Antioxidant activity of flavonoids from Sideritis raeseri

Nine 7-o-allosyl glucosides of 5,8-dihydroxy substituted flavones were isolated from a fraction of the methanol extract of the aerial parts of Sideritis raeseri Boiss et Heldr. subsp. raeseri. The structures were identified by spectroscopic methods. The antioxidant activity of this fraction, evaluated by the Co(II) EDTA-induced luminol chemiluminescence and by the DPPH scavenging activity, was found to be moderate. The activity can be related with the presence of 5- and 8-o-disubstituted flavones.