Studies on flavonoids and their antioxidant activities of Artemisia annua

OBJECTIVE To study the flavonoids and their antioxidant activities of Artemisia annua. METHODS Isolation and purification were carried out by silica gel and Sephadex LH-20 column chromatographies. Compounds were identified by physicochemical properties and spectral analysis, then their antioxidant activities were evaluated by ORAC assay. RESULTS Five flavonoids were isolated from the plant. Their structures were identified as 5-hydroxy-3,7,4'-trimethoxyflavone(1), 5-hydroxy-6,7,3',4'-tetramethoxyflavonol(2), blumeatin(3), 5, 4'-dihydroxy-3,7,3'-trimethoxyflavone(4) and quercetin(5), respectively. Compounds 1-5 could slow up the attenuation rate of the fluorescence induced by AAPH. CONCLUSION Compounds 1-3 are isolated from the plant for the first time. Compounds 1-5 all possess the potential antioxidant activities.