UHPLC–MS/MS Analysis on Flavonoids Composition in Astragalus membranaceus and Their Antioxidant Activity

Astragalus membranaceus is a valuable medicinal plant species widely distributed in Asia. Its root is the main medicinal tissue rich in methoxylated flavonoids. Origin can highly influence the chemical composition and bioactivity. To characterize the principal chemicals influenced by origin and provide more information about their antioxidant profile, the extracts of A. membranaceus roots from four origins were analysed by UHPLC-MS/MS. Thirty-four flavonoids, including thirteen methoxylated flavonoids, fifteen flavonoid glycosides and six flavonols, were identified. By principal component analysis, eighteen identified compounds were considered to be principal compounds. They could be used to differentiate A. membranaceus from Shanxi, Inner Mongolia, Heilongjiang and Gansu. The antioxidant activity was analysed by ORAC assay, DPPH radical scavenging activity assay and cell antioxidant activity assay. ‘Inner Mongolia’ extract showed the highest antioxidant activity. These results were helpful to understand how origin influenced the quality of A. membranaceus.