8 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 8 / 8
Öğe New voltammetric strategy for determination and electrochemical behaviors of metformin by pencil graphite electrode in the NaOH(Indian Chemical Society, 2020) Altunkaynak, Yalçın; Yavuz, Ömer; Levent, AbdulkadirMetformin(MET), an oral antidiabetic drug commonly used in the treatment of diabetes, is a drug that increases insulin sensitivity in the biguanide group [1]. MET shows its pharmacological effect by lowering the glucose level in the blood. In the literature research, there are studies using electrochemical techniques for the analysis of MET in biological fluid and drug forms[1-6]. In this study, the electrochemical properties of MET, one of the drugs used in the treatment of diabetes, were performed using a pencil graphite electrode in NaOH (0.1 M) solution. This compound was recorded with an irreversible and diffusion controlled adsorption oxidation peak at approximately +1.28 V by cyclic voltammetry. With square wave stripping voltammetry, it was observed that the peak current signals of MET in the concentration range of 2.76-24.8 µM in 0.1M NaOH solution increased linearly. At a concentration of 2.76 µM (n = 9), the limit of detection and relative standard deviation were calculated as 9.03 nM (1.495 ngmL-1 ) and 3.25 %, respectively. This method has been successfully applied for MET analysis in pharmaceutical preparations and urine samples without any separation.Öğe Plantago major protective effects on antioxidant status after administration of 7,12-dimethylbenz(a)anthracene in rats(Asian Pacific Organization for Cancer Prevention, 2011) Oto, Gökhan; Ekin, Suat; Özdemir, Hülya; Demir, Halit; Yaşar, Semih; Levent, Abdulkadir; Berber, İsmet; Kaki, BarışAim: 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.Öğe Separation, optimization, and quantification of cytokinins by a recently developed amide-embedded stationary phase(Taylor & Francis, 2017-07-06) Aral, Hayriye; Haşimi, Duygu; Aral, Tarık; Levent, Abdulkadir; Ziyadanoğulları, BerrinIn this study, some plant growth regulators known as cytokinins [kinetin (K), zeatin (Z), thidiazuron (TDZ), benzylaminopurine (BAP), and dimethylallylaminopurine (AAP)] were separated by HPLC using an amide-embedded mixed-mode stationary phase which was synthesized by Aral et al. in recent years. The effect of mobile phase content, mobile phase pH, buffer concentration, and temperature on separation process was studied. In addition, a quantitative determination of cytokinins from Salvia limbata extract was studied, and some validation parameters such as limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation (RSD) were calculated as a range of 0.03–0.1, 0.1–0.26 mg/L, and 0.03–0.08, respectively.Öğe Determination of trace metal and mineral levels in the tobacco and cigarette samples using by FASS(Chemical Society of Pakistan, 2013-04) Levent, Abdulkadir; Yardım, Yavuz; Demir, CengizCigarettes 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.Öğe Electrooxidation of thiourea and its square-wave voltammetric determination using pencil graphite electrode(Walter de Gruyter, 2011-04-01) Levent, Abdulkadir; Keskin, Ertuğrul; Yardım, Yavuz; Şentürk, ZühreThe 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 6.3-30μm, with a detection limit of 1.29μm. The applicability to direct assays of wastewaters was also tested.Öğe Synthesis and characterization of a new difunctional ligand and its metal complexes: An experimental, theoretical, cyclic voltammetric, and antimicrobial study(Taylor & Francis, 2015-07-29) Baykara, Hacı; İlhan, Salih; Öztomsuk, Abdussamet; Seyitoğlu, Mehmet Salih; Levent, Abdulkadir; Okumuş, Veysi; Dündar, AbdurrahmanA new difunctional Schiff base ligand and its some metal complexes were synthesized. The compounds were characterized by elemental analysis, 1H-NMR, 13C-NMR, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis techniques. Additionally, DPPH scavenging, metal chelating and antibacterial activity of compounds were examined via in vitro methods. The lowest DPPH scavenging activity observed by Co(II) as 36.28% and highest was ligand as 52.00%. A cyclic voltammetric study was also carried out to determine redox potentials of the compounds. Some theoretical studies such as 1H-NMR, HOMO-LUMO, and mapped electron density of the ligand were also carried out successfully.Öğe New voltammetric strategy for determination and electrochemical behaviors of oxaliplatin by CPT-BDD electrode(Indian Chemical Society, 2020) Aslan, Mehmet; Levent, AbdulkadirVarious drugs made of metal compounds have been used in many diseases including cancer[1]. Studies on Oxaliplatin in the literature are these [2-6]. Oxaliplatin (OxPt), which is a platinum analogue with anti-cancer effect, was accentuated. OxPt is separated from cisplatin, one of analogues of platinum, by replacing 1,2-diaminocyclohexane with amine groups. In this study, a simple, fast and sensitive voltammetric method was developed for OxPt which shows anticancer effects with cytotoxic properties. The boron-doped diamond (BDD) electrode was activated electrochemically in cathodic direction in 0.5 M H2SO4 medium. Electrochemical properties of OxPt were investigated on BDD electrode surface using square-wave and cyclic voltammetry techniques. OxPt in Britton-Robinson(BR) buffer (pH 5.0) gave a well-determined voltammetric response at +1.01 V (vs. Ag/AgCl) using the square-wave voltammetry technique. The developed voltammetric technique was found to be linear with the concentration range of 1.0-3.5 μM in the BR (pH 5.0) medium and the limit of detection was 0.276 μM (0.109 μg mL-1 ). Recommended method was successfully applied to drug forms of OxPt.Öğe Two-component organogelators: combination of Nε-alkanoyl-L-lysine with various N-alkanoyl-L-amino acids: additional level of hierarchical control(Taylor & Francis, 2018-10-02) Çolak, Mehmet; Barış Cebe, Deniz; Evcil, Murat; Demirel, Nadir; Hoşgören, HalilSynthesis of two-component organogelation system was performed very easy and concise manner from Nε-palmitoyl-L-lysine ethyl ester and Nε-miristoyl-L-lysine ethyl ester in which they were used as base component and N-lauroyl-L-amino acids (amino acids:, alanine, leucine and phenylalanine as acid components.). And their organogelation properties were examined in different pharmaceutical fluids such as liquid paraffin, fatty acid ethyl, and isopropyl esters. In this way, gelation efficiency was ascertained variations of alkanoyl moieties and combination of different amino acids in the gelator structures. Characterization of gelators was performed via thermal measurement such as Tg and gel–sol enthalpy change; SEM and FTIR as optical methods.
