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Piperazine
Terms modified by Piperazine Selected AbstractsHydrated salts of 3,5-dihydroxybenzoic acid with organic diamines: hydrogen-bonded supramolecular structures in two and three dimensionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001Colin J. Burchell The trigonally trisubstituted acid 3,5-dihydroxybenzoic acid forms hydrated salt-type adducts with organic diamines. In 1,4-diazabicyclo[2.2.2]octane,3,5-dihydroxybenzoic acid,water (1/1/1) (1), where Z, = 2 in P21/c, the constitution is [HN(CH2CH2)3N]+·[(HO)2C6H3COO],·H2O: the anions and the water molecules are linked by six O,H,O hydrogen bonds to form two-dimensional sheets and each cation is linked to a single sheet by one O,H,N and one N,H,O hydrogen bond. Piperazine,3,5-dihydroxybenzoic acid,water (1/2/4) (2) and 1,2-diaminoethane,3,5-dihydroxybenzoic acid,water (1/2/2) (3) are also both salts with constitutions [H2N(CH2CH2)2NH2]2+·2[(HO)2C6H3COO],·4H2O and [H3NCH2CH2NH3]2+·2[(HO)2C6H3COO],·2H2O, respectively. Both (2) and (3) have supramolecular structures which are three-dimensional: in (2) the anions and the water molecules are linked by six O,H,O hydrogen bonds to form a three-dimensional framework enclosing large centrosymmetric voids, which contain the cations that are linked to the framework by two N,H,O hydrogen bonds; in (3) the construction of the three-dimensional framework requires the participation of cations, anions and water molecules, which are linked together by four O,H,O and three N,H,O hydrogen bonds. [source] ChemInform Abstract: Stereoselective Synthesis of a Novel Chiral Piperazine (VIII)CHEMINFORM, Issue 41 2008Satoshi Kojima Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Asymmetric Synthesis of 1-(2- and 3-Haloalkyl)azetidin-2-ones as Precursors for Novel Piperazine, Morpholine, and 1,4-Diazepane Annulated ,-Lactams.CHEMINFORM, Issue 1 2007Willem Van Brabandt Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Facile Synthesis of 4-Substituted-4-aminopiperidine Derivatives, the Key Building Block of Piperazine-Based CCR5 Antagonists.CHEMINFORM, Issue 46 2004Xiao-Hua Jiang Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Photochemical Addition Reactions of [60]Fullerene with 1,2-Ethylenediamine and Piperazine.CHEMINFORM, Issue 30 2002Nai-Xing Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Rapid capillary electrophoresis time-of-flight mass spectrometry separations of peptides and proteins using a monoquaternarized piperazine compound (M7C4I) for capillary coatingsELECTROPHORESIS, Issue 8 2008Anisa Elhamili Abstract A monoquaternarized piperazine, 1-(4-iodobutyl) 4-aza-1-azoniabicyclo[2,2,2] octane iodide (M7C4I), has been evaluated as a surface derivatization reagent for CE in combination with TOF MS for the analysis of proteins, peptides, and protein digests. The M7C4I piperazine, at alkaline pH, forms a covalent bond via alkylation of the ionized silanols producing a cationic surface with a highly stable and reversed EOF. The obtained surface yields rapid separations (less than 5,min) of peptides and proteins at acidic pH with high separation efficiencies (up to 1.1×106 plates/m for peptides and up to 1.8×106 plates/m for proteins) and no observed bleeding of the coating reagent into the mass spectrometer. The simplicity of the coating procedure also enables fast (2,min) regeneration of the surface, if necessary. This is useful in the analysis of complex samples in order to prevent possible memory effects. The potential of using M7C4I-coated capillaries for MS analysis of complex samples is demonstrated by the separation of peptides, proteins, and protein digests. Even more, the spectacular thing in which large intact proteins with molecular masses over 0.5,MDa could be separated. The coating showed good ability to handle these large proteins with high efficiency and retained peak shape as demonstrated by separation of IgG1 (150,kDa) and thyroglobulin (669,kDa). [source] Individual differences in the effects of chronic prazosin hydrochloride treatment on hippocampal mineralocorticoid and glucocorticoid receptorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2007Mohamed Kabbaj Abstract The aim of this study was to investigate the noradrenergic regulation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in high responder (HR) and low responder (LR) male rats, an animal model of individual differences in hypothalamo-pituitary-adrenal axis activity and vulnerability to drugs of abuse. The effects of a chronic treatment with the noradrenergic ,1 antagonist (1-[4-amino-6,7-dimethoxy-2-quinazolinyl]-4-[2-furanylcarbonyl] piperazine) hydrochloride (prazosin) (0.5 mg/kg, i.p., 35 days) were assessed on stress-induced corticosterone (CORT) secretion and on hippocampal MRs and GRs in adrenally intact rats. In order to ascertain whether the effects of chronic prazosin treatment on hippocampal MRs and GRs were direct or indirect, through prazosin-induced CORT secretion, we also assessed the effects of the same treatment on adrenalectomized rats with CORT substitutive therapy. When compared with LR rats, HR rats exhibited a delayed return to the basal level of CORT following acute restraint stress; this was associated with a lower binding of MRs and GRs in HR rats than in LR rats. Chronic prazosin treatment had no effect in HR animals but markedly reduced hippocampal MRs and GRs, and increased stress-induced CORT secretion in LR rats. In LR adrenalectomized rats, prazosin reduced hipppocampal MRs but did not change GRs. Our results provide evidence of a differential regulation by noradrenaline of hippocampal MRs and GRs in HR and LR rats. These data could have clinical implications in terms of individual differences in the resistance to antidepressant treatments and individual differences in drug abuse. [source] Facile Synthesis of Flexible Bis(pyrazol-1-yl)alkane and Related Ligands in a Superbasic MediumEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2007Andrei S. Potapov Abstract Flexible ligands 1,3-bis(pyrazol-1-yl)propanes, bis[2-(pyrazol-1-yl)ethyl] ethers, and bis[2-(3,5-dimethylpyrazol-1-yl)ethyl]amine were prepared by a facile procedure involving the reaction of pyrazoles with 1,3-dibromopropane, bis(2-chloroethyl) ether or bis(2-chloroethyl)amine hydrochloride in a superbasic medium (dimethyl sulfoxide/potassium hydroxide). Reaction of bis(2-chloroethyl)amine and pyrazole unexpectedly led to 1,4-bis[2-(pyrazol-1-yl)ethyl]piperazine. The corresponding 4,4,-diiodo-substituted bis(pyrazole) derivatives were prepared by oxidative iodination with I2/HIO3/H2SO4 in acetic acid. Vilsmeier,Haak formylation of some of the prepared compounds yielded the corresponding dialdehydes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Metabolic therapy in the treatment of ischaemic heart disease: the pharmacology of trimetazidineFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 2 2003William C. Stanley Abstract The primary result of myocardial ischaemia is reduced oxygen consumption and adenosine triphosphate (ATP) formation in the mitochondria, and accelerated anaerobic glycolysis, lactate accumulation and cell acidosis. Classic pharmacotherapy for demand-induced ischaemia is aimed at restoring the balance between ATP synthesis and breakdown by increasing the oxygen delivery (i.e. with long acting nitrates or Ca2+ channel antagonist) or by decreasing cardiac power by reducing blood pressure and heart rate (i.e. with , -blocker or Ca2+ channel antagonist). Animal studies show that fatty acids are the primary mitochondrial substrate during moderate severity myocardial ischaemia, and that they inhibit the oxidation of carbohydrate and drive the conversion of pyruvate to lactate. Drugs that partially inhibit myocardial fatty acid oxidation increase carbohydrate oxidation, which results in reduced lactate production and a higher cell pH during ischaemia. Trimetazidine (1-[2,3,4-trimethoxibenzyl]-piperazine) is the first and only registered drug in this class, and is available in over 90 countries world-wide. Trimetazidine selectively inhibits the fatty acid , -oxidation enzyme 3-keto-acyl-CoA dehydrogenase (3-KAT), and is devoid of any direct haemodynamic effects. In double-blind placebo-controlled trials trimetazidine significantly improved symptom-limited exercise performance in stable angina patients when used either as monotherapy or in combination with , -blockers or Ca2+ channel antagonists. Given available evidence, trimetazidine is an excellent alternative to classic haemodynamic agents, and is unique in its ability to reduce symptoms of angina when used in patients resistant to a haemodynamic treatment as vasodilators, , -blockers or Ca2+ channel antagonists. [source] Synthesis, characterization, and thermal and antimicrobial studies of newly developed transition metal,polychelates derived from polymeric Schiff baseJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Nahid Nishat Abstract Monomeric Schiff base derived from salicylaldehyde and 1,3-diaminopropane was subjected to polycondensation reaction with formaldehyde and piperazine in basic medium. The resin was found to form polychelates readily with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. The materials were characterized by elemental analysis, spectral studies (IR, 1H-NMR, 13C-NMR, and UV,visible), magnetic moment measurements, and thermal analysis. The electronic spectra and magnetic moment measurements of the synthesized polychelates confirmed the geometry of the central metal ion. Metal,resin bonds were registered in the IR spectra of the polychelates. The thermogravimetric analysis data indicated that the polychelates were more stable than the corresponding polymeric Schiff base. All the synthesized metal,polychelates showed excellent antibacterial activities against the selected bacteria. The antimicrobial activities were determined by using the shaking flask method, where 25 mg/mL concentrations of each compound were tested against 105 CFU/mL bacteria solutions. The number of viable bacteria was calculated by using the spread-plate method, where 100 ,L of the incubated antimicrobial agent in bacteria solutions were spread on agar plates, and the number of bacteria was counted after 24 h of incubation period at 37°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Synthesis, characterization, and antimicrobial properties of novel quaternary amine methacrylate copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Supriya Punyani Abstract A novel amine methacrylate monomer trimethylolpropane trimethacrylate,piperazine,ethyleneglycol dimethacrylate (TMPTMA-PPZ-EGDMA) was synthesized by amination of trimethylolpropane trimethacrylate (TMPTMA) with excess of piperazine (PPZ) followed by reaction with ethyleneglycol dimethacrylate (EGDMA). Copolymerization of TMPTMA-PPZ-EGDMA with 2-hydroxyethyl methacrylate (HEMA) was carried out by free radical polymerization using ammonium persulfate (APS) and N,N,N,,N,-tetramethyl ethylenediamine (TEMED) as a redox initiator. The copolymers obtained were then quaternized with 1-iodooctane. The monomers were characterized by FTIR and 1H NMR spectral studies. The molecular weights and polydispersity values of the monomers were determined with gel permeation chromatography. Quaternized copolymers containing more than 20% amine methacrylate monomer showed microporosity in the range of 9.9,10.4 ,m. The antibacterial activity of the quaternized copolymers against Escherichia coli and Staphylococcus aureus was studied using UV,vis spectrophotometer and scanning electron microscopy. Quaternized copolymers showed broad-spectrum contact-killing antibacterial properties without releasing any active agent as checked by iodide selective ion meter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effects of hyperbranched poly(amido-amine)s structures on synthesis of Ag particlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Youyi Sun Abstract The synthesis of Ag particles stabilized poly (N,N,-methylene bisacrylamide N -aminoethyl piperazine) (MBA-AEPZ) and poly(N,N,-dodecyl diacrylamide N -aminoethyl piperazine) (MDA-AEPZ) was reported. The effects of hyperbranched polymer structures and hyperbranched polymer concentrations were studied on the size and size distribution of Ag particles, which were determined from the UV plasmon absorption band and transmission electronmicroscopic analyses. The data show that slight change (10.3 and 9.7 nm) and large change on particle size (3.9 and , 200 nm) were observed with increase in concentrations of poly(MBA-AEPZ) and poly(MDA-AEPZ) at the same M:D, respectively. The difference is explained in terms of a mechanism of structure-dependent stabilization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Validation of an LC,MS Method for the Detection and Quantification of BZP and TFMPP and their Hydroxylated Metabolites in Human Plasma and its Application to the Pharmacokinetic Study of TFMPP in Humans,JOURNAL OF FORENSIC SCIENCES, Issue 5 2010Ushtana Antia M.Sc. Abstract:, An LC,MS method was developed for benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP), constituents of "party pills" or "legal herbal highs," and their metabolites in human blood plasma. Compounds were resolved using a mixture of ammonium formate (pH 4.5, 0.01 M) and acetonitrile (flow rate of 1.0 mL/min) with a C18 column. Calibration curves were linear from 1 to 50 ng/mL (R2 > 0.99); the lower limit of quantification (LLOQ) was 5 ng/mL; the accuracy was >90%; the intra- and interday relative standard deviations (R.S.D) were <5% and <10%, respectively. Human plasma concentrations of TFMPP were measured in blood samples taken from healthy adults (n = 6) over 24 h following a 60-mg oral dose of TFMPP: these peaked at 24.10 ng/mL (±1.8 ng/mL) (Cmax) after 90 min (Tmax). Plasma concentrations of 1-(3-trifluoromethyl-4-hydroxyphenyl) piperazine peaked at 20.2 ng/mL (±4.6 ng/mL) after 90 min. TFMPP had two disposition phases (t½ = 2.04 h (±0.19 h) and 5.95 h (±1.63 h). Apparent clearance (Cl/F) was 384 L/h (±45 L/h). [source] Synthesis of bis-heteroaryl piperazine derivatives as potential reverse transcriptase inhibitorsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2001Jean Guillaumel Vinylogous analogs of non-nucleoside reverse transcriptase inhibitors belonging to the bis-(hetero-aryl)piperazine (BHAP) series were synthesized by coupling a piperazine derivative with (E)-propenoyl derivatives of heterocyclic moieties. [source] Absorber intercooling in CO2 absorption by piperazine-promoted potassium carbonateAICHE JOURNAL, Issue 4 2010Jorge M. Plaza Abstract Intercooling was evaluated as a process option in CO2 absorption by piperazine (PZ) promoted potassium carbonate. The system performance with 4.5 m K+/4.5 m PZ was simulated by a model in Aspen Plus® RateSepÔ. The absorber was evaluated for use with a double matrix stripper by optimizing the position of the semilean feed and intercooling stages to maximize CO2 removal. Additionally, a simple absorber system was modeled to observe the effect of intercooling on systems with variable CO2 lean loading. Intercooling increases CO2 removal by as much as 10% with the double matrix configuration. With a simple absorber, the effectiveness of intercooling depends on solvent rate. Near a critical liquid/gas ratio (L/G) there is a large improvement with intercooling. This is related to the position of the temperature bulge. An approximation is proposed to estimate the critical L/G where intercooling may maximize removal. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] A general method for the fluorine-18 labelling of fluoroquinolone antibioticsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2003Oliver Langer Abstract Fluoroquinolones are an important class of antibiotic agents with a broad spectrum of antibacterial activity. Labelling of fluoroquinolones with fluorine-18 is of interest for the performance of pharmacokinetic measurements and the visualization of bacterial infections in humans with positron emission tomography. A two-step radiosynthetic pathway to prepare fluorine-18-labelled ciprofloxacin (1-cyclopropyl-6-[18F]fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-quinoline-3-carboxylic acid) has previously been developed. In the present work this approach was applied to the preparation of the structurally related compounds [18F]norfloxacin (1-ethyl-6-[18F]fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-quinoline-3-carboxylic acid) and [18F]pefloxacin (1-ethyl-6-[18F]fluoro-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-quinoline-3-carboxylic acid). The first step of the radiosynthesis consisted of a 18F for 19F exchange reaction on a 7-chloro-substituted precursor molecule, followed by coupling reactions with the amines piperazine or 1-methylpiperazine. Starting from 51,58 GBq of [18F]fluoride 1.9,2.0 GBq of [18F]norfloxacin or [18F]pefloxacin, ready for intravenous injection, could be obtained in a synthesis time of 130 min (3.5,3.8% overall radiochemical yield). Moreover, the preparation of [18F]levofloxacin ((-)-(S)-9-[18F]fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylicacid) was attempted but failed to afford the desired product in practical amounts. Copyright © 2003 John Wiley & Sons, Ltd. [source] New designer drug 1-(3,4-methylenedioxybenzyl) piperazine (MDBP): studies on its metabolism and toxicological detection in rat urine using gas chromatography/mass spectrometry,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2004Roland F. Staack Abstract Studies are described on the metabolism and toxicological analysis of the piperazine-derived designer drug 1-(3,4-methylenedioxybenzyl)piperazine (MDBP) in rat urine using gas chromatography/mass spectrometry (GC/MS). The identified metabolites indicated that MDBP was metabolized by demethylenation and subsequent methylation to N -(4-hydroxy-3-methoxybenzyl)piperazine followed by partial glucuronidation or sulfation. Additionally, degradation of the piperazine moiety to N -(3,4-methylenedioxybenzyl)ethylenediamine and 3,4-methylenedioxybenzylamine and N -dealkylation to piperazine were observed. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid/liquid extraction and microwave-assisted acetylation allowed the detection of MDBP and its above-mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of MDBP by analysis of human urine. Copyright © 2004 John Wiley & Sons, Ltd. [source] Implication of Rho-associated kinase in the elevation of extracellular dopamine levels and its related behaviors induced by methamphetamine in ratsJOURNAL OF NEUROCHEMISTRY, Issue 2 2003Minoru Narita Abstract A growing body of evidence suggests that several protein kinases are involved in the expression of pharmacological actions induced by a psychostimulant methamphetamine. The present study was designed to investigate the role of the Rho/Rho-associated kinase (ROCK)-dependent pathway in the expression of the increase in extracellular levels of dopamine in the nucleus accumbens and its related behaviors induced by methamphetamine in rats. Methamphetamine (1 mg/kg, subcutaneously) produced a substantial increase in extracellular levels of dopamine in the nucleus accumbens, with a progressive augmentation of dopamine-related behaviors including rearing and sniffing. Methamphetamine also induced the decrease in levels of its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA). Both the increase in extracellular levels of dopamine and the induction of dopamine-related behaviors by methamphetamine were significantly suppressed by pretreatment with an intranucleus accumbens injection of a selective ROCK inhibitor Y-27632. In contrast, Y-27632 had no effect on the decrease in levels of DOPAC and HVA induced by methamphetamine. Under these conditions, there were no changes in protein levels of membrane-bound RhoA in the nucleus accumbens following methamphetamine treatment. It is of interest to note that the microinjection of Y-27632 into the nucleus accumbens failed to suppress the increases in extracellular levels of dopamine, DOPAC, and HVA in the nucleus accumbens induced by subcutaneous injection of a prototype of µ-opioid receptor agonist morphine (10 mg/kg). Furthermore, perfusion of a selective blocker of voltage-dependent Na+ channels, tetrodotoxin (TTx) into the rat nucleus accumbens did not affect the increase in extracellular levels of dopamine in the rat nucleus accumbens by methamphetamine, whereas the morphine-induced dopamine elevation was eliminated by this application of TTx. The extracellular level of dopamine in the nucleus accumbens was also increased by perfusion of a selective dopamine re-uptake inhibitor 1-[2-[bis(4-fluorophenyl)methoxy]-4-(3-phenylpropyl)piperazine (GBR-12909) in the nucleus accumbens. This effect was not affected by pretreatment with intranucleus accumbens injection of Y-27632. These findings provide first evidence that Rho/ROCK pathway in the nucleus accumbens may contribute to the increase in extracellular levels of dopamine in the nucleus accumbens evoked by a single subcutaneous injection of methamphetamine. In contrast, this pathway is not essential for the increased level of dopamine in this region induced by morphine, providing further evidence for the different mechanisms of dopamine release by methamphetamine and morphine in rats. [source] Tissue Distribution, Autoradiography, and Metabolism of 4-(2,-Methoxyphenyl)-1-[2, -[N -2,-Pyridinyl)- p -[18F]Fluorobenzamido]ethyl]piperazine (p -[18F]MPPF), a New Serotonin 5-HT1A Antagonist for Positron Emission TomographyJOURNAL OF NEUROCHEMISTRY, Issue 2 2000An In Vivo Study in Rats The in vivo behavior of 4-(2,-methoxyphenyl)-1-[2,-[N -(2,-pyridinyl)- p -[18F]fluorobenzamido]ethyl]-piperazine (p -[18F]MPPF), a new serotonin 5-HT1A antagonist, was studied in awake, freely moving rats. Biodistribution studies showed that the carbon-fluorine bond was stable in vivo, that this compound was able to cross the blood-brain barrier, and that a general diffusion equilibrium could account for the availability of the tracer. The great quantity of highly polar metabolites found in plasma did not contribute to the small amounts of metabolites found in hippocampus, frontal cortex, and cerebellum. Exvivo p -[18F]MPPF and in vitro 8-hydroxy-2-(di- n -[3H]propylamino)tetralin autoradiography were compared both qualitatively and quantitatively. Qualitative evaluation proved that the same brain regions were labeled and that the p -[18F]MPPF labeling is (a) in total agreement with the known distribution of 5-HT1A receptors in rats and (b) characterized by very low nonspecific binding. Quantitative comparison demonstrated that the in vivo labeling pattern obtained with p -[18F]MPPF cannot be explained by differences in regional blood flow, capillary density, or permeability. The 5-HT1A specificity of p -[18F]MPPF and binding reversibility were confirmed in vivo with displacement experiments. Thus, this compound can be used to evaluate parameters characterizing 5-HT1A binding sites in the brain. [source] Alternative stripper configurations for CO2 capture by aqueous aminesAICHE JOURNAL, Issue 12 2007Babatunde A. Oyenekan Abstract Aqueous absorption/stripping is a promising technology for the capture of CO2 from existing or new coal-fired power plants. Four new stripper configurations (matrix, internal exchange, flashing feed, and multipressure with split feed) have been evaluated with seven model solvents that approximate the thermodynamic and rate properties of 7m (30 wt %) monoethanolamine (MEA), potassium carbonate promoted by piperazine (PZ), promoted MEA, methyldiethanolamine (MDEA) promoted by PZ, and hindered amines. The results show that solvents with high heats of absorption (MEA, MEA/PZ) favor operation at normal pressure. The relative performance of the alternative configurations is matrix > internal exchange > multipressure with split feed > flashing feed. MEA/PZ and MDEA/PZ are attractive alternatives to 7m MEA. The best solvent and process configuration, matrix with MDEA/PZ, offers 22 and 15% energy savings over the baseline and improved baseline, respectively, with stripping and compression to 10 MPa. The energy requirement for stripping and compression to 10 MPa is about 20% of the power output from a 500 MW power plant with 90% CO2 removal. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Anti-plasmodial and anti-leishmanial activity of conformationally restricted pentamidine congenersJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2006Tien L. Huang A library of 52 pentamidine congeners in which the flexible pentyldioxy linker in pentamidine was replaced with various restricted linkers was tested for in-vitro activity against two Plasmodium falciparum strains and Leishmania donovani. The tested compounds were generally more effective against P. falciparum than L. donovani. The most active compounds against the chloroquine-sensitive (D6, Sierra Leone) and -resistant (W2, Indochina) strains of P. falciparum were bisbenzamidines linked with a 1,4-piperazinediyl or 1, 4-homopiperazinediyl moiety, with IC50 values (50% inhibitory concentration, inhibiting parasite growth by 50% in relation to drug-free control) as low as 7 nM based on the parasite lactate dehydrogenase assay. Seven piperazine-linked bisbenzamidines substituted at the amidinium nitrogens with a linear alkyl group of 3,6 carbons (22, 25, 27, 31) or cycloalkyl group of 4, 6 or 7 carbons (26, 32, 34) were more potent (IC50 < 40 nM) than chloroquine or pentamidine as anti-plasmodial agents. The most active anti-leishmanial agents were 4,4,-[1,4-phenylenebis(methyleneoxy)]bisbenzenecarboximidamide (2, IC50 , 0.290 ,M) and 1,4-bis[4-(1H-benzimidazol-2-yl)phenyl] piperazine (44, IC50,0.410 ,M), which were 10- and 7-fold more potent than pentamidine (IC50 , 2.90 ,M). Several of the more active anti-plasmodial agents (e.g. 2,31, 33, 36,38) were also potent anti-leishmanial agents, indicating broad antiprotozoal properties. However, a number of analogues that showed potent anti-plasmodial activity (1, 18, 21, 22, 25,28, 32, 43, 45) were not significantly active against the Leishmania parasite. This indicates differential modes of anti-plasmodial and anti-leishmanial actions for this class of compounds. These compounds provide important structure-activity relationship data for the design of improved chemotherapeutic agents against parasitic infections. [source] High-performance liquid chromatographic resolution of 1-(1,4-benzodioxane-2-formyl)- piperazine enantiomers after chiral derivatizationJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005Zhiqiong Chen Abstract Chiral separation of racemic mixtures is of the greatest importance to the pharmaceutical industry, as the isomers of a given racemate may exhibit substantially different pharmacological effects, not to mention possibly differing toxicity behaviour. A novel chiral separation method is developed for the determination of 1-(1,4-benzodioxane-2-formyl)piperazine (BFP) enantiomers. The indirect resolution is performed by applying precolumn derivatization with the chiral reagent 2,3,4,6-tetra- O -acetyl-,-D-glucopyranosyl isothiocyanate (GITC). The resulting diastereoisomers are separated on a reversed-phase ODS column with methanol-potassium dihydrogen phosphate (0.02mol/L, 50:50) as mobile phase. UV detection is at 250 nm. The effect of mobile phase composition upon resolution and analysis time is investigated. Two diastereoisomers show nearly base-line separation under optimal chromatographic conditions. The presented study provides a simple and accurate method for the enantiomeric quality control and the optical purity assay of BFP. [source] Analysis of flunarizine in the presence of some of its degradation products using micellar liquid chromatography (MLC) or microemulsion liquid chromatography (MELC) , Application to dosage formsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005Dina T. El-Sherbiny Abstract The separation of flunarizine hydrochloride (FLZ) and five of its degradation products , 1-[bis(4-fluorophenyl)methyl]-4-(3-phenyl-2-propenyl)piperazine, 4-oxide (A), bis(4-fluorophenyl)methanone (B), bis(4-fluorophenyl)methanol (C), 1-(3-phenyl-2-propenyl)piperazine (D), and 1-[bis-4-fluorophenyl) methyl] piperazine (E) , could be accomplished by reversed phase liquid chromatography using either micellar or microemulsion mobile phases. Cyanopropyl-bonded stationary phase has been used with UV detection at 254 nm. Microemulsion mobile phase consisting of 0.15 M SDS, 10% n -propanol, 1% n -octanol, and 0.3% triethylamine in 0.02 M phosphoric acid of pH 7.0, has been used for the separation of FLZ and its degradation products (B, C, D, and E). Micellar mobile phases consisting of 0.15 M sodium dodecyl sulphate (SDS), 10% n -propanol, 0.3% triethylamine (TEA) in 0.02 M phosphoric acid of pH values either 4.0 or 6.8 have been used for the separation of FLZ from its degradation products, i.e. either from (B, C, D, and E) or from (A, B, C, and D), respectively. Micellar liquid chromatography (MLC) was applied to the determination of FLZ in pure form as well as in dosage forms; the calibration graph was linear over the concentration range of 0.15,50 ,g/mL with detection limit of 0.02 ,g/mL (4.19×10,8M). [source] Acaricidal properties of piperazine and its derivatives against house-dust and stored-food mitesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2009Chi-Hoon Lee Abstract BACKGROUND: Piperazine derivatives possess pharmacological properties, yet the acaricidal activity of these compounds has not been investigated. This study was conducted to evaluate the colour alteration and acaricidal activity of piperazine derivatives against Dermatophagoides spp. and Tyrophagus putrescentiae (Schrank) using filter paper and fumigant methods. RESULTS: In a fumigant bioassay, 1-phenylpiperazine (7.83 µg cm,2) against D. farinae (Hughes) was found to be 4.7 times more toxic than DEET (36.84 µg cm,2), followed by benzyl benzoate (9.72 µg cm,2), piperazine (11.41 µg cm,2), 1-ethoxycarbonylpiperazine (20.14 µg cm,2) and 1-(2-methoxyphenyl)piperazine (22.14 µg cm,2). In a filter paper bioassay, 1-(2-methoxyphenyl)piperazine (3.65 µg cm,2) was 5.7 times more toxic than DEET (20.64 µg cm,2), followed by 1-ethoxycarbonylpiperazine (4.02 µg cm,2), 1-phenylpiperazine (4.75 µg cm,2), benzyl benzoate (7.83 µg cm,2) and piperazine (10.59 µg cm,2). Similar results have been exhibited with piperazine derivatives against D. pteronyssinus (Troussart). However, no activity against T. putrescentiae was observed for piperazine derivatives, except for piperazine. CONCLUSIONS: These results indicate that piperazine derivatives may be suitable as vapour-phase acaricide fumigants owing to their high volatility, acaricidal activity and safety. 1-Phenylpiperazine was found to be an excellent mite indicator based on the colour change it induced. Taken together, these findings indicate that piperazine derivatives may be used to replace existing problematical acaricides owing to their activity and ability to act as a mite indicator. Copyright © 2009 Society of Chemical Industry [source] Formation of a fibrillar morphology of crosslinked epoxy in a polystyrene continuous phase by reactive extrusionPOLYMER ENGINEERING & SCIENCE, Issue 4 2004Françoise Fenouillot An immiscible polymer blend where the dispersed phase is fibrillar was prepared by in situ crosslinking of the minor phase. A model polystyrene/epoxy-amine blend was selected on the basis of rheological (achievement of the fibrillar structure) and reactivity (fast crosslinking) criteria. The system was a polystyrene/diglycidyl ether of bisphenol A (DGEBA)-aminoethyl piperazine (AEP) blend. At the temperature of extrusion, 180°C, the DGEBA is immiscible in PS and heterogeneous material is obtained. The elongational flow imposed by drawing the extrudate at the die exit permitted controlled generation of a fibrillar morphology of the dispersed epoxy phase, with a fiber diameter of 1 ,m and an aspect ratio greater than 100. It was shown that when the amine comonomer was injected into the extruder, its reactivity with DGEBA at high temperature was high enough to ensure partial crosslinking of the epoxy. The fibrils were formed even though the gel point of the epoxy phase was exceeded. However, above a certain critical insoluble fraction that we estimated to be between 45% and 70%, a coarsening of the structure appeared, caused by the decreasing deformability of the domains and their coalescence. Finally, for our system, the crosslinking of the dispersed phase up to 90% of insoluble fraction did not totally stabilize the morphology after the second processing step (injection molding). Polym. Eng. Sci. 44:625,637, 2004. © 2004 Society of Plastics Engineers. [source] A synchrotron study of (2R,5,S)-5,-benzyl-5-bromo-6-methoxyspiro[indane-2,2,-piperazine]-3,,6,-dione dimethylformamide solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Gary S. Nichol Synchrotron radiation was used to study the structure of the title compound, C20H19BrN2O3·C3H7NO, which was obtained as fine fragile needle-shaped crystals by recrystallization from dimethylformamide (DMF), one molecule of which is incorporated per asymmetric unit into the crystal. The compound adopts a compact closed conformation with the orientation of the benzyl group such that the aryl ring is positioned over the piperazinedione ring, resulting in a Cspiro...Ctrans,C,CPh pseudo-torsion angle of ,3.3,(3)°. The five-membered ring is present in an expected envelope conformation and the six-membered piperazinedione ring adopts a less puckered boat-like conformation. Reciprocal amide-to-amide hydrogen bonding between adjacent piperazinedione rings and C,H...O interactions involving DMF molecules propagate in the crystal as a thick ribbon in the a -axis direction. [source] Synthesis of Dimeric Quinazolin-2-one, 1,4-Benzodiazepin-2-one, and Isoalloxazine Compounds as Inhibitors of Amyloid Peptides AssociationARCHIV DER PHARMAZIE, Issue 8 2009Alexander Barthel Abstract The synthesis of dimeric compounds derived from quinazolin-2-one and 1,4-benzodiazepin-2-one possessing a piperazine or homopiperazine spacer was investigated. In addition, a piperazine spacered bis-isoalloxazine and a bis-riboflavin compound were prepared and their ability to interrupt the association of prion proteins and Alzheimer-specific A, peptides was investigated using a fast screening system based on flow cytometry. The bis-isoalloxazine 14 was identified as a new lead structure. [source] Human cytochromes mediating gepirone biotransformation at low substrate concentrationsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2003David J. Greenblatt Abstract Biotransformation of gepirone to 1-(2-pyrimidinyl)-piperazine (1-PP) and 3'-OH-gepirone, as well as two other hydroxylated metabolites, was studied in vitro using a human liver microsomal preparation and heterologously expressed human CYP3A4 and CYP2D6. The focus was on a low range of gepirone concentrations (1000 nM and below). Liver microsomes formed 1-PP and 3'-OH-gepirone with similar reaction velocities. Two other hydroxylated metabolites (2-OH- and 5-OH-gepirone) were also formed, but pure reference standards were not available for purposes of quantitative analysis. The CYP3A inhibitor ketoconazole completely eliminated 1-PP formation, reduced 3'-OH-gepirone formation to less than 20% of control, and reduced 2-OH-gepirone formation to 7% of control. All metabolites were formed by expressed CYP3A4; however, CYP2D6 formed 3'-OH- and 5-OH-gepirone, but not 1-PP or 2-OH-gepirone. Based on estimated relative abundances of the two isoforms in human liver, CYP3A4 was predicted to account for more than 95% of net clearance of gepirone in vivo at low concentrations approaching the therapeutic range. CYP2D6 would account for less than 5% of net clearance. The findings are consistent with previous in vitro studies of gepirone using higher substrate concentrations. Copyright © 2003 John Wiley & Sons, Ltd. [source] ChemInform Abstract: Synthesis of 7-Substituted-(2,3-dihydro-1,4-benzodioxin-5-yl)-piperazine.CHEMINFORM, Issue 52 2008Fabio Rancati Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Isostructural Materials Achieved by Using Structurally Equivalent Donors and Acceptors in Halogen-Bonded CocrystalsCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2008Dominik Cin Abstract We demonstrate the supramolecular and structural equivalence of two halogen-bond donors (I and Br) and three acceptors (O, NH and S) through the synthesis of seven isostructural halogen-bonded cocrystals, involving six different molecules: 1,4-dibromo- and 1,4-diiodotetrafluorobenzene (donors) and thiomorpholine, thioxane, morpholine, and piperazine (acceptors). The formation of isostructural cocrystals indicates how cocrystallization may be used to overcome shape and functional group dissimilarities that control molecular arrangement in the solid state. The differences in composition between the seven isostructural cocrystals directly affect the strength and nature of halogen bonds between their constituents, allowing the systematic variation of cocrystal physical properties, in particular the melting point, without affecting their crystal structure. Replacement of each O or S halogen-bond acceptor with an NH group provided an approximate 70,°C increase in melting point, whereas the replacement of I with Br as the halogen-bond donor lowered the melting point of the resulting solid by a similar amount. [source] | |||||||||||||||||||||||||||||||||||||