Amino acid end-group in commercial heparin. III. Determination of the number of amino groups of amino acid and hexosamine residues per heparin molecule

The reactions of heparin with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were studied spectrometrically. Seven different commercial heparins were used in this study. The amino groups react with TNBS to form equimolar amounts of trinitrophenylated (TNP) amino groups and bisulfite ions. The TNP-amino groups further react with bisulfite ions to form the monosubstituted anionic sigma complex. The absorption spectrum with two maxima at approximately 350 nm and approximately 420 nm, characteristic of either the TNP-amino groups or the complex, was analyzed for the reaction of TNBS with heparin. It was shown that the reactivities of TNBS with amino groups from α-amino acid and hexosamine residues are greatly different. By combining the results of the reaction kinetics and the reaction of heparin with Sanger's reagent, the number of the α-amino groups and the free amino groups in hexosamine residues were determined. These data have been performed with a range of heparins from different commercial sources, of different activities and physical characteristics. No correlation was found between the free amino contents of these heparins and biological potency. © 1993 John Wiley & Sons, Inc.     

Transformation of Cinchona alkaloids into 1-N-oxide derivatives by endophytic Xylaria sp isolated from Cinchona pubescens

The microbial transformation of four Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine) by endophytic fungi isolated from Cinchona pubescens was investigated. The endophytic filamentous fungus Xylaria sp. was found to transform the Cinchona alkaloids into their 1-N-oxide derivatives.     

Effect of equimolar salt to decyltrimethylammonium decyl sulfate on vesicle formation and surface adsorption

The aqueous solution of mixture of sodium decyl sulfate (SDeS) and decyltrimethylammonium bromide (DeTAB) has been found to form equilibrium multilamellar vesicles (MLV) spontaneously. We measured the surface tension of the aqueous solution of 1:1 mixture of SDeS and DeTAB as a function of temperature T at various molalities m under atmospheric pressure. The surface density, the entropy of adsorption and the entropy of vesicle formation are evaluated and compared with those of the decyltrimethylammonium decyl sulfate (DeTADeS) aqueous solution system to investigate the role of small counterions in the mechanism of equilibrium vesicle formation. The saturated surface density Gamma (H,C ) vs T curve of the SDeS/DeTAB system sits below that of the DeTADeS system. Therefore, sodium and bromide ions are negatively adsorbed and nevertheless, they neutralize the electric charge of the decyl sulfate ion DeS(-) and the decyltrimethylammonium ion DeTA(+) to some extent to weaken the electrostatic attraction between the polar head groups in the adsorbed film. The net surfactant concentration required for vesicle formation was larger in the SDeS/DeTAB system. Hence, the electrostatic attraction between the polar head groups of the surfactant ions which is one of the major driving forces for vesicle formation is weakened by the presence of the counterions Na(+) and Br(-). Small but distinct changes in the surface density and the entropies of MLV formation of the SDeS/DeTAB system from those of the DeTADeS system were also found.     

A new method of removing excess of reagent from organic phases in the solvent extraction of metal complex anions with quaternary ammonium salts: Spectrophotometric determination of micro amounts of cobalt with 2-nitroso-1-naphthol-4-sulfonic acid

The removal of excess reagent extracted into an organic phase in the solvent extraction of a metal complex anion with a quaternary ammonium ion is discussed. With a given chelating ligand (HO—R—SO₃H), the order of extractability is HO—R—SO₃^- > M(OR—SO₃)^n- > X^- > ^-O—R—SO₃^- when an anion such as nitrate or halide is added. If suitable amounts of the anion are added, only the excess of reagent can be removed. The principle is applied to the extraction with zephiramine of the cobalt complex anion formed with 2-nitroso-1-naphthol-4-sulfonic acid. Micro amounts of cobalt in pure nickel salts were determined spectrophotometrically.     

Syntheses and biological activities of renin inhibitors containing statine analogues

Syntheses and biological activities of dipeptide renin inhibitors that contain statine analogues are described. The key steps of the synthetic approach to dipeptide renin inhibitors are the asymmetric synthesis of 2(R)-substituted-3-aminocarbonylpropionic acids and the diastereoselective syntheses of (3S,4S)-statine analogues. These inhibitors (2,14-40) inhibited human renin in the 3-140 nM range. Inhibitor ES 6864 (2) was found to be a highly potent inhibitor of human renin (IC50: 4.6 x 10(-9) M) and showed high enzyme specificity. Oral administration of ES 6864 at 3 mg/kg to conscious, sodium-depleted marmosets inhibited plasma renin activity (PRA) more than 80% after 1 h.     

Targeting of mitomycin C to the liver by the use of asialofetuin as a carrier.

Desialylated fetuin (asialofetuin) was adopted as a carrier for introducing drugs in parenchymal liver cells. Mitomycin C, as a model guest-compound, was covalently attached to asialofetuin through a spacer of the succinyl group. The asialofetuin-mitomycin C conjugate contained 4.4 w/w% of mitomycin C and liberated it gradually at physiological conditions (t1/2 = 37 h). The survival time of the conjugate in rat blood circulation was significantly smaller than that of the non-desialylated fetuin conjugate; the elimination half-life was 7.3 min after intravenous injection. At 30 min after injection of the conjugate in rats, 40% of the dose was present in the liver. Parenchymal cells in the liver selectively took up the conjugate, which was highly distributed to the lysosomal fraction in the cell. The greater uptake of the conjugate by hepatocytes reflected the increased excretion in the bile; totally 10.4% of the dose was recovered.     

Chiral ligand-controlled asymmetric conjugate addition of lithium amides to enoates

The external chiral ligand-controlled asymmetric conjugate addition reaction of lithium amides with alpha,beta-unsaturated esters provided beta-amino esters in high yields and high enantioselectivities.     

Requirement for radiation shields of transportation pipe for on line inhalation gases from compact cyclotron in positron emission tomography

In the unit housing of a compact cyclotron and positron emission CT (PET), positron emitting gas such as 15O, 11C, C15O2, C15O etc. is supplied from a cyclotron to a PET room through a transportation pipe with an appropriate shield to reduce positron annihilation radiation. Using lead or concrete shield blocks with various thicknesses, radiation leakage through the shield was measured by an ionization chamber type survey meter during continuous and constant supply of 15O gas of 1.85 GBq/min concentration which is the maximum dose for clinical use. The leakage radiation measured was 213.7, 56.0, 15.3, 5.0 muSv/week for lead shield with 1, 2, 3, and 4 cm thickness, respectively, and 193.3, 30.5 and 5.1 muSv/week for concrete shields with thickness of 10, 20, and 30 cm, respectively. The present study shows that to keep less than 300 muSv/week, which is the permissible dose rate of the boundary zone around the radiation controlled area by Japan Science and Technology Agency, it is required to use more than 8 mm thick lead shield or 7 cm thick concrete for continuous supply of 1.85 GBq/min 15O gas.