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 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 Immobilization of pectinase on polyethyleneimine based support via spontaneous amino-yne click reaction(ELSEVIER, 2020) OKTAY, BURCU; Oktay, Burcu; Demir, Serap; Kayaman-Apohan, NilhanThe immobilization of an enzyme can improve catalytic activity, stability, and reusability of its. In this study, we investigated a new method for enzyme immobilization. Alkyne-pectinase was first immobilized on the polyethyleneimine-based cryogel via a spontaneous amino-yne click reaction under very mild conditions and then the apple juice was clarified. Amino-yne click reactions do not need any photoinitiator or catalyst, unlike other click reactions. The immobilization efficiency of the alkyne pectinase was 90%. The immobilized enzyme continued to retain 70% of its initial activity after 60 days. An improvement observed in the pH tolerance in the range of 6.5-8.0. The higher thermal tolerance of the immobilized pectinase was increased above 50 degrees C. Immobilized pectinase showed 100% activity at 55 degrees C and pH 6.5. The clarification rate of apple juice was achieved about 50% by the pectinase immobilized support. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Publication Open Access Immobilization of acetylcholinesterase onto pyrrole-containing photocured thermosets(2023-04-01) DEMİR, SERAP; ÇAKMAKÇI, EMRAH; OGAN, AYŞE; ALI K. K., DEMİR S., ÇAKMAKÇI E., OGAN A.Acetylcholinesterase (AChE; EC 3.1.1.7) is a group of enzymes that catalyzes the hydrolysis of the neurotransmitter acetylcholine (ACh) into choline and acetate. AChE inhibition is commonly utilized as a biomarker for pesticides. In membrane based AChE biosensors the enzyme immobilization onto an electrode surface is of prime importance. In previous studies, conducting polymers-based supports have been used for the immobilization of AChE. In this study, a novel immobilization platform was developed. The simultaneous polymerization of pyrrole and functional thiol/ene monomers was performed to prepare conductive thermosets. AchE was covalently immobilized onto the membranes through the epoxy functional groups. After the immobilization process, the optimal temperature increased to 50 °C, displaying a better thermal stability and the optimum pH was elevated to 8.5. The activity of the immobilized enzyme was tested in the presence of several metals, and it was found that Cu2+ ions caused a noticable inhibition. After 10 cycles, the immobilized enzyme retained 51% of its original activity. In accordance with our results; the durability and the stability of the immobilized enzyme were improved. In future studies, the method applied here can be used in the design of an AchE biosensor.Publication Open Access Poly(lactic acid) nanofibers containing phosphorylcholine grafts for transdermal drug delivery systems(2022-06-01) OKTAY, BURCU; DEMİR, SERAP; KAYAMAN APOHAN, NİLHAN; OKTAY B., Eroglu G. O., DEMİR S., KURUCA D. S., KAYAMAN APOHAN N.The continuous and prolonged releases of chemotherapeutic drugs are required for successful treatment in cancer treatment. The project focused on a new material design to meet this requirement. We developed a constant and sustained release system and investigated the release profiles of Paclitaxel (PTX). Polylactic acid (PLA) nanofiber surface was grafted with poly (methacryloyloxyethyl phosphorylcholine) (PMPC) by the UV-induced grafting method. The morphological structure of the PLA nanofibers did not change with an increase in the MPC content. PMPC blocks contribute to the solubility of PTX, which shows low resolution. When the amount of MPC is 5%, the PTX loading efficiency increased two times compared with PLA nanofiber. The nanofiber mats exhibited an initial fast release during the first 3 h. Endothelial cells were cultured on nanofiber mats to investigate whether this material was toxic or not. The mats showed good biocompatibility with HUVEC. Thus, it was confirmed that nanofiber mats would not be toxic when releasing drugs during in vivo use. We think that PMPC facilitates the pass of drugs through the lipid-rich biological membrane and so anticancer drugs can be delivered to direct tumor sites. (C) 2022 Elsevier Ltd. All rights reserved.Publication Open Access Preparation and characterization of hybrid nanomaterials containing magnetic fe3o4 nanoparticles as drug delivery system(2022-09-01) DEMİR, SERAP; Demir S.In this study, magnetic Fe3O4 nanoparticles were synthesized and the magnetic surfaces of the nanoparticles were modified with thiol groups. The chitosan polymer was modified with allyl groups and then bound to magnetic nanoparticles by the thiol-en click reaction. The drugs paclitaxel (PTX) and doxorubicin (DOX) were loaded separately and together into this prepared hybrid material, and then drug releases from the hybrid material were studied. The aim of this paper is to present the results on the controlled release of DOX and PPT cancer drugs from chitosan-Fe3O4 nanoparticles at two different pH values (5.0 and 7.4). PTX was effectively loaded into chitosan-Fe3O4 nanoparticles and slowly released up to 72.66% at pH 5 and 41.45% at pH 7.4 after 48 hours. DOX was effectively loaded into chitosan-Fe3O4 nanoparticles and slowly released up to 30.5% at pH 5 and 23.3% at pH 7.4 after 48 hours.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 Open Access Design, synthesis and biological evaluation of novel benzocoumarin derivatives as potent inhibitors of MAO-B activity(2024-11-15) MELETLİ, FURKAN; DEMİR, SERAP; DANIŞ, ÖZKAN; MELETLİ F., Gündüz C., Alparslan M. M., ATTAR A., DEMİR S., İskit E., DANIŞ Ö.The continued research of novel reversible inhibitors targeting monoamine oxidase (MAO) B remains crucial for effectively symptomatic treatment of Parkinson\"s disease. In this study we synthesized and evaluated a new series of 3-aryl benzo[g] and benzo[h] coumarin derivatives as MAO-B inhibitors. Compound A6 has been found to display the most potent inhibitory activity and selectivity against the MAO-B isoform (IC50 = 13 nM and SI = >7693.31 respectively). Inhibition mode of A6 on MAO-B was predicted as mixed reversible inhibition with a Ki value of 3.274 nM. Furthermore, in order to elaborate structure–activity relationships, the binding mode of A6 was investigated by molecular docking simulations.