Screening of antioksidant activities of methanol extract of Sideritis libanotica Labill. ssp. linearis (Bentham) Bornm?s

The genus Sideritis (Labiatae) is represented by 46 species and 53 Taxa in Turkey, 42 Taxa being endemic. Sideritis are widely used as herbal tea and folk medicine in Turkey under the names dağ çayı and yayla çayı. In this study, the antioxidant properties of crude methanol extracts of Sideritis libanotica Labill ssp linearis was examined for its antioxidant potential and protective ability against DNA damage. The antioxidant activity of crude methanol extract of plant was evaluated by several in vitro systems such as determination of total phenolic compounds, DPPH radical scavenging activity and lipid peroxidation in rat brain homogenate.Phenols are very important plant constituents due to their radical scavenging ability. The total phenolic content of extract was quantified with the Folin-Ciocalteu reagent and total phenolic content of one-miligram of methanol extract was equivalent to 179±13.The DPPH radical scavenging ability of crude methanol extract of sideritis was found to be in the range of 7.5 ± 0.70 % - 91.0 ± 2.1 % at the concentration range between 5-500 µg/ml. Methanol extract of Siderits showed strong inhibitory activity toward lipid peroxidation of rat liver homogenate induced by FeCl2-H2O2 system.The inhibition of lipid peroxidation by ?- tokoferol and methanol extract of Sideritis was found to be 76.0 ± 1.5 % and 66.0 ± 1.3 %, respectively. The extract was also protected plasmid DNA from cleavege induced by hydroxyl radicals. These results showed sideritis exhibits antioxidant activity.Key Words: Sideritis, Antioxidant activity, DNA damage, lipid peroxidation