Extremely Rare Flavonoid Glycosides Identified in the Stems of Ephedra gerardiana by HPLC-MS and Their Antioxidant Activity

The plants of the genus Ephedra are mainly known for the contents of alkaloids; however, it has recently been found that they also contain phenolic constituents that show interesting bioactivities, e.g., antioxidative or antimicrobial. From among the Ephedrae herba, the <i>Ephedra gerardiana</i> seems to be relatively poorly researched in terms of flavonoid presence. In this study, on the basis of the results of high-pressure liquid chromatography-mass spectrometry (HPLC-MS) with cone voltage-induced fragmentation analysis, which are discussed in detail, the flavonoid glycosides present in <i>Ephedra gerardiana</i> have been identified. Besides the flavonoids typical of the genus Ephedra, e.g., afzelin, herbacetin 7-<i>O</i>-glucoside, and vicenin-2, compounds that are very rare in nature have been detected as well, namely the <i>p</i>-coumaroyl conjugates of 4'-<i>O</i>-methylafzelin and malonyl flavone <i>C</i>-glycosides. Therefore, <i>Ephedra gerardiana</i> can be regarded as a valuable source of these compounds. Furthermore, the antioxidant activity of the methanol extract indicates that these compounds show potential interesting biological activities.