Atay, İrem | Kırmızıbekmez, Hasan | Yeşilada, Erdem | Gören, Ahmet Ceyhan

Other | 2015 | Turkish Journal of Chemistry39 ( 1 ) , pp.34 - 41

Abstract: A new nonglycosidic iridoid, sambulin B (1), was isolated from the methanol extract of Sambucus ebulus L. leaves along with a recently reported new nonglycosidic iridoid, 10-O-acetylpatrinoside aglycone (sambulin A) (2); 2 flavonoids, isorhamnetin-3-O-eta-D-glucopyranoside (3) and isorhamnetin-3-O-rutinoside (4); and a mixture of 2 flavonoids (5), quercetin-3-O-eta-D-glucopyranoside and quercetin-3-O-eta-D-galactopyranoside. Their structures were elucidated by 1-D and 2-D nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) experiments.

Acar, Ebru Türköz | Onar, Atiye Nur

Article | 2016 | Turkish Journal of Chemistry40 ( 1 ) , pp.106 - 116

The electrochemical behavior of valproic acid (VAL) was investigated using square wave voltammetry, cyclicvoltammetry, and sampled direct current polarography and a new square wave voltammetric method was developed fordetermination of VAL in pharmaceutical preparations. VAL showed two reduction peaks at about {0.2 V and {0.8 V vs.Ag/AgCl 3 M KCl with a hanging mercury drop electrode in 0.05 M pH 3.3 Britton{Robinson (BR) buffer. These peakswere named peak I and peak II, respectively. The types of limiting current of both peaks were determined as diffusioncontrolled based on cyclic voltammetry studies. A linear calibration graph was . . .obtained in the range 1.46104{1.0103M. The limit of detection (LOD) and limit of quanti cation (LOQ) were 1.09104M (21.05g/mL) and1.10104M (144.20g/mL), respectively. Recovery studies for the accuracy of the method were performed byadding known amounts of VAL and it was found to be 109.674.85%. The proposed method was successfully appliedto pharmaceutical products on the market Daha fazlası Daha az

Demirci, A. | Karayel, K.G. | Tatar, E. | Okullu, S.Ö. | Unübol, N. | Taşli, P.N. | Küçükgüzel, I.

Article | 2018 | Turkish Journal of Chemistry42 ( 3 ) , pp.839 - 858

A series of 5-substituted-1,3,4-thiadiazole-based fluoroquinolone derivatives were designed as potential antibacterial and anticancer agents using a molecular hybridization approach. The target compounds 16–25 were synthesized by reacting the corresponding N-(5-substituted-1,3,4-thiadiazol-2-yl)-2-chloroacetamides with ciprofloxacin or norfloxacin. The purity and identity of the synthesized compounds were determined by the use of chromatographic and spectral techniques (NMR, IR, MS, etc.) besides elemental analysis. Antibacterial, antituberculosis, and anticancer activity of the target compounds were evaluated against selected strai . . .ns and cancer cell lines. Compound 20 was appreciated as the most active agent representing antibacterial activity against Escherichia coli and Staphylococcus aureus with MIC values of 4 µg/mL and 2 µg/mL, respectively. Amongst the synthesized fluoroquinolone derivatives, compounds 19 and 20 were found to have modest antitubercular activity with 8 µg/mL MIC values for each. Most potent derivative, compound 20 was docked against Staphylococcus aureus and Mycobacterium tuberculosis DNA gyrase enzymes to visualize the possible conformation of the compound. Additionally, anticancer activities of target compounds were evaluated on seven different cancer cell lines. © TÜBITA Daha fazlası Daha az

Berk, Barkın | Us, Demet | Öktem, Sinem | Kocagöz, Z. Tanıl | Çağlayan, Berrak | Kurnaz, Işıl Aksan | Erol, Dilek Demir

Article | 2011 | Turkish Journal of Chemistry35 ( 2 ) , pp.317 - 330

The World Health Organization lists tuberculosis among the top 3 leading causes of death from a single infectious agent, and reported cases of multidrug-resistant tuberculosis (MDR-TB) are on the rise. In an attempt to improve MDR-TB drug-directed therapy, we synthesized 11 4-substituted piperazine derivatives of 3-hydroxy-6-methyl-4H -pyran-4-one pharmacophore by reacting 5-hydroxy-2-methyl- 4H-pyran-4-one with suitable piperazine derivatives under Mannich reaction conditions. Inhibitory effects of the 11 compounds on Escherichia coli DNA gyrase were evaluated via DNA gyrase supercoiling assay. The minimum inhibitory concentrations . . . (MIC) of the 11 compounds and 41 compounds from our previous studies against Mycobacterium tuberculosis H37RV were assessed, in vitro, by a broth dilution method. To determine the interaction pattern between active site amino acids and all 52 compounds, homology modeling for the construction of M. tuberculosis DNA gyrase B subunit was performed, followed by a docking study. The data presented here could prove useful in future studies on interaction field analysis and high throughput virtual screening of the derivatives of the 3-hydroxy-6-methyl-4H -pyran-4-one pharmacophore toward the development of more clinically applicable compounds Daha fazlası Daha az

Us, Demet | Berk, Barkın | Gürdal, Ece | Aytekın, Nihan | Kocagöz, Tanıl | Layan, Berrak Çağ | Erol, Dilek Demir

Article | 2010 | Turkish Journal of Chemistry34 ( 3 ) , pp.447 - 456

A series of 3-hydroxy-6-methyl-2-[(substitutedpiperidine-1-yl)methyl]-4H -pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H -pyran-4-one with suitable piperidine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli ATCC 25922, S. paratyphi ATCC BAA-1250, S. flexneri ATCC 12022, E. gergoviae ATCC 33426, and M. smegmatis ATCC 14468 were assessed in vitro by the broth dilution method for determination of minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay . . .. All the synthesized compounds showed a MIC value of either 8 or 16 μg/mL for M. smegmatis, whereas minimum to moderate activity was achieved for the others. Those tested in the supercoiling assay had at best a very mild inhibition of the enzyme. This series deserves further attention for testing over Mycobacterium species and topoisomerase II inhibition to develop new lead drugs to treat non-tuberculous mycobacterial infections Daha fazlası Daha az

Us, Demet | Gürdal, Ece | Berk, Barkın | Öktem, Sinem | Kocagöz, Tanıl | Çağlayan, Berrak | Erol, Dilek Demir

Article | 2009 | Turkish Journal of Chemistry33 ( 6 ) , pp.803 - 812

A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1-yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 &am . . .p;#956;g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling assay had at best a very mild inhibition of the enzyme. This series deserves further attention for testing over Mycobacterium species and topoisomerase II inhibition to develop new lead drugs Daha fazlası Daha az

İnce, Ahmet T. | Snook, Richard D. | Dawson, John B.

Other | 2000 | Turkish Journal of Chemistry24 ( 1 ) , pp.43 - 58

A study of inherent noise sources present in a purpose built flame atomic magneto-optic rotation (AMOR) spectrometer system was carried out with a view to identifying their sources. Two different optical configurations were employed, a crossed polariser and a 45° offset polariser configuration. The offset polariser configuration was operated in both an AMOR and atomic absorption (AA) mode for the noise measurements. Two main interference frequencies were found to occur in all the optical measurement modes. An interference flame feature frequency (15.5 Hz -39.0 Hz) which arose from an "organ-pipe" effect in the gas flow . . . through the flame cooling sheets. The second interference frequency (at 100 Hz) was thought, to arise due to modulation of the analytes magneto-optic properties due to ripple on the electromagnet d.c. power supply. Photon noise and fluctuation noise were found to be present as background noise. The fluctuation noise was dominant at. higher analyte concentrations. The characteristics and origins of fluctuation noise are discussed and investigated for each measurement mode. The noise spectra of the conventional AA measurements were compared with those of the contemporary AMOR measurements, to ascertain any differences in noise power spectra which may affect, the signal-to-noise ratio Daha fazlası Daha az

Gökhan, Nesrin | Köksal, Meriç | Küpeli, Esra | Yeşilada, Erdem | Erdoğan, Hakkı

Article | 2005 | Turkish Journal of Chemistry29 ( 4 ) , pp.445 - 454

The synthesis of a novel series of Mannich bases of 5-methyl-3-substituted piperazinomethyl-2-benzoxazolinones is described. The structures attributed to compounds 3c, 3d and 3f-3n were elucidated using IR and 1H NMR spectroscopic techniques as well as elemental analysis. The compounds were examined for their in vivo anti-inflammatory and analgesic activities in 2 different bioassays, namely, carrageenan-induced hind paw edema and p-benzoquinone-induced abdominal constriction tests in mice, respectively. In addition, the ulcerogenic effects of the compounds were determined. Among the derivatives tested the most promising results wer . . .e obtained for the compounds bearing electron-withdrawing substituents (F, Cl, COCH_3) in the para position of the phenyl nucleus on the piperazine ring at the 3 position of benzoxazolinone moiety (3a, 3c, 3i). The analgesic activities of all compounds are higher than their anti-inflammatory activities and therefore these high analgesic activities indicated that the compounds could a show central effect Daha fazlası Daha az

Kalay, Saban | Blanchet, Clement | Culha, Mustafa

Article | 2014 | Turkish Journal of Chemistry38 ( 5 ) , pp.686 - 700

The charge and size of molecules chemically attached to nanoparticles (NPs) play an important role in their interaction behavior in suspensions. Gold nanoparticles (AuNPs) were modified systematically with peptides and the modification was verified with surface-enhanced Raman scattering (SERS). The behavior of the modified AuNPs in suspension and at the liquidsolid interface was monitored using small angle X-ray scattering (SAXS), UV/Vis spectroscopy and dynamic light scattering (DLS) in suspension, and atomic force microscopy (AFM) at the solid liquid interface. It was found that while negatively charged peptide modified AuNPs beha . . .ve very similar to citrate reduced AuNPs due to their negatively charged surface, positively charged peptide modified AuNPs showed significantly different assembly/aggregation properties in suspension. The formation of linear assemblies of positively charged peptide (CKRHSKRHRSKRHSKRHSKRHSKR) modified AuNPs was clearly observed from the AFM analysis of the droplet areas of its colloidal suspension. The combined analyses of data obtained from the employed techniques suggest that the positively charged large peptide modified AuNPs can form linear and 3D-like networks in the suspension. This study reveals important information regarding the surface property dependent behavior of NPs that may help in efforts to build higher structures using NPs as building blocks Daha fazlası Daha az

Akgün, Hülya | Berk, Barkın | Erol, Demir Dilek | Mercanoğlu, Güldem | Bayrak, Faruk Ömer | Çağlayan, Berrak | Kurnaz, Aksan Işıl

Article | 2009 | Turkish Journal of Chemistry33 ( 1 ) , pp.107 - 121

New series of [(2-chloroethyl)ureido] benzoic acids (compounds 3-8) and nitric oxide releasing derivatives of [(2-chloroethyl)ureido] benzoic acid esters (compounds 9-14) were synthesized as potential anti-cancer agents. These compounds were screened for their anti-proliferative activities on A549 (human lung carcinoma) cells and for their cytotoxic effects on L929 (mouse fibroblast) cells. The compounds 3-8 exhibited mild cytotoxic effects on L929 cells (cell viability from 100% to 85% – 90% only) whereas they had very little antiproliferative activities towards A549 lung carcinoma cells. On the other hand, compounds 10, . . .11, and 13 had some growth inhibition activity in A549 (human lung carcinoma) cells. Among them, compounds 11 and 13 exhibited better anti-proliferative activities towards A549 cells, but also appeared to be cytotoxic towards L929 cells. In this group, the compound 10 with (1-(2-nitrooxyethyl)-3-[(2-chloroethyl)ureido]benzoate) structure appeared to have very weak anti-neoplastic activity towards A549 cells, with very little cytotoxic activity towards fibroblasts at physiological concentrations. Therefore, this compound is a better candidate for a potential anti-cancer therapy for non-small cell lung carcinomas. However, further studies are required in order to show applicability and effectiveness in animal models for this type of cancer Daha fazlası Daha az

İnce, T Ahmet

Other | 2001 | Turkish Journal of Chemistry25 ( 2 ) , pp.135 - 143

Analytical signals in an Atomic Magneto-Optic Rotation spectrometer are buried in noise at the limit of detection. The noisy analytical signals were analysed by carrying out mathematical correlation of their time domain waveforms. The noise components of signals were removed by auto-correlation to simplify the study. If noise interferes in analytical signals whose source is unclear, a cross-correlation of the output waveform with noise source may identify the source, e.g., mains frequencies and background radio signals. A cross-correlation will reveal whether the two signals are derived from the same source. This can also lead to an . . . improvement in the signal detection limit. Either of the two above situations can occur in studying analytical signals. In this study, both auto-and cross-correlation studies were carried out on analytical signals which had discrete noise sources present in their waveforms Daha fazlası Daha az

Akgün, H. | Berk, B. | Demir Erol, D. | Mercanoglu, G. | Bayrak, Ö.F. | Çag Layan, B. | Aksan Kurnaz, I.

Article | 2009 | Turkish Journal of Chemistry33 ( 1 ) , pp.107 - 121

New series of [(2-chloroethyl)ureido] benzoic acids (compounds 3-8) and nitric oxide releasing derivatives of [(2-chloroethyl)ureido] benzoic acid esters (compounds 9-14) were synthesized as potential anti-cancer agents. These compounds were screened for their anti-proliferative activities on A549 (human lung carcinoma) cells and for their cytotoxic effects on L929 (mouse fibroblast) cells. The compounds 3-8 exhibited mild cytotoxic effects on L929 cells (cell viability from 100% to 85% - 90% only) whereas they had very little antiproliferative activities towards A549 lung carcinoma cells. On the other hand, compounds 10, 11, and 13 . . . had some growth inhibition activity in A549 (human lung carcinoma) cells. Among them, compounds 11 and 13 exhibited better anti-proliferative activities towards A549 cells, but also appeared to be cytotoxic towards L929 cells. In this group, the compound 10 with (1-(2-nitrooxyethyl)-3-[(2-chloroethyl)ureido]benzoate) structure appeared to have very weak anti-neoplastic activity towards A549 cells, with very little cytotoxic activity towards fibroblasts at physiological concentrations. Therefore, this compound is a better candidate for a potential anti-cancer therapy for non-small cell lung carcinomas. However, further studies are required in order to show applicability and effectiveness in animal models for this type of cancer. © TÜBİTAK Daha fazlası Daha az