No abstract

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are various forms of activated oxygen and nitrogen, which include free radicals such as superoxide ions (O 2 · Ϫ ), hydroxyl (OH · ) and nitric oxide radicals (NO · ), as well as non-free-radical species such as hydrogen peroxide (H 2 O 2 ) and nitrous acid (HNO 2 ). [1][2][3] In living organisms ROS and RNS can form in different ways. Normal aerobic respiration, stimulated polymorphonuclear leukocytes and macrophages, and peroxisomes appear to be the main endogenous sources of most of the oxidants produced by cells. [4][5][6] Exogenous sources of free radicals include tobacco smoke, ionising radiation, organic solvents and pesticides.7-10) Free radicals can cause lipid peroxidation in foods that leads to their deterioration. 11)Oxidation does affect not only lipids. ROS and RNS may cause DNA damage that could lead to mutation. 12,13) In addition, ROS and RNS have been implicated in more than 100 diseases, including malaria, acquired immunodeficiency syndrome, heart disease, stroke, arteriosclerosis, diabetes and cancer.6,14-16) When produced in excess, ROS can cause tissue injury, whilst, tissue injury can itself cause ROS generation.12) Nevertheless, all aerobic organisms, including human beings, have antioxidant defenses that protect against oxidative damage and numerous damage removal and repair enzymes to remove or repair damaged molecules. 8,[17][18][19] However, the natural antioxidant mechanisms can be inefficient, hence dietary intake of antioxidant compounds becomes important. 5,16,20,21) Although there are some synthetic antioxidant compounds, such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), which are commonly used in processed foods, it has been reported that these compounds may have side effects. [22][23][24][25][26][27][28] In addition, it has been suggested that there is an inverse relationship between dietary intake of antioxidant-rich foods and the incidence of a number of human diseases. 29,30) Therefore, research into the determination of natural antioxidant sources is important.In this study, it is aimed to determine the antioxidant activity (AA) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (DPPH-RSA), reducing powers (RP) and amount of total phenolic compounds (APC) of the some medicinal plants which have been used especially in Eastern Turkey. (AEF 21172). Activity studies were performed on decoctions (5%) and/or methanolic extracts (5%) of used parts of plants in the treatment. Extraction solvents and parts of plants were chosen by taking consideration the usage form of plants by public. Methanol extract was evaporated and then lyophilized, water extract was directly lyophilized. In the AA and DPPH-RSA studies, different concentration ranges were studied and data of 50, 100, 250 and 500 mg/l concentrations were given in all figures. MATERIALS AND METHODS Collection of Plants, Identification and ExtractionDetermination of Antioxidant Properties The in vitro antioxidant activit...

No abstract

In this study, antioxidant properties of Thymus sipyleus Boiss. subsp. sipyleus var. sipyleus, Teucrium chamaedrys L., Mentha longifolia (L.) Hudson subsp. longifolia, Salvia limbata C.A. Meyer, and Thymus fallax Fisch. & Mey. were investigated. Antioxidant and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, reducing powers, and the amount of total phenolic compounds of the extracts were studied. The highest antioxidant activity was shown by T. chamaedrys (decoction, IC 50 : 9.2 mg=ml), and the lowest one was S. limbata (decoction, IC 50 : 619.5 mg=ml). The highest DPPH radical scavenging activity was shown by T. fallax [decoction, IC 50 S: 56 mg=ml (IC 50 S is the extract concentration (mg=ml) required for 50% inhibition of the DPPH solution absorbance at 517 nm)] while the lowest one was S. limbata (decoction, IC 50 S: 335.8 mg=ml). The highest reducing power and amount of total phenolic compounds was shown by T. chamaedrys (decoction, 29.9 mg=ml ascorbic acid equivalent, 27.9 mg=ml gallic acid equivalent, respectively), and the lowest one was S. limbata (decoction, 5.1 mg=ml ascorbic acid equivalent, 9.9 mg=ml gallic acid equivalent, respectively) at 250 mg=ml extract concentration.

Sideritis L. species are widely used as medicinal plants and as herbal teas in Turkey, in which 45 species of the genus are naturally found. The aim of this study was to determine the antioxidant activity of Sideritis species found in the Mediterranean region. In this study, the antioxidant activities of the lyophilized extracts obtained from aerial parts of 17 species (18 taxa) of Sideritis were compared, of which 15 taxa were endemic. The antioxidant activities of aqueous extracts were studied by two different techniques: qualitative DPPH (1,1-diphenyl-2picrylhydrazyl radical) assay to detect the free radical scavenging activity and the TBA assay to detect liposome lipid peroxidation. All the extracts (except S. erithrantha subsp. erithrantha, S. dichotoma, S. syriaca subsp. nusariensis, S. tmolea) showed a strong antioxidant activity with the DPPH test. High activity was observed in the S. brevibracteata (IC 50 mg=ml ¼ 0:16), S. condensata (IC 50 mg=ml ¼ 0:33), S. serratifolia (IC 50 mg=ml ¼ 0:31) extracts with the lipid peroxidation assay method.