Yazar "Sezgin, Mehmet" seçeneğine göre listele
Listeleniyor 1 - 19 / 19
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Alterations of trace elements and malondialdehyde levels in blood, brain and hippocampus following functional pinealectomy in rats(2009) Tüzmen, M. Nalan; Sezgin, MehmetMetal plays an important role in neural toxicity. The changes of some essential metal levels are important in increasing oxidative stress and enhancing neurodegenerative disorders. The objective of this study was to determine the effect of light and dark treatment on the level of some essential elements such as Al, Fe, Zn and Cu and lipid peroxidation and the relationship between aging and changes in the level of these elements. Animals were divided into three groups: 24 h dark throughout the study (highest melatonin release), 24 h light exposure (light-induced functional pinealectomy) and 12 h light/12 h dark exposure (control group). Thereafter, each group was divided into two groups as young and old animals. All groups had access to food and water ad libitum for four weeks. After this period, lipid peroxidation end product, malondialdehyde (MDA), and Al, Fe, Zn and Cu concentrations were measured in blood and brain tissue as well as hippocampus tissue. According to our findings MDA increased especially in dark groups of hippocampus tissue. It can be an indicator of increased free radical formation related to Al influenced light-dark treatment.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 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 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 Enantioselective Hydrolysis of Rasemic Naproxen Methyl Ester with Sol-Gel Encapsulated Lipase in the Presence of Sporopollenin(Elsevier, 2010) Yılmaz, Elif; Sezgin, Mehmet; Yılmaz, MustafaSporopollenin is a natural polymer obtained from Lycopodium clavatum, which is highly stable with constant chemical structure and has high resistant capacity to chemical attack. In this study, the Candida rugosa lipase (CRL) was encapsulated within a chemically inert sol-gel support prepared by polycondensation with tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) in the presence and absence of sporopollenin and activated sporopollenin as additive. The catalytic properties of the immobilized lipases were evaluated into model reactions, i.e. the hydrolysis of p-nitrophenylpalmitate (p-NPP), and the enantioselective hydrolysis of rasemic Naproxen methyl ester that was studied in aqueous buffer solution/isooctane reaction system. The results indicated that the sporopollenin based encapsulated lipase particularly had higher conversion and enantioselectivity compared to the sol-gel free lipase. In this study, excellent enantioselectivity (E > 400) has been noticed for most lipase preparations (E = 166 for the free enzyme) with an ee value similar to 98% for S-Naproxen. Moreover, (S)-Naproxen was recovered from the reaction mixture with 98% optical purity.Öğe Enhancement of the Activity and Enantioselectivity of Lipase by Sol-Gel Encapsulation Immobilization onto beta-cyclodextrin-Based Polymer(SPRINGER, 2012) Yilmaz, Elif; Sezgin, MehmetCandida rugosa lipase was encapsulated within a chemically inert sol-gel support prepared by polycondensation with tetraethoxysilane and octyltriethoxysilane in the presence of beta-cyclodextrin-based polymer. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenylpalmitate and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yield of the encapsulated lipase was 65 U/g, which is 7.5 times higher than that of the covalently immobilized lipase. The beta-cyclodextrin-based encapsulated lipases had higher conversion and enantioselectivity compared with covalently immobilized lipase. The study confirms an excellent enantioselectivity (E > 300) for the encapsulated lipase with an enantiomeric excess value of 98% for S-naproxen.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 Fatty Acid Compositions of Some Feed Raw Materials in Poultry Diets(Asian Journal of Chemistry, 2010) Çitil, Özcan Barış; Sezgin, Mehmet; Güler, Gökalp Özmen; Aktümsek, AbdurrahmanIn this study. total fat content and fatty acid composition of 5 feed raw materials in animal source and 10 feed raw materials in vegetables source were determined by gas chromatography Polyunsaturated fatty acids (PUPA) were found to be higher than saturated laity acids (SPA) and monounsaturated fatty acids (MUFA) in all samples except for rendering oil, tallow and meat bone samples Palmitic acid was the major saturated fatty acid (7 65-20.31% of total fatty acids) in all samples except for rendering oil and tallow Oleic acid was identified as the major monounsaturated fatty acid (14.39-40.00% of total fatty acids) in all samples Linoleic acid was the most abundant polyunsaturated fatty acid (2.53-60.80% of total fatty acids) in all samples except for fish oil and fish meal It was shown that the fatty acid composition. (031(06 fatty acids ratio and SFA/PUFA ratio between the raw feed materials in poultry diets were variedÖğe Immobilization of Candida rugosa lipase on glass beads for enantioselective hydrolysis of racemic Naproxen methyl ester(ELSEVIER SCI LTD, 2011) Yilmaz, Elif; Can, Keziban; Sezgin, Mehmet; Yilmaz, MustafaCandida rugosa lipase (CRL) was immobilized on glutaraldehyde-activated aminopropyl glass beads by using covalent binding method or sal-gel encapsulation procedure and improved considerably by fluoride-catalyzed hydrolysis of mixtures of RSi(OCH3)(3) and Si(OCH3)(4). The catalytic properties of the immobilized lipases were evaluated into model reactions, i.e. the hydrolysis of p-nitrophenylpalmitate (p-NPP). It has been observed that the percent activity yield of the encapsulated lipase was 166.9, which is 5.5 times higher than that of the covalently immobilized lipase. The enantioselective hydrolysis of racemic Naproxen methyl ester by immobilized lipase was studied in aqueous buffer solution/isooctane reaction system and it was noticed that particularly, the glass beads based encapsulated lipases had higher conversion and enantioselectivity compared to covalently immobilized lipase. In short, the study confirms an excellent enantioselectivity (E > 400) for the encapsulated lipase with an ee value of 98% for S-Naproxen. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Immobilization of Candida rugosa lipase on magnetic sol-gel composite supports for enzymatic resolution of (R,S)-Naproxen methyl ester(ELSEVIER, 2011) Yilmaz, Elif; Sezgin, Mehmet; Yilmaz, MustafaIn the present study, the Candida rugosa lipase (CRL) was encapsulated within a chemically inert sol-gel support prepared by polycondensation with tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) in the presence and absence of magnetic Fe3O4 nanoparticles or sporopollenin with Fe3O4 as additive. The catalytic properties of the immobilized lipases were evaluated through model reactions, i.e. the hydrolysis of p-nitrophenylpalmitate (p-NPP), and the enantioselective hydrolysis of racemic Naproxen methyl ester that was studied in aqueous buffer solution/isooctane reaction system. The results indicate that the sporopollenin based encapsulated lipase (Fe3O4-Spo-E) particularly has higher conversion and enantioselectivity compared to the encapsulated lipase without supports (lipase-enc). It has also been noticed that the sporopollenin based encapsulated lipase has excellent enantioselectivity (E = > 400) as compared to the free enzyme (E = 166) with an ee value of similar to 98% for S-Naproxen. (C) 2010 Elsevier B.V. All rights reserved.Öğe Immobilized copper-ion affinity adsorbent based on a cross-linked beta-cyclodextrin polymer for adsorption of Candida rugosa lipase(TAYLOR & FRANCIS LTD, 2009) Yilmaz, Elif; Sezgin, Mehmet; Yilmaz, MustafaLipase from Candida rugosa was immobilized on a beta-cyclodextrin-based polymer by adsorption and subsequent cross-linking with epichlorohydrin (EP-CD). The ligand iminodiacetic acid (IDA) was then bonded with the cross-linked beta-cyclodextrin (EP-CD-IDA). This affinity adsorbent was further chelated with Cu2+ for the purpose of binding affinity and stability. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. Results showed that 266 mu g protein with an activity of 17.85 U was bound per gram of matrix, giving 188% of the specific activity of the free enzyme and a total recovered activity of 79.7% under the optimum conditions. The pH and thermal stabilities of lipase were improved after immobilization on the beta-cyclodextrin-based polymer (EP-CD-IDA-Cu2+). In addition, experimental results indicated that the residual activity of the immobilized lipase was 50% after eight cycles of reuse.Öğe Phytochemical profile and antioxidant properties of two Brassicaceae species: Cardaria draba subsp. draba and Descurainia sophia(ELSEVIER SCIENCE BV, 2018) Mahomoodally, Mohamad Fawzi; Zengin, Gökhan; Aumeeruddy, Muhammad Zakariyyah; Sezgin, Mehmet; Aktümsek, AbdurrahmanBrassicaceae is one of the most popular family of vegetables consumed worldwide. Owing to their wide range of phenolic compounds, the attention of researchers has shifted towards their pharmacological exploitation. This study investigates into the antioxidant properties of three solvent extracts (acetone, methanol, and aqueous) of C. draba and D. sophia using six assays including DPPH, ABTS, CUPRAC, FRAP, phosphomolybdenum, and beta-carotene/linoleic acid inhibition. Spectrophotometric and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) techniques were used to determine the total and individual phytocompounds, respectively. Results showed that among the C. draba extracts, the methanolic one displayed the highest antioxidant activities in CUPRAC, FRAP, and phosphomolybdenum assays while the aqueous extract exerted the strongest DPPH and ABTS scavenging, and beta-carotene inhibition. As for D. sophia extracts, the acetone extract displayed the highest activity in CUPRAC and phosphomolybdenum assays; the methanol extract was the most effective DPPH scavenger while the aqueous extract showed the highest ABTS scavenging and ferric reducing power, and beta-carotene inhibitory effect. Total phenolic content was highest in the acetone extract of C. draba, while the methanolic extract of D. sophia showed the highest total flavonoid content. The most abundant compounds in C. draba extract were verbascoside and chlorogenic acid, while hesperidin and hyperoside were most abundant in the extract of D. sophia. The present findings revealed that both species had potent antioxidant properties and could be utilized as new natural antioxidants for therapeutic purposes.Öğe Synthesis and characterization of cyclodextrin-based polymers as a support for immobilization of Candida rugosa lipase(ELSEVIER, 2009) Ozmen, Elif Yilmaz; Sezgin, Mehmet; Yilmaz, MustafaThe objective of this study was to prepare cross-linked beta-cyclodextrin polymers for immobilization of Candida rugosa lipase. The structures of synthesized macrocyclic compounds were characterized by Fourier transform infrared spectroscopy (FTIR). thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) techniques. Properties of the immobilized systems were assessed and their performance on hydrolytic reaction were evaluated and compared with the free enzyme. The influence of activation agents (glutaraldehyde (GA) and hexamethylene diisocyanate (HMDI)) and thermal and pH stabilities of the biocatalyst was evaluated. After the optimization of immobilization process, the physical and chemical characterization of immobilized lipase was performed. Obtained data showed that the immobilized enzyme seemed better and offered some advantages in comparison with free enzyme. It can be observed that the free lipase loses its initial activity within around 80 min at 60 degrees C, while the immobilized lipases retain their initial activities of about 56% by HMDI and 82% by GA after 120 min of heat treatment at 60 degrees C. Results showed that the specific activity of the immobilized lipase with glutaraldehyde was 62.75 U/mg protein, which is 28.13 times higher than that of the immobilized lipase with HMDI. (c) 2008 Elsevier B.V. All rights reserved.Öğe Synthesis of beta-cyclodextrin and starch based polymers for sorption of azo dyes from aqueous solutions(ELSEVIER SCI LTD, 2008) Ozmen, Elif Yilmaz; Sezgin, Mehmet; Yilmaz, Aydan; Yilmaz, MustafaThree beta-cyclodextrin (polymers 1-3) and a starch-based (polymer 4) polymers were synthesized using hexamethylene diisocyanate (HMDI) as a cross-linking agent in dry dimethylformamide and used as a sorbent for the removal of some selected azo dyes from aqueous solutions. The cross-linked polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric and differential scanning calorimetric analysis. Results of sorption showed that cyclodextrin and starch based polymers can be effectively used as a sorbent for the removal of anionic azo dyes. The Influence of the amide groups and the chemical structure of azo dyes are also studied. Results of sorption experiments showed that these adsorbent exhibited high sorption capacities toward Direct Violent 51 (80% for polymer 1, 69% for polymer 2, 70% for polymer 3 and 78% for polymer 4). The sorption capacity of dyes on the polymers was dependent on the presence of sulfonate groups of the anionic dyes. In order to explain the results an adsorption mechanism mainly physical adsorption and interactions such as hydrogen bonding, ion-exchange due to the nature of the polymer network and the formation of an inclusion complex due to the beta-CD molecules through host-guest interaction is proposed. (c) 2007 Elsevier Ltd. All rights reserved.Öğe Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions(WILEY, 2009) Akkuş, Gülderen Uysal; Memon, Shahabuddin; Sezgin, Mehmet; Yılmaz, MustafaThe present study reports the synthesis of a novel ionophore, calix[4]azacrown (5) bearing two amino groups at the lower rim along with its oligomeric analogue (6). The liquid-liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that (3) and (6) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species (5) shows remarkable extraction properties at low pH, whereas species (6) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants.Öğe The Synthesis of Three New Macrocyclic Ligands and Preparation of Some of Their Cationic Complexes(MARCEL DEKKER INC, 1993) Sezgin, Mehmet; Bedük Dinçer, A.; Ertul, Şeref; Koçak, AhmetIn this study the synthesis of macrocyclic ligands 15,21-dinitro-2,5,8,11-tetraoxatricyclo(17,4,0,0(12,17)) tricosa-1 (23),12,14,16,19,21-hexaene-3,10-dione (I); 18,24-dinitro-2,5,8,11,14-pentaoxatricyclo(20,4,0,0(15,20)) hexacosa-1(26),15, 17,19,22,24-hexaene-3,13-dione (II) and 15,21-di-t-butyl-2,5,8,11-tetraoxatricyclo(17,4,0,0(12,17)) tricosa-1(23),12,14,16, 19,21-hexaene-3,10-dione (III) are described. Attemption of the preparation of their complexes in crystalline form with NaClO4.H2O, KClO4, and Ba(ClO4)2 . 3H2O are discussed.Öğe Taç Eter İhtiva Eden İki Makrosiklik Lakton'un Sentezi Metal Komplekslerinin Hazırlanması ve Ekstraksiyon Çalışmaları(Selçuk Üniversitesi Fen-Edebiyat Fakültesi, 2007) Bedük, Ahmet Dinçer; Ertul, Şeref; Koçak, Ahmet; Sezgin, Mehmet; Bayrakçı, MevlütBu çalışmada oksijen ihtiva eden makrosiklik ligandlar 2,3,5,6-Bis[373")-t-but545) metilbenzo)-8,15-diketo-15C4 (Lu). 2,3,5,6-Bis[3(35)-t-batil-545')metilbenzo) 8,18-diketo-1805 (La) sentezlenmiş ve oluşan ligandlarin alkali ve gecis metallerle olan kompleksleşme yetenekleri incelenmiştir. Sentezlenen bileşiklerin yapıları 'H. NMR, IR, Elemental analiz yöntemleri ile aydınlatılmaya çalışılmiştir. Ayrıca oluşan ligandlann metal-pikrat ekstrasiyon çalışmaları yapılmıştır.Öğe Taç Eter ihtiva Eden Makrosiklik Ligandların Sentezi ve Ekstraksiyon Çalışmaları(Selçuk Üniversitesi Fen-Edebiyat Fakültesi, 2007) Koçak, Ahmet; Sezgin, Mehmet; Ertul, Şeref; Bedük, Ahmet Dinçer; Malkondu, SaitBu çalışmada oksijen ihtiva eden makrosiklik ligandlar 2,3,5,6-Bis[3'-bromo3,5-di-tert-butil benzo-5 fenil benzo]12C3 (L1), 2,3,5,6-Bis[3'-bromo-3,5-di-tert-butil benzo-5 fenil benzo)15C4 (L2) 2,3,5,6-Bis[3-bromo-3,5-di-tert-butil benzo-5 fenil benzo)-8,12 diketo 1203 (L3). 2,3,5,6-Bis[3-bromo-3,5-di-tert-butil benzo-5 fenil 1-8 18 diketo 18C5 (L) sentezleri gerçekleştirilm ve geçiş metallerle olan metal-pikrat ekstraksiyon çalışmaları denenmiştir. Sentezlenen bileşiklerin yapıları 'H-NMR, IR, Elemental analiz yöntemleri ile aydınlatılmaya çalışılmıştır.Öğe A Versatile Approach Toward Calix(Aza)crown Oligomers: Synthesis and Metal Ion Extraction(Marcel Dekker Inc, 2003) Akkuş, Gülderen Uysal; Memon, Shahabuddin; Sezgin, Mehmet; Yılmaz, MustafaFour new calix(aza)crown oligomers (5-8) have been synthesized by reacting p-tertbutylcalix[4](aza)crowns (3 and 4) with triethylene glycol ditosylate or 1,5-dibromopentane. Their phase transfer studies were performed by using liquid-liquid extraction procedure. It has been deduced from the observations that, the oligomers 5 and 7 are good extractants, whereas, oligomers 6 and 8 show different extraction behavior toward selected alkali (Li+, Na+, K+, Cs+) and transition metal cations (Ni+2, Cu+2, Co+2, Cd+2, Hg+2, Pb+2).
