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OGAN, AYŞE

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    Preparation and drug release properties of lignin-starch biodegradable films
    (WILEY-V C H VERLAG GMBH, 2012) OGAN, AYŞE; Calgeris, Ilker; Cakmakci, Emrah; Ogan, Ayse; Kahraman, M. Vezir; Kayaman-Apohan, Nilhan
    Starch is one of the most commonly available natural polymers which are obtained from agro-sources. It is renewable and abundant in nature. Unfortunately due to its poor mechanical properties and hygroscopic nature, there are some strong limitations to the development of starch-based products. Usually blends of starch are prepared and plasticized with glycerol to improve some of its properties. In this study, lignin was extracted from hazelnut shells and investigated as a potential additive for starch biofilms. The structural characterization of hazelnut lignin was performed by employing UV spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Lignin was blended with corn starch in different ratios to obtain biofilms. Mechanical and thermal properties of the biofilms were enhanced as the lignin amount was increased in the formulations. Water absorption tests were performed at pH 2.0, 4.0, and 6.0. The percent swelling values of the starch/lignin films increased as pH increased. Also, the biofilm exhibiting the best properties was chosen for the drug release studies. Biofilms showed a fast ciprofloxacin (CPF) release within an hour and then the drug release rate decreased. A pH dependent drug release mechanism was also observed according to KoshnerPeppas model. The drug release increased with a decrease in pH.
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    Investigation of HMG-CoA reductase inhibitory and antioxidant effects of various hydroxycoumarin derivatives
    (WILEY-V C H VERLAG GMBH, 2020) OGAN, AYŞE; Ozalp, Lalehan; Danis, Ozkan; Yuce-Dursun, Basak; Demir, Serap; Gunduz, Cihan; Ogan, Ayse
    Cardiovascular diseases are one of the primary causes of deaths worldwide, and the development of atherosclerosis is closely related to hypercholesterolemia. As the reduction of the low-density lipoprotein cholesterol level is critical for treating these diseases, the inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, which is essentially responsible for cholesterol biosynthesis, stands out as a key solution to lower plasma cholesterol levels. In this study, we synthesized several dihydroxycoumarins and investigated their antioxidant and in vitro HMG-CoA reductase inhibitory effects. Furthermore, we carried out in silico studies and examined the quantum-chemical properties of the coumarin derivatives. We also performed molecular docking experiments and analyzed the binding strength of each coumarin derivative. Our results revealed that compoundIVdisplayed the highest HMG-CoA reductase inhibitory activity (IC50 = 42.0 mu M) in vitro. Cupric-reducing antioxidant capacity and ferric-reducing antioxidant power assays demonstrated that coumarin derivatives exhibit potent antioxidant activities. Additionally, a close relationship was found between the lowest unoccupied molecular orbital energy levels and the antioxidant activities.
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    Kumarin türevlerinin fizyolojik pH’da sığır serum albümine bağlanmasının spektral ve moleküler yerleştirme ile incelenmesi
    (2022-10-05) MELETLİ, FURKAN; DANIŞ, ÖZKAN; OGAN, AYŞE; Meletli F., Kazancıçok Z., Akın N., Danış Ö., Ogan A.
    Serum albümin, kan plazmasında en yaygın bulunan proteinlerden biridir. Ozmotik basıncın ayarlanması,kan pH’nın belirlenmesi ve serbest radikallerin azaltılması gibi birçok farklı fizyolojik görevlerinin yanı sırakanda bulunan endojen ve eksojen maddelerin (yağ asitleri, ilaçlar ve metabolitler vb.) taşınmasında birincilişlevi olan çok fonksiyonlu ve önemli bir proteindir. İlaçlar hedeflerine ulaşmak için kan plazmasındataşınırken kaçınılmaz olarak serum albümin ile etkileşime girmektedirler. Serum albümin ile ilaç etkileşimiilacın terapötik etkisi hakkında bilgi vermektedir. Bu etkileşimlerin incelenmesi ilaç kimyasında, tıpta,biyoteknolojide ve biyokimyada önemli bir araştırma alanıdır. Sığır serum albümin (BSA), 582 amino asitkalıntısından oluşan ve insan serum albümini ile %76 benzerliği olan bir proteindir. Düşük maliyetli olması,yaygın olarak bulunabilmesi ve saflaştırma işleminin kolay olması nedeniyle BSA, araştırmacılar tarafındanligandların proteine bağlanma çalışmaları için sıklıkla tercih edilen, protein-ilaç etkileşimleri ve bağlanmamekanizmalarının belirlenmesi için model olan bir taşıma sistemidir. Kumarinler bir benzen halkası ilebir α-piron halkasının kaynaşması sonucu oluşan benzopiron adı verilen bir bileşik sınıfının üyesidirler.Doğal olarak bitkilerde bulunabildiği gibi sentetik olarak da elde edilebilmektedir. Kumarinlerin sahipoldukları konjuge çift halka sistemleri, onları farklı araştırma alanları için ilginç moleküller haline getirmiştir.Kumarin türevleri geniş bir biyolojik aktivite yelpazesi sergilemektedirler. Bunlar arasında anti-oksidan,anti-enflamatuar, anti-bakteriyel, anti-viral, anti-tümör ve anti-koagülan özellikleri öne çıkmaktadır.Kumarinler tıpta ve özellikle ilaç endüstrisinde yaygın olarak kullanılmaktadırlar. Çalışmamızda uygunEmilim, Dağılım, Metabolizma ve Atılım (ADME) özelliklerine göre farmakokinetik ve farmakodinamiketkileri iyi olan daha önceden sentezlenmiş ve karakterize edilmiş kumarin türevlerinin BSA’ya bağlanmalarıve taşınmaları in silico ve in vitro yöntemlerle araştırılmıştır. In silico çalışmalarda moleküler yerleştirme(moleküler docking) ve in vitro çalışmalarda UV-vis absorbans, floresans gibi multi-spektroskopik yöntemlerkullanılmıştır. BSA ile kumarin türevlerinin etkileşimleri in silico ve in vitro yöntemlerle aydınlatılmıştır. Insilico çalışmalar sonucunda kumarinlerin bağlanma enerjileri, ligand verimliliği değerleriyle birlikte proteinligandetkileşimleri ve konformasyonları belirlenmiştir. Ayrıca in vitro multi-spektroskopik analizlerindeğerlendirilmesiyle; bileşikler BSA’nın floresans şiddetinde, absorbansında ve ikincil yapısında değişikliklerizlenmiş, kuençleşme mekanizmaları, bağlanma sabitleri ve bağlanma bölgelerinin sayıları belirlenmiştir.
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    Soybean oil based resin: A new tool for improved immobilization of alpha-amylase
    (WILEY, 2006) OGAN, AYŞE; Kahraman, MV; Kayaman-Apohan, N; Ogan, A; Gungor, A
    Acrylated epoxidized soybean resin has been utilized to immobilize the alpha-amylase via UV-curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. (c) 2006 Wiley Periodicals, Inc.
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    İnsan monoamin oksidaz a ve b inhibitörleri olarak benzokumarin türevlerinin sentezi ve biyolojik olarak değerlendirilmesi
    (2015-05-07) DANIŞ, ÖZKAN; DEMİR, SERAP; OGAN, AYŞE; ERDEM, SAFİYE; Danış Ö., Yüce Dursun B., Demir S., Alparslan M., Ogan A., Erdem S.
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    Preparation and characterization of sol-gel hybrid coating films for covalent immobilization of lipase enzyme
    (ELSEVIER, 2016) OGAN, AYŞE; Yuce-Dursun, Basak; Cigil, Asli Beyler; Dongez, Dilek; Kahraman, M. Vezir; Ogan, Ayse; Demir, Serap
    In this study UV-curable hybrid epoxy-silica polymer films were prepared via sol-gel method. Lipase (EC 3.1.1.3) from Candida rugosa was covalently immobilized onto hybrid epoxy-silica polymer films and immobilization capacity of polymer films was found 7.22 mg g(-1). The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Immobilized and free enzymes were used in two different reaction systems: hydrolysis of p-nitrophenyl palmitate in aqueous medium and synthesis of p-nitrophenyl linoleate (from p-nitrophenol and linoleic acid) in n-hexane medium. The effect of temperature on hydrolytic and synthetic activities was investigated and observed maximum activities at 50 degrees C and 45 degrees C for immobilized enzyme, orderly. Km values for free enzyme were determined 0.71 and 1.12 mM by hydrolytic and synthetic activity assays, respectively, while these values were observed as 0.91 mM and 1.19 mM for immobilized enzyme. At the end of 30 repeated cycles, 56% and 59% of initial activities remained for hydrolytic and synthetic assays, respectively. Native enzyme lost its activity completely within 20 days, whereas the immobilized enzyme retained for hydrolytic and synthetic activities was approximately 82% and 72%, respectively, under the same storage time. (C) 2016 Elsevier B.V. All rights reserved.
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    Preparation, characterization, and in vitro evaluation of isoniazid and rifampicin-loaded archaeosomes
    (WILEY, 2018) OGAN, AYŞE; Attar, Azade; Bakir, Ceren; Yuce-Dursun, Basak; Demir, Serap; Cakmakci, Emrah; Danis, Ozkan; Birbir, Meral; Ogan, Ayse
    The ability of Archaea to adapt their membrane lipid compositions to extreme environments has brought in archaeosomes into consideration for the development of drug delivery systems overcoming the physical, biological blockades that the body exhibits against drug therapies. In this study, we prepared unilamellar archaeosomes, from the polar lipid fraction extracted from Haloarcula 2TK2 strain, and explored its potential as a drug delivery vehicle. Rifampicin and isoniazid which are conventional drugs in tuberculosis medication were loaded separately and together in the same archaeosome formulation for the benefits of the combined therapy. Particle size and zeta potential of archaeosomes were measured by photon correlation spectroscopy, and the morphology was assessed by with an atomic force microscope. Encapsulation efficiency and loading capacities of the drugs were determined, and in vitro drug releases were monitored spectrophotometrically. Our study demonstrates that rifampicin and isoniazid could be successfully loaded separately and together in archaeosomes with reasonable drug-loading and desired vesicle-specific characters. Both of the drugs had greater affinity for archaeosomes than a conventional liposome formulation. The results imply that archaeosomes prepared from extremely halophilic archaeon were compatible with the liposomes for the development of stable and sustained release of antituberculosis drugs.
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    Changes in intracellular protein expression in cortex., thalamus and hippocampus in a genetic rat model of absence epilepsy
    (PERGAMON-ELSEVIER SCIENCE LTD, 2011) OGAN, AYŞE; Danis, Ozkan; Demir, Serap; Gunel, Aslihan; Aker, Rezzan Gulhan; Gulcebi, Medine; Onat, Filiz; Ogan, Ayse
    Epilepsy is a chronic disorder characterized by repeated seizures resulting from abnormal activation of neurons in the brain. Although mutations in genes related to Na+, K+, Ca2+ channels have been defined, few studies show intracellular protein changes. We have used proteomics to investigate the expression of soluble proteins in a genetic rat model of absence epilepsy Genetic Absence Epilepsy Rats from Strasbourg (GAERS). The advantage of this technique is its high throughput quantitative and qualitative detection of all proteins with their post-translational modifications at a given time. The parietal cortex and thalamus, which are the regions responsible for the generation of absence seizures, and the hippocampus, which is not involved in this activity, were dissected from GAERS and from non-epileptic control rat brains. Proteins from each tissue sample were isolated and separated by two-dimensional gel electrophoresis. Spots that showed significantly different levels of expression between controls and GAERS were identified by nano LC-ESI-MS/MS. Identified proteins were: ATP synthase subunit delta and the 14-3-3 zeta isoform in parietal cortex; myelin basic protein and macrophage migration inhibitory factor in thalamus; and macrophage migration inhibitory factor and 0-beta 2 globulin in hippocampus. All protein expressions were up-regulated in GAERS except 0-beta globulin. These soluble proteins are related to energy generation, signal transduction, inflammatory processes and membrane conductance. These results indicate that not only membrane proteins but also cytoplasmic proteins may take place in the pathophysiology and can be therapeutic targets in absence epilepsy. (C) 2011 Elsevier Inc. All rights reserved.
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    Amine functional magnetic nanoparticles via waterborne thiol-ene suspension photopolymerization for antibody immobilization
    (ELSEVIER SCIENCE BV, 2018) OGAN, AYŞE; Muhsir, Pelin; Cakmakci, Emrah; Demir, Serap; Ogan, Ayse
    The modification of magnetic nanoparticles (MNPs) via different routes for biomolecule binding is an attractive area of research. Waterborne thiol-ene suspension photopolymerization (TESP) can be a useful method for preparing functional MNPs. In this study, for the very first time waterborne TESP was performed in the presence of MNPs. Neat MNPs were coated and in situ functionalized with amine groups by using thiol-ene chemistry. Engrailed-2 (EN2) protein, a potential biomarker for various cancers such as prostate cancer, bladder cancer, breast cancer and ovarian cancer, is known to be a strong binder to a specific DNA sequence (50-TAATTA-30) to regulate transcription. Anti-EN2 antibodies were immobilized onto these MNPs by physical adsorption and covalent bonding methods, respectively. The amount of the physically immobilized antibodies (0.54 mg/g) were found to be lower than the loading of the covalently bonded antibodies (1.775 mg/g). The biomarker level in the artificial solutions prepared was determined by enzyme-linked immunosorbent assay. Coated MNPs were characterized by FTIR, TGA, SEM and STEM. After TESP, the average diameter of the neat magnetite nanoparticles increased from similar to 15 nm to similar to 32 nm.