Browsing by Author "Mete E."

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    Studies on the antioxidant activity of essential oil and different solvent extracts of Vitex agnus castus L. fruits from Turkey
    (2009) Sarikurkcu C.; Arisoy K.; Tepe B.; Cakir A.; Abali G.; Mete E.
    This study is designed to examine the chemical composition and antioxidant activity of the essential oil and different solvent extracts of Vitex agnus castus. GC and GC-MS analysis was resulted in the detection of 27 components, representing 94.5% of the oil. Major components of the oil were 1,8-cineole (24.98%), sabinene (13.45%), α-pinene (10.60%), α-terpinyl acetate (6.66%), and (Z)-β-farnesene (5.40%). Antioxidant activities of the samples were determined by three different test systems, DPPH, β-carotene/linoleic acid and reducing power assays. In all systems, water extract exhibited excellent activity potential than those of other extracts (hexane, dichloromethane, ethyl acetate and methanol) and the oil. As expected, amount of total phenolics was very high in this extract (112.46 ± 1.22 μg GAEs/mg extract). Dichloromethane extract has been found to be rich in flavonoids. A positive correlation was observed between the antioxidant activity potential and total phenolic and flavonoid levels of the extracts. © 2009 Elsevier Ltd. All rights reserved.
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    Essential oil composition and antioxidant activity of Thymus longicaulis C. Presl subsp. longicaulis var. longicaulis
    (2010) Sarikurkcu C.; Sabih Ozer M.; Eskici M.; Tepe B.; Can Ş.; Mete E.
    This study is designed to examine the chemical composition and in vitro antioxidant activity of the hydrodistillated essential oil and various extracts obtained from Thymus longicaulis subsp. longicaulis var. longicaulis. GC and GC-MS analysis of the essential oil were resulted in determination 22 different compounds, representing 99.61% of total oil. γ-terpinene, thymol and p-cymene were determined as the major compounds of the oil (27.80, 27.65 and 19.38%, respectively). Antioxidant activities of the samples were determined by four different test systems namely β-carotene/linoleic acid, DPPH, reducing power and chelating effect. Essential oil showed the highest antioxidant activity in β-carotene/linoleic acid system among the experiments examined. In the case of other test systems, in general, methanol and water extracts exhibited the strongest activity profiles. Especially, reducing power of water extract was found superior than those of synthetic antioxidants. As well as the antioxidant activities of the extracts, they were evaluated in terms of their total phenolic and flavonoid contents. Hexane and water extracts were found to be rich-in phenolics. However, flavonoids were determined in the highest level in methanol extract. © 2010 Elsevier Ltd.
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    GC/MS evaluation and in vitro antioxidant activity of essential oil and solvent extracts of an endemic plant used as folk remedy in Turkey: Phlomis bourgaei boiss.
    (2013) Sarikurkcu C.; Sabih Ozer M.; Cakir A.; Eskici M.; Mete E.
    This study was outlined to examine the chemical composition of hydrodistilled essential oil and in vitro antioxidant potentials of the essential oil and different solvent extracts of endemic Phlomis bourgaei Boiss. used as folk remedy in Turkey. The chemical composition of the oil was analyzed by GC and GC-MS, and the predominant components in the oil were found to be β-caryophyllene (37.37%), (Z)-β-farnesene (15.88%), and germacrene D (10.97%). Antioxidant potentials of the solvent extracts and the oil were determined by four testing systems including β-carotene/linoleic acid, DPPH, reducing power, and chelating effect. In β-carotene/linoleic acid assay, all extracts showed the inhibition of more than 50% at all concentrations. In DPPH, chelating effect, and reducing power test systems, the water extract with 88.68%, 77.45%, and 1.857 (absorbance at 700 nm), respectively, exhibited more excellent activity potential than other extracts (hexane, ethyl acetate and methanol) and the essential oil at 1.0 mg/mL concentration. The amount of the total phenolics and flavonoids was the highest in this extract (139.50 ± 3.98 g gallic acid equivalents (GAEs)/mg extract and 22.71 ± 0.05 g quercetin equivalents (QEs)/mg extract). © 2013 Cengiz Sarikurkcu et al.