Sodium Borodeuteride Research Articles

Stereoselective synthesis of [11 β‐3H]prostaglandin E1

AbstractThis report describes an efficient stereoselective synthesis of [11β‐3H]prostaglandin E1 ([11β‐3H]PGE1). The key multiply protected 11‐keto intermediate was prepared in only three steps from PGE1. Reduction of the ketone function at C‐11 with sodium borodeuteride and sodium borotritide, followed by sequential removal of protecting groups, afforded PGE1 labeled with deuterium and tritium, respectively, at the 11‐beta position. The reduction and deprotection were accomplished in one reaction flask without requiring purification of intermediates. Trace amounts of C11‐epimer formed in the reduction were readily separated by means of preparative reversed‐phase HPLC. Using sodium borotritide of nominally 67 Ci/mmol, we obtained [11β‐3H]PGE1 with specific activity of 15 Ci/mmol. A disposition study in the monkey with intravenous administration of this material indicated excellent in vivo metabolic stability of the 11β‐tritium label.

Screening techniques for the detection of inborn errors of bile acid metabolism by direct injection and micro-high performance liquid chromatography-continuous flow/fast atom bombardment mass spectrometry

Two methods, direct injection-continuous flow fast atom bombardment (DI-CF/FAB) mass spectrometry and micro-high-performance liquid chromatography (mu HPLC)-CF/FAB) mass spectrometry were developed for the clinical analysis of urinary bile acids and their conjugates, specifically for the diagnosis of disorders of bile acid metabolism. The method based upon DI of urine extracts into the CF/FAB flow stream was developed for the rapid screening of large numbers of patient samples. It allows injections to be made at 4 min intervals for high sample throughput. Analyses of standard mixtures of bile salts demonstrate that linear response curves are obtained over more than a hundred-fold concentration range with a minimum detectable amount in the picogram range. Oxo bile salts are identified by reduction with sodium borodeuteride followed by reanalysis for detection of any reduction products. This methodology has been used for the analysis of over 1000 specimens. A reverse-phase mu HPLC-CF/FAB mass spectrometric method was also developed for use in the confirmation or further investigation of screening results. With no additional sample preparation this method permits the separation, identification and quantitation of urinary bile salt isomers within a 45 min analysis time.

The in Vivo Glycation of Diabetic Tendon Collagen Studied by Neutron Diffraction

Glycation (non-enzymatic glycosylation) sites in the axial unit cell of diabetic tendon collagen were investigated by neutron diffraction. Samples of diabetic and control tendon were reacted with sodium borodeuteride and sodium cyanoborodeuteride. This facilitated deuteration at aldimine, aldol or ketoimine groups in the molecule. These are natural collagen cross-links and sites where non-enzymatic glycation had occurred. The introduction of a deuteron at specific locations allowed the diabetic glycation collagen to be treated as multiple isomorphous derivatives for neutron fibre diffraction. Neutron diffraction was conducted at the Institut Laue Langevin, Grenoble. Standard crystallographic refinement techniques (modified for axial projections) were used to determine the structure of the control (non-diabetic) and diabetic samples. The results are shown as difference maps, these indicate that glycation takes place at different rates within the collagen axial unit cell. The position of glycation correlates well with the position of hydroxylysine residues. The reactions of periodate with enzymatically attached sugars, proteoglycan, natural cross-links and glycation products lead to complications in map interpretation.

Chemical characterization and toxicity of dihydro derivatives of nodularin and microcystin-LR, potent cyanobacterial cyclic peptide hepatotoxins.

Dihydro derivatives of nodularin (1) and microcystin-LR (4), potent cyclic peptide hepatotoxins isolated from Nodularia spumigena and Microcystis aeruginosa, respectively, were prepared by sodium borohydride reduction of the dehydroamino acid residues. The two stereoisomers of both dihydronodularin (2 and 3) and dihydromicrocystin-LR (5 and 6), isolated by reversed-phase HPLC, showed similar toxicity to each other [ip in mice, LD50 = 150 (2), 150 (3), 85 (5), and 100 (6) micrograms/kg]. The stereochemistries of the reduced amino acids obtained by acid hydrolysis of dihydronodularin and dihydromicrocystin-LR [respectively, alpha-(methylamino)butyric acid and N-methylalanine] were determined by GC on a permethylated beta-cyclodextrin capillary column as their trifluoroacetyl methyl ester derivatives. Authentic L- and DL-N-methylamino acids were prepared to compare directly with the natural amino acids. Deuterated derivatives were also prepared using sodium borodeuteride (98 atom % D), and the location (beta) and percentage (78-84%) of the deuterium incorporation were determined.

A Facile Catalytic Deuteration of Unsaturated Fatty Acids and Phospholipids

Selectively chain-deuterated fatty acids and phospholipids were synthesized by a modified method of the balloon technique used in the catalytic hydrogenation of unsaturated dicarboxylic acids. The modified method uses a specially designed twin-flask apparatus, with an attached inflatable bulb to control the pressure and act as a safety device. Deuterium gas was generated in situ from sodium borodeuteride and concentrated deuterium chloride in a compartment separate from the reaction mixture of lipid and catalyst. Two catalysts. platinum tetrachloride on activated charcoal and tris(triphenylphosphine)chlororhodium(I) were employed and compared. Quantitative yields of the deuterated products were obtained as analyzed by proton, deuterium. and phosphorus-31 NMR spectroscopy and by mass spectrometry.

Gas-Chromatographic-Mass Spectrometric Assay of Tissue Malondialdehyde, 4-Hydroxynonenal, and Other Aldehydes after Their Reduction to Stable Alcohols

Measurement of specific aldehydes such as malondialdehyde, hexanal, or 4-hydroxynonenal provides a method to evaluate the extent of lipid peroxidation. However, assay of aldehydes is complicated by their high reactivity toward other molecules and their chemical instability. In the proposed method, aldehydes are reduced to stable alcohols. Except for malondialdehyde, this is readily accomplished under neutral conditions at room temperature or at 4°C with either sodium borodeuteride (NaB 2H 4) or sodium horohydride (NaBH 4). Complete reduction of malondialdehyde requires a more powerful reducing agent, borane trimethylamine. After ether extraction and evaporation of the organic phase, the alcohols are converted to t-butyldimethylsilyl ethers and analyzed by selected ion monitoring gas chromatography-mass spectrometry in the positive chemical ionization mode for malondialdehyde and 4-hydroxynonenal and electron impact mode for all other aldehydes. Quantitation is achieved using internal standards of 1,3-[ 2H 8]propanediol for MDA, of 4-[2- 2H]hydroxynonenal for 4-hydroxynonenal, and of the corresponding saturated per-deuterated alcohols for all saturated aldehydes, for example and [ 2H 13]hexanol for hexanal. Saturated per-deuterated alcohols also serve as external standards for their unsaturated aldehydes with same chain length. The detection limit for individual aldehydes is 0.5 nmol in a given sample. In addition to being highly sensitive and selective, the present method allows one to verify the identity of each aldehyde by observing a mass shift when aldehydes are reduced with either NaB 2H 4 or NaBH 4. The usefulness of our method is demonstrated by measuring aldehyde accumulation in autoxidized arachidonic acid solutions and in heart homogenates before and after induction of peroxidation.

Gas Chromatography-Mass Spectrometric Determinations of Iduronic and Glucuronic Acids in Glycosaminoglycans after Reduction of Carboxylic Group Using Sodium Borodeuteride

A gas chromatography-mass spectrometry procedure for the determination of subnanomolar amounts of uronic acids derived from glycosarninoglycans (GAGs) is described. It involves stoichiometric reduction of carboxyl groups by sodium borodeuteride coupled with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and methanolysis in methanolic hydrogen chloride (1.0 M) at 80°C for 24 h followed by trimethylsilylation. The uronic acid compositions of commercially available GAGs, such as dermatan sulfate from pig skin, heparan sulfate from bovine kidney, and heparin from bovine intestinal mucosa, were investigated by the present method. The results were confirmed by the quantitative 1H-NMR spectroscopy. The method is also applicable to complex samples such as human urinary GAGs.

Synthesis of deuterium-labeled 5α-androstane-3α,17β-diol and its 17β-glucuronide

Using unlabeled androsterone as starting material, 5α-[16,16- 2H 2]androstan-3α-ol-17-one was synthesized by exchange using deuterated potassium methoxide. This labeled androsterone product was reduced by sodium borodeuteride, which gave predominantly trideuterated 5α-androstane-3α,17β-diol. The labeled androstanediol was conjugated with glucuronide by using the Koenig-Knorr reaction with methyl-I-bromo-I-deoxy-2,3,4-tri-O-acetyl-α-D-glucopyranosuronate. The dominant product was identified by thermospray high-performance liquid chromatography/mass spectrometry (MS) and electrospray MS as 5α-[16,16,17- 2H 3]androstane-3α,17β-diol,17β-glucuronide.

Associations of the bacterial mutagenicity of halogenated 2(5H)-furanones with their MNDO-PM3 computed properties and mode of reactivity with sodium borohydride.

Electrophilicity as a general basis for both the mutagenicity and nucleophile inactivation of halogen-substituted 2(5H)-furanones was tested. Lowest unoccupied molecular orbital (LUMO) energy levels and stabilities of 2(5H)-furanone radical anions and C-2, C-3, and C-4 anionic hydride adducts were computed with MNDO-PM3 for each of 10 compounds. These three computed sets of values were considered electrophilicity indicators. Each individual value from a given indicator set was plotted against the logarithm of the Salmonella typhimurium (TA100) mutagenicities (log Mm) for each of the corresponding compounds. Highest occupied molecular orbital (HOMO) energy levels for the 10 compounds were also computed. Strong negative correlations were obtained from the plots of LUMO and radical anion stability against log Mm of the 10 compounds. Also, a negative correlation was observed for the plot of the stability of the C-4 anionic hydride adduct for a smaller set of six compounds possessing a 4-(chloromethyl)-2(5H)-furanone structure and having the same HOMO characteristics. HOMO energies failed to correlate with mutagenicity. Neither computed atomic charge nor 13C chemical shift values for the larger compound group of 10 correlated well with mutagenicity or with each other. Sodium borohydride and borodeuteride reductions of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone demonstrated experimentally that hydride became attached to C-4.

Synthesis of Specifically Deuteriated Derivatives of D-Galactose and D-Galactosamine

Abstract Simple and convenient methods for introducing deuterium label at C-3 and C-6 position of N-acetyl-D-galactosamine and D-galactose, respectively, are described. For the synthesis of 2-acetamido-2-deoxy-D-3-[2H] galactopyranose, benzyl 2-acetamido-2-deoxy-4,6-O-benzylidene-α-D-galactopyranoside was oxidized with dimethyl sulfoxide- acetic anhydride and the product was reduced with sodium borodeuteride to introduce the deuterium at C-3. After benzylidene reduction, the mixture was subjected to hydrogenolysis and purified by column chromatography. 1,2:3,4-di-O-isopropylidene-α-D-galactopyranoside was oxidized followed by reduction with sodium borodeuteride and deprotection to yield D-6-[2H] galactose.

Synthesis of 14‐[2H]arteether, an experimental antmalarial drug

AbstractA reaction sequence employing a fungus mediated oxidation of arteether, an experimental antimalarial drug, was used to introduce a hydroxyl group on C‐14. The hydroxyl group was replaced by a deuterium by preparing the tosylate and reductively cleaving it with sodium borodeuteride in DMSO. A reaction sequence to introduce a second label was also demonstrated it involved oxidation of the alcohol, with catalytic quantities of tetra‐n‐propylammonium perruthenate, followed by reduction with sodium borodeuteride to regenerate the alcohol. Use of both reactions sequences yield arteether containing two deuterium.

Identification of 3-deoxy-lyxo-2-heptulosaric acid in the core region of lipopolysaccharides from Rhizobiaceae

A 3-deoxy-2-heptulosaric acid (DHA), very probably with the lyxo-configuration, was identified in the R-core region of lipopolysaccharides from nodulating strains of Rhizobium leguminosarum, Rhizobium meliloti and from all three biovars of the phytopathogenic Agrobacterium tumefaciens. Its structure could be deduced from the fragmentation pattern of the corresponding alditol acetates obtained after reduction of the 2-keto and the 1.7-carboxy groups by sodium borohydride or sodium borodeuteride. DHA in lipopolysaccharide was not destroyed by periodate and is therefore not in a terminal position. Two DHA-containing oligosaccharides, namely glucosyl (1----4)-3-deoxy-2-heptulosaric acid and rhamnosyl-rhamnosyl-(1----5)-3-deoxy-2-heptulosaric acid could be tentatively identified by mass spectrometric methods amongst the products of mild acidic hydrolysis of lipopolysaccharides of Rhizobium leguminosarum strain 24. The two types of non-nodulating mutants of Rhizobium leguminosarum included in this study did not contain 3-deoxy-2-heptulosaric acid.

Identification of 3-deoxy-lyxo-2-heptulosaric acid in the core region of lipopolysaccharides from Rhizobiaceae

A 3-deoxy-2-heptulosaric acid (DHA), very probably with the lyxo-configuration, was identified in the R-core region of lipopolysaccharides from nodulating strains of Rhizobium leguminosarum, Rhizobium meliloti and from all three biovars of the phytopathogenic Agrobacterium tumefaciens. Its structure could be deduced from the fragmentation pattern of the corresponding alditol acetates obtained after reduction of the 2-keto and the 1.7-carboxy groups by sodium borohydride or sodium borodeuteride. DHA in lipopolysaccharide was not destroyed by periodate and is therefore not in a terminal position. Two DHA-containing oligosaccharides, namely glucosyl (1----4)-3-deoxy-2-heptulosaric acid and rhamnosyl-rhamnosyl-(1----5)-3-deoxy-2-heptulosaric acid could be tentatively identified by mass spectrometric methods amongst the products of mild acidic hydrolysis of lipopolysaccharides of Rhizobium leguminosarum strain 24. The two types of non-nodulating mutants of Rhizobium leguminosarum included in this study did not contain 3-deoxy-2-heptulosaric acid.

Reactions of methyl 4,6- O-benzylidene-2,3-dideoxy-2- C- p- tolylsulfonyl-β- d- erythro-hex-2-enopyranoside and its phenyl analog with several nucleophiles; stereoselective preparation of 3- O-acyl- d- arabino- and d- ribo-hex-1-enitol derivatives

Reactions of methyl 2- C- p-tolylsulfonyl-2-enopyranoside ( 6) with nucleophiles (methoxide, nitromethane, 2,4-pentanedione, and ammonia) afforded the β- d- gluco adducts with high stereoselectivity. However, similar treatment of the phenyl analog 11 with sodium borodeuteride, nitromethane, methoxide, and lithium hydroxide led mainly to an S n2′ process to give 1-enitol derivatives having the arabino configuration. Conversely, treatment of 11 with carboxylic acids in pyridine gave the 1-enitol derivatives having the ribo configuration as the major product.

Syntheses of poly-deuterated 9(O)-methano-Δ6(9α)-prostaglandin I1 methyl esters

Two types of poly-deuterated isocarbacyclin [9(O)-methano-Δ6(9α)-prostaglandin I1] methyl ester have been synthesized for the use of GC-MS quantitative analysis as internal standards and for the use of metabolic study as substrates. The 5,13,14-2H3 derivative 2 was prepared via H-D exchange, deuteroboration, and sodium borodeuteride reduction. The 2,2,3,3,4,4-2H6 derivatives 3, 4 were prepared starting from tetrahydrofuran-d8.

Synthesis of [2H5]arecoline for use as internal standard in mass spectrometric assay

AbstractFive deuterium atoms, three in the N‐methyl group and one each in positions 2 and 6, were incorporated into the cholinergic agonist, arecoline (1), methyl 1‐methyl‐1,2,5,6‐tetrahydropyridine‐3‐carboxylate, with 96% efficiency. Trideuterated pyridinium iodide (2) was reduced with sodium borodeuteride or sodium cyanoborodeuteride in acidic medium to yield [2H5]arecoline (3). Significantly greater deuterium incorporation occurred when 2 was reduced with sodium cyanoborodeuteride. This reduction process is discussed. The synthesized labelled compound was determined to be a suitable internal standard for mass spectrometric assays.

Cross-linkage sites in type I collagen fibrils studied by neutron diffraction

Cross-links in tendon collagen are essential for the biomechanical strength of healthy tissue. The nature and position of these cross-links has long been a subject for conjecture. We have approached this problem in a non-destructive manner, by studying neutron diffraction from collagen fibrils that have been specifically deuterated by reduction at keto-amine and Schiff base groups with sodium borodeuteride (NaB2H4). The intensities of the first 23 meridional reflections were recorded for both native and reduced tendons. These data were used to calculate the neutron-scattering density profile of the 67 nm (D) repeat of type I collagen fibrils in rat tail tendon. This approach not only succeeds in determining the location of the cross-linkage sites with respect to the fibril structure, as projected onto the fibre axis, but also presents a novel form of the isomorphous derivative solution to the phase problem.

Further structural studies of anti-complementary acidic heteroglycans from the leaves of Panax ginseng C.A. Meyer

The three potent anti-complementary polysaccharides, GL-PI, GL-PII, and GL-PIV, isolated from the leaves of Panax ginseng C.A. Meyer, were subjected to base-catalysed β-elimination in the presence of sodium borodeuteride or enzymic digestion with endo-α- d-(1→4)-polygalacturonase. β-Eliminative degradation of GL-PI and GL-PII each gave neutral (IN and IIN) and acidic (IA and IIA) fractions. Each fraction N consisted of Ara, Rha, Gal, and Glc, whereas each fraction A comprised a large proportion of GalA in addition to Rha, Gal, Glc, and GlcA. Methylation analysis and g.l.c.-m.s. showed that each fraction IN and IIN contained Rha-(1→2)-Rha-ol- 1-d, Rha-(1→4)-Rha-ol- 1-d, Ara-(1→4)-Rha-ol- 1-d, Gal-(1→4)-Rha-ol- 1-d, Gal-(1→6)-Gal-ol- 1-d, and GlcA-(1→4)-Rha-ol- 1-d, and that IA and IIA contained Rha→Rha-ol- 1-d, HexA→Rha-ol- 1-d, and HexA→-Rha→Rha-ol- 1-d. Methylation analysis indicated that IN and IIN also contained high-molecular-weight 6-linked galactan and 4-linked glucan, and that IA and IIA consisted mainly of 2-linked Rha, 4-linked GalA, and terminal and 6-linked Gal. IIA contained more 2-linked Rha than IA. Endo-α- d-(1→4)-polygalacturonase-mediated digestion of GL-PIV produced a high-molecular-weight fraction (PG-1) which was rich in neutral sugars, fragments of intermediate size (PG-2), and oligosaccharides (PG-3). PG-1 contained a rhamnogalacturonan core, galactan (which mainly comprised terminal, 6-linked, and 4,6-disubstituted Gal), and 4-linked glucans. PG-2 contained (1→4)-linked α-galacturonan partially branched at position 2 or 3 and a rhamnogalacturonan core in addition to small proportions of Gal and Glc. PG-3 contained large proportions of oligogalacturonides.

Comparison of the reactions induced by ultrasound and gamma rays in aqueous lactose solutions

The products obtained in aerated aqueous lactose solutions after irradiation with ultrasound and gamma rays were compared. The dose rate of gamma irradiation equivalent to the effect of ultrasound in our experiments was determined to be 1.384 kGy h −1 using the Fricke dosimeter. Separation and identification of the products were performed by gas chromatography-mass spectrometry. Three methods for the derivation of products were used: (1) trimethylsilylation of the OH-groups; (2) methoximation of the carbonyl groups followed by trimethylsilylation of the OH-groups; and (3) reduction of the carbonyl and carboxyl groups to alcohols by sodium borohydride and sodium borodeuteride. The formation of products for both types of irradiation was identical, showing only minor deviations in the yield. The main reaction was oxidative splitting of the glucosidic bond, resulting in the formation of galactonic acid, glucose and galactose. Hexosuloses, gluconic acid, hexulosonic acids and glucuronic acid were detected as secondary products still containing the intact monosaccharide units. In addition, oxidation products with three to five carbon atoms were observed. The main product still containing 12 carbon atoms was lactobionic acid.

Reactions of 3-[formula omitted]-acetyl-2-[formula omitted]-[formula omitted]-tolylsulfonyl-D-[formula omitted]- and -[formula omitted]-[formula omitted]-hex-1-enitol derivatives with nucleophiles; the SN2′ mechanism is proved firstly in glycal derivatives

Reactions of the title compounds with sodium methoxide and sodium borodeuteride were found to proceed mainly via the SN2′ mechanism; nucleophiles selectively attacked the anomeric carbon atom from the same side of the leaving acetoxyl group at C-3.