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Basic Medium (basic + medium)
Selected AbstractsAiding Factors in the Formation of Azaplatinacyclobutane Rings , X-ray and Crystal Structure of [Pt{CH(Ph)CH2NEt2 -,C,,N}(N,N,N,,N, -tetramethylethylenediamine)]+ and of Its Open-Chain PrecursorEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2007Giuseppe Lorusso Abstract The addition products 2 of a secondary amine to a coordinated olefin, in the cationic complexes [PtCl(,2 -CH2=CHR)(tmeda)]+ (tmeda = N,N,N,,N, -tetramethylethylenediamine; R = Me, 1a; Ph, 1b, H, 1c), undergo in basic medium an intramolecular nucleophilic substitution with elimination of the chlorido ligand and formation of an azaplatinacyclobutane ring 3. The ring-closing process occurs notwithstanding the absence of a labilizing ligand trans to the leaving chlorido ligand and of bulky substituents on the amino,ethanide chain. If the addition product 2 is a mixture of Markovnikov and anti-Markovnikov isomers, the ring-closing reaction is faster for the anti-Markovnikov form, and this leads to an increase of the relative amount of the anti-Markovnikov isomer in the cyclized species 3. The difference in the rate of formation of the azaplatinacyclobutane ring between the two isomers has been interpreted on the basis of a more favorable stereochemistry in the case of the anti-Markovnikov form. The X-ray crystal structures of [Pt{CH(Ph)CH2NEt2 -,C,,N}(tmeda)]+ (3bn) and of its open-chain precursor, [PtCl{CH(Ph)CH2NHEt2}(tmeda)]+ (2bn) fully support this hypothesis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Reductive-Cyclization-Mediated Synthesis of Fused Polycyclic Quinolines from Baylis,Hillman Adducts of Acrylonitrile: Scope and Limitations,,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2009Virender Singh Abstract The synthesis of a variety of polycyclic quinolines is described. The target molecules were obtained in two steps by an initial reductive cyclization followed by another intramolecular cyclization in the allylamines afforded from either the acetates or allyl bromides of Baylis,Hillman adducts of 2-nitrobenzaldehydes and acrylonitrile. The two steps proceeded in one-pot for those substrates in which a formyl or hydroxy group reacted with the amino group of the 2-aminoquinoline in the second intramolecular cyclization. In contrast, a basic medium was necessary for the second intramolecular cyclization reaction in substrates in which an alkoxycarbonyl group and the amino group participated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Carbon-Carbon Double Bond versus Carbonyl Group Hydrogenation: Controlling the Intramolecular Selectivity with Polyaniline-Supported Platinum CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2008Martin Steffan Abstract The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI-supported platinum catalysts (particle sizes between 1.7 and 3.7,nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition-precipitation of H2PtCl6 onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol-method). The PANI-supported platinum catalysts were applied in the selective hydrogenation of the ,,,-unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO2), alumina (Al2O3), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO2 on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the ,-PtO2 form) which is able to efficiently hydrogenate the conjugated CC bond of citral (selectivity to citronellal=87%), whereas reduction of the CO group occurs with polyaniline-supported platinum (selectivity to geraniol/nerol=78%) prepared via the sol-method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated CC or CO group is not only particularly useful for the selective hydrogenation of ,,,-unsaturated aldehydes but also unveils the great potential of conducting polymer-supported precious metals in the field of hitherto barely investigated chemical catalysis. [source] Consequences of eicosapentaenoic acid (n-3) and arachidonic acid (n-6) supplementation on mast cell mediatorsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 7-8 2004T. Gueck Summary Mast cells are important players in the pathogenesis of atopic diseases. These cells release immediate-phase and late-phase mediators of inflammation. Fatty acids are incorporated in cellular membranes and therefore seem to influence mediator production and release. A study was conducted to assess the effects of eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (AA, 20:4n-6) on mast cell mediators in a canine mastocytoma cell line (C2). Cells were cultured in a basic medium (Dulbecco's modified Eagle's medium/HAM's F12 1 : 1, DEH), DEH supplemented with 14.0 ,m EPA (DEH-EPA) or 14 ,m AA (DEH-AA). The DEH-AA cultured cells had increased spontaneous and mastoparan-stimulated PGE2 production and histamine release. Furthermore, the tryptase activity was increased. The DEH-EPA cultured cells rendered elevated levels of PGE2 and histamine release compared with DEH only after stimulation. These levels were significantly lower in comparison to DEH-AA. The increased PGE2 production of C2 cultured in DEH-AA is the consequence of the AA enrichment, because AA is the precursor of PGE2. However, the different effects by AA and EPA on mast cell mediators possibly reflect the higher susceptibility of long chain polyunsaturated fatty acids (PUFA) to undergo lipid peroxidation, because it is known that altered cellular redox state influences mediator production and release. [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 studies of new 3-benzyl-4H -1,2,4-triazole-5-thiol and thiazolo[3,2- b][1,2,4]triazole-5(6H)-one heterocyclesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2008Abdelwareth A. O. Sarhan 3-Benzyl-4-phenyl-1,2,4-triazole-5-thiol (1) was synthesized and used as starting material for preparation of 1,2,4-triazole bearing substituted thiosemicarbazides moiety (4a-d) in high yields. The thiosemicarbazides 4a-d were cyclized in basic medium to give two triazole rings linked by thiomethylene group (5a-d), while cyclization of thiosemicarbazides 4a-d with chloroacetyl chloride in the presence of CHCl3 and K2CO3 afforded the thiazolidinone derivatives 6a-d. The reaction of thiosemicarbazides 4a-c with phenacyl bromide in the presence of EtOH and fused CH3COONa gave the corresponding thiazoline ring systems 7a-c. Condensation of the 3-benzyl-1,2,4-triazole-5(1H)-thiol (1) with chloroacetic acid and aromatic aldehydes (8a- g) in boiling acetic acid/acetic anhydride mixture in the presence of fused sodium acetate gave one single isomer only, which might be 9a-g or 10a-g. Upon application of Micheal addition reaction on compounds 9a-e with cyclic secondary amines such as piperidine or morpholine the 2-benzyl-6-(,-amino-aryl/methyl)-1,3-thiazolo[3,2- b][1,2,4]-triazol-5-ols (11a-j) were obtained in good yields The structure of all new compounds were determined using both spectral and elemental analyses. [source] Analysis of the Stability and Degradation Products of TriptolideJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2000YAN PING MAO Triptolide is the major active ingredient of the Chinese herbal remedy Tripterygium wilfordii Hook F. (TwHF). As triptolide content is used to estimate the potency of preparations of TwHF, assessment of its stability is warranted. The accelerated stability of triptolide was investigated in 5% ethanol solution in a light-protected environment at pH 6.9, within a temperature range of 60,90°C. The observed degradation rate followed first-order kinetics. The degradation rate constant (K25°C) obtained by trending line analysis of Arrhenius plots of triptolide was 1.4125 times 10,4 h,1. The times to degrade 10% (t1/10) and 50% (t1/2) at 25°C were 31 and 204 days, respectively. Stability tests of triptolide in different solvents and different pH conditions (pH 4,10) in a light-protected environment at room temperature demonstrated that basic medium and a hydrophilic solvent were the major factors that accelerated the degradation of triptolide. Triptolide exhibited the fastest degradation rate at pH 10 and the slowest rate at pH 6. In a solvent comparison, triptolide was found to be very stable in chloroform. The stability of triptolide in organic polar solvents tested at both 100% and 90% concentration was greater in ethanol than in methanol than in dimethylsulphoxide. Stability was also greater in a mixture of solvent: pH 6 buffer (9:1) than in 100% solvent alone. An exception was ethyl acetate, which is less polar than the other solvents tested, but permitted more rapid degradation of triptolide. Two of the degradation products of triptolide were isolated and identified by HPLC and mass spectroscopy as triptriolide and triptonide. This suggested that the decomposition of triptolide occurred at the C12 and C13 epoxy group and the C14 hydroxyl. The opening of the C12 and C13 epoxy is an irreversible reaction, but the reaction occurring on the C14 hydroxyl is reversible. These results show that the major degradation pathway of triptolide involves decomposition of the C12 and C13 epoxy group. Since this reaction is very slow at 4°C at pH 6, stability is enhanced under these conditions. [source] Primary kinetic hydrogen isotope effects in deprotonations of a nitroalkane by intramolecular phenolate groupsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2010Nicholas Backstrom Abstract Rate constants and kinetic isotope effects have been determined for the formation of nitronate anions from the ethers 1-(2-methoxyphenyl)-2-nitropropane, 7(X,=,H, L,=,H and D) and 1-(2-methoxy-5-nitrophenyl)-2-nitropropane, 7(X,=,NO2, L,=,H and D), and from the corresponding phenols, 1-(2-hydroxyphenyl)-2-nitropropane, 3(X,=,H, L,=,H and D), and 1-(2-hydroxy-5-nitrophenyl)-2-nitropropane, 3(X,=,NO2, L,=,H and D), in aqueous basic medium. For the ethers 7, rates of deprotonation by hydroxide are comparable with those found for deprotonations of 2-nitropropane, with kH/kD (25,°C),=,7.7 and 7.8, respectively. In both the cases, the isotope effects are conventionally temperature dependent. For the corresponding phenols 3, conditions have been established under which the deprotonations of the nitroalkane are dominated by intramolecular deprotonation by the kinetically first-formed phenolate anion, with an estimated effective molarity EM,,,250. For 3 (X,=,H, L,=,H or D), kH/kD (25,°C),=,7.8, with E,,,E,=,6.9,kJ,mol,1 and AH/AD,=,0.5. For 3(X,=,NO2, L,=,H or D), rates of intramolecular deprotonation are reduced 30-fold, and an elevated kinetic isotope effect is found (kH/kD (25,°C),=,10.7). Activation parameters (E,,,E,=,17.8,kJ,mol,1 and AH/AD,=,0.008) are compatible with an enhanced tunnelling contribution to reactivity in the H-isotopomer. Copyright © 2009 John Wiley & Sons, Ltd. [source] Study of the adsorption of benzimidazole and 2-mercaptobenzothiazole on an iron surface by confocal micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2004G. Wang Abstract Benzimidazole (BIMH) and 2-mercaptobenzothiazole (HMBT) dissolved in ethanol were chosen for the investigation of the interaction between organic molecules and surface atoms of iron or iron oxide by confocal micro-Raman spectroscopy. Both BIMH and HMBT show enhanced and highly structured spectra in the 200,1500 cm,1 region when the iron is at a potential of ca ,0.7 to ,0.9 V in a neutral medium. BIMH had a weak interaction with the iron surface in a basic medium but it was chemically adsorbed in a neutral medium. HMBT was chemically adsorbed on the iron via the exocyclic S and N atoms in acidic and neutral solutions, whereas in basic media it was bound electrostatically. Copyright © 2004 John Wiley & Sons, Ltd. [source] Selective recognition of thymidine homopolymer (poly T) oligonucleotide with cobalt(II),4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene complexLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2009Feng Ling Guo Abstract The interactions of cobalt(II),4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) complex with different kinds of homopolymer oligonucleotides in basic medium were investigated based on the measurements of resonance light scattering, UV,vis, circular dichroism spectra and dark field light-scattering imaging. Experiments showed that only thymidine homopolymer (poly T) oligonucleotides with the length in the range of poly T6 to poly T18 could interact with the Co(II),5-Cl-PADAB complex in alkaline conditions and cause evident color and spectral change. Thus, the binary complex of Co(II),5-Cl-PADAB could be employed as a visual probe for selectively recognizing the poly T oligonucleotides. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fibroblast Growth Factor 2 Promotes Endothelial Differentiation of Adipose Tissue-Derived Stem CellsTHE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009Hongxiu Ning PhD ABSTRACT Introduction., Adipose tissue-derived stem cells (ADSC) could potentially restore endothelial function in vasculogenic erectile dysfunction (ED). The mechanism for ADSC endothelial differentiation remained unidentified. Aim., To test whether ADSC could differentiate into endothelial cells in the penis and to identify the underlying mechanism of ADSC endothelial differentiation. Methods., For in vivo endothelial differentiation, ADSC were labeled with bromodeoxyuridine (BrdU), injected into rat corpora cavernosa, and localized by immunofluorescence and phase-contrast microscopy. For in vitro endothelial differentiation, ADSC were grown in endothelial growth medium 2 (EGM2), stained for endothelial markers CD31, von Willebrand Factor (vWF), and endothelial nitric oxide synthase (eNOS), and assessed for the ability to form tube-like structures in Matrigel and to endocytose acetylated low-density lipoprotein (Ac-LDL). To identify factors that promote ADSC endothelial differentiation, ADSC were grown in various media, each of which contained a specific combination of supplemental factors and assessed for LDL-uptake. PD173074, a selective inhibitor of fibroblast growth factor 2 (FGF2) receptor, was used to confirm the importance of FGF2 signaling for ADSC endothelial differentiation. Main Outcome Measures., In vivo endothelial differentiation was assessed by immunofluorescence microscopy. In vitro endothelial differentiation was assessed by immunofluorescence, Matrigel tube formation, and Ac-LDL uptake. Results., Injected ADSC were localized to the sinusoid endothelium, some of which stained positive for both BrdU and endothelial antigen rat endothelial cell antigen. ADSC proliferated at a faster rate in EGM2 than in standard DMEM, expressed endothelial markers CD31, vWF, and eNOS, formed tube-like structures in Matrigel, and endocytosed Ac-LDL. These properties were greatly diminished when ADSC were grown in the absence of FGF2 but were unaffected when grown in the absence of vascular endothelial growth factor, insulin-like growth factor, or epidermal growth factor. Furthermore, ADSC displayed similar endothelial properties when grown in FGF2-supplemented basic medium as in EGM2. Finally, blockade of FGF2 signaling with PD173074 abrogated ADSC endothelial differentiation. Conclusions., ADSC could differentiate into endothelial cells in the penis. FGF2 signaling mediates ADSC endothelial differentiation. Ning H, Liu G, Lin G, Yang R, Lue TF, and Lin CS. FGF2 promotes endothelial differentiation of adipose tissue-derived stem cells. J Sex Med **;**:**,**. [source] Effects of glucose and nitrogen source concentration on batch fermentation kinetics of Lactococcus lactis under hemin-stimulated respirative conditionBIOTECHNOLOGY PROGRESS, Issue 4 2008Azher Razvi Abstract Analytical solutions to the ordinary differential equations governing the kinetics of cell growth, substrate utilization, and product formation of batch fermentation processes were derived and used to study the kinetics of the hemin-stimulated respiratory cultivation of Lactococcus lactis at varied initial glucose concentrations and nitrogen source concentrations. Studies revealed that initial glucose concentration varying in the range of 60 to 90 g/L had no significant substrate inhibitive effect. Furthermore, elevating the concentration of complex nitrogen sources while maintaining glucose concentration at 60% led to a high final biomass concentration of 6.6 g/L, substantially higher than that obtained with the basic medium, which was 4.1 g/L. [source] Production and Characteristics of an Enantioselective Lipase from Burkholderia sp.CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2008GXU5 Abstract The lipase production of Burkholderia sp. GXU56 was influenced by carbon and nitrogen sources, inorganic salts, initial pH of the medium and cultivation temperature. The maximum lipase production was 580.52,U/mL and reached 5,times the level of the basic medium in the optimum medium at pH 8.0, 32,°C, 200,rpm and 40,48,h. The lipase was purified 53.6,fold to homogeneity and the molecular weight was 35,KDa on SDS-PAGE. The optimum pH and temperature of the lipase were 8.0 and 40,°C, respectively, and it was stable in the range of pH 7,8.5 and at temperatures below 45,°C. The lipase activity was strongly inhibited by Zn2+, Cu2+, Co2+, Fe2+, Fe3+ ions and SDS, while it was stimulated by Li+ and Ca2+ ions and in presence of 0.1,% CTAB, 0.1,% Triton X-100 and 10,% DMSO. Km and Vmax of the lipase were calculated to be 0.038,mmol/L, and 0.029,mmol/L min,1, respectively, with PNPB as the substrate. The GXU56 lipase showed enantioselective hydrolysis of (R,S)-methyl mandelate to (R)-mandelic acid, which is an important intermediate in the pharmaceutical industry. [source] Preparation of Mesoporous Molecular Sieves Al-MSU-S Using Ionic Liquids as TemplateCHINESE JOURNAL OF CHEMISTRY, Issue 10 2006Xin-Yu Yu Abstract Mesoporous molecular sieves Al-MSU-S has been prepared from the precursor of zeolite Y using ionic liquids 1-hexadecane-3-methylimidazolium bromide (CMIMB) as a template in basic medium, which exhibited larger pore diameter, pore volume and surface area than that synthesized using cetyl trimethyl ammonium bromide (CTAB) template. [source] A practical approach to the synthesis of insect antifeedant tonghaosu analogs,CHINESE JOURNAL OF CHEMISTRY, Issue 12 2001Jun-Fa Fan Abstract Tonghaosu and its analogs are a class of structurally interesting spiroketal enol-ether compounds. A practical route to furandiol, a key intermediate for their syntheses, was developed. Using Friedel-Crafts benzoylation of 3-(2-fury I) propyl acetate, a diarylketone was obtained in high yield, which was further transformed into corresponding furandiol by reduction with NaBH4 in basic medium with simultaneous ester hydrolysis. The furandiol was then cyclized into the desired spiroketal enol-ether compound in the presence of CuSO4 5H2O. [source] Enantioselective LC/MS method for the determination of an antimalarial agent Fenozan B07 in dog plasmaCHIRALITY, Issue 5 2006Ciriaco Maraschiello Abstract A chiral liquid chromatography/mass spectrometry (LC/MS) bioanalytical procedure has been developed for the analysis of the antimalaric agent Fenozan B07 in dog plasma. Normal-phase chromatography involving a phenylcarbamate derivative of cellulose coated on silica gel as the chiral stationary phase was used to resolve (,)-(S,S)-B07 from (+)-(R,R)-B07. The enantiomers were detected by a mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) interface operated in the negative ion mode. A mass spectrum, characterized by a base peak of m/z 285, was obtained for each enantiomer. The m/z 285 ion was very specific for the analysis of both enantiomers in the plasma. The selected ion monitoring analysis of the plasma samples was therefore performed at m/z 285 for quantitative purposes. The enantiomers were extracted from the plasma in a basic medium and purified by solid-phase extraction using a hydrophilic,lipophilic balanced sorbent. A lower limit of quantification of 2 ng/mL in plasma was achieved for both enantiomers. The quantitative procedure reported in this study was highly specific and sensitive, and was validated according to the FDA guidance on bioanalytical method validation. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||