Yazar "Çakmak, Reşit" seçeneğine göre listele

Listeleniyor 1 - 12 / 12
  • Küçük Resim
    Öğe
    Anticholinesterase and antioxidant activities of novel heterocyclic Schiff base derivatives containing an aryl sulfonate moiety
    (Wiley-V C H Verlag GMBH, 2022) Kamalı, Ayfer; Çakmak, Reşit; Boğa, Mehmet
    In this research, nine novel heterocyclic Schiff base derivatives (10-18) bearing an aryl sulfonate moiety were designed, synthesized for the first time, and characterized. Then, their inhibitory effects on acetyl- and butyrylcholinesterase (AChE and BChE) were investigated in vitro conditions. Moreover, their antioxidant activities were examined by DPPH and ABTS methods. The results indicated that some of the tested molecules had varying enzyme inhibition and antioxidant activities. We determined that compounds 8, 9, 14, 17, and 18 indicated inhibitory effects with IC50 values ranging from 89.30 to 111.28 mu M against BChE, respectively compared to standard compound galanthamine (IC50 = 125.88 mu M). On the other hand, of the molecules tested, only compound 5 (IC50 = 36.64 mu M) displayed inhibitory activity higher than galanthamine against AChE. In DPPH assay, compounds 15 (IC50 = 161.93 mu M), 16 (IC50 = 191.76 mu M) and 17 (IC50 = 107.55 mu M) showed higher antioxidant activity than BHT (IC50 = 203.50 mu M). On the other hand, it was determined in ABTS assay that Schiff bases 10-17 (except for compound 18) indicated higher antioxidant activity than BHT.
  • Küçük Resim
    Öğe
    Heterocyclic Schiff base derivatives containing pyrazolone moiety: Synthesis, characterization, and in vitro biological studies
    (Wiley, 2021) Çınar, Ercan; Başaran, Eyüp; Erdoğan, Ömer; Çakmak, Reşit; Boğa, Mehmet; Çevik, Özge
    In this study, some pyrazolone-based Schiff base derivatives 2a-e (except 2a)were synthesized for the first time and structurally illuminated by some spec-troscopic techniques (1H,13C NMR, FT-IR) and elemental analysis. Allsynthesized molecules were screened for their anticancer and antioxidantactivities, as well as AChE, BChE, and tyrosinase inhibitory properties.The obtained results exhibited that compounds 1b (IC50= 9.497 Μ) and 2a(IC50= 30.49 Μ) significantly decreased the proliferation of HeLa cells. Onthe other hand, the apoptotic effects of these two compounds were investigatedwith acridine orange/propidium iodide double staining. The apoptotic cellratios of the molecules treated with these two compounds were determined as60 and 64%. Compound 2b (IC50= 17.95 ± 0.47 Μ ) was determined to be avery active substance in the ABTS assay. Compound 2e (A0.5= 43.75± 0.62 M) indicated the closest antioxidant activity to the standard compoundα-TOC (A0.5= 50.58 ± 0.39 M) in the cupric reducing antioxidant capacity(CUPRAC) assay. In inhibition studies of enzymes, it was determined thatcompound 2c had a very active molecule in AChE, BChE, and tyrosinaseinhibitory activities with 82.79 ± 1.03, 91.39 ± 1.06, and 92.60 ± 1.80% inhibi-tion, respectively. It was determined that the target molecules 2a-e showedbetter antioxidant and enzyme inhibitory activities than those of ester deriva-tives 1a-e.
  • Küçük Resim
    Öğe
    Manyetik Fe3O4 nanopartiküllerine Candida rugosa lipaz enziminin immobilizasyonu ve rasemik organik asit esterlerinin enantiyoseçimli hidrolizi
    (Dicle Üniversitesi, Fen Bilimleri Enstitüsü, 2015) Çakmak, Reşit; Topal, Giray
    Enantiyomerlerin farklı biyolojik aktivite göstermelerinden dolayı, farklı yöntemler kullanılarak enantiyomerikçe saf bileşiklerin elde edilmesi, başta ilaç endüstrisi olmak üzere zirai kimyasallar, gıda ve parfüm endüstrisi için oldukça önemlidir. Lipaz enzimleri, rasemik bileşiklerin rezolüsyonunda yüksek enantiyoseçicilik sağlamaları, kofaktöre ihtiyaç duymamaları, geniş substrat spesifikliği ve kiral tanıma yeteneğine sahip olmaları nedeniyle yaygın olarak kullanılmaktadır. Saf enzim fiyatlarının pahalı oluşu, enzim saflaştırma işlemlerinin uzun zaman alması ve maliyet gerektiren bir işlem olması nedeniyle çalışmalarda, serbest enzim yerine immobilize enzimler kullanılmaktadır. Günümüzde, reaksiyon verimi yüksek ve düşük maliyetli çalışmalar yaparak saf ilaç etken maddelerinin üretimine yönelik araştırmaların devam ettiği bilinmektedir. Bu yüzden, bu araştırmalara katkı sunmak amacıyla bu çalışma doktora tezi olarak hazırlandı. Bu çalışma üç bölümden oluşmaktadır. Birinci bölümde, manyetik Fe3O4 nanopartikülleri hazırlandı. Hazırlanan nanopartiküllere, enzimi immobilize etmek için iki farklı organik uzatma kolu takıldı. Birinci organik uzatma kolu için (3-aminopropil) trietoksisilan ve glutaraldehit kullanıldı. İkinci organik uzatma kolu için rasemik epiklorhidrin kullanıldı. Hazırlanan manyetik nanopartikül ve organik uzatma kollarına sahip manyetik nanopartiküllerin yapılarının aydınlatılması için SEM, XRD, TGA ve FT-IR kullanıldı. İkinci bölümde, organik uzatma kollarına sahip partiküllere kovalent bağlanma metoduna göre CRL immobilize edildi. Ardından; serbest ve immobilize enzimlerin: enzimatik aktiviteleri, optimum pH'ları, optimum sıcaklıkları, termal kararlılıkları ve depolama kararlılıkları belirlendi. Ayrıca, immobilize enzimlerin tekrar kullanılabilirlikleri de belirlendi. Üçüncü bölümde, immobilize enzimler kullanılarak, rasemik bütil Mandelat esteri, rasemik İbuprofen metil esteri ve rasemik Naproksen metil esterinin enantiyoselektif hidroliz çalışmaları yapıldı. Hidroliz tepkimesi sonucu verim hesabı yapılarak, çalışmanın başarısı değerlendirildi.
  • Küçük Resim
    Öğe
    Öğretmen adaylarının su hakkındaki bilgi düzeyleri ve kavram yanılgıları
    (International Balkan University, 2018) Çakmak, Mürşet; Çakmak, Reşit; Topal, Giray
    Öz:Bu çalışma, öğretmen adaylarının cinsiyete, okudukları bölüme,öğrenim gördükleri sınıfa göre ve su hakkındaki bilgi düzeyleri ilekavram yanılgılarını incelemek amacı ile yapılmıştır. Çalışma, 2018yılında Dicle Üniversitesi Ziya Gökalp Eğitim Fakültesi’nde okuyan fenbilgisi ve kimya öğretmen adayları (N=87) ile yapılmıştır. Bu çalışmadatarama modeli kullanılmıştır. Çalışmada veri toplama aracı olarak SuBilgisi Testi (SBT) kullanılmıştır. Araştırmacılar tarafından hazırlananbu test, suyun fiziksel, kimyasal ve biyolojik özellikleri ile ilgili toplam57 madde olarak yazılmış ve geliştirilmiştir. Geliştirilen testin geçerlikve güvenirlik analizleri yapılmıştır. Testin madde güçlük ve ayırt edicilikindisleri hesaplanmıştır Yapılan analiz sonucunsa madde ayırt edicilikve güçlük indisleri 0,20’den düşük olan 26 madde testten elenmiştir.Geriye kalan diğer 31 madde ise SBT’de kullanılmıştır. Testin KR-20güvenirliği 0,79’dur. Verilerin değerlendirilmesi için yüzde ve frekansdeğerleri çıkartılmıştır. Elde edilen testin bulgularına göre öğretmenadaylarının su hakkındaki bilgi seviyelerinin yüzde 50’ye yakın olduğuve su hakkında kavram yanılgı oranlarının çok olduğu görülmüştür.Ayrıca cinsiyete, okudukları bölüm ve bulundukları sınıfa göre yapılanincelemeye göre de benzer sonuçların olduğu söylenebilir. Öğretmenadaylarının en çok “Suyun sıcaklığı artıkça içinde çözünen gazlarınmiktarı artar”, “Su ile tuz (NaCI) karıştırıldığında aralarında kimyasalbir reaksiyon gerçekleşir ve tuz parçalanır”, “Kar ve yağmur suları doğada bulunan en saf sulardır”, “Su tüm sıvı haldeki maddelerlekarışır”, “Su net bir dipol momente sahiptir”, “Bir insanın biyolojikihtiyaçlarını karşılaması ve yaşamını sürdürebilmesi için, günde en az 1litre su tüketmesi gerektiği kabul edilir” gibi maddelerde kavramyanılgıları taşıdıkları görülmüştür. Bu bulgulardan hareketlearaştırmacı ve uygulayıcılar için bazı öneriler verilmiştir.
  • Küçük Resim
    Öğe
    Resolution of (±)-?-Methylphenylethylamine by a Novel Chiral Stationary Phase for Pirkle-Type Column Chromatography
    (Wiley, 2010) Yılmaz, Hayrullah; Topal, Giray; Çakmak, Reşit; Hoşgören, Halil; 0000-0002-5275-6606; 0000-0003-0401-7419; 0000-0002-7056-3912
    In this study, a new Pirkle-type chiral column stationary phase for resolution of beta-methylphenylethyl amine was described by using activated Sepharose 4B as a matrix, L-tyrosine as a spacer arm, and an aromatic amine derivative of L-glutamic acid as a ligand. The binding capacities of the stationary phase were determined at different pH values (pH = 6, 7, and 8) using buffer solutions as mobile phase, and enantiomeric excess (ee) was determined by HPLC equipped with chiral column. The ee was found to be 47%. Chirality 22:252-257, 2010. (C) 2009 Wiley-Liss, Inc.
  • Küçük Resim
    Öğe
    Schiff base derivatives of 4-aminoantipyrine as promising molecules: Synthesis, structural characterization, and biological activities
    (Pleiades journals, 2022) Çakmak, Reşit; Başaran, Eyüp; Boğa, Mehmet; Erdoğan, Ömer; Çınar, Ercan; Çevik, Özge
    Abstract: In this study, some Schiff bases derived from 4-aminoantipyrine (4-AAP) (VI–X) were synthesized, characterized by elemental analysis (C, H, N) and three spectral techniques (FT-IR, 1H, and 13C NMR), and then their antioxidant activity was investigated by employing four different methods. Subsequently, the inhibitory influences of the synthesized molecules against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase enzymes were tested. More importantly, the cytotoxic effects of all title molecules were also evaluated on HeLa human cervical cancer and L929 mouse fibroblast cell lines. According to the results obtained, compound (VI) (IC50: 16.82 ± 0.17 μM) showed higher ABTS cation radical scavenging activity than BHA (IC50: 17.59 ± 0.10 μM). In CUPRAC assay, it was determined that the activity ordering of the bioactive molecules has been determined as VII > X > VII > α-TOC > IX > I > II > V > VI. In AChE assay, compound (I) indicated a high potent inhibition activity with 91.75 ± 1.15% better than galanthamine. In BChE assay, compound (VII) had good BChE inhibition activity (78.76 ± 1.47%) better than galanthamine. Compound (V) showed strong tyrosinase inhibition activity with 52.85 ± 0.23% value at 200 μM concentration. Compound (III) showed the best cytotoxic effect on HeLa cells with an IC50 dose of 21.47 µM. Consequently, it can be said that some of these synthesized molecules were potentially new anti-Alzheimer drug candidate molecules.
  • [ X ]
    Öğe
    SOME NOVEL SCHIFF BASE DERIVATIVES AS PROMISING CHOLINESTERASE INHIBITORS WITH ANTIOXIDANT ACTIVITY AGAINST ALZHEIMER’S DISEASE: SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION
    (2022) Boğa, Mehmet; Çınar, Ercan; Topal, Giray; Çakmak, Reşit
    In this study, five novel Schiff base derivatives (6-10) except for 9 were synthesized for the first time, characterized, and tested for their inhibition activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Also, the Antioxidant activities of these molecules were examined by DPPH and ABTS assays. Their molecular structures were characterized by three spectroscopic techniques. In AChE assay, compound 6 (95.87±1.59 % inhibition) inhibited this enzyme better than galanthamine (76.98±0.42 % inhibition). In BChE assay, compound 10 with an 87.92±1.08% inhibition value in the series indicated the highest activity compared to galanthamine (76.30±0.28 % inhibition). In ABTS radical scavenging assay, compounds 7, 8, and 9 except for 6 and 10 indicated higher antioxidant activities compared to butylated hydroxytoluene (BHT). It is believed that these results may contribute to the design and synthesis of novel antioxidant agents, AChE, and BChE inhibitors.
  • [ X ]
    Öğe
    Synthesis of new fluorinated sulfonates and their Schiff bases as anti-Alzheimer drug candidates: An in vitro-in silico study
    (Elsevier B.V., 2025) Çakmak, Reşit; Başaran, Eyüp; Ercan, Selami; Boğa, Mehmet; Çınar, Ercan; Topal, Giray
    In this research, we designed and synthesized a series of new 3- or 4-(trifluoromethyl)- substituted sulfonate esters (1–14) linked heterocyclic Schiff base derivatives (15–28) as potential inhibitors of acetylcholinesterase and butyrylcholinesterase. The chemical structures of the target compounds were elucidated using elemental analysis and various spectral techniques. In vitro inhibitory results revealed IC50 values ranging from 12.05±0.10 to 43.08±0.20 μM against acetylcholinesterase and 0.42±0.04 to 95.52±0.00 μM against butyrylcholinesterase. Among the tested compounds, most sulfonates were found to inhibit acetylcholinesterase better than butyrylcholinesterase. In contrast, their Schiff base derivatives inhibited butyrylcholinesterase more effectively acetylcholinesterase did. Compounds 19, 20, and 21 inhibited butyrylcholinesterase better than galanthamine. The effects of trifluoromethyl group at positions 3 or 4 of the sulfonate moiety and the biosubstitutions at position R2 of the spacer moiety on the inhibitory activities were evaluated. Moreover, the antioxidant potency of these compounds was assessed by three different assays (DPPH free radical scavenging activity, ABTS cationic radical decolorization, and cupric reducing antioxidant capacity. The newly synthesized derivatives showed very low antioxidant activity (>1000 μM) in the DPPH and ABTS assays, while some of 3- trifluoromethyl substituted Schiff base derivatives (compounds 15, 20, and 21) showed activity closer to α-tocopherol in cupric reducing antioxidant capacity assay. The binding modes and binding free energies for acetylcholinesterase and butyrylcholinesterase inhibitor candidates were determined through docking studies. Taken together, we consider some inhibitor candidates to be valuable lead structures that can be used in further studies to design new anti-Alzheimer's disease drugs. © 2025 Elsevier B.V.
  • Küçük Resim
    Öğe
    Synthesis of novel N-Acylhydrazones derived from 3,5-dinitrobenzohydrazide and evaluation of their anticholinesterase and antioxidant activities
    (Pleiades Publishing, 2024) Çakmak, Reşit; Çınar, Ercan; Başaran, Eyüp; Tuneğ, Gülsüm; İzgi, Sevcan; Boǧa, Mehmet
    Abstract: Objective: In this study, it was aimed to determine the antioxidant activities and enzyme inhibition properties of newly synthesized N-acylhydrazone compounds (IIIa–IIIp) bearing an aryl sulfonate moiety. Methods: For this purpose, a series of hydrazone derivatives based on 3,5-dinitrobenzohydrazide (I) was synthesized for the first time and characterized by spectrometric methods (FT-IR, 1H NMR and 13C NMR) and elemental analysis. In vitro anticholinesterase activities of novel hydrazone derivatives were evaluated against acetyl- and butyrylcholinesterase (AChE and BChE) at 200 µM concentration. Moreover, the antioxidant potentials of the same molecules were determined by 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and cupric ion reducing antioxidant capacity (CUPRAC) assays. Results: The obtained results displayed that some of the tested hydrazone compounds had varying enzyme inhibition and antioxidant activities. Discussion: In enzyme inhibition studies, N′-[2-{[4-fluorobenzensulfonyl]oxy}benzylidene]-3,5-dinitrobenzohydrazide (IIIb) with inhibition value 77.13 ± 0.14% showed the closest activity to the standard compound galanthamine with inhibition value 78.14 ± 0.65%. Compared to DPPH and ABTS assays, all of the molecules tested in CUPRAC assay showed antioxidant activities. The molecules tested in CUPRAC assay did not show as much activity as standard molecules (BHA, BHT and α-TOC). Conclusions: Compounds N′-[4-{[4-fluorobenzensulfonyl]oxy}benzylidene]-3,5-dinitrobenzohydrazide (IIIf) and N′-[4-{[4-methoxybenzensulfonyl]oxy}benzylidene]-3,5dinitrobenzohydrazide (IIIh) in this assay were determined to be the most active molecules.
  • Küçük Resim
    Öğe
    Synthesis, characterization and biological evaluation of esterderivatives of 4-(diethylamino) salicylaldehyde cholinesterase and tyrosinase inhibitors
    (INESEG Yayıncılık, 2021) Çakmak, Reşit; Çınar, Ercan; Başaran, Eyüp; Boğa, Mehmet
    Alzheimer's disease, one of the diseases that still has no a specific therapy, has become amajor public health issue owing to the increasing population of the elderly, particularly in richcountries. Inhibitory of cholinesterase enzymes (acetylcholinesterase (AChE) and butyrylcholinesterase(BChE), which hydrolyze acetylcholine (ACh) and butyrylcholine (BCh) neurotransmitters, haverecently become a choice for the therapy of this disease. Therefore, there is currently a great demandfor novel enzyme inhibitors with desirable properties for applying in the treatment of AD. In this study,a series of ester derivatives of 4-(diethylamino)salicylaldehyde (1-5) were successfully prepared andstructurally illuminated with FT-IR, 1H- and 13C NMR spectroscopy. The inhibitory properties of thesynthesized molecules on AChE, BChE, and tyrosinase enzymes were investigated, respectively.Compound 1 indicated potent inhibitory activity against BChE with 87.28±0.87% inhibition better thangalanthamine (73.83±0.25 %inhibition) employed as standard. Compound 3 showed significantinhibitory effect against tyrosinase with 87.73±0.22 % inhibition, which is better than kojic acid utilizedas standard. The obtained results clearly revealed that some of these molecules have the potential to be used as potent enzyme inhibitor candidates in the future studies.
  • Küçük Resim
    Öğe
    Synthesis, spectroscopic, thermal analysis and in vitro cytotoxicity, anticholinesterase and antioxidant activities of new Co(II), Ni(II), Cu(II), Zn(II), and Ru(III) complexes of pyrazolone-based Schiff base ligand
    (Elsevier B.V., 2023) Çakmak, Reşit; Ay, Burak; Çınar, Ercan; Başaran, Eyüp; Akkoç, Senem; Boğa, Mehmet; Taş, Eşref
    Metal-based drugs have gained significant importance in medicine in recent years. In this research, a series of new Co(II), Ni (II), Cu (II), Zn(II), and Ru(III) complexes of a Schiff base ligand, (1,5-dimethyl-4-((1-(3-nitrophenyl)ethylidene) amino)-2-phenyl-1,2-dihydro-3H-pyrazol-3-one), were prepared for the first time in excellent yields, and characterized by elemental analysis, FT-IR, 1 H NMR, 13C NMR, ICP-OES, and thermal analysis. The in vitro antiproliferative, anticholinesterase, and antioxidant properties of complexes 1–5 were evaluated. The cytotoxic effects of complexes 1–5 on the viability of colon cancer (DLD-1), breast cancer (MDA-MB-231), and healthy lung (Wl-38) cell lines were investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method in vitro. The anticancer activities of the ligand and its metal complexes were lower than those of the reference drug, cisplatin. In anticholinesterase activity studies, complex 4 (88.46±0.45% inhibition) in butyrylcholinesterase (BChE) assay showed a higher inhibitory effect than the standard compound galanthamine with 78.14±0.55% inhibition. In antioxidant assays, some complexes showed higher antioxidant activities than standard antioxidant butylated hydroxytoluene (BHT). Among the prepared complexes, complex (4) (IC50=5.91±0.17 µM) in ABTS assay showed the highest antioxidant activity compared to BHT (IC50=16.19 ±0.17 µM). Also, this complex (IC50=10.17±0.36 µM) showed the best antioxidant activity in CUPRAC assay compared to BHT (IC50=39.37±0.12 µM).
  • [ X ]
    Öğe
    THE PREPARATION OF A NEW PROTEIN BASED HPLC COLUMN PACKING MATERIAL AND ENANTIOMERIC RESOLUTION OF SOME PHARMACEUTICAL RELATED COMPOUNDS VIA THIS COLUMN
    (Bilal GÜMÜŞ, 2016) Erdoğan, Ömer; Topal, Giray; Çakmak, Reşit; Sünkür, Murat; Canpolat, Mutlu
    In this study, BSA was bounded to 3-chloropropyl functionalized silica gel via ethylenediamine and glutaric dialdehyde. The prepared CSP was packed into 150X4.6mm HPLC column according to slurry method. The enantiomeric resolution of some pharmaceutical related compounds such as rac-mandelic acid, rac-methyl mandelate, rac-epinephrine, rac-propranolol, rac-?-phenylethylamine and rac-3-hydroxybutyric acid was employed in 1mL/rpm, 1,5mL/rpm, 2mL/rpm, 2,5mL/rpm, 3mL/rpm flow rate in various pHs such pH=6, pH=7, pH=8 0,1M phosphate buffer. Chromatographic parameters such as Rs and ? were calculated for each resoluted compounds.