M-Reza Rashidi | Tabriz University Of Medical Sciences (original) (raw)

Papers by M-Reza Rashidi

Background and the purpose of the study: The binding ability of a drug to serum albumin has influ... more Background and the purpose of the study: The binding ability of a drug to serum albumin has influence on the pharmacokinetics of a drug. In the present study, the mutual interaction of anticancer drug erlotinib hydrochloride with bovine serum albumin (BSA) using fluorescence and UV/vis spectroscopy was investigated.
Methods: The BSA solution (0.1 mM) was prepared daily in Tris buffer (0.05 mol l-1, pH =7.4) and treated at final concentration of 1.67×10-5 M with different amounts of erlotinib hydrochloride to obtain final concentrations of 0, 0.2, 0.4, 0.8, 1, 2, 4, 6, 8, 20 and 42 μM receptively. The mixture was allowed to stand for 5 min and the fluorescence quenching spectra were recorded at 298, 303, 308 and 313 K.
Results: It was found that erlotinib hydrochloride caused the fluorescence quenching of BSA by the formation of a BSA-erlotinib hydrochloride complex. The mechanism of the complex formation was then analyzed by determination of the number of binding sites, apparent binding constant Ka, and calculation of the corresponding thermodynamic parameters such as the free energy (ΔG), enthalpy (ΔH) and entropy changes (ΔS) at different temperatures. Results showed that binding of erlotinib hydrochloride to BSA was spontaneous, and the hydrophobic forces played a major role in the complex formation. The distance, r, between donor (BSA) and acceptor (erlotinib hydrochloride) was found to be less than 8 nm suggesting the occurrence of non-radiative energy transferring and static quenching between these two molecules.
Conclusion: The results provided preliminary information on the binding of erlotinib hydrochloride to BSA and the presence of a single binding site on BSA and Ka values for the association of BSA with erlotinib hydrochloride increased by the increase in temperature.

6-Mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of chi... more 6-Mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). It is catabolized to 6-thiouric acid (6TUA) through 8-hydroxo-6-mercaptopurine (8OH6MP) or 6-thioxanthine (6TX) intermediates. Methods: High-performance liquid chromatography (HPLC) is usually used to determine the contents of therapeutic drugs, metabolites and other important biomedical analytes in biological samples. In the present study, the multivariate calibration methods, partial least squares (PLS-1) and principle component regression (PCR) have been developed and validated for the simultaneous determination of 6MP and its oxidative metabolites (6TUA, 8OH6MP and 6TX) without analyte separation in spiked human plasma. Mixtures of 6MP, 8-8OH6MP, 6TX and 6TUA have been resolved by PLS-1 and PCR to their UV spectra. Results: Recoveries (%) obtained for 6MP, 8-8OH6MP, 6TX and 6TUA were 94.5-97.5, 96.6-103.3, 95.1-96.9 and 93.4-95.8, respectively, using PLS-1 and 96.7-101.3, 96.2-98.8, 95.8-103.3 and 94.3-106.1, respectively, using PCR. The NAS (Net analyte signal) concept was used to calculate multivariate analytical figures of merit such as limit of detection (LOD), selectivity and sensitivity. The limit of detections for 6MP, 8-8OH6MP, 6TX and 6TUA were calculated to be 0.734, 0.439, 0.797 and 0.482 μmol L-1, respectively, using PLS and 0.724, 0.418, 0783 and 0.535 μmol L-1, respectively, using PCR. HPLC was also applied as a validation method for simultaneous determination of these thiopurines in the synthetic solutions and human plasma. Conclusion: Combination of spectroscopic techniques and chemometric methods (PLS and PCR) has provided a simple but powerful method for simultaneous analysis of multicomponent mixtures

Valproic acid(VA)is an acidic anticonvulsant and mood stabilizing drug with very weak fluorescenc... more Valproic acid(VA)is an acidic anticonvulsant and mood stabilizing drug with very weak fluorescence and absorption properties. A simple, inexpensive and sensitive method was established for determination of VA using thiogycolicacid(TGA)-capped Cd Te quantum dots (QDs) based on pH-dependent fluorescence of the prepared QDs. The TGA-capped Cd Te QDs of various sizes were successfully synthesized in aqueous
medium and characterized by fluorescence spectroscopy, UV–vis absorption spectra, infrared spectroscopy and transmission electron microscopy(TEM). Under the optimal conditions, plotting ln(F0/F) versus concentration of VA showed a linear relationship in the range of 0.3–7.5 mg/L with correlation coefficient of 0.998. The limit of detection (LOD)was 0.24 mg mL1. The proposed method was successfully applied for determination of VA in commercial tablets, human serum, and urine samples satisfactorily.

Pakistan Journal of Biological Sciences, 2008

The aim of this study was to investigate the effects of onion on serum uric acid levels and hepat... more The aim of this study was to investigate the effects of onion on serum uric acid levels and hepatic Xanthine Dehydrogenase/Xanthine Oxidase activities in normal and hyperuricemic rats. Hyperuricemia was induced by intraperitoneal injection of 250 mg kg(-1) potassium oxonate in rats. Oral administration of onion at 3.5 and 7.0 mg kg(-1) day(-1) for 7 days was able to reduce serum uric acid levels in hyperuricemic rats with no significant effects on the level of this compound in the normal animals. In addition, onion when tested in vivo on rat liver homogeneities elicited significant inhibitory actions on the Xanthine Dehydrogenase (XDH) and Xanthine Oxidase (XO) activities. This effect resulted less potent than that of allopurinol. However, the hypouricemic effect observed in the experimental animal did not seem to parallel the change in XDH and XO activities, implying that the onion might be acting via other mechanisms apart from simple inhibition of enzyme activities. Such hypouricemic action and enzyme inhibitory activity of onion makes it a possible alternative for allopurinol, or at least in combination therapy to minimize the side-effects of allopurinol, in particular in long-term application.

International Journal of Cardiology, 2011

Although the term 'evidence-based medicine' (EBM) is of recent origin, its roots are generally ag... more Although the term 'evidence-based medicine' (EBM) is of recent origin, its roots are generally agreed to lie in earlier times. Several writers have suggested that the 11th century CE physician and philosopher Avicenna (Ibn Sina) formulated an approach to EBM that broadly resembles modern-day principles and practice. The aim of this paper is to explore the origins and influence of Avicenna's version of EBM. A survey of the literature suggests that two influences on Avicenna's thought were crucial: the doctrine of Ijma; and Stoic logic, perhaps transmitted via the writings of Galen. In turn, Avicenna is known to have been a major influence on both medical practice and the development of logic in medieval Europe. Through this route, Avicennian logic (notably its inductive aspect) inspired the new style of thought associated with the scientific revolution, which later came to be reflected in 'scientific medicine', and may therefore have been an indirect source of EBM today.

Total of 500 samples from triceps, gluteal and diaphragm muscles, kidney, and liver, were obtaine... more Total of 500 samples from triceps, gluteal and diaphragm muscles, kidney, and liver, were obtained randomly from beef carcasses of a slaughterhouse in Tabriz.

Journal of Pharmacy and Pharmacology, 1999

Although 7-hydroxymethotrexate is a major metabolite of methotrexate during high-dose therapy, ne... more Although 7-hydroxymethotrexate is a major metabolite of methotrexate during high-dose therapy, negligible methotrexate-oxidizing activity has been found in-vitro in the liver in man. The goals of this study were to determine the role of aldehyde oxidase in the metabolism of methotrexate to 7-hydroxymethotrexate in the liver and to study the effects of inhibitors and other substrates on the metabolism of methotrexate. Methotrexate, ( AE )methotrexate and (À)-methotrexate were incubated with partially puri®ed aldehyde oxidase from the liver of rabbit, guinea-pig and man and the products analysed by HPLC. Rabbit liver aldehyde oxidase was used for purposes of comparison.

Journal of Insect Science, 2007

Aaps Pharmscitech, 2001

The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensit... more The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensitive swelling and drug release properties. Methacrylic-type polymeric prodrugs with different content levels of 5-amino salicylic acid (5-ASA) were synthesized by free radical copolymerization of metacrylic acid (MAA), polyethylene glycol monomethacrylate (PEGMA), and a methacrylic derivative of 5-ASA (methacryloyloxyethyl 5-amino salicylate [MOES]). The copolymers were characterized, and the drug content of the copolymers was determined. The effect of copolymer composition on the swelling behavior and hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). The swelling and hydrolytic behavior of the copolymers was dependent on the content of MAA groups and caused a decrease in gel swelling in SGF or an increase in gel swelling in SIF. Drug release studies showed that increasing content of MAA in the copolymer enhances the hydrolysis in SIF but has no effect in SGF. The results suggest that hydrogen-bonded complexes are formed between MAA and PEG pendant groups and that these pH-sensitive systems could be useful for preparation of a controlled-release formulation of 5-ASA.