Person: DEMİR, SERAP
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DEMİR
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SERAP
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Publication Metadata only 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, AyseCardiovascular 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.Publication Metadata only 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.Publication Metadata only 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, SerapIn 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.Publication Metadata only 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, AyseThe 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.Publication Metadata only 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, AyseEpilepsy 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.Publication Metadata only 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, AyseThe 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.Publication Metadata only Preparation, characterization, and drug release properties of poly(2-hydroxyethyl methacrylate) hydrogels having beta-cyclodextrin functionality(JOHN WILEY & SONS INC, 2008) OGAN, AYŞE; Demir, Serap; Kahraman, M. Vezir; Bora, Nil; Apohan, Nilhan Kayaman; Ogan, AyseA new beta-cyclodextrin urethane-methacrylate monomer was synthesized from the reaction of toluene-2,4-diisocyanate, 2-hydroxyethyl methacrylate (HEMA), and beta-cyclodextrin (beta-CD). Based on inclusion character of beta-CD, a series of hydrogels were prepared by irradiating the mixtures of beta-cyclodextrin urethane-methacrylate monomer (beta-CD-UM), poly(ethylene glycol) diacrylate (PEG-DA), HEMA, and the photoinitator. Gel percentages and equilibrium swelling ratios (%) of hydrogels were investigated. It was observed that the equilibrium-swelling ratio increased with increasing beta-CD-UM content in the hydrogel composition. SEM images demonstrated that beta-CD-UM based hydrogel have porous fractured surface. In this study four different drug molecules, salicylic acid, sulfathiazole, rifampicin, and methyl orange as model drug, which are capable of forming inclusion complexes with beta-CD were chosen. For sulfathiazole and rifampicin, the drug loadings are very low (0.04 and 0.008 mmol/g dry gel), whereas methyl orange and salicylic acid drug uptakes are found as 0.15 and 0.18 mmol/g dry gel, respectively. The incorporation of beta-CD-UM comonomer into the gel slightly reduces the methyl orange and salicylic acid releases. However, a significant enhancement was achieved in the case of sulfathiazole delivery. It can be concluded that the inclusion complex formation capability of beta-CD moiety increases the drug release by improving the aqueous solubility of hydrophobic drugs. On the other hand, in the case of hydrophilic drugs, the drug release retards by forming strong drug-beta-CD complex and reducing the drug diffusivity. (C) 2008 Wiley Periodicals, Inc.Publication Metadata only Optimizing the immobilization conditions of beta-galactosidase on UV-cured epoxy-based polymeric film using response surface methodology(WILEY, 2021) OGAN, AYŞE; KAHRAMAN, MEMET VEZİR; DANIŞ, ÖZKAN; DEMİR, SERAP; Beyler-Cigil, Asli; Danis, Ozkan; Sarsar, Onur; Kahraman, Memet Vezir; Ogan, Ayse; Demir, SerapUV-cured epoxy-based polymeric film was prepared from glycidyl methacrylate, trimethylolpropane triacrylate, and poly(ethylene glycol) methylether acrylate. 2-hydroxy-2- methylpropiophenone was used as photo initiator. Covalent binding through epoxy groups was employed to immobilize beta-galactosidase from Escherichia coli onto this film, and immobilization conditions were optimized by the response surface methodology. ATR-Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analysis was carried out to characterize the epoxy-based polymeric film. Immobilization yield of beta-galactosidase on the material was calculated as 3.57 mg/g and the highest enzyme activity for the immobilized enzyme recorded at pH 6.5 degrees C and 60 degrees C. The immobilized enzyme preserved 51% of its activity at the end of 12 runs. Free and immobilized enzyme hydrolyzed 163.8 and 172.3 mu M lactose from 1% lactose, respectively. Kinetic parameters of both free and immobilized beta-galactosidase were also investigated, and K-m values were determined to be 0.647 and 0.7263 mM, respectively. Practical applications In our study we prepared a UV-cured epoxy-based polymeric film and optimized the immobilization conditions of beta-galactosidase from Escherichia coli onto this polymeric film by using response surface methodology (RSM). For this purpose, three-level and three-factor Box-Behnken design, which is an independent, rotatable or nearly rotatable, quadratic design, was applied. Optimal levels of three variables, namely, the amount of enzyme, immobilization time, and pH were determined using Box-Behnken experimental design. Lactose hydrolysis studies were performed from milk and lactose samples using free and immobilized enzyme. In addition, kinetic parameters, storage stability, and re-usability of immobilized beta-galactosidase were examined.Publication Metadata only EVALUATION OF ANTIOXIDANT, RADICAL-SCAVENGING AND ACETYLCHOLINESTERASE INHIBITORY ACTIVITIES OF VARIOUS CULINARY HERBS CULTIVATED IN SOUTHERN TURKEY(WILEY, 2014) OGAN, AYŞE; Danis, Ozkan; Yuce-Dursun, Basak; Cimen, Talin; Demir, Serap; Salan, Umit; Yalcin, Guler; Ogan, AyseThe purpose of this study was to determine the antioxidant, radical-scavenging, and acetylcholinesterase inhibitory capabilities of water and methanol extracts of Rhus coriariaL., Ocimum basilicumL., Rosmarinus officinalisL., Salvia officinalisL. and Thymbra spicataL., which are grown in the Hatay province of Turkey. Total antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (22-782.6g/mL EC50),OH scavenging (3.93-33.43g/mL EC50), ferric (0.143-3.083mmol trolox equivalent (TE)/g), and cupric-reducing antioxidant power (0.143-3.083mmol TE/g) assays. The phenolic composition of the methanolic extract of R.coriaria leaves was also investigated, and the active compound was identified as 4-O-methylgallic acid. The highest IC50 value of acetylcholinesterase inhibitory activity (1.170.04mg/mL) was observed in R.coriaria leaves. Principal component analysis showed that R.coriaria leaves possessed greater antioxidant and anti-acetylcholinesterase potential as compared with the other evaluated plants. Practical ApplicationsAntioxidants are widely used in the food industry to prevent the formation of toxic oxidation products and prolong shelf life. Because of increasing concern among consumers about the use of synthetic antioxidants, there has been a great interest in the identification and use of natural antioxidants. The present study reveals that Rhus coriaria leaves, which are not commonly used in Mediterranean cuisine, are a promising source of natural antioxidants and could be considered as a potential source of anti-acetylcholinesterase agents and food preservatives. Both the antioxidant and anti-acetylcholinesterase effects of R.coriaria leaves may be beneficial in the treatment of Alzheimer's disease.Publication Metadata only Intrinsic factor and vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] microspheres: preparation, characterization and drug release(WILEY, 2008) OGAN, AYŞE; Demir, Serap; Ogan, Ayse; Kayaman-Apohan, NilhanBACKGROUND: Vitamin B12 is an essential vitamin required by all mammals. Absorption of vitamin B12 is facilitated by binding of intrinsic factor-vitamin B12 complex to specific receptors in the ileum. In humans a deficiency of this vitamin or a lack of intrinsic factor leads to pernicious anaemia. The major objective of the present study was to prepare intrinsic factor-vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] (PLGA)-based microparticles and to investigate their release kinetics. RESULTS: PLGA copolymer was synthesized by the ring-opening polymerization method and characterized using gel permeation chromatography, Fourier transform infrared spectroscopy and H-1 NMR. The glass transition temperature measurement showed a single T-g at 40 degrees C. The intrinsic factor-vitamin B12 complex-loaded PLGA microspheres were prepared by a water-in-oil-in-water double emulsion solvent extraction/evaporation technique. An environmental scanning electron microscopy investigation demonstrated that the PLGA particles had a mean particle diameter of 38 gm. Interestingly, different drug release patterns (bi- and triphasic ones) were observed for vitamin B12-loaded and intrinsic factor-vitamin B12 complex-loaded microspheres. In contrast to the rapid release of vitamin B12 by itself, in vitro release tests showed that intrinsic factor and vitamin B12 in the complex were released from PLGA microspheres in a sustained manner over 15 days. CONCLUSION: PLGA microspheres can be an effective carrier for the intrinsic factor-vitamin B12 complex. (C) 2007 Society of Chemical Industry.