Facile Synthesis of 8, 2′-S-Cyclopurine Nucleoside

Abstract

This paper describes the synthesis of 8,2 -anhydro-8-mercapto-9-(β-D-arabinofuranosyl)purine (8,2′-S-cyclopurinenucleoside, 1) via the shorter route from 3′,5′-di-O-acectyl-8,2′-S-cycloadenosine (6) and by direct reductive deamination with n- pentyl nitrite in tetrahydrofuran (THF) and deacetylation. The preparation of 8,2′-S-cycloadenosine (2) was achieved in good yield by the cyclization of the protected 8-mercaptoadenosine with triphenylphosphine and diethyl azodicarboxylate (DEAD) in THF at room temperature, under Mitsunobu reaction conditions.     

2′-C-Cyano-2′-deoxy-1-β-D-arabinofuranosylcytosine (CNDAC): A Mechanism-Based DNA-Strand-Breaking Antitumor Nucleoside1

Abstract

The antitumor mechanism of action of 2′-C-cyano-2′-deoxy-1-β-d-arabinofuranosylcytosine (CNDAC) has been examined. CNDAC was designed as a potentially DNA-self-strand-breaking nucleoside. It had potent antitumor effects against various solid tumors in vitro as well as in vivo. Using a chain-extension method with Vent (exo^?) DNA polymerase and a short primer/template system, we found that 5′-triphosphate of CNDAC (CNDACTP) was incorporated into the primer at a site opposite a guanine residue in the template. After further chain-extension reaction of the primer containing CNDAC at the 3′-terminus, chain elongation was not observed. Therefore, CNDACTP appeared to act as a chain-terminator. Analyses of the structure of the 3′-terminus in the primer revealed 2′-C-cyano-2′,3′-didehydro-2′,3′-dideoxycytidine (ddCNC) together with CNDAC and 2′-C-cyano-2′-deoxy-1-β-d-ribofuranosylcytosine (CNDC). The existence of ddCNC in the 3′-end of the primer would be due to the self-strand-break by the nucleotide incorporated next to CNDAC. We also found that CNDAC was epimerized to CNDC in near-neutral to alkaline media. Therefore, CNDC found in the primer was epimerized after incorporation of CNDACTP into the primer. We also described the metabolism of CNDAC.     

A Convenient Synthesis of A Novel Nucleoside Analogue: 4-(δ-Diformyl-methyl)-1-(β-D-ribofuranosyl)-2-pyrimidinone

Abstract

The nucleoside analogue 4-(δ-diformyl-methyl)-1-(β-D-ribofuranosyl)-2-pyrimidinone (5) was prepared from the corresponding 4-methyl pyrimidinone nucleoside by means of the Vilsmeier reaction. The unprotected nucleoside can be phosphorylated directly with phosphorus oxychloride in triethyl phosphate.     

Intracellular Metabolism and Action of an Antitumor Nucleoside, 2′-C-Cyano-2′-Deoxy-1-β-d-arabinofuranosylcytosine (CNDAC)

Abstract

The mechanism of antitumor activity of 2′-C-cyano-2′-deoxy-1-β-D-arabinofuranosylcytosine (CNDAC) has been examined. Intracellular metabolism of CNDAC using human leukemia cell lines are described. Incorporation of CNDAC triphosphate into DNA and the consequence of this incorporation have been evaluated in vitro using DNA primer extension assay with purified human DNA polymerase α and defined DNA primer/templates.     

Definitive Solution Structures for the 6-Formylated Versions of 1-(βD-Ribofuranosyl)-, 1-(2′-Deoxy-β-D-Ribofuranosyl)-, and 1-β-D-Arabinofuranosyluracil,and of Thymidine

Abstract

ROESY and NOESY NMR spectroscopic analyses of the ribofuranosyl (1a), 2′-deoxyribofuranosyl (1b), and arabinofuranosyl (1c) derivatives of 6-formyluracil in (CD₃)₂SO and D₂O solutions have established that each exclusive 7,05′-cyclic hemiacetal diastereomer of 1a,b and the major 7,O2′-cyclic hemiacetal diastereomer of 1c possess the 7R configuration. In addition, (7R)-1c has been shown to be thermodynamically more stable than (7S)-1c, contrary to our previous indication. A new, higher yielding synthetic route to 1a has been developed, 1b has been obtained for the first time in crystalline form, the route to 1c has been modified to better accommodate large scale preparations, and a new, fourth member of this class, 6-formylthymidine (1d), has been synthesized and its solution structures in (CD₃)₂SO, D₂O, and CD₃OD have been determined. Antitumor and antiviral evaluations of 1a-c have revealed no significant levels of activity.     

Synthese von 1,3,5-Triazinen aus Aminosäure-Derivaten (III)

An extracellular acidic polysaccharide produced by Serratia piscatorum IFO 12527 was found to exhibit a marked antiinflammatory activity. The polysaccharide was purified by fractional precipitation with cetyltrimethylammonium bromide and then by gel filtration on Sepharose 2B to give two homogeneous fractions, PLS N–I and PLS N–II, the former exhibiting the antiinflammatory activity.

PLS N-I was a complex polysaccharide composed of l-rhamnose, d-galactose and d-galacturonic acid in the molar ratio of 2: 1; 1, together with small portions of d-glucosamine, d-galactosamine, protein and fatty acids such as acetic, lauric, myristic, β-hydroxyrnyristic and palmitic acids. Physicochemical and biological properties of PLS N–I and PLS N–II were also described.     

A New Antitumor Nucleoside, 1-(3-C-Ethynyl-β-d-ribo-pentofuranosyl)-cytosine (ECyd), Is a Potent Inhibitor of RNA Synthesis

Abstract

The antitumor activity, metabolism, and mechanism of action of a newly developed antitumor nucleoside, 1-(3-C-Ethynyl-β-_d-ribo-pentofuranosyl)cytosine (ECyd) are described.     

Action of rat liver Galβ1-4GlcNAc α(2-6)-sialyltransferase on Manβ1-4GlcNAcβ-OMe,GalNAcβ1-4GlcNAcβ-OMe,Glcβ1-4GlcNAcβ-OMe and GlcNAcβ1-4GlcNAcβ-OMe as synthetic substrates

Incubation of synthetic Man\1-4GlcNAc-OMe, GalNAc1-4GlcNAc-OMe, Glc1-4GlcNAc-OMe, and GlcNAc1-4GlcNac-OMe with CMP-Neu5Ac and rat liver Gal1-4GlcNAc (2-6)-sialyltransferase resulted in the formation of Neu5Ac2-6Man1-4GlcNAc-OMe, Neu5Ac2-6GalNAc1-4GlcNAc-OMe, Neu5Ac2-6Glc1-4GlcNAc-OMe and Neu5Ac2-6GlcNAc1-4GlcNAc-OMe, respectively. Under conditions which led to quantitative conversion of Gal1-4GlcNAc-OEt into Neu5Ac2-6Gal1-4GlcNAc-OEt, the aforementioned products were obtained in yields of 4%, 48%, 16% and 8%, respectively. HPLC on Partisil 10 SAX was used to isolate the various sialyltrisaccharides, and identification was carried out using 1- and 2-dimensional 500-MHz¹H-NMR spectroscopy.Abbreviations 2D 2-dimensional - CMP cytidine 5-monophosphate - CMP-Neu5Ac cytidine 5-monophospho--N-acetylneuraminic acid - COSY correlation spectroscopy - DQF double quantum filtered - HOHAHA homonuclear Hartmann-Hahn - MLEV composite pulse devised by M. Levitt - Neu5Ac N-acetylneuraminic acid - Neu5Ac2en 2-deoxy-2,3-didehydro-N-acetylneuraminic acid     

Synthesis of 6β-Hydroxyaristeromycin - A Novel Type of Carbocyclic Nucleoside Analogue

Abstract

The synthesis of racemic 6β-hydroxyaristeromycin (1) is described.     

Synthetic mucin fragments. Methyl 6-O-(2-acetamido-2-deoxy-β-D-glycopyranosyl)-β-D-galactopyranoside,methyl 3,4-di-O-(2-acetamido-2-deoxy-β-D-glycopyranosyl)-β-D-galactopyranoside,and methyl O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1 å 3)-O-β-D-galactopyranosyl-(1 å 3)-O-(2-acetamido-2-deoxy-β- D-glucopyranosyl)-(1 å 3)-β-D-galactopyranoside

Condensation of methyl 2,6-di-O-benzyl-β-d-galactopyranoside with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)-[2,1,-d]-2-oxazoline (1) in 1,2-dichloroethane, in the presence of p-toluenesulfonic acid, afforded a trisaccharide derivative which, on deacetylation, gave methyl 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2,6-di-O-benzyl-β-d- glactopyranoside (5). Hydrogenolysis of the benzyl groups of 5 furnished the title trisaccharide (6). A similar condensation of methyl 2,3-di-O-benzyl-β-d-galactopyranoside with 1 produced a partially-protected disacchraide derivative, which, on O-deacetylation followed by hydrogenolysis, gave methyl 6-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-β-d-glactopyranoside (10). Condensation of methyl 3-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-benzyl-β-d- galactopyranoside with 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-acetyl-α-d-galactopyranosyl bromide in 1:1 benzene-nitromethane in the presence of powdered mercuric cyanide gave a fully-protected tetrasaccharide derivative, which was O-deacetylated and then subjected to catalytic hydrogenation to furnish methyl O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→3)-O-β-d-galactopyranosyl-(1å3)-O-(2-acetamido-2-deoxy- β-d-glucopyranosyl)-(1å3)-β-d-galactopyranoside (15). The structures of 6, 10, and 15 were established by ¹³C-n.m.r. spectroscopy.     

X-Ray Crystallographic and Kinetic Analysis of Human Purine Nucleoside Phosphorylase Complexes with 1-β-D-Ribofuranosyl-1,2,4-triazole-3-carobxamide and 1-β-D-Ribofuranosyl-1,2,4-triazole-3-carboxamidine

Abstract

The three-dimensional structures of the complexes between human erythrocytic purine nucleoside phosphorylase (PNP) and both 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (ribavirin) and 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamidine (TCNR) have been determined using X-ray crystallographic techniques. The structures have been refined at 2.9 Å resolution using simulated annealing and conjugate-gradient minimization techniques to an R value of 21.8% for ribavirin and 20.8% for TCNR. Ribavirin and TCNR are truncated nucleosides corresponding to adenosine and inosine, respectively, and are of potential interest as PNP inhibitors. Kinetic parameters have been determined for recombinant wild-type PNP and for a mutant PNP in which Asn 243 is converted to Asp. The K_i value for ribavirin is 4.9 mM with wild-type PNP and 4.7 mM with the Asn243Asp mutant, while the K_i values for TCNR are 17.6 μM and 3.8 μM with wild-type and mutant, respectively. X-ray crystallographic studies showed that the binding geometry for both of these substrate analogues was similar to that seen for natural substrates. The glycosidic torsion angles (χ) were ?34° for ribavirin and ?39° for TCNR which are in good agreement with values seen for other studied nucleoside complexes with PNP, but which are unusual when compared to those seen for free nucleic acid derivatives. Based upon the three-dimensional structure, interactions of Asn 243 and Glu 201 with a protonated carboxamidine of TCNR explain the stronger inhibition of PNP observed for TCNR over ribavirin.     

Synthese der amadori-verbindung: 2-desoxy-2-[(1-desoxy-D-fructofuranuronsäure)-1-yl]amino-α-D-glucopyranose

Condensation of 2-amino-2-deoxy-D-glucose hydrochloride with D-glucuronic acid in methanol containing a trace of pyridine gave crystalline 2-deoxy-2-[(1-deoxy-D-fructofuranuronic acid)-1-yl]amino-α-D-glucopyranose (2) in a yield of 34%. The compound was characterized by analytical and spectroscopic data and by its hepta-O-acetyl derivative. At pH 6.5, 2 was split quantitatively into 2-amino-2-deoxy-D-glucose and D-glucuronic acid.     

Synthesis of methyl O-(3-deoxy-3-fluoro-β-d-galactopyranosyl)-(1→6)-β-d-galactopyranoside and methyl O-(3-deoxy-3-fluoro-β-d-galactopyranosyl)-(1→6)-O-β-d-galactopyranosyl-(1→6)-β-d-galactopyranoside

Condensation of 2,4,6-tri-O-acetyl-3-deoxy-3-fluoro-α-d-galactopyranosyl bromide (3) with methyl 2,3,4-tri-O-acetyl-β-d-galactopyranoside (4) gave a fully acetylated (1→6)-β-d-galactobiose fluorinated at the 3′-position which was deacetylated to give the title disaccharide. The corresponding trisaccharide was obtained by reaction of 4 with 2,3,4-tri-O-acetyl-6-O-chloroacetyl-α-d-galactopyranosyl bromide (5), dechloroacetylation of the formed methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-β-d-galactopyranosyl)-(1→6)- 2,3,4-tri-O-acetyl-β-d-galactopyranoside to give methyl O-(2,3,4-tri-O-acetyl-β-d-galactopyranosyl)-(1→6)-2,3,4-tri-O-acetyl-β-d-galactopyranoside (14), condensation with 3, and deacetylation. Dechloroacetylation of methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-β-d-galactopyranosyl)-(1→6)-O-(2,3,4-tri-O-acetyl- β-d-galactopyranosyl)-(1→6)-2,3,4-tri-O-acetyl-β-d-galactopyranoside, obtained by condensation of disaccharide 14 with bromide 5, was accompanied by extensive acetyl migration giving a mixture of products. These were deacetylated to give, crystalline for the first time, the methyl β-glycoside of (1→6)-β-d-galactotriose in high yield. The structures of the target compounds were confirmed by 500-MHz, 2D, ¹H- and conventional ¹³C- and ¹⁹F-n.m.r. spectroscopy.     

Glycosylations of Inosine and Uridine Nucleoside Bases and Synthesis of the New 1-(β-D-Glucopyranosyl)-Inosine-5′, 6″-diphosphate

Abstract

Gluco- and ribosylation of the bases of sugar protected inosine and uridine were investigated, obtaining only adducts with β-configuration at the new glycosidic carbon; stereospecific insertion of a sugar moiety at the 1-N of inosine was achieved either using a Mitsunobu approach (for ribosylation) or by direct coupling of 1-δ-bromoglucose 13 with 2′,3′,5′-tri-O-acetylinosine for glucosylation. 1-(β-D-glucosyl)-inosine, chosen as starting substrate for glucosylated analogs of cyclic IDP-ribose, was phosphorylated at the primary hydroxyls and tested in intramolecular pyrophosphate bond formation.     

The linear tetrasaccharide,Galβ1-4GlcNAcβ1-6Galβ1-4GlcNAc,isolated from radiolabeled teratocarcinoma poly-N-acetyllactosaminoglycan resists the action ofE. freundii endo-β-galactosidase

A novel linear tetrasaccharide, Gal1-4GlcNAc1-6Gal1-4GlcNAc, was isolated from partial acid hydrolysates of metabolically labeled poly-N-acetyllactosaminoglycans of murine teratocarcinoma cells. It was characterized by exo-glycosidase sequencing and by mild acid hydrolysis followed by identification of all partial cleavage products. The tetrasaccharide, and likewise labelled GlcNAc1-6Gal1-4GlcNAc, resisted the action of endo--galactosidase (EC 3.2.1.103) fromE. freundii at a concentration of 125 mU/ml, while the isomeric, radioactive teratocarcinoma saccharides Gal1-4GlcNAc1-3Gal1-4GlcNAc and GlcNAc1-3Gal1-4GlcNAc were cleaved in the expected manner.Abbreviations WGA wheat germ agglutinin - BSA bovine serum albumin - [³H]GlcNAc1-4-GlcNAc1-4GlcNAcOL N,N,NN'-triacetylchitotriose reduced with NaB³H₄     

Construction of linear GlcNAcβ1-6Galβ1-OR type oligosaccharides by partial cleavage of GlcNAcβ1-3(GlcNAcβ1-6)Galβ1-OR sequences with jack bean β-N-acetylhexosaminidase

Radiolabelled GlcNAc beta 1-3(GlcNAc beta 1-6)Gal (1), GlcNAc beta 1-3)GlcNAc beta 1-6)Gal beta 1-OCH3 (4), GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc (7), and GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (10) were cleaved partially with jack bean beta-N-acetylhexosaminidase (EC 3.2.1.30), and the digests were analysed chromatographically. All four oligosaccharides were hydrolysed faster at the (1-6) branch, than at the (1-3) branch, but a high branch specificity was observed only with the glycan 4. The saccharides 1 and 7 resembled each other in the kinetics of the enzyme-catalysed release of their two non-reducing N-acetylglucosamine units, but the glycan 10 was rather different. The partial digestions made it possible to obtain radiolabelled GlcNAc beta 1-6Gal, GlcNAc beta 1-6Gal beta 1-OCH3, GlcNAc beta 1-6Gal beta 1-4Glc, and, in particular, GlcNAc beta 1-6Gal beta 1-4GlcNAc.     

Nachweis von Zearalenon-4-β-D-Glucopyranosid in Weizen

Maize (Zea mays) cell cultures were used for the production of zearalenone-4-β-D-glucopyranoside as standard compound. Wheat samples were extracted with acetonitrile: water, applied to a florisil column and eluted with methanol:ethyl acetate. For determination and quantification of zearalenone-4-β-D-glucopyranoside and zearalenone a LC-MS method was developed. A concentration of 10 μg/kg zearalenone-4-β-D-glucopyranoside and zearalenone was detectable. The recovery rates were calculated to be 69% and 89% at a concentration level of 100 μg/kg for zearalenone-4-β-D-glucopyranoside and zearalenone, respectively.24 Bavarian wheat samples from harvest 1999 were analyzed. Zearalenone was present in 22 out of 24 field samples, the levels ranged from 11–860 μg/kg. Zearalenone-4-β-D-glucopyranoside was found in 10 out of the zearalenone positive samples (42%) at levels ranging from 17 to 104 μg/kg. The amounts of zearalenone-4-β-D-glucopyranoside were correlated to those of zearalenone (r2=0,86; b=0,10).     

Synthesis of 2,2′-Anhydro-2-Hydroxy- and 6,2′-Anhydro-6-Hydroxy-1-β-D-Arabindfuranosylnicotinamide as Conformationally Restricted Nicotinamide Nucleoside Analogs1

Abstract

1-(β-D-Ribofuranosy1)-2(1H)-pyridone-3-carboxamide (6a) and the 6(1H)-pyridone derivative (6b) were prepared by condensation of 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose (3) with 2- and 6-hydroxynicotinic acid, respectively, to 4a and 4b, followed by conversion of the carboxylic acid function of 4a,b into their corresponding carboxamides 5, and then deprotection of 5. Bath 6a and 6b were then treated with 1,3-dichlom-1,1,3,3-tetraisopropyldisiloxane to give the corresponding 3′,5′-O-TPDS derivatives, 7a and 7b. Mesylation of 7a,b with mesyl chloride in pyridine afforded the stable, protected mesylates 8a,b. Upon de-O-silylation of 8a,b with ET₃NHF gave a mixture of unprotectd mesylates 9a,b and 2,2-anhydro- and 6,2′-anhydronucleosides, 1a and 1b. Upon storage of 9a,b at man temperature, they are quantitatively converted into 1a,b. Mild alkaline hydrolysis of 1a,b afforded their corresponding arabino nucleosides 10a,b.