Presence Of Magnesium Acetate Research Articles

The first example of a polyhedral boron derivative of gadolinium(III) phthalocyaninate as a promising prototype of a theranostic agent

We report the first synthesis of a polyhedral boron derivative of gadolinium(III) phthalocyaninate. Initially, reaction of 4-nitrophthalonitrile with 4-formylphenol in the presence of base was carried out to give 4-(4-formylphenoxy)phthalonitrile. This compound was then converted to 4-(4-hydroxymethylphenoxy)phthalonitrile using sodium tris-acetoxy borohydride in THF. Sequential cyclotetramerisation of this semiproduct in the presence of magnesium acetate, treatment of the resulting complex with trifluoroacetic acid, and complexation with gadolinium(III) acetate afforded gadolinium(III) phthalocyanine containing four hydroxymethylphenoxy groups at the peripheral (β) positions. Then, a nucleophilic addition reaction of this complex with acetonitrilium derivative of [B10H10]2- anion afforded gadolinium(III) phthalocyaninate decorated with four closo-decaborate units in good/satisfactory yield. The new product was characterised by various techniques (CHN analysis, MALDI-TOF mass spectrometry and UV–Vis spectroscopy). The boron content in this product is 21.5 wt% (40 atoms), and the r1 relaxivity of the conjugate 6.1 ± 0.7 mM-1s−1 (at 3.0 T, 20 °C in water), which makes it a promising prototype for theranostic agents for MRI-guided BNC therapy in future investigations.

MAGNESIUM ACETATE – AN EFFECTIVE ELECTROPHILIC ACTIVATOR OF THE CARBONYL GROUP IN TRANSESTERIFICATION OF DIALKYLAZIRIDINE DICARBOXYLATES

A method for transesterification of the ester groups in dialkylaziridine dicarboxylates by electrophilic activation of the carbonyl group in the presence of magnesium acetate with the preservation of the aziridine ring was developed and the use of modified aziridine dicarboxylates in the synthesis of sterically hindered derivatives of fullerenes C 60 , 2',5'-disubstituted fulleropyrrolidines, was demonstrated. Authors: Angelina V. Kazakova, Dmitriy V. Androsov, Alexander S. Konev*, Alexander F. Khlebnikov

Magnesium acetate – an effective electrophilic activator of the carbonyl group in transesterification of dialkylaziridine dicarboxylates

A method for transesterification of the ester groups in dialkylaziridine dicarboxylates by electrophilic activation of the carbonyl group in the presence of magnesium acetate with the preservation of the aziridine ring was developed and the use of modified aziridine dicarboxylates in the synthesis of sterically hindered derivatives of fullerenes C60, 2',5'-disubstituted fulleropyrrolidines, was demonstrated.

One-step synthesis of differently bis-functionalized isoxazoles by cycloaddition of carbamoylnitrile oxide with β-keto esters

A new protocol for synthesizing different functionalized isoxazoles is provided. Carbamoylnitrile oxide generated from nitroisoxazolone underwent inverse electron-demand 1,3-dipolar cycloaddition with 1,3-dicarbonyl compounds in the presence of magnesium acetate that formed magnesium enolate in situ. Although electron-deficient trifluoroacetoacetate did not undergo this cycloaddition under the same conditions, conversion to sodium enolate furnish the corresponding bis-functionalized trifluoromethylisoxazole. The DFT calculations using B3LYP 6-31G+(d,p) also supported the aforementioned reactivity.

Enzymatic Production of Cellobiose from Starch and Its Reduction to Cellobiitol

Cellobiose (528-50-7) was synthesized from starch using two phosphorylases. α-Glucan phosphorylase (EC 2.4.1.1) converted 39.6% of glucose residues in the starch molecule into glucose 1-phosphate in the presence of 1 M inorganic phosphate. Inorganic phosphate was selectively dialyzed out from the resultant reaction mixture by electrodialysis equipped with an ion exchange membrane having a molecular weight cut-off of 100. Thus glucose1-phosphate solution free from inorganic phosphate was obtained with 82.1% yield. Cellobiose phosphorylase (EC 2.4.1.20) converted 89.2% of added glucose 1-phosphate into cellobiose when the above G1P solution was incubated with a roughly equimolar amount of glucose in the presence of magnesium acetate under alkaline conditions (pH 8.0). As a result of three successive steps using two phosphorylases, cellobiose was produced from starch with a 29.0% yield. Cellobiose was reduced under a sponge nickel catalyst (Raney nickel) and the obtained cellobiitol was crystallized with an 86.7% yield. The 1H- and 13C-NMR spectra of this compound agreed well with those expected from 4-O-β-glucosyl-D-glucitol (cellobiitol, 535-94-4). The X-ray crystallographic analysis of the obtained cellobiitol crystal revealed it to be a monoclinic space group P21 (4), with the following unit-cell parameters: a = 1.0007, b = 0.8683, c = 2.3137 nm, β = 127.27°. From a thermo gravimetric-differential scanning calorimetric analysis, the cellobiitol crystal was found to have a melting point of 103.6°C and to be in the form of a monohydrate. Cellobiitol showed a relative sweetness of around 20, being less sweet than other sugar alcohols such as glucitol (sorbitol) and maltitol. Cellobiitol was found to be much less hygroscopic than sorbitol and maltitol. The median lethal dose of cellobiitol in rats was determined to be more than 5000 mg/kg body weight. All these properties of cellobiitol indicate it to be a promising compound as a food ingredient.

Synthesis of cellobiose from starch by the successive actions of two phosphorylases

Cellobiose was enzymatically synthesized from starch using two phosphorylases. Under the presence of 1 M Pi inorganic phosphate), glucan phosphorylase converted 40% of glucose residues in the starch molecule into G1P (glucose-1-phosphate). By electrodialysis fitted with an ion exchange membrane having molecular weight cutoff of 100, Pi was effectively dialyzed out and G1P was recovered with 80% yield. G1P and glucose were incubated with cellobiose phosphorylase in the presence of magnesium acetate at an alkaline condition. Inorganic phosphate coformed with cellobiose was immediately removed as insoluble magnesium ammonium phosphate and 85% of added G1P was converted into cellobiose. On the whole, cellobiose was produced with 60% yield from G1P and, at least, 23.7% yield from starch.

Determination of phosphorus in polymeric systems using an ashing procedure and inductively coupled plasma atomic emission spectrometry

Phosphorus in different forms is used in a variety of applications (catalysts, thermal stabilizers, flame retardants) in polymeric formulations. It is important to be able to determine its concentration in raw materials, intermediates and final products. The challenge of measuring low concentrations of P, combined with the volatility of the organic phosphorus compounds, has been solved through a novel analytical procedure with a method detection limit of 0.4 µg g−1 P (10σ). The volatilization of organic P compounds was prevented by pre-oxidation with periodic acid, which allows ashing in the presence of magnesium acetate while maximizing the weight to final volume ratio. Using factorial design of experiments, experimental factors including ashing temperature, time, and the amount of the reagents were optimized with respect to accuracy and precision of the technique. The influence of Ti when present in the samples was eliminated by complexing it with H2O2. Additional pre-treatment with NH4OH was found to improve recovery for some reactive samples. Comparison with other established methods was carried out and is discussed.

Copolyesters of hydroxyphenylalkanoic acids: synthesis and thermal properties of poly{(4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} and poly{(3‐bromo‐4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate

AbstractCopolyesters of 8‐(3‐hydroxyphenyl)octanoic acid (HPOA), a monomer with kink and flexible segment derived from cardanol, and 4‐hydroxybenzoic acid (HBA) or its brominated derivative, 3‐bromo‐4‐hydroxybenzoic acid (BrHBA), were synthesized by acidolysis melt polycondensation of the in situ generated acetoxyderivative in the presence of magnesium acetate as catalyst by a one‐pot method and characterized. The formation of the copolyester was confirmed by elemental analysis, FTIR and 1H NMR spectroscopy. These polymers were highly insoluble in most solvents except highly polar solvents, such as trifluoroacetic acid. The inherent viscosities of the soluble polymers were in the range of 0.8–1.1 dlg−1. The thermal and phase behaviour of the copolyesters were studied by DSC and polarized light microscopy. Poly{(4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} with 50 mole% of HPOA showed a birefringent melt with opalescence and a worm‐like texture of a nematic phase. The effect of bromine substitution in the analogue poly{(3‐bromo‐4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} was evident when it showed a lower transition with minimum 45% Br‐HBA at 225 °C showing enhanced melt processability. These copolymers, with hydrolytically degradable aliphatic carbonyl group and better crystallinity compared to poly(hydroxyalkanoate)s, are interesting in possible biomedical applications.© 2002 Society of Chemical Industry

Macrocyclic Cu(II)(2), Cu(II)(4), Ni(II)(3), and Ni(II)(4) Complexes: Magnetic Properties of Tetranuclear Systems.

A binuclear tetraprotonated macrocyclic complex [Mg(2)(L(2)-H(4))(NO(3))(2)](NO(3))(2).6H(2)O (1) has been obtained by template condensation of 4-methyl-2,6-diformylphenol and 1,2-diaminoethane in the presence of magnesium acetate and nitrate. Complex 1 on reduction with NaBH(4), followed by the removal of magnesium, yields the 36-membered octaaminotetraphenol macrocyclic ligand H(4)L(1). The replacement of magnesium in 1 with copper(II) leads to the formation of the binuclear complex [Cu(2)L(3)(ClO(4))(2)] (2) derived from the [2+2] cyclization product of 4-methyl-2,6-diformylphenol and 1,2-diaminoethane. From H(4)L(1) a series of tetranuclear nickel(II) complexes 5-8 with the core cation [Ni(4)L(1)(&mgr;(2)-X)(2)(&mgr;(2)-H(2)O)(2)](2+) (X = NCS, N(3), OAc, or Cl) have been synthesized and characterized. The trinuclear complex [Ni(3)L(1)(acac)(2)(H(2)O)(2).2H(2)O (9), obtained by reacting nickel(II) acetylacetonate with H(4)L(1), on treatment with nickel(II) perchlorate produces the tetranuclear compound [Ni(4)L(1)(acac)(2)(H(2)O)(4)](ClO(4))(2) (10). Variable-temperature (4-300 K) magnetic susceptibility measurements have been carried out for the tetracopper(II) complex [Cu(4)L(1)(H(2)O)(4)](ClO(4))(4) (3) and the tetranickel(II) complexes [Ni(4)L(1)(&mgr;(3)-OH)(&mgr;(2)-H(2)O)(2)(ClO(4))](ClO(4))(2).2CH(3)COCH(3).H(2)O (4), [Ni(4)L(1)(&mgr;(2)-NCS)(2)(&mgr;(2)-H(2)O)(2)](ClO(4))(2).2CH(3)CN (5), [Ni(4)L(1)(&mgr;(2)-N(3))(2)(&mgr;(2)-H(2)O)(2)](ClO(4))(2).2CH(3)OH (6), [Ni(4)L(1)(&mgr;(2)-OAc)(2)(&mgr;(2)-H(2)O)(2)](ClO(4))(2).2H(2)O (7), and [Ni(4)L(1)(&mgr;(2)-Cl)(2)(&mgr;(2)-H(2)O)(2)]Cl(2).4H(2)O (8). The X-ray structure of 5 has been determined. The complex (C(50)H(70)N(12)O(14)Cl(2)S(2)Ni(4)) crystallizes in the triclinic space group P&onemacr; with a = 11.794(6) Å, b = 12.523(4) Å, c = 12.794(5) Å, alpha = 117.28(5) degrees, beta = 96.38(4) degrees, gamma = 109.65(3) degrees, and Z = 1. In the asymmetric unit each of the nickel(II) centers with distorted octahedral geometry is triply-bridged by a phenoxide group, a water molecule, and a N-bonded thiocyanate and these metal centers are further bridged to their symmetry-related counterparts by another phenoxide group. The experimental susceptibility data have been analyzed using appropriate Heisenberg spin coupling models (H = -2J(ij)()S(i)().S(j)()) and the best-fit spin exchange parameters obtained are as follows: J = -288(3) cm(-)(1) (3); J(1) = -8.1(2) cm(-)(1), J(2) = -10.2(2) cm(-)(1) (4); J(1) = -34.5(1.0) cm(-)(1), J(2) = -9.5(2.0) cm(-)(1) (5); J(1) = -34(1) cm(-)(1), J(2) = 11(2) cm(-)(1) (6); J(1) = -30(1) cm(-)(1), J(2) = -7.0(1.5) cm(-)(1) (7); J(1) = -32(1) cm(-)(1), J(2) = -4(1) cm(-)(1) (8).

Nucleotide sequence analysis reveals novel features of the phase-variable cytadherence accessory protein HMW3 of Mycoplasma pneumoniae.

The Mycoplasma pneumoniae hmw3 gene was sequenced and its gene product was characterized with the goal of elucidating the functional role of HMW3 as an accessory component in cytadherence. A total of 2,016 bp of the hmw3 locus was sequenced, revealing an open reading frame large enough to encode a 672-amino-acid protein with a molecular weight of 73,725. No consensuslike ribosome binding or promoter sequences were identified. However, hmw3 was flanked by upstream and downstream open reading frames. Gene identity was confirmed by comparing the deduced amino acid sequence with the amino acid sequence obtained directly from N-terminal amino acid sequencing of HMW3. Analysis of the deduced amino acid sequence indicated an acidic pI (4.4), an unusual distribution of charged residues, a high degree of hydrophilicity, and a high proline content for HMW3. M. pneumoniae protein profiles obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) following culturing in the presence of [3H]Pro were consistent with the high Pro content predicted for HMW3 and indicated the same for cytadherence accessory protein HMW1. A discrepancy existed between the predicted size of HMW3 (Mr, 73,725) and the size of HMW3 obtained by SDS-PAGE (Mr, 140,000). Variable electrophoretic mobility in SDS-PAGE was observed at different acrylamide concentrations for HMW3, indicating that anomalous migration might account for the size discrepancy. The relative mobility of HMW3 was enhanced only slightly in the presence of magnesium acetate, suggesting that the unusual charge distribution might only be partially responsible for the anomalous migration. Secondary structure predictions were dominated by beta-sheets and nonrepetitive turns or coils, suggesting a probable extended, rigid conformation for HMW3. Finally, an unusual, highly acidic domain (residues 180 to 280) which might have particular functional significance relative to the role of HMW3 as a cytadherence accessory protein was identified.

The effect of limited proteolysis on rabbit muscle creatine kinase.

Creatine kinase from rabbit muscle is inactivated by limited proteolysis with proteinase K from Tritirachium album. Gel-filtration and cross-linking studies showed that the limited proteolysis did not affect the molecular weight of the enzyme under non-denaturing conditions, but did cause changes in the reactivity of the reactive thiol group on each subunit and in the ability of the enzyme to form a 'transition-state analogue' complex in the presence of magnesium acetate plus ADP plus creatinine plus NaNO3.

Improved Durable-Press Cotton by a Two-Step Poly-Set Process

A crossrinking treatment on scoured, bleached, mercerized, and desized cotton fabric with dimethyloldihydroxyethylene urea (DMDHEU) by a two-step poly-set process is reported. The fabric was also treated with DMDHEU by the conventional pad-dry-cure tecnhique. The resin-finished fabric, along with a control, were studied for various physiochemical properties by standard methods. The number of crosslinks (expressed as CL/GPU) and length of crosslinks were calculated from formaldehyde yields and nitrogen values. The data on resin add-on, CL/GPU, and length of crosslinks of cotton crosslinked with varying concentrations of the resin in the presence of polymerization catalysts is discussed. The add-on values in the case of the sample treated by zinc acetate was much higher compared to the similar sample treated in the presence of magnesium acetate. The number of CL/GPU and length of crosslink increased with the increase of resin concentration. Homopolymerization of resin was evident in step 1. The fabric processed in step 2 showed marked improvement in wrinkle-recovery angle and other properties such as strength, elongation, abrasion, and toughness, compared to the samples treated by the conventional process. The relationship between various properties of the fabric is also dealt with.

The Control of Phosphoprotein Phosphatase by the Second‐Site Phosphorylation of a Substrate

The phosphorylation of Ser-32, in addition to Ser-36 of H2B histone, stimulated the rate of Pi release from Ser-36 by the small form (Mr 31 000) of pig heart phosphoprotein phosphatase both in the absence and presence of 50 mM magnesium acetate. By phosphorylation at Ser-32, the Km value for Ser-36 phosphate in H2B histone was increased from 0.38 microM to 1.16 microM in the absence of magnesium acetate, but not significantly changed (from 37.4 microM to 26.2 microM) in the presence of magnesium acetate. With the large form (Mr 224000) of the phosphoprotein phosphatase, however, the phosphorylation at Ser-32 suppressed the rate of Pi release from Ser-36 both in the absence and presence of magnesium acetate. The Km value of the large form for Ser-36 phosphatase in H2B histone was nevertheless increased by phosphorylation at Ser-32, from 1.2 microM to 5.3 microM in the presence of magnesium acetate, but not changed (from 0.26 microM to 0.23 microM) in the absence of magnesium acetate.

Polyamines and protein synthesis: V. Effect of salt solutions on aminoacyl transfer RNA formation

1. The effect of salt solutions on the aminoacylation of tRNA in the presence of either magnesium acetate or spermine was compared. 2. Aminoacylation of tRNA with leucine, isoleucine and valine stimulated by either magnesium acetate or spermine was sensitive to NaCl, a slight difference in sensitivity being observed. 3. The salts KCl, NH 4Cl and LiCl as well as NaCl inhibited isoleucyl-tRNA formation stimulated by either magnesium acetate or spermine. 4. Phenylalanyl-tRNA formation was not inhibited by NaCl, KCl and NH 4Cl in the presence of magnesium acetate but was inhibited by these salt solutions in the presence of spermine. 5. The salts NaCl and LiCl inhibited the binding of spermine to tRNA. 6. It is suggested that the inhibitory effect of salt solutions on aminoacyl-tRNA formation might be due to the inhibition of the binding of spermine to tRNA.

Determination of Fluoride Content in Cheese by a Microdiffusion Method

A simple method has been developed for determination of fluoride in cheese. It consists of ashing a cheese sample in the presence of magnesium acetate, which converts fluorine into the magnesium salt. The ash is then quantitatively transferred to the sample compartment of a modified Conway microdiffusion cell. Fluoride is liberated as HF upon mixing with sulfuric acid and absorbed by the sodium hydroxide in the center compartment. The soluble sodium fluoride thus formed is determined colorimetrically with a lanthanum-alizarin complexan reagent. Experimental conditions for the quantitative recovery of fluoride in cheese have been established for this method, which can measure up to 40μg of fluoride in the cheese sample. The fluoride contents in several Italian cheeses have been analyzed; the average concentration ranges from 4 to 7μg of fluoride per gram of dry cheese solids.

Metabolic Products of Fungi. XVII. The Structure of Flavoskyrin.

Emodin was obtained by the air-oxidation of flavoskyrin in the presence of magnesium acetate, which gave an evidence for the proposed structural formula (I). By the action of chromium trioxide or active manganese dioxide, flavoskyrin yielded dianhydrorugulosin which resulted by oxidative coupling. In methanolic alkaline solution flavoskyrin was converted into a skyrin-like compound.

Metabolic products of fungi. XIII. The structure of oxyskyrin.

Emodin was obtained by the air-oxidation of flavoskyrin in the presence of magnesium acetate, which gave an evidence for the proposed structural formula (I). By the action of chromium trioxide or active manganese dioxide, flavoskyrin yielded dianhydrorugulosin which resulted by oxidative coupling. In methanolic alkaline solution flavoskyrin was converted into a skyrin-like compound.