Betula pendula is widespread in Europe and Asia. It has been used in traditional medicine since ancient times. Birch leaf extracts are known to exhibit a number of pharmacological activities. Antioxidant activity has also been reported.The aim of this work was to investigate the antioxidant activity of a dry leaf extract from Betula pendula Roth.The total flavonoid content was determined. Some of the most commonly used methods were applied to evaluate the antioxidant capacity of the extract in vitro and in vivo. The ability of the extract to scavenge DPPH free radicals was evaluated by the method described by Brand-Williams with suitable modifications. ABTS decolorization assay was also applied. The in vivo assay was performed after acute and chronic administration of the extract into white albino rats, in a dose of 100 and 500 mg/kg bw. The antioxidant potential of the plasma was determined using FRAP reagent.A total flavonoid content of 42.5 mg/g was found, expressed as quercetin. The antioxidant activity against ABTS was concentration and time dependent. For example the concentration of 200 μg/ml led to 70.95% - 99.46% scavenging activity. DPPH scavenging activity was found to be about 98% at a concentration of 80 μg/ml. The extract possesses antioxidant potential, comparable with that of Trolox, in acute application. In chronic application, poorer results are observed, probably due to biotransformation and elimination processes.Dried birch leaf extract has a relatively high antioxidant potential and could be used as a natural source of antioxidants.
