Browsing by Author "Levent, Abdulkadir"

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Colorimetric and Atomic Absorption Spectometric Determination of Mucolytic Drug Ambroxol Through Ion-Pair Formation With Iron(iii) and Thiocyanate
(2007) Levent, Abdulkadir; Şentürk, Zühre
Colorimetric and Atomic Absorption Spectrometric Determination of Mucolytic Drug Ambroxol Through Ion-Pair Formation With Iron and Thiocyanate
(Bentham Science Publ Ltd, 2010) Levent, Abdulkadir; Senturk, Zuhre
Colorimetric and atomic absorption spectrometric methods have been developed for the determination of mucolytic drug Ambroxol. These procedures depend upon the reaction of iron(III) metal ion with the drug in the presence of thiocyanate ion to form stable ion-pair complex which is extractable in chloroform. The red-colored complex was determined either colorimetrically at 510 nm or by indirect atomic absorption spectrometry (AAS) via the determination of the iron content in the formed complex. The optimum experimental conditions for pH, concentrations of Fe3+ and SCN, shaking time, phase ratio, and the number of extractions were determined. Under the proposed conditions, linearity was obeyed in the concentration ranges 4.1x10(-6) -5.7x10(-5) M (1.7-23.6 mu g mL(-1)) using both methods, with detection limits of 4.6x10(-7) M (0.19 mu g mL(-1)) for colorimetry and 1.1x10(-6) M (0.46 mu g mL(-1)) for AAS. The proposed methods were applied for the determination of Ambroxol in tablet dosage forms. The results obtained were statistically analyzed and compared with those obtained by applying the high-performance liquid chromatographic method with diode-array detection.
Determination of 7,12-Dimethylbenz[a]anthracene in Orally Treated Rats by High-Performance Liquid Chromatography and Transfer Stripping Voltammetry
(Bentham Science Publ Ltd, 2012) Yardim, Yavuz; Levent, Abdulkadir; Ekin, Suat; Keskin, Ertugrul; Oto, Gokhan; Senturk, Zuhre
A number of polycyclic aromatic hydrocarbons (PAHs) have been shown to be toxicants, and induce carcinogenic and immunotoxic effects. As a model PAH agent, 7,12-dimethylbenz[a]anthracene (DMBA) was the strongest one tested in terms of its biological activities and biotransformation. A new and simple high-performance liquid chromatographic (HPLC) method with diode-array detection at 290 nm was developed and validated for monitoring of DMBA in different matrices (serum, liver and kidney) of rats orally treated with DMBA. Furthermore, the applicability of adsorptive transfer stripping voltammetry (AdTSV) on the pencil-lead graphite electrode to these samples was illustrated using our previously reported data for bulk aqueous solutions of DMBA. HPLC and AdTSV methods, which were compatible with each other, allowed DMBA to be detected down to the levels of 3.82x10(-9) M (0.98 ppb) and 6.73x10(-9) M (1.73 ppb), respectively. Olive oil solutions of DMBA in dose 50 mg/kg were orally administered. 60 days after a single dose of DMBA, its concentrations in these biological samples from rats were measured by means of both methods. Because of rapid biotransformation, DMBA could not be detected in serum. Only low levels of the compounds were deposited unchanged in kidney whereas its levels were considerably higher in liver. These methods were also applied to the assay whether there is an influence of the intake of aqueous extracts of Hypericum Perforatum L. plant on the parent DMBA levels accumulated in rat tissues.
Determination of Trace Metal and Mineral Levels in the Tobacco and Cigarette Samples Using by Fass
(Chem Soc Pakistan, 2013) Levent, Abdulkadir; Yardim, Yavuz; Demir, Cengiz
Cigarettes and tobacco products are consumed in large amounts by human beings in the world. Also, tobacco is one of the most important agricultural products in Turkey. The accumulation of heavy metals in tobacco leaves in accordance with a possible risk of transferring them to people by smoke is well known. This study was carried out to estimate trace metal and mineral levels in tobacco and cigarettes from Eastern and South-eastern Anatolia, Turkey. The analysis was done by flame atomic absorption spectrometry using dry ashing or wet digestion. Results obtained are in agreement with data reported in the literature.
Development of an Ion-Pair Hplc Method for Determination of Acebutolol in Pharmaceuticals
(Taylor & Francis inc, 2010) Levent, Abdulkadir; Senturk, Zuehre
A simple and accurate ion-pair reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for determination of acebutolol (ACE) in tablet dosage forms. Both ACE and ambroxol (internal standard) were well separated using a reversed phase column and a mobile phase consisting of a mixture of methanol-0.05 M acetic acid (containing 8 mM sodium 1-heptanesulfanate) (65:35 v/v) with pH adjusted to 3.2 with triethylamine. The mobile phase was pumped at 0.80 mLmin(-1) flow rate and ACE was detected by diode-array detection at 240 nm. The retention times for ACE and internal standard (IS) were 4.574 and 8.236 min, respectively. A linear response (r = 0.9998) was observed in the range of 0.27-2.93 mu g mL(-1) in mobile phase. The limit of detection and limit of quantification were found as 0.07 and 0.23 mu g mL(-1) in the mobile phase. Validation parameters such as precision, accuracy, selectivity, reproducibility, and system suitability tests were also determined. The excipients did not interfere with the assay of ACE in tablet dosage forms. It is suggested that the proposed method can be used for routine quality control and dosage-form assay of ACE.
The Effect of Plantago Major Linnaeus on Serum Total Sialic Acid, Lipid-Bound Sialic Acid, Some Trace Elements and Minerals After Administration of 7,12-Dimethylbenz(a)anthracene in Rats
(Sage Publications inc, 2012) Oto, Gokhan; Ekin, Suat; Ozdemir, Hulya; Levent, Abdulkadir; Berber, Ismet
The present study was designed to evaluate the effect of Plantago major Linnaeus (PM) extract on serum total sialic acid (TSA), lipid-bound sialic acid (LSA), some trace elements (copper (Cu), zinc (Zn) and iron) and mineral levels (magnesium, calcium and sodium) in Wistar albino rat administrated 7,12-dimethylbenz(a)anthracene (DMBA). Rats were divided into three equal groups (n = 6). Group I comprised the control group, group II was treated with DMBA (100 mg/kg, single dose) and group III was treated with DMBA (100 mg/kg single dose) and aqueous extract of PM 100 mg/kg/day for 60 days. After 60 days, statistical analyses showed that TSA and LSA levels in DMBA and DMBA + PM groups were significantly higher compared to the control group (TSA: p < 0.01, p < 0.05; LSA: p < 0.05, p < 0.05, respectively). Serum Zn levels were decreased in subjects treated with DMBA (p < 0.01) and DMBA + PM (p < 0.05) compared to the control group values. Serum Cu levels were increased in DMBA group and PM-treated group compared to the control group values. The results of this investigation showed that the levels of TSA and LSA changed significantly, which are sensitive markers for detecting the toxic effects of DMBA. On the other hand, observed decline in Zn levels in rats from DMBA + PM group might be due to decreased generation of free radicals and oxidative stress. Results from this study suggest that PM may be partially effective in preventing carcinogenesis initiated by environmental carcinogen DMBA.
Electrochemical Determination of Norepinephrine by Adsorptive Stripping Voltammetry Using a Bare Boron-Doped Diamond Electrode
(Editura Acad Romane, 2019) Keskin, Ertugrul; Yardim, Yavuz; Levent, Abdulkadir; Senturk, Zuhre
A boron-doped diamond electrode was used for the first time for sensitive and selective analysis of norepinephrine (NE) using square wave voltammetry (SWV) technique. NE displayed one welldefined, irreversible and adsorption-controlled oxidation peak at about +0.85 V (vs. Ag/AgCl) in Britton-Robinson buffer (BR, 0.1 M, pH 2.0) using cyclic voltammetry (CV) technique. The effect of supporting electrolyte, solution pH and instrumental variables on oxidation peak current were optimized. In optimal experiment conditions, it was found that there was an excellent correlation between oxidation peak current and NE concentration in the range of 1 to 100 mu g mL(-1) (4.9X10(-6) M-4.9 x10(-4) M) with a detection limit of 0.254 mu g mL(-1) (1.2X10(-6) M) in 0.1 M BR buffer (pH 2.0) solution employing square-wave stripping mode. The developed technique can be used for the quantification of NE in the pharmaceutical formulation with acceptable recoveries.
Electrochemical Performance of Boron-Doped Diamond Electrode in Surfactant-Containing Media for Ambroxol Determination
(Elsevier Science Sa, 2014) Levent, Abdulkadir; Yardim, Yavuz; Senturk, Zuhre
A novel application of boron-doped diamond electrode is introduced for the determination of ambroxol, a potential antioxidant drug belonging to the expectorant class. The electrochemical oxidation of ambroxol was first investigated by cyclic voltammetry using boron-doped diamond and glassy carbon electrodes in aqueous solutions both with and without the addition of surfactant. The compound was irreversibly oxidized in one/two steps at high positive potentials, resulting in the formation of a couple with a reduction and re-oxidation wave at less positive potentials. Special attention was given to the use of adsorptive stripping voltammetry at a surface of mildly oxidized boron-doped diamond electrode in aqueous solutions over the pH range of 1.0-10.0. Addition of anionic surfactant (sodium dodecylsulfate) to ambroxol-containing electrolyte enhanced the stripping current signal. Using square-wave stripping mode, the drug yielded a well-defined voltammetric response in phosphate buffer pH 2.5 containing 4 x 10(-4) M sodium dodecylsulfate at +1.02V (versus Ag/AgCl) (after 30s accumulation at +0.50V). The process could be used to determine ambroxol in the concentration range of 0.05-0.7 mu M, with a detection limit of 0.010 mu M (4.2 ng mL(-1)). The suggested method was successfully applied to pharmaceuticals and spiked human urine samples. (C) 2014 Elsevier B.V. All rights reserved.
Electrooxidation of Thiourea and Its Square-Wave Voltammetric Determination Using Pencil Graphite Electrode
(Walter de Gruyter Gmbh, 2011) Levent, Abdulkadir; Keskin, Ertugrul; Yardim, Yavuz; Senturk, Zuhre
The electrochemical properties of thiourea (TU) were investigated in pH range 2.0-12.0 by cyclic and square-wave voltammetry. The compound was irreversibly oxidized at a pencil graphite electrode in one or two oxidation steps which are pH-dependent. Based on the voltammetric peak for the second oxidation process of TU in phosphate buffer at pH 12.0, a square-wave voltammetric method was proposed for the determination of the compound in the range 6.3-30 mu m, with a detection limit of 1.29 mu m. The applicability to direct assays of wastewaters was also tested.
Fluorescence Properties and Electrochemical Behavior of Some Schiff Bases Derived From N-Aminopyrimidine
(Springer/plenum Publishers, 2014) Gulcan, Mehmet; Dogru, Umit; Ozturk, Gulsiye; Levent, Abdulkadir; Akbas, Esvet
A series of Schiff bases (L (1) , L (2) and L (3) ) were prepared by refluxing aromatic aldehydes with N-Aminopyrimidine derivatives in methanol and ethanol. The structures of synthesized compounds were characterized by FTIR, H-1 NMR, C-13 NMR and microanalysis. The electrochemical behaviors of the Schiff base ligands were also discussed. Moreover, the evaluation of absorption and emission properties of the structures were carried out in five different solvents. The products show visible absorption maxima in the range of 304-576 nm, and emission maxima from 636 to 736 nm in all solvents tested.
Grafen-modifiye Elektrotların İlaçlarda ve Gıda Örneklerinde İki Yeni Uygulaması. Bor-katkılı Elmas Elektrotla Kıyası
(2016) Levent, Abdulkadir; Çelebi, Metin; Yiğit, Aydın; Şentürk, Zühre; Yardım, Yavuz; Alpar, Nurcan
Graphene/Nafion Composite Film Modified Glassy Carbon Electrode for Simultaneous Determination of Paracetamol, Aspirin and Caffeine in Pharmaceutical Formulations
(Elsevier Science Bv, 2016) Yigit, Aydin; Yardim, Yavuz; Celebi, Metin; Levent, Abdulkadir; Senturk, Zuhre
A graphene-Nafion composite film was fabricated on the glassy carbon electrode (GR-NF/GCE), and used for simultaneous determination of paracetamol (PAR), aspirin (ASA) and caffeine (CAF). The electrochemical behaviors of PAR, ASA and CAF were investigated by cyclic voltammetry and square-wave adsorptive anodic stripping voltammetry. By using stripping one for simultaneous determination of PAR, ASA and CAF, their electrochemical oxidation peaks appeared at +0.64,1.04 and 1.44 V, and good linear current responses were obtained with the detection limits of 18 ng mL(-1) (1.2 x 10(-9) M), 11.7 ng mL(-1) (6.5 x 10(-8) M) and 7.3 ng mL(-1) (3.8 x 10(-8) M), respectively. Finally, the proposed electrochemical sensor was successfully applied for quantifying PAR, ASA and CAF in commercial tablet formulations. (C) 2016 Elsevier B.V. All rights reserved.
Investigation of the Electrochemical Properties of Benzo[K]fluorenthene Using a Glassy Carbon Electrode and Development of a Square-Wave Voltammetric Method for Its Quantification
(indian Acad Sciences, 2023) Altun, Ahmet; Yardim, Yavuz; Levent, Abdulkadir
The electrochemical behaviour of benzo[k]fluorenthene was studied using a bare glassy carbon electrode, cyclic voltammetry, and square wave voltammetry with a wide range of supporting electrolytes and a variety of pH values. An irreversible wave was generated due to adsorption-controlled diffusion at a potential of about +0.80 V at the glassy carbon electrode in benzo[k]fluoranthene BR medium with a pH of 3.0. Using the square-wave adsorptive voltammetry tecnhique, an extremely linear correlation was established between the anodic peak current and the concentration measured at the glassy carbon electrode in the BR medium with a pH value of 3.0. Using a glassy carbon electrode containing 80 mu M benzo[k]fluoranthene, the newly developed voltammetric technique was found to have a repeatability of 1.97% relative standard deviation. The voltammetric technique was applied to tap water samples without prior purification or separation steps. In this study, the results of the newly created voltammetric technique were evaluated together with those of chromatographic and spectroscopic analyses, which were found to be consistent with each other.
Metal-Organic Framework Mil-101 as an Efficient Heterogeneous Catalyst for Clean Synthesis of Benzothiazoles and Single Crystal X-Ray Diffraction, Quantum Chemical Studies, Electrochemical Performance, Molecular Docking and Dna Interactions
(Wiley-V C H Verlag Gmbh, 2025) Akbas, Esvet; Ruzgar, Adem; Sahin, Ertan; Levent, Abdulkadir
Benzothiazoles have emerged as a prominent area of research in recent years due to their broad spectrum of biological activities. These heterocyclic compounds, which contain thiazole and benzene rings in their molecular structure, exhibit a wide range of pharmacological effects, including anticancer, antimicrobial, antifungal, antiparasitic, anti-inflammatory, and antitubercular activities. In this study, benzo[d]thiazole derivatives 1 and 2 were synthesized in good yield using catalyst MIL101. The structures of these compounds were analyzed using elemental analysis, IR, 1H, 13C NMR and single crystal X-ray diffraction. The quantum chemical calculations of these compounds were performed density functional theory method, DGDZVP base set and B3LYP functions with Gaussian09W software package. The electrochemical properties of these compounds were investigated by cyclic voltammetry technique on a glassy carbon electrode. In addition, the interactions of the compounds with DNA were investigated by electrochemical, spectrophotometric and molecular docking techniques. It was observed that the chemical calculations and molecular docking results were compatible with each other.
A New Pyrimidine-Derived Ligand, N-Pyrimidine Oxalamic Acid, and Its Cu(Ii), Co(Ii), Mn(Ii), Ni(Ii), Zn(Ii), Cd(Ii), and Pd(Ii) Complexes: Synthesis, Characterization, Electrochemical Properties, and Biological Activity
(Taylor & Francis Ltd, 2010) Sonmez, Mehmet; Celebi, Metin; Levent, Abdulkadir; Berber, Ismet; Senturk, Zuehre
A new heterocyclic compound N-(5-benzoyl-2-oxo-4-phenyl-2H-pyrimidin-1-yl)-oxalamic acid has been synthesized from N-amino pyrimidine-2-one and oxalylchloride. Bis-chelate complexes of the ligand were prepared from acetate/chloride salts of Cu(II), Co(II), Mn(II), Ni(II), Zn(II), Cd(II), and Pd(II) in methanol. The structures of the ligand and its metal complexes were characterized by microanalyses, IR, AAS, NMR, API-ES, UV-Vis spectroscopy, magnetic susceptibility, and thermogravimetric analyses. An octahedral geometry has been suggested for all the complexes, except for Pd(II) complex, in which the metal center is square planar. Each ligand binds using C(2)=O, HN, and carboxylate. The cyclic voltammograms of the ligand and the complexes are also discussed. The new synthesized compounds were evaluated for antimicrobial activities against Gram-positive, Gram-negative bacteria and fungi using the microdilution procedure. The Cu(II) complex displayed selective and effective antibacterial activity against one Gram-positive spore-forming bacterium (Bacillus cereus ATCC 7064), two Gram-positive bacteria (Staphylococcus aureus ATCC 6538 and S. aureus ATCC 25923) at 40-80 mu g mL-1, but poor activity against Candida species. The Cu(II) complex might be a new antibacterial agent against Gram-positive bacteria.
Pirimidinamino Asit Yapılı Yeni Ligand ve Bazı Metal Komplekslerinin Sentezi, Elektrokimyasal ve Biyolojik Özelliklerinin İncelenmesi
(2008) Sönmez, Mehmet Emin; Berber, İsmet; Şentürk, Zühre; Çelebi, Metin; Levent, Abdulkadir
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Plantago Major Protective Effects on Antioxidant Status After Administration of 7,12-Dimethylbenz(a)anthracene in Rats
(Asian Pacific Organization Cancer Prevention, 2011) Oto, Gokhan; Ekin, Suat; Ozdemir, Hulya; Demir, Halit; Yasar, Semih; Levent, Abdulkadir; Kaki, Baris
Aim: The present study was designed to evaluate effects of Plantago major extract on oxidative status in Wistar albino rats administrated 7,12-dimethylbenz(a)anthracene (DMBA). Methods: Rats were divided into three equal groups of 6 animals each: Group 1 controls, group 2 treated with DMBA (100 mg/kg, single dose) and group 3 receiving the DMBA and the aqueous extract at 100 mg/kg/d for 60 days. Results: Significant decrease in catalase (P<0.05), carbonic anhydrase (p <= 0.01), reduced glutathione (GSH) (P<0.01) and total protein (P<0.01) values was observed in the DMBA group compared with the healthy controls and DMBA + Plantago major groups. Conclusion: The results suggest preventive effects of Plantago major on DMBA induced oxidative damage in Wistar albino rats that might be due to decreased free radical generation.
Sensitive Voltammetric Determination of Testosterone in Pharmaceuticals and Human Urine Using a Glassy Carbon Electrode in the Presence of Cationic Surfactant
(Pergamon-elsevier Science Ltd, 2014) Levent, Abdulkadir; Altun, Ahmet; Yardim, Yavuz; Senturk, Zuhre
In this work, the electrochemical investigation of testosterone, a steroid hormone from the androgen group, was carried out in aqueous and aqueous/surfactant solutions using a glassy carbon (GC) electrode. In cyclic voltammetry, the compound showed one irreversible and adsorption-controlled reduction peak. Addition of cationic surfactant (cetyltrimethylammonium bromide, CTAB) was found to enhance the reduction current signal of testosterone, whereas, anionic (sodium dodecylsulfate, SDS) and non-ionic (Tween 80) surfactants exhibited opposite effect. Using square-wave adsorptive stripping voltammetry, the current showed a linear dependence with concentration in the range between 10 and 70 nM in Britton-Robinson buffer, pH 5.0 containing 3 mM CTAB. A detection limit of 1.18 nM (0.34 ng mL(-1)), and relative standard deviation of 4.12% for a concentration level of 35 nM (n = 11) were calculated. This method was successfully applied for the analysis of testosterone in oil-based pharmaceutical preparations and urine samples without any separation. (C) 2013 Elsevier Ltd. All rights reserved.
Silica Gel-Immobilized 5-Aminoisophthalohydrazide: a Novel Sorbent for Solid Phase Extraction of Cu, Zn and Pb From Natural Water Samples
(Wiley, 2020) Aydin, Funda; Cakmak, Resit; Levent, Abdulkadir; Soylak, Mustafa
A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO2-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO2-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 mu g L-1 for Cu, 7.4 mu g L-1 for Zn and 3.5 mu g L-1 for Pb mu g L-1. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO2-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.
Simultaneous Determination of Retinol, Retinyl Palmitate and Β-Carotene in Rat Serum Treated With 7,12-Dimethylbenz[a]anthracene and Hypericum Perforatum L. by High-Performance Liquid Chromatography With Diode-Array Detection
(de Gruyter Poland Sp Z O O, 2010) Levent, Abdulkadir; Ekin, Suat; Oto, Goekhan
A new and simple high-performance liquid chromatography method was developed and validated for the simultaneous determination of retinol, retinyl palmitate and beta-carotene in rat serum treated with Hypericum Perforatum L. and 7,12-dimethylbenz[a] anthracene. Furthermore, vitamin C was determined spectrophotometrically. High-performance liquid chromatography analysis was performed utilizing an Inertsil ODS3 reversed phase column with methanol-acetonitrile-tetrahydrofuran (65:30:5, v/v/v) as mobile phase, at a flow rate of 1.5 mL min(-1) and 40 degrees C. Diode-array detection was conducted at 325 and 450 nm for retinol and retinyl palmitate, and beta-carotene, respectively with a running time of 26 min. The high-performance liquid chromatography assay and extraction procedure proposed are simple, rapid, sensitive and accurate. This method was then applied to determine the amounts of retinol, retinyl palmitate and beta-carotene in rat serum. Results of this study demonstrated that at 60(th) day in the 7,12-dimethylbenz[a] anthracene-treated group there was a significant decrease (p<0.001), (p<0,01), (p<0.05) in levels of retinol, retinyl palmitate and vitamin C, respectively compared to the control group levels. A significant decrease (p<0.01) in retinyl palimitate was observed in the 7,12 dimethylbenz[a] anthracene + Hypericum Perforatum L. treated group compared to the control group..