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Öğe Antibacterial activities of extracts from twelve centaurea species from Turkey(INST BIOLOSKA ISTRAZIVANJA SINISA STANKOVIC, 2011) Tekeli, Yener; Zengin, Gökhan; Aktümsek, Abdurrahman; Sezgin, Mehmet; Torlak, EmrahMembers of the genus Centaurea (Asteraceae) have been used in traditional plant-based medicine. The methanol extracts of twelve Centaurea species, of which five are endemic to Turkey flora, were screened for antibacterial activity against four bacteria (Escherichia coli, Bacillus cereus, Salmonella enteritidis, Staphylococcus aureus). The antibacterial activity was evaluated by the microdilution method and the minimum inhibition concentrations (MIC) of the extracts were determined. C. cariensis subsp. microlepis exhibited an antimicrobial effect on all tested microorganisms. The extracts from eight Centaurea species (C. balsamita, C. calolepis, C. cariensis subsp. maculiceps, C. cariensis subsp. microlepis, C. kotschyi var. kotschyi, C. solstitialis subsp. solstitialis, C. urvillei subsp. urvillei and C. virgata) possessed antibacterial activity against several of the tested microorganisms.Öğe Antioxidant Activities of Black Cumin (Nigella Sativa L.) Seeds Cultivating in Different Regions of Turkey(Wıley, 2010) Şen, Nejdet; Kar, Yakup; Tekeli, YenerIn this study, the antioxidant activity of the methanolic extracts of the black cumin (Nigella sativa L.) seeds collected from Konya, Isparta, Corum, Burdur, Afyon and Samsun was evaluated using three different methods, specifically the beta-carotene and linoleic acid system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power assays. Among the six black cumin samples of different origins, the black cumin sample origins from Konya city showed the most potent radical scavenging activity in each assay, showing 94.59% (at 1 mg/mL) in the beta-carotene bleaching method and 44.44% in the DPPH radical scavenging method (at 0.5 mg/mL). Positive correlations were found between the total phenolic content in the black cumin extracts and their antioxidant activities. The values of their antioxidant activity were either equivalent to or higher than those of positive BHA and BHT controls. These satisfying results lead to expect the use of black cumin seeds as health-promoting ingredients such as dietary supplements and nutraceuticals.Öğe Antioxidant property of Centaurea solstitialis L. from Konya, Turkey(ASIAN JOURNAL OF CHEMISTRY, 2008) Tekeli, Yener; Sezgin, Mehmet; Aktümsek, AbdurrahmanIn this study, Centaurea solstitialis L. was extracted with petroleum ether using a Soxhlet apparatus. The antioxidant properties of plant extract and synthetic antioxidant compounds were evaluated using different antioxidant tests, including reducing power, DPPH free radical scavenging activity and total phenolic compound. Results were compared with standard butylated hydroxytoluene and butylated hydroxyanisole.Öğe Bazı ikili sıvı-sıvı karışımları için artık termodinamik büyüklüklerin tayini(Selçuk Üniversitesi, Fen Bilimleri Enstitüsü, 2001) Tekeli, Yener; Yıldız, SalihBu çalışmada Benzen Hekzan benzen Karbonterra klorür, toluen hegzan ve benzen toluen karışımlarının 7 farklı bileşimde 7 farklı sıcaklıkta artık hacim, artık vizlkosite, artık kırılma indisi ve artık Gibbssrbest enerjisi incelendi. Farklı sabit sıcaklıklarsa yapılan ölçümlerde sabit sıcaklık ortamı sağlayabilmek için belli ağırlıkltaki piknometrenin etrafında bir su cketi oluşturuldu. Bu şekilde karışımların yopunlukları termal denge oluşturulduktan sonra analitik terazide tartmak sutetiyle bulundu. Karışımların vizkositeleri Oswald viskosimetresi ile kırılma indisleri ise Abbe refraktometresi ile tayin edildi. Bu ölçümlerden faydalanarakdaha sonra teori bölümünde verdiğimiz bağıntıla kullanaraka fonksiyonlarını hesapladık. Artık Gibbs serbest enerjisi ise bulduğumuz viskositeler kullanaraka hesaplandı. İlk üç karuşım için bulunan arytık termodinmik özelliklerden bunlkarın gerçek karışım karakteristiklerinie uymadığı görüldü. Bulunan parametreler ilgili tablolarda ve grafiklerde gösterilmiştir.Öğe Comparison of the Fatty Acid Compositions of Six Centaurea Species(SPRINGER, 2013) Tekeli, Yener; Zengin, Gökhan; Aktümsek, Abdurrahman; Sezgin, MehmetFatty acids have very important biological functions, including as a source of energy and as components of biological membranes. The dietary intake of fatty acids is very important because many degenerative diseases such as cardiovascular diseases are associated with fatty acids.Öğe Determination of antioxidant activity of Cantharellus cibarius Fr.(ASIAN JOURNAL OF CHEMISTRY, 2008) Tekeli, Yener; Dogan, Hasan Huseyin; Uslu, UfukOxidative stress is a general term used to describe the steady state level of oxidative damage in a cell. It can affect a specific molecule or the entire organism. Reactive oxygen species (ROS), such as free radicals and peroxides exist inherently in all aerobic organisms, Antioxidants have been widely used as food additives to provide protection against oxidative degradation of foods by free radicals. These antioxidants bind and inactivate the free radicals plant: and mushrooms are good antioxidant materials. In present study, antioxidant activity of Cantharellus cibarius Fr. determined. Total phenolic concentration of the extracts was estimated with Folin-Ciocalteu reagent using gallic acid as standard. Free radical scavenging activities were determined based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Results were compared with standard butylated hydroxytoluene and butylated hydroxyanisole.Öğe THE EFFECTS OF SEASONS ON CHOLESTEROL CONTENT AND FATTY ACID COMPOSITIONS OF MUSCLE OF HELIX ASPERSA LIVING IN KONYA, TURKEY(AFRICAN NETWORKS ETHNOMEDICINES, 2014) Citil, Ozcan Baris; Tekeli, Yener; Danahaliloglu, Hatice; Bucak, SerbayBackground: The aim of the present study is the determination of the effects of seasonal variations on the proximate analysis, cholesterol content and fatty acid compositions of Helix aspersa. Materials and Methods: Garden snails (Helix aspersa) were picked up by hand from the Central Anatolia Region of Turkey, in autumn (November) and spring (April) in 2011. Fatty acid methyl esters (FAMEs) and cholesterol analysis were analyzed by gas chromatography (GC). The protein contents of snail muscle were determined with Kjeldahl distillation units. Statistical comparisons were made by using SPSS Software (version 16.0). Results: Thirty different fatty acids of different saturation levels were detected. As the predominant fatty acids, stearic acid (C18:0), oleic acid (C18:1 omega 9), linoleic acid (C18:2 omega 6), palmitic acid (C16:0), arachidonic acid (C20:4 omega 6), eicosadienoic acid (C20:2) and linolenic acid (C18:3 omega 3) were found in Helix aspersa. Palmitic acid (C16:0) was identified as the major SFA in autumn and spring. Linoleic acid (C18:2 omega 6), eicosadienoic acid (C20:2) and arachidonic acid (C20:4 omega 6) have the highest levels among the PUFAs. In the present study, omega 3 were found 5.48% and 13.94% in autumn and spring, respectively. Conclusion: Linolenic acid and omega-3 fatty acid amounts in the spring increased significantly but cholesterol content was not affected in Helix aspersa both in season.Öğe Fatty Acid Composition of Six Centaurea Species Growing in Konya, Turkey(Taylor & Francis Ltd, 2010) Tekeli, Yener; Sezgin, Mehmet; Aktümsek, Abdurrahman; Güler, Gökalp Özmen; Şanda, Murad AydınIn this study, fatty acid compositions of six Centaurea species growing in the Konya region were determined. The fatty acid composition of Centaurea balsamita, Centaurea calolepis, Centaurea carduiformis subsp. carduiformis, Centaurea cariensis subsp. maculiceps, C. cariensis subsp. microlepis and Centaurea iberica were analysed. Four species of these six Centaurea are endemic to Turkey. The endemic Centaurea species are C. calolepis, C. carduiformis subsp. carduiformis, C. cariensis subsp. maculiceps and C. cariensis subsp. microlepis. Generally, C 18:2 6 linoleic acid, C 16:0 palmitic acid, C 18:3 3 linolenic acid and C 18:1 oleic acid were found to be the major fatty acids in all species. Polyunsaturated fatty acids (PUFAs) were found in higher amounts than saturated fatty acids and monounsaturated fatty acids in all species. PUFAs were determined at 55.10%, 50.25%, 51.41%, 41.02%, 46.18% and 58.80% in C. balsamita, C. calolepis, C. carduiformis subsp. carduiformis, C. cariensis subsp. maculiceps, C. cariensis subsp. microlepis and C. iberica, respectively.Öğe In vitro Antioxidant Activity of Enteromorpha intestinalis (Linnaeus) Nees(ASIAN JOURNAL OF CHEMISTRY, 2009) Akköz, Cengiz; Tekeli, Yener; Doğan, Hasan HüseyinIn this study, antioxidant activity of Enteromorpha intestinalis was determined by three different methods. Total phenolic concentration of the extracts was estimated with Folin-Ciocalteu reagent using gallic acid as standard. Free-radical scavenging activities were determined based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). The copper(II) ion reducing ability of polyphenols is measured by CUPRAC method. Results were compared with standard butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA).Öğe Konya bölgesindeki bazı Centaurea türlerinin bazı kimyasal ve biyolojik özelliklerinin belirlenmesi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2008) Tekeli, Yener; Sezgin, MehmetBu çalışmada, Konya Bölgesi'nden toplanan 12 Centaurea türünün bazı kimyasal ve biyolojik özellikleri belirlendi. Bu bitkilerin Antioksidan kapasiteleri beş farklı metodla tayin edildi. Bu metotlar, Folin metodu, DPPH serbest radikal süpürme etkisi, İndirgeme metodu, ß-Karoten-linoleik asit sistemi ve Cuprac metodudur. Sonuçlar sentetik antioksidan bileşikler (BHA ve BHT) ile kıyaslandı. Bitkilerin fenolik bileşenleri ve yağ asidi kompozisyonları sırasıyla HPLC ve GC ile tayin edildi. Antimikrobiyal etkisi ise dört farklı bakteri ile mikrodilüsyon metoduyla belirlendi. Centaurea türlerinin fenolik madde ve doymamış yağ asidi açısından zengin olduğu anlaşıldı. Aynı zamanda bazı türlerin bakterilere karşı etkili olduğu bulundu.Öğe Toluen - Hekzan Karışımlarının 20 C - 80 C Arasında Artık (Excess) Termodinamik Fonksiyonlarının Tayin Edilmesi(Selçuk Üniversitesi Fen-Edebiyat Fakültesi, 2005) Tekeli, Yener; Yıldız, SalihBu çalışmada, toluen-hekzan karışımının 7 farklı bileşimde 4 farklı sıcaklıkta artık hacim, artık viskozite, artık kırmaindisi ve artık Gibbs serbest enerjileri tayin edildi. Farklı sabit sıcaklıklarda yapılan ölçümlerde sabit sıcaklık ortamı sağlayabilmek için belirli ağırlıktaki bir piknometrenin etrafında bir su ceketi oluşturuldu. Bu şekilde karışımların yoğunlukları, termal denge oluşturulduktan sonra analitik olarak tartılmak suretiyle tespit bulundu. Karışımların viskoziteleri Oswald Viskozimetresi ile, kırma indisleri ise Abbe Refraktometresi ile ölçüldü. Bu ölçümlerden faydalanarak verdiğimiz bağıntıları kullanarak artık fonksiyonlar hesaplandı. Artık Gibbs serbest enerjisi ise bulduğumuz viskoziteler kullanılarak hesaplandı.
