Aysegul Golcu

Anodic voltammetric behavior and determination of cefixime in pharmaceutical dosage forms and biological fluids.

The voltammetric behavior of cefixime was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. The oxidation of cefixime was irreversible and exhibited diffusion controlled process depending on pH. The oxidation mechanism was proposed and discussed. Different parameters were tested to optimize the conditions for the determination of cefixime. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was investigated. According to the linear relationship between the peak current and the concentration, differential pulse (DPV) and square wave (SWV) voltammetric methods for cefixime assay in pharmaceutical dosage forms and biological fluids were developed. For the determination of cefixime were proposed in acetate buffer at pH 4.5, which allows quantitation over the 6 x 10(-6)-2 x 10(-4)M range in supporting electrolyte and spiked serum sample; 8 x 10(-6)-2 x 10(-4)M range in urine sample; 6 x 10(-6)-1 x 10(-4)M range in breast milk samples for both techniques. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and in the biological samples, respectively.

New, simple, and validated UV-spectrophotometric method for the estimation of some beta blockers in bulk and formulations

A sensitive, extraction, derivatization, evaporation and complexation-free, direct spectrophotometric method is developed for the determination of some anthypertensive drugs such as acebutolol hydrochloride (ACH), atenolol (ATE), and propranolol hydrochloride (PRH) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of aqua solutions of drugs are established. The method permits the determination of ACH, ATE, and PRH over a concentration range of 37.3–111.9, 53.3–213.1 and 14.8–51.8 μg/mL, respectively. Detection and quantification limits are calculated. The obtained results showed good recoveries of 99.60, 99.20 and 99.80% with relative standard deviations of 0.82, 0.79 and 1.70% for ACH, ATE, and PRH, respectively. The repeatability and reproducibility of the drugs for aqua media are determined. Precision and accuracy of the developed methods are used for the recovery studies. The proposed method is applicable for the assay of the three drugs under investigation in dosage forms and the results are in good agreement with those obtained by the literature method.A sensitive, extraction, derivatization, evaporation and complexation-free, direct spectrophotometric method is developed for the determination of some anthypertensive drugs such as acebutolol hydrochloride (ACH), atenolol (ATE), and propranolol hydrochloride (PRH) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of aqua solutions of drugs are established. The method permits the determination of ACH, ATE, and PRH over a concentration range of 37.3–111.9, 53.3–213.1 and 14.8–51.8 μg/mL, respectively. Detection and quantification limits are calculated. The obtained results showed good recoveries of 99.60, 99.20 and 99.80% with relative standard deviations of 0.82, 0.79 and 1.70% for ACH, ATE, and PRH, respectively. The repeatability and reproducibility of the drugs for aqua media are determined. Precision and accuracy of the developed methods are used for the recovery studies. The proposed method is applicable for the assay of the three drugs under investigation in dosage forms and the results are in good agreement with those obtained by the literature method.

Synthesis of trimethoprim metal complexes: Spectral, electrochemical, thermal, DNA-binding and surface morphology studies.

Complexes of trimethoprim (TMP), with Cu(II), Zn(II), Pt(II), Ru(III) and Fe(III) have been synthesized. Then, these complexes have been characterized by spectroscopic techniques involving UV-vis, IR, mass and (1)H NMR. CHN elemental analysis, electrochemical and thermal behavior of complexes have also been investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with the reference drug TMP. Almost all types of complexes show excellent activity against all type of bacteria and fungi. The morphology of the CT DNA, TMP, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with CT DNA has been studied by means of differential pulse voltammetry (DPV) at CT DNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism.

Anodic Voltammetric Behavior and Determination of Antihistaminic Agent: Fexofenadine HCl

Abstract A voltammetric study of the oxidation of fexofenadine HCl (FEXO) has been carried out at the glassy carbon electrode. The electrochemical oxidation of FEXO was investigated by cyclic, linear sweep, differential pulse (DPV), and square wave (SWV) voltammetry using glassy carbon electrode. The oxidation of FEXO was irreversible and exhibited diffusion‐controlled process depending on pH. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. Different parameters were tested to optimize the conditions for the determination of FEXO. For analytical purposes, a very well resolved diffusion‐controlled voltammetric peak was obtained in Britton‐Robinson buffer at pH 7.0 with 20% constant amount of methanol for DPV and SWV techniques. The linear response was obtained in supporting electrolyte in the ranges of 1.0×10−6–2.0×10−4 M with a detection limit of 6.6×10−9 M and 5.76×10−8 M and in serum samples in the ranges of 2.0×10−6–1.0×10−4 M with a detection limit of 8.08×10−8 M and 4.97×10−8 M for differential pulse and square wave voltammetric techniques, respectively. Only square wave voltammetric technique can be applied to the urine samples, and the linearity was obtained in the ranges of 2.0×10−6–1.0×10−4 M with a detection limit of 2.00×10−7 M. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of FEXO in dosage forms and biological fluids. For the precision and accuracy of the developed methods, recovery studies were used. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from the endogenous substances and additives present in tablets.

New metal based drugs: Spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties

The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

Transition Metal Complexes of Propranolol Dithiocarbamate: Synthesis, Characterization, Analytical Properties and Biological Activity

Propranolol dithiocarbamate (PDTC) and its complexes with Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) have been synthesized and characterized by elemental analyses, FT-IR, electronic spectra, atomic absorption spectra, molar conductance, mass and 1H-n.m.r. spectral data. Information on the stoichiometry of the complexes was obtained from the continuous variation method (Job’s method). The thermal decomposition behaviour of PDTC metal complexes was investigated in a nitrogen atmosphere using TG and DTA techniques. The antimicrobial activity studies of the metal complexes have been recorded against the Bacillus megaterium, Bacillus brevis, Yersinia enterocolitica, Micrococcus luteus, Pseudomonas aeruginosa, Enterococcus faecalis, Kluyveromyces marxianus, Candida tropicalis, Candida albicans and Kluvyeromyces fragilis.

Synthesis and Characterization of Metal Complexes of Acebutolol, Atenolol, and Propranolol Antihypertension Drugs

Abstract The complexation of two transition metal ions with the β‐blocker drugs acebutolol (HL1), atenolol (HL2), and propranolol (HL3) was studied in methanol and acetonitrile media at M:L (metal:ligand) molar ratio from 1:1 to 1:10. Cu(II) complexes with ligands having the stoichiometric ratio 1:4 (mononuclear copper(II) complexes) and 1:1 (binuclear copper(II) complexes) were prepared. The analytical data show that the metal to ligand ratio in the mononuclear Co(II) complexes was 1:2. The complexes were characterized on the basis of analytical data, magnetic moments, atomic absorption, infrared and electronic spectral data. Molar conductivities of the complexes at room temperature were measured. The conductivity values of the mononuclear Cu(II) complexes indicate weak electrolyte behavior, whereas the binuclear Cu(II) and mononuclear Co(II) complexes are non‐electrolytes. The thermal properties of all complexes have been studied by the DTA and TG.

Electrochemical investigation and DNA-binding studies of pefloxacin–metal(II/III) complexes

Complexes of pefloxacin (PEF), with Cu(II), Zn(II), Pt(II), Ru(III), and Fe(III) have been synthesized and characterized by spectroscopic techniques involving UV-Vis, IR, 1H-HMR, CHN elemental analysis, electrochemical, and thermal behaviors. The electrochemical properties of all complexes were investigated by cyclic voltammetry (CV) using a glassy carbon electrode. The biological activities of the complexes have been evaluated by examining their ability to bind to calf thymus DNA (CT-DNA) with UV spectroscopy and CV. UV studies of the interaction of the complexes with DNA show that these compounds can bind to CT-DNA and the binding constants have been calculated. The cyclic voltammograms of the complexes in the presence of CT-DNA show that the complexes can bind to CT-DNA by intercalative and electrostatic binding. The antimicrobial activities of these complexes have been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activities against two different fungi have been evaluated and compared with pefloxacin as reference. Almost all complexes show excellent activity against all bacteria and fungi.

Tetradentate Schiff base ligands and their complexes: synthesis, structural characterization, thermal, electrochemical and alkane oxidation.

Three Schiff base ligands (H(2)L(1)-H(2)L(3)) with N(2)O(2) donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D ((1)H, (13)C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the (1)H and (13)C resonance assignments of the three ligands. Ligands H(2)L(1) and H(2)L(3) were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated.

Spectrophotometric Determination of Metoprolol Tartrate in Pharmaceutical Dosage Forms on Complex Formation with Cu(II)

A new, simple, sensitive and accurate spectrophotometric method has been developed for the assay of metoprolol tartrate (MPT), which is based on the complexation of drug with copper(II) [Cu(II)] at pH 6.0, using Britton-Robinson buffer solution, to produce a blue adduct. The latter has a maximum absorbance at 675 nm and obeys Beers law within the concentration range 8.5-70 μg/mL. Regression analysis of the calibration data showed a good correlation coefficient (r = 0.998) with a limit of detection of 5.56 μg/mL. The proposed procedure has been successfully applied to the determination of this drug in its tablets. In addition, the spectral data and stability constant for the binuclear copper(II) complex of MPT (Cu2MPT2Cl2) have been reported.