Person: OGAN, AYŞE
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OGAN
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AYŞE
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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 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.Publication Open Access In vitro and in silico investigation of inhibitory activities of 3-arylcoumarins and 3-phenylazo-4-hydroxycoumarin on MAO isoenzymes(2022-11-01) DANIŞ, ÖZKAN; DEMİR, SERAP; ERDEM, SAFİYE; OGAN, AYŞE; Yuce-Dursun B., DANIŞ Ö., Ozalp L., Sahin E., DEMİR S., ERDEM S., OGAN A.A series of 3-aryl coumarin derivatives and 3-phenylazo-4-hydroxycoumarin were evaluated for their monoamine oxidase (MAO) A and B inhibitory activity and selectivity by fluorometric enzymological assays. Among 21 coumarin derivatives, compound 21 (3-phenylazo-4-hydroxycoumarin) displayed a good inhibitory activity (0.12 +/- 0.02 mu M) and very high selectivity for MAO-B (SI > 833.33). The inhibition was determined as mixed-type and not time-dependent. Docking studies, molecular dynamics and molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) calculations were performed to elucidate in vitro results. Our results reveal that the insertion of an azo linker between coumarin and phenyl rings in 3-arylcoumarins enhances MAO-B selectivity enormously since such a linker leads to the perfect alignment of the coumarin ring in the aromatic cage and the phenyl ring in the entrance cavity of MAO-B active site. Hydrogen bond interactions with Cys172 in the active site entrance of MAO-B also contributes to the remarkably higher inhibitory activity and selectivity for MAO-B.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, 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 Preparation of poly(3-hydroxybutyrate-co-hydroxyvalerate) films from halophilic archaea and their potential use in drug delivery(SPRINGER JAPAN KK, 2015) OGAN, AYŞE; Danis, Ozkan; Ogan, Ayse; Tatlican, Pinar; Attar, Azade; Cakmakci, Emrah; Mertoglu, Bulent; Birbir, MeralHalophilic archaea offer a potential source for production of polyhydroxyalkanoates (PHAs). Hence, the experiments were carried out with five extremely halophilic archaeal isolates to determine the highest PHA-producing strain. PHA production of each isolates was separately examined in cheap carbon sources such as corn starch, sucrose, whey, apple, melon and tomato wastes. Corn starch was found to be a fairly effective substrate for PHA production. Among the strains studied here, the strain with the highest capability for PHA biosynthesis was found to be 1KYS1. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that 1KYS1 closely related to species of the genus Natrinema. The closest phylogenetic similarity was with the strain of Natrinema pallidum JCM 8980 (99 %). PHA content of 1KYS1 was about 53.14 % of the cell dry weight when starch was used as a carbon source. The formation of large and uniform PHA granules was confirmed by transmission electron microscopy and the biopolymer was identified as poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV). PHBV produced by 1KYS1 was blended with low molar mass polyethylene glycol (PEG 300) to prepare biocompatible films for drug delivery. Rifampicin was used as a model drug and its release from PHBV films was investigated at pH 7.4, 37 A degrees C. It was found that PHBV films obtained from 1KYS1 were very effective for drug delivery. In conclusion, PHBV of 1KYS1 may have a potential usage in drug delivery applications.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 Antioxidant and anti-collagenase activity of st. John's wort (hypericum perforatum l.)(2022-11-30) ERDEM, SAFİYE; DANIŞ, ÖZKAN; OGAN, AYŞE; YILDIZ İ., Özalp L., ERDEM S., MOUTSİNGA E. G. B. K. , DANIŞ Ö., OGAN A.