DNA damage protecting activity and antioxidant potential of Cyclotrichium niveum extracts

Cyclotrichium niveum, a herb of the labiate family, has been widely used as aflavoring agents in Turkey. Although many benefits have been claimed for this plant,few scientific studies are available in the literature. In this thesis, the antioxidant activityof C.niveum aerial parts (stems, leaves and flowers) were determined on methanol, ethylacetate and n-butanol extracts. The total phenolic contents of extracts were quantifiedwith the Folin-Ciocalteu reagent and total phenolic content of one-miligram ofmethanol, ethyl acetate and n-butanol extracts were equivalent to 200,9±35.0,192,4±42.0, 252,0±42.0 ?g of gallic acid, respectively.The antioxidant potency of methanol, ethyl acetate and n-butanol extracts ofC.niveum were investigate employing various established in vitro systems, such as lipidperoxidation in rat brain homogenate, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hyrdoxylradical scavenging, reducing power and iron chelation. Methanol, ethyl acetate and nbutanolextracts of C.niveum aerial parts showed strong inhibitory activity toward lipidperoxidation of rat brain homogenate induced by the FeCl2-H2O2 system. Futhermore,C.niveum extracts exhibited a strong concentration-independent inhibition ofdeoxyribose oxidation. C.niveum extracts also showed a considerable antioxidantavtivity in the DPPH radical system. The DPPH radical scavenging activity of C.niveummethanol, ethyl acetate and n-butanol extracts were found to be % 90,3±1.2, 91.4±0.7,91.7±0.7 at 500 ?g/mL, respectively. The multiple antioxidant avtivity of C.niveumextracts on ferrous ions were found to be lower than EDTA. Our data also showed thatC.niveum extracts protect plasmid DNA from cleavage induced by hydroxyl radicals.These results may explain, at least in part, its use as a flavoring agents in Turkey.Furher studies are needed to identify and characterize the bioactive constituentsof the methanol, ethyl acetate and n-butanol extracts, as well as the efficiency ofindividual and synergistic phenolic constituents for the antioxidant activity of C.niveumextracts.Keywords: Cyclotrichium niveum, Antioxidant activity, DNA damage, Free radicals