Synthesis of Carboxymethyl Cellulose Based Drug Carrier Hydrogel Using Ionizing Radiation for Possible Use as Site Specific Delivery System

A unique natural polymer based colon specific drug carrier was prepared from carboxymethyl cellulose (CMC) and acrylic acid (AAc) in aqueous solution employing γ‐radiation induced copolymerization and crosslinking. The effect of preparation conditions such as the natural polymer content and irradiation dose on gelation process was investigated. The swelling behavior of the prepared hydrogels was characterized by investigating the time and pH dependent swelling of the (CMC/AAc) hydrogels of different CMC content. The effects of the hydrogel composition and pH of the swelling medium on the swelling indices were estimated. The results show that the increment in the CMC content in the feed solution enhances the gelation process. The results also show the dependence of the swelling indices on both hydrogel composition and pH value of the swelling medium. To evaluate the ability of the prepared hydrogel to be used as a colon‐specific drug carrier, the release profile of theophylline was studied as a function of time at pH 1 and pH 7.     

A PVC Membrane Sensor for Potentiometric Determination of Atorvastatin in Biological Samples and Pharmaceutical Preparations

The present article reports for the first time the use of Aliquat 336S‐atorvastatin as an electroactive material in a poly(vinyl chloride) matrix membrane sensor plasticized with ortho‐nitrophenyl‐octylether (o‐NPOE) or dioctylphthalate (DOP) for determination of atorvastatin in biological samples (human plasma) and in pharmaceutical preparations. The sensor shows fast, stable and reproducible response over the concentration range of 1.0×10^?7–1.0×10^?2 mol L^?1 atorvastatin with anionic slopes of 60.94±0.2 and 58.22±0.2 and pH range of 5.0–9.0 for o‐NPOE and DOP plasticized based membrane sensors, respectively. The response time of the sensor is stable and fast (10 s). Results were achieved with average recoveries of 99.5 % and 99.3 % and mean standard deviations of ±1.1 % and ±1.4 % for o‐NPOE and DOP plasticized based membrane sensors, respectively. The sensor exhibits high selectivity towards atorvastatin in the presence of many anions, drug excipients and diluents. Validation of the method according to the quality assurance standards shows suitability of the proposed sensors for use in the quality control assessment of the drug.     

A theoretical study on the reaction pathways of peroxynitrite formation and decay at nonheme iron centers

A computational study based on density functional theory was undertaken to identify possible reaction pathways for the formation and decomposition of peroxynitrite at models of the active sites of the nonheme superoxide scavenging enzymes superoxide reductase (SOR) and iron superoxide dismutase (FeSOD). Two peroxynitrite isomers and their possible protonated states were investigated, namely Fe? OONO^?, Fe? N(O)OO^?, Fe? OONOH, and Fe? N(O)OOH. Peroxynitrite formation at the active sites was assumed by either the interaction of a peroxynitrite cis/trans anion with the pentacoordinated iron active site or the interaction between a nitric oxide bound adduct and superoxide; both scenarios were found to be facile for all models investigated. The ferrous adducts of the Fe? OONO^?isomer were found to undergo instant heterolytic cleavage of the O? ONO bond to yield nitrite, whereas for the ferric adducts, the homolytic cleavage of the O? ONO bond to yield nitrogen dioxide was found to be energetically facile. For the Fe? N(O)OO^? isomer, the active site models of FeSOD and SOR were only able to accommodate the cis isomer of peroxynitrite. Ferric adducts of the cis Fe? OONO^? isomer were found to be energetically more stable than their trans counterparts and were also more stable than the cis adducts of the Fe? N(O)OO^? isomer; conversely, the protonated forms of all adducts of the Fe? OONOH isomer were found to be lower in energy than their equivalent Fe? N(O)OOH adducts. Multiple reaction pathways for the decomposition of the formed peroxynitrite adducts (whether the anions or the protonated forms) were proposed and explored. The energy requirements for the decomposition processes ranged from exothermic to highly demanding depending on the peroxynitrite isomer, the type of model (whether an SOR or FeSOD active site), and the oxidation state of iron. © 2014 Wiley Periodicals, Inc.     

Synthesis of some fused heterocyclic systems and their nucleoside candidates

A series of pyridofuro compounds were synthesized from 4-(4-chlorophenyl)-1,2-dihydro-2-oxo-6-(thiophen-2-yl)pyridine-3-carbonitrile (1) as starting material. Alkylation of 1 with ethyl bromoacetate gave the corresponding ester 2, which was condensed with hydrazine hydrate to afford the corresponding acid hydrazide derivative 3. Thrope-Ziegler cyclization of 2 with sodium methoxide gave furo[2,3-b]pyridine derivative 4, which was reacted with thiosemicarbazide, allyl isothiocyanate, formamide or hydrazine hydrate to give furopyridine derivatives 5–8, respectively. The latter compound 8 was cyclized with acetylacetone or formic acid to give the corresponding compounds 9 and 10, respectively. Furthermore, sulfurization of 1 with P₂S₅ gave the corresponding thioxopyridine 11, which was reacted with glycosyl (or galactosyl) bromide, morpholine or piperidine to give the corresponding thioglycoside 12a,b and Mannich base 14a,b derivatives. The deacetylation of 12a,b gave the corresponding deacetylated thioglycosides 13a,b, respectively. All the newly synthesized compounds were characterized by the elemental analyses and spectroscopic evidences (IR, ¹H- and ¹³C NMR).     

Graphene-based Disposable Electrochemical Sensor for Chlorhexidine Determination

In this work, simple, reliable, eco-friendly, and quantitative electrochemical sensors were developed to detect chlorhexidine Digluconate (CHX) in a variety of dosage forms, including mouthwashes and intimate douches, as well as chlorhexidine in spiked human saliva. Without any sample pre-treatment or extraction processes, CHX was measured in colored aqueous formulations. Based on carbon screen-printed electrodes, two potentiometric sensors (sensors I and II), utilizing graphene nanocomposites (Gr-NC), were designed (SPEs). An ionophore, 2-hydroxypropyl-β-cyclodextrin, was doped into the Poly Vinyl Chloride (PVC) polymeric membrane to improve sensor selectivity.     

Synthesis of novel substituted pyridines from 1-(3-aminophenyl)-3-(1<Emphasis Type="Italic">H</Emphasis>-indol-3-yl)prop-2-en-1-one and their anticancer activity

A series of novel substituted pyridine derivatives have been synthesized via the reaction of 3-indole carboxaldehyde with 3-aminoacetophenone. The products structures have been elucidated from elemental analysis as well as IR, ¹H NMR, ¹³C NMR, and MS spectroscopy data. All the synthesized compounds have shown anticancer activity against HEPG2 and MCF-7 in vitro; some of them have exhibited the in vivo activity.     

Synthesis,reactions, and antimicrobial activity of some novel fused thiazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-5<Emphasis Type="Italic">H</Emphasis>-indeno[1,2-<Emphasis Type="Italic">d</Emphasis>]pyrimidine derivatives

Series of novel substituted thioxopyrimidine and thiazolo[3,2-a]pyrimidine compounds that combine various heteroaryl rings have been synthesized via Biginelli one-pot three-component reaction and elucidated with chemical and spectral analysis. Several products were tested for their antimicrobial properties.     

Quantification of terbutaline in pharmaceutical formulation and human serum by adsorptive stripping voltammetry at a glassy carbon electrode

The electrochemical oxidative behavior of terbutaline at the glassy carbon electrode was studied in a series of the Britton-Robinson buffer of pH 2--11. Cyclic and square-wave voltammograms of terbutaline at the pH values 相似文献   

Functionalization of Ethyl 6-Amino-4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate: Facile Synthesis of a New Series of Pyrano[2,3-d]pyrimidine Derivatives

Russian Journal of General Chemistry - Herein, synthesis of a new series of pyrano[2,3-d]pyrimidine scaffolds is presented. Ethyl 6-amino-4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate...