we added different metallic ions. 3,The chemical components of Huangqi and Shengma herb pair were detected using the HPLC. It was found that there were 43 components in the ethanol extracts of the herb pair. Furthermore, 14 constituents were identified by the HPLC-DAD-MS/MS technique, which mainly belong to flavonoid and triterpenoid saponin. Moreover, the antioxidant components in the ethanol extraction of herb pair were also identified by HPLC-DPPH technique, and we found that 11 components presented antioxidant effect. In our study, ten of them were identified: 3′-hydroxy-5′-methoxyisflavones-7-O-β-D-glycoside, Cimicifugamide, Cimigemol, 10-hydroxy-3,9-dimethoxypterocarpan, Ononin, 9,10-Dimethoxyptero-carpan-3-O-β-D- glucopyranoside, Formononetin, AstragalosideⅡ, 23-O-acetyl-7,8- didehydro shengmanol 3-O-β- D- galactopyranoside, 4-O-acetyl-caffeic acid.4,The total flavonoids of Huangqi and Shengma were isolated by polymide column in order to further study the mechanism of the synergistic antioxidant effect. It was found that the significant synergistic antioxidant effect was observed when 95% ethanol elution fraction of Huangqi was combined respectively with the total flavonoid and 95% ethanol elution fraction of Shengma, and then the chemical components of 95% ethanol elution fraction of Huangqi were identified. We inferred that five components in the 95% ethanol elution fraction of Huangqi may contribute to the the synergistic antioxidant effect. Four compounds were flavonoid glycosides, which were Calycosin -7- O-β-D-Glucopyranoside, 2′- Dihydroxy-3′,4′- dimethyl– isoflavan - 7–O–β– D - glucopyranoside, 4'-methoxyisoflavone-7-O-β-D- glucopyranoside, Calycosin-7-O-β- D- glucopyranoside-6′′-O-malonate, and Formononetin belonged to flavonoid. According to the above station and many references, we inferred that the synergistic effect was affected by the structure of the components (the aglycon and the number and the position of the hydrogen bonds and methoxy) and the relative concentration. Moreover, the changes of the components'structure caused by some reaction were another reason.
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