- Characterization of a novel resistance-related deoxycytidine deaminase from Brassica oleracea var. capitata
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Brassica oleracea deoxycytidine deaminase (BoDCD), a deoxycytidine deaminase (DCD, EC 3.5.4.14) enzyme, is known to play an important role in the Trichoderma harzianum ETS 323 mediated resistance mechanism in young leaves of B. oleracea var. capitata during Rhizoctonia solani infection. BoDCD potentially neutralizes cytotoxic products of host lipoxygenase activity, and thereby BoDCD restricts the hypersensitivity-related programmed cell death induced in plants during the initial stages of infection. To determine the biochemical characteristics and to partially elucidate the designated functional properties of BoDCD, the enzyme was cloned into an Escherichia coli expression system, and its potential to neutralize the toxic analogues of 2′-deoxycytidine (dC) was examined. BoDCD transformants of E. coli cells were found to be resistant to 2′-deoxycytidine analogues at all of the concentrations tested. The BoDCD enzyme was also overexpressed as a histidine-tagged protein and purified using nickel chelating affinity chromatography. The molecular weight of BoDCD was determined to be 20.8 kDa as visualized by SDS-PAGE. The substrate specificity and other kinetic properties show that BoDCD is more active in neutralizing cytotoxic cytosine β-d-arabinofuranoside than in deaminating 2′-deoxycytinde to 2′-deoxyuridine in nucleic acids or in metabolizing cytidine to uridine. The optimal temperature and pH of the enzyme were 27 C and 7.5. The Km and Vmax values of BoDCD were, respectively, 91.3 μM and 1.475 mM for its natural substrate 2′-deoxycytidine and 63 μM and 2.072 mM for cytosine β-d-arabinofuranoside. The phenomenon of neutralization of cytotoxic dC analogues by BoDCD is discussed in detail on the basis of enzyme biochemical properties.
- Shibu, Marthandam Asokan,Yang, Hsueh-Hui,Lo, Chaur-Tsuen,Lin, Hong-Shin,Liu, Shu-Ying,Peng, Kou-Cheng
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Read Online
- Convenient synthesis of oligodeoxyribonucleotides bearing arabinofuranosyl pyrimidine derivatives and its duplex formation with complementary DNA
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The oligodeoxyribonucleotides bearing 2,2′-anhydro-β-D-arabinofuranosyluracil derivatives were synthesized and the modified residue was converted to β-D-arabinofuranosyluracil derivatives or β-D-arabinofuranosylisocytosine derivatives by post-synthetic modification method. The melting profiles of their ODNs with complementary DNA were studied.
- Ozaki, Hiroaki,Nakajima, Kiyohiro,Tatsui, Kaoru,Izumi, Chieko,Kuwahara, Masayasu,Sawai, Hiroaki
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Read Online
- METHODS AND REAGENTS FOR SYNTHESIZING NUCLEOSIDES AND ANALOGUES THEREOF
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The present invention relates to methods and intermediates for the synthesis of nucleosides and nucleoside analogues (NAs). More specifically, the present invention relates to methods of synthesizing nucleosides and NAs, using simple achiral materials by a 'one-pot' proline-catalyzed halogenation of a heteroaryl-substituted acetaldehyde together with a tandem enantioselective aldol reaction followed by a reduction or organometallic addition and cyclization (annulation) reaction involving halide displacement.
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Paragraph 0066; 00288-00290
(2021/10/02)
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- MODIFIED OLIGOMERIC COMPOUNDS AND USES THEREOF
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The present disclosure provides oligomeric compounds comprising a modified oligonucleotide having at least one stereo-non-standard nucleoside. An oligomeric compound comprising a modified oligonucleotide consisting of 12-30 linked nucleosides, wherein at least one nucleoside of the modified oligonucleotide is a stereo-non-standard nucleoside; and wherein the oligomeric compound is selected from among an RNAi compound, a modified CRISPR compound, and an artificial mRNA compound.
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Page/Page column 83; 86
(2021/02/19)
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- MODIFIED OLIGOMERIC COMPOUNDS AND USES THEREOF
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The present disclosure provides oligomeric compounds comprising a modified oligonucleotide having at least one stereo-non-standard nucleoside.
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Page/Page column 93
(2020/05/15)
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- A short de novo synthesis of nucleoside analogs
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Nucleoside analogs are commonly used in the treatment of cancer and viral infections. Their syntheses benefit from decades of research but are often protracted, unamenable to diversification, and reliant on a limited pool of chiral carbohydrate starting materials. We present a process for rapidly constructing nucleoside analogs from simple achiral materials. Using only proline catalysis, heteroaryl-substituted acetaldehydes are fluorinated and then directly engaged in enantioselective aldol reactions in a one-pot reaction. A subsequent intramolecular fluoride displacement reaction provides a functionalized nucleoside analog. The versatility of this process is highlighted in multigram syntheses of D- or L-nucleoside analogs, locked nucleic acids, iminonucleosides, and C2′- and C4′-modified nucleoside analogs. This de novo synthesis creates opportunities for the preparation of diversity libraries and will support efforts in both drug discovery and development.
- Adluri, Bharanishashank,Britton, Robert,Campeau, Louis-Charles,Cohen, Ryan,Lehmann, Johannes,Meanwell, Michael,Silverman, Steven M.,Wang, Yang
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p. 725 - 730
(2020/09/02)
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- DEAMINATION OF ORGANOPHOSPHORUS-NUCLEOSIDES
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The invention relates to a new synthethic process for obtaining compounds of formula (I) from compounds of formula (II) by means of cytidine deaminase enzymes.
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Page/Page column 30
(2016/10/24)
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- PROBE OF IODINE-123 MARKER THYMIDINE (FLT)ANALOGUE [123I]-IARAU
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A tumor radiation probe of iodine-123 marker thymidine (FLT) analogue [123I]-IaraU is disclosed. Commercial available uridine is used as the raw material for the synthesis of the precursor. A radioactive iodine-123 is marked on an alkaline group of uridine to obtain [123I]-IaraU, which is distinguishable from [18F]-FLT marking 18F on a glycosyl group to obtain a novel tumor radiation probe. The marking procedures include mixing the marker precursor with Na [123I] solution, acetic acid and hydrogen peroxide solution, and the solution of chloroform and sodium hydroxide. The sonication time increases from 1 minute to 10 minutes, so that [123I]-IaraU has radiologically chemical purity of higher than 98% and radiological specific activity of not less than 0.196 GBq/umole, and the yield can increase from 8% to 40%. Its radioactive specific activity, yield and purity reach to the degree for the use in biological experiments, while reducing production cost.
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Paragraph 0018-0019
(2014/03/25)
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- Independent generation and reactivity of uridin-2'-yl radical
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The uridin-2'-yl radical (1) has been proposed as an intermediate during RNA oxidation. However, its reactivity has not been thoroughly studied due to the complex conditions under which it is typically generated. The uridin-2'-yl radical was independently generated from a benzyl ketone (2a) via Norrish type I photocleavage upon irradiation at λmax = 350 nm. Dioxygen and β-mercaptoethanol are unable to compete with loss of uracil from 1 in phosphate buffer. Thiol trapping competes with uracil fragmentation in less polar solvent conditions. This is ascribed mostly to a reduction in the rate constant for uracil elimination in the less polar solvent. Hydrogen atom transfer to 1 from β-mercaptoethanol occurs exclusively from the α-face to produce arabinouridine. Mass balances range from 72 to 95%. Furthermore, the synthesis of 2a is amenable to formation of the requisite phosphoramidite for solid-phase oligonucleotide synthesis. This and the fidelity with which the urdin-2'-yl radical is generated from 2a suggest that this precursor should be useful for studying the radical's reactivity in synthetic oligonucleotides.
- Paul, Rakesh,Greenberg, Marc M.
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p. 10303 - 10310
(2015/02/19)
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- Developing a collection of immobilized nucleoside phosphorylases for the preparation of nucleoside analogues: Enzymatic synthesis of arabinosyladenine and 2',3'-dideoxyinosine
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The use of nucleoside phosphorylases (NPs; EC 2.4.2.n) represents a convenient alternative to the chemical route for the synthesis of natural and modified nucleosides. We purified four recombinantly expressed nucleoside phosphorylases from the bacterial pathogens Citrobacter koseri, Clostridium perfringens, and Streptococcus pyogenes (CkPNPI, CkPNPII, CpUP, SpUP) and their substrate specificity was investigated towards either natural pyrimidine or purine nucleosides and some analogues, namely, arabinosyladenine (araA) and 2',3'-dideoxyinosine (ddI). A 2-3 % activity towards these latter compounds (compared to the natural substrates) was observed. Enzyme activities were compared to the specificities obtained for the enzymes pyrimidine nucleoside phosphorylase from Bacillus subtilis (BsPyNP) and purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNPII) previously reported by some of the authors. The enzymes displaying the suitable specificity for the synthesis of araA and ddI were immobilized on aldehyde-agarose. The immobilized preparations were highly stable at alkaline pH and in the presence of methanol or acetonitrile as cosolvent. They were used in the synthesis of araA and ddI by a one-pot, bienzymatic transglycosylation achieving 74 and 44 % conversion, respectively. Something different: Nucleoside phosphorylases are a convenient alternative to the chemical route for the synthesis of natural and modified nucleosides. Four new nucleoside phosphorylases have been prepared, characterized, and tested for their use in biocatalyzed syntheses of araA and ddI (see scheme). A generally applicable immobilization technique has been found to provide active and stable biocatalysts.
- Serra, Immacolata,Ubiali, Daniela,Piskur, Jure,Christoffersen, Stig,Lewkowicz, Elizabeth S.,Iribarren, Adolfo M.,Albertini, Alessandra M.,Terreni, Marco
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p. 157 - 165
(2013/04/24)
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- Comparative investigations on thermostable pyrimidine nucleoside phosphorylases from Geobacillus thermoglucosidasius and Thermus thermophilus
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The recombinant expression and biocatalytic characterization of two thermostable pyrimidine nucleoside phosphorylases (PyNP), isolated from Geobacillus thermoglucosidasius (Gt) and Thermus thermophilus (Tt) is described. Both enzymes are highly thermostable (half life of GtPyNP is 1.6 h at 70 °C, half life of TtPyNP is >24 h at 80 °C). Kinetic parameters for the phosphorolysis of natural substrates were determined for GtPyNP at 60 °C (Km for uridine 2.3 mM, Km for thymidine 1.3 mM) and TtPyNP at 80 °C (Km for uridine 0.15 mM, Km for thymidine 0.43 mM). The kcat values for uridine are almost identical for both enzymes (ca. 277 s-1), while the kcat value for thymidine is about 8 times higher for TtPyNP than for GtPyNP (679 s-1 vs. 83 s-1). Both enzymes were tested towards the ability to catalyze the phosphorolytic cleavage of 2′-fluorosubstituted pyrimidine nucleosides - a prerequisite for the efficient synthesis of a number of relevant purine nucleoside analogues. GtPyNP showed poor activity towards 2′-deoxy-2′-fluorouridine (dUrd2′F; 0.4% substrate conversion after 30 min), and the phosphorolysis of the epimeric counterpart 1-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)uracil (dUrd2′F) could not be detected at all. By contrast, TtPyNP showed dramatically higher conversion rates (15.6% and 1.6% conversion in 30 min of both substrates, respectively). The amount of converted pyrimidine nucleosides increased significantly with time. After 17 h 65% of dUrd2′F and 46% of dUrd2′F was phosphorolytically cleaved. Our results demonstrate the potential of TtPyNP as a biocatalyst in transglycosylation reactions aiming at the production of 2′-fluorosubstituted purine nucleosides that are highly bioactive but hardly accessible by chemical methods.
- Szeker, Kathleen,Zhou, Xinrui,Schwab, Thomas,Casanueva, Ana,Cowan, Don,Mikhailopulo, Igor A.,Neubauer, Peter
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- Enzymatic regioselective and complete deacetylation of two arabinonucleosides
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Candida antarctica lipase B (CAL-B)-catalysed regioselective deacetylation of 2′,3′,5′-tri- O-acetyl-1-β- d-arabinofuranosyluracil (1) and 2′,3′,5′-tri- O-acetyl-9-β- d-arabinofuranosyladenine (2) was studied. The choice of the reaction medium allowed the regioselective formation of products bearing different degree of acetylation: in isopropanol, CAL-B catalysed the formation of the corresponding 2′- O-acetylated arabinonucleosides, while hydrolyses afforded the 2′,3′-di- O-acetylated products. In particular, the procedure herein described allows a simple and efficient preparation of the reported vidarabine prodrug 2′,3′-di- O-acetyl-9-β- d-arabinofuranosyladenine, avoiding the utilisation of protective groups. Moreover, to achieve full deacetylation of the assayed substrates, a set of commercial hydrolases and fungal keratinases from Doratomyces microsporus (DMK) and Paecilomyces marquandii (PMK) were tested. While only PMK and DMK catalysed the quantitative complete deacetylation of 1, DMK accomplished full deacetylation of 2 in shorter time than the other assayed enzymes.
- Sabaini, Maria B.,Zinni, Maria A.,Mohorcic, Martina,Friedrich, Jozefa,Iribarren, Adolfo M.,Iglesias, Luis E.
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experimental part
p. 225 - 229
(2010/11/02)
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- Phosphoramidates of 2′-β-d-arabinouridine (AraU) as phosphate prodrugs; design, synthesis, in vitro activity and metabolism
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2′-β-d-Arabinouridine (AraU), the uridine analogue of the anticancer agent AraC, was synthesized and evaluated for antiviral activity and cytotoxicity. In addition, a series of AraU monophosphate prodrugs in the form of triester phosphoramidates (ProTides) were also synthesized and tested against a range of viruses, leukaemia and solid tumour cell lines. Unfortunately, neither the parent compound (AraU) nor any of its ProTides showed antiviral activity, nor potent inhibitory activity against any of the cancer cell lines. Therefore, the metabolism of AraU phosphoramidates to release AraU monophosphate was investigated. The results showed carboxypeptidase Y, hog liver esterase and crude CEM tumor cell extracts to hydrolyse the ester motif of phosphoramidates with subsequent loss of the aryl group, while molecular modelling studies suggested that the AraU l-alanine aminoacyl phosphate derivative might not be a good substrate for the phosphoramidase enzyme Hint-1. These findings are in agreement with the observed disappearance of intact prodrug and concomitant appearance of the corresponding phosphoramidate intermediate derivative in CEM cell extracts without measurable formation of araU monophosphate. These findings may explain the poor antiviral/cytostatic potential of the prodrugs.
- Mehellou, Youcef,Valente, Rocco,Mottram, Huw,Walsby, Elisabeth,Mills, Kenneth I.,Balzarini, Jan,McGuigan, Christopher
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experimental part
p. 2439 - 2446
(2010/06/19)
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- Method for the synthesis of cyclouridine
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Method for the synthesis of possibly substituted cyclic derivatives of uridine, of formula (II) wherein R is chosen in the group that comprises: hydrogen, halogen and C1-4 alkyl, the method comprising the step of reacting a possibly substituted uridine of formula (III) wherein R has the same meanings as in formula (II), and glycerol carbonate in the presence of an alkaline carbonate at a temperature of 70°C-130°C.
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Page/Page column 7-8
(2008/12/09)
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- Bisphosphonate derivatives of nucleoside antimetabolites: Hydrolytic stability and hydroxyapatite adsorption of 5′-β,γ-methylene and 5′-β,γ-(1-hydroxyethylidene) triphosphates of 5-fluorouridine and ara-cytidine
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(Chemical Equation Presented) Kinetics of the hydrolytic reactions of four bisphosphonate derivatives of nucleoside antimetabolites, viz., 5-fluorouridine 5′-β,γ-(1-hydroxyethylidene) triphosphate (4), 5-fluorouridine 5′-β,γ-methylene triphosphate (5), ara-cytidine 5′-β,γ-(1-hydroxyethylidene) triphosphate (6), and ara-cytidine 5′-β,γ-methylene triphosphate (7), have been studied over a wide pH range (pH 1.0-8.5) at 90°C. With each compound, the disappearance of the starting material was accompanied by formation of the corresponding nucleoside 5′-monophosphate, the reaction being up to 2 orders of magnitude faster with the β,γ-(1-hydroxyethylidene) derivatives (4, 6) than with their β,γ-methylene counterparts (5, 7). With compound 7, deamination of the cytosine base competed with the phosphate hydrolysis at pH 3-6. The measurements at 37°C (pH 7.4) in the absence and presence of divalent alkaline earth metal ions (Mg2+ and Ca2+) showed no sign of metal ion catalysis. Under these conditions, the initial product, nucleoside 5′-monophosphate, underwent rapid dephosphorylation to the corresponding nucleoside. Hydrolysis of the β,γ-methylene derivatives (5, 7) to the corresponding nucleoside 5′-monophosphates was markedly faster in mouse serum than in aqueous buffer (pH 7.4), the rate-acceleration being 5600- and 3150-fold with 5 and 7, respectively. In human serum, the accelerations were 800- and 450-fold compared to buffer. In striking contrast, the β,γ-(1-hydroxyethylidene) derivatives did not experience a similar decrease in hydrolytic stability. The stability in human serum was comparable to that in aqueous buffer (τ1/2 = 17 and 33 h with 4 and 6, respectively), and on going to mouse serum, a 2- to 4-fold acceleration was observed. To elucidate the mineral-binding properties of 4-7, their retention on a hydroxyapatite column was studied and compared to that of zoledronate (1a) and nucleoside mono-, di-, and triphosphates.
- Ora, Mikko,Loennberg, Tuomas,Florea-Wang, Diana,Zinnen, Shawn,Karpeisky, Alexander,Loennberg, Harri
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p. 4123 - 4130
(2008/09/21)
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- Synthesis of 5-radioiodoarabinosyl uridine analog for probing the HSV-1 thymidine kinase gene
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Tumor cells transduced with herpes simplex virus thymidine kinase gene have been intensively applied to the field of positron emission tomography via imaging of its substrate. As a pilot synthesis approach, a facile preparation of 5-[125I]iodoarabinosyl uridine starting from commercially available uridine is reported herein.
- Lin, Kun-I.,Chiang, Li-Wu,Wu, Chien-Hung,Chen, Shao-Wei,Yu, Chung-Shan
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p. 563 - 568
(2008/02/10)
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- Treatment of EBV and KHSV infection and associated abnormal cellular proliferation
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A method and composition for the treatment, prevention and/or prophylaxis of a host, and in particular, a human, infected with Epstein-Barr virus (EBV), is provided that includes administering an effective amount of a 5-substituted uracil nucleoside or its pharmaceutically acceptable salt or prodrug, optionally in a pharmaceutically acceptable diluent or excipient.
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- Enantioselective synthesis and biological evaluation of 5-o-carboranyl pyrimidine nucleosides
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Base-modified carborane-containing nucleosides such as 5-o-carboranyl-2'-deoxyuridine (CDU) when combined with neutrons have potential for the treatment of certain malignancies. Lack of toxicity in various cells, high accumulation in cancer cells and intracellular phosphorylation are desirable characteristics for modified nucleosides used in boron neutron capture therapy (BNCT) for brain tumors and other malignancies. The aim of this work was to synthesize the two β-enantiomers of several 5-o-carboranyl-containing nucleosides. These derivatives may possess favorable properties such as high lipophilicity, high transportability, the ability to be phosphorylated, and resistance to catabolism. β-Isomers of 2',3'-dihydroxynucleosides and analogues containing a heteroatom in the sugar moiety were also synthesized. Carboranyl pyrimidine nucleosides were prepared either from the parent β-D-nucleoside, β-L-nucleoside, or by a coupling reaction. The dioxolane derivative 7Scheme 1Reagents and conditions: (a) 1,1,1,3,3,3-hexamethydisilazane, ammonium sulfate, reflux, 6 h; (b) tin(IV) chloride, CH2Cl2, 0°C, 2h; (c) tetrabutylammonium fluoride, 1 M sol in THF, 0°C, 3h. was prepared by a coupling reaction between protected 5-o-carboranyluracil (8, CU) and the corresponding protected heterocycle. Specific catalysts were used during the N-glycosylation process to favor the formation of the β-isomer. Biological evaluation of these new chiral 5-o-carboranyl pyrimidine derivatives indicated that most of these compounds have low toxicity in a variety of normal and malignant cells and achieved high cellular levels in a lymphoblastoid cell line. Increasing the number of hydroxyl groups on the sugar moiety decreased the cellular accumulation and serum binding to different extents. Five compounds were identified for further biological evaluation as potential agents for BNCT. Copyright (C) 1999 Elsevier Science Ltd.
- Mourier, Nicolas S.,Eleuteri, Alessandra,Hurwitz, Selwyn J.,Tharnish, Phillip M.,Schinazi, Raymond F.
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p. 2759 - 2766
(2007/10/03)
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- Synthesis of Several Pyrimidine L-Nucleoside Analogues as Potential Antiviral Agents
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β-L-5-Iodo-2'-deoxyuridine (β-L-IUdR, 7) and 1-uracil (β-L-BV-ara-U, 10) have been synthesized via a multi-step synthesis from L-arabinose. 2',3'-Dideoxy-β-L-5-azacytidine (18), 2',3'-dideoxy-β-L-2-thiocytidine (20) and their respective α-anomers, compounds 19 and 21, also were synthesized by direct coupling of 1-O-acetyl-5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-L-ribofuranose (13) with the corresponding silylated bases, in the presence of EtAlCl2 in CH2Cl2, followed by separation of the α- and β-isomers and deblocking of the 5'-protecting groups.In addition, 2',3'-dideoxy-β-L-5-fluorocytidine (34), a potent anti-HIV and anti-HBV agent, was synthesized by an alternative methodology from 2',3'-dideoxy-β-L-5-fluorouridine (31) via a 4-triazolylpyrimidinone intermediate.These L-nucleoside analogues were tested in vitro against HIV, HBV, HSV-1, and HSV-2.Among these compounds, 2',3'-dideoxy-β-L-5-azacytidine (18) was found to show significant activity against HBV in vitro at approximately the same level as 2',3'-dideoxy-β-D-cytidine (ddC), which is a known potent anti-HBV agent.
- Lin, Tai-Shun,Luo, Mei-Zhen,Liu, Mao-Chin
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p. 1055 - 1068
(2007/10/02)
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- Synthesis and investigation of N4-substituted cytarabine derivatives as prodrugs.
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Esters of Cytarabine-N4-carboxylates 2a-i and succinamates 3a-f were synthesized as prodrugs of cytarabine (Ara-C) with the aim of developing improved derivatives for oral or parentral administration. At pH 2 series 2 showed relative higher stability than 3, while both series of esters revealed matched stability at pH 7. All esters were susceptible to enzymatic hydrolysis by rat plasma and liver homogenate with half lives ranged from 0.14 h to 12 d, and showed improved stability against cytidine deaminase. A parabolic relation was shown between Kobs of enzymatic hydrolysis and Vw. All compounds are more lipophilic than the parent drug, Ara-C.
- Fadl,Hasegawa,Youssef,Farag,Omar,Kawaguchi
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p. 382 - 387
(2007/10/02)
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- Synthesis of 1-β-L-arabinofuranosylcytosine (β-L-Ara-C) and 2'-deoxy- 2'-methylene-β-L-cytidine (β-L-DMDC) as potential antineoplastic agents
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1-β-L-Arabinofuranosylcytosine (β-L-Ara-C, 7) and 2'-deoxy-2'-methylene- β-L-cytidine (β-L-DMDC, 14) have been synthesized via a multi-step synthesis from L-arabinose. These compounds were tested in vitro against L1210, P388, Sarcoma 180, and CEM cells, and found not to be active at a concentration up to 100 μM. β-L-Ara-C and β-L-DMDC were also tested against HSV-1 and HSV-2 and yielded ID50 values of >100 μM.
- Lin,Luo,Liu
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p. 1861 - 1870
(2007/10/02)
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- Enzymatic acylation and alkoxycarbonylation of α-, xylo-, anhydro-, and arabino-nucleosides
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5'-O-acyl and 5'-O-alkoxycarbonyl derivatives of α-, anhydro-, xylo- and arabinonucleosides could be obtained through a lipase-mediated reaction with SP 435 lipase (from Candida antarctica) by using acetoxime butyrate or butyric anhydride, together with benzyloxycarbonyl-O-acetoxine as acylating agents. Alkoxycarbonylation gave poorer yields than acylation and other lipases tested gave non-selective reaction or not reaction at all.
- Moris,Gotor
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p. 10089 - 10098
(2007/10/02)
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- Ionization of purine nucleosides and nucleotides and their components by 193-nm laser photolysis in aqueous solution: Model studies for oxidative damage of DNA 1
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The effect of 20-ns pulses of 193-nm laser light on aqueous solutions of purine bases, (2′-deoxy)nucleosides, and (2′-deoxy)nucleotides was investigated, and monophotonic ionization was observed. Although (deoxy)ribose and (deoxy)ribose phosphates are also ionized by 193-nm light, the photoionization of the (deoxy)nucleosides and -tides takes place predominantly (90%) at the purine moiety, due to the much higher extinction coefficients at 193 nm of the bases as compared to the (deoxy)ribose phosphates. The quantum yields of photoionization (φPl) of the purines are in the range 0.01 to 0.08, based on φ(Cl-) at 193 nm of 0.46. As shown by comparison with data obtained from pulse radiolysis, the ionized purines, i.e., the radical cations, deprotonate in neutral solution, yielding neutral radicals. The radical cation of 1-methylguanosine, produced by photoionization in oxygen-saturated aqueous solution, deprotonates with the rate constant 3.5 × 105 s-1. In the absence of oxygen, the hydrated electrons resulting from the photoionization react with the untransformed purine derivatives to yield the corresponding radical anions. As these are rapidly protonated by water (as concluded from pulse radiolysis), the photoionization in deaerated neutral solution results in two different neutral radicals: a deprotonated radical cation and a protonated radical anion.
- Candeias,Steenken
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p. 699 - 704
(2007/10/02)
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- Antiviral compounds
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The present invention relates to certain novel 5-substituted pyrimidine nucleosides and pharmaceutically acceptable derivatives thereof and their use in the treatment of varicella zoster virus, cytomegalovirus and Epstein Barr virus infections. Also provided are pharmaceutical formulations and processes for the preparation of the compounds according to the invention.
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- Process for the preparation of pyrimidine nucleosides
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A process is provided for the preparation of a compound of formula (I) or a salt thereof: wherein R1 is hydrogen or a C1 4 alkyl, comprising reacting a compound of formula II: with an agent serving to introduce the alkynyl radical of formula -C≡CR1 (wherein R1 is as described above) at the 5-position of the pyrimidine base, the reaction being carried out in the presence of an N1 6 alkylmorpholine, wherein said alkyl moiety being optionally substituted by an alkoxy or halogen group; and optionally thereafter converting into a salt.
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- Nucleic Acid Related Compounds. 65. New Syntheses of 1-(β-D-Arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (IVAraU) from Vinylsilane Precursors. Radioiodine Uptake as a Marker for Thymidine Kinase Positive Herpes Viral Infections
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(Trimethylsilyl)acetylene was coupled with 1-(2,3,5-tri-O-acetyl-β-D-arabinofuranosyl)-5-iodouracil (3) to give 1-(2,3,5-tri-O-acetyl-β-D-arabinofuranosyl)-5-uracil (4).Lindlar hydrogenation of 4 gave 1-(2,3,4-tri-O-acetyl-β-D-arabinofuranosyl)-5(Z)-uracil (5).Treatment of 5 with iodine monochloride (or sodium iodide/phenyliodine(III) dichloride) in benzene gave 1-(2,3,5-tri-O-acetyl-β-D-arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (7), whereas polar solvents favored the (Z)-iodovinyl isomer 8.Deacetylation of 7gave 1-β-D-arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (IVAraU,9).A microscale in situ synthesis with Na*I gave IVAraU.Treatment of HSV-infected cells with IVAraU resulted in virus-dependent uptake associated with nucleoside phosphorylation by wild type or acyclovir-resistant DNA polymerase mutants (but not with TK-HSV-1 mutants).Uptake was virus-inoculum dependent and was detectable within 4 h postinfection.The process was not completely reversible.Virus-specified uptake of IVAraU may allow automated in vitro detection of HSV isolates.
- Robins, Morris J.,Manfredini, Stefano,Wood, Steven G.,Wanklin, R. James,Rennie, Bruce A.,Sacks, Stephen L.
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p. 2275 - 2280
(2007/10/02)
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- 1-(β-D-arabinofuranosyl)-5-propynyluracil for treatment of VZV infections
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The invention is a method for using 1-(β-D-arabinofuranosyl)-5-propynyluracil or its salts as the active ingredient in pharmaceutical compositions in the treatment of varicella zoster viral infections whether expressed as chicken pox or shingles.
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- Anti-HBV pyrimidine nucleoside
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This invention relates to 1-(β-D-Arabinofuranosyl)5-prop-1-ynyluracil and pharmaceutically acceptable derivatives thereof for use in the treatment of hepatitis viral infections, particularly hepatitis B viral infections.
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- Substituent effects on degradation rates and pathways of cytosine nucleosides.
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A previous report on the influence of a 6-methyl substituent on cytosine nucleoside degradation proposed that N-glycosyl hydrolysis predominated over the deamination pathway which was characteristic of the unsubstituted parent compounds. The UV absorption data which led to this hypothesis were not conclusive. Evidence for N-glycosyl hydrolysis was indirect and the product concentration was not quantitated. In the present study, specific HPLC methods were employed to assay four cytosine nucleosides and their corresponding bases, thus allowing comparison of the N-glycosyl hydrolysis rate to the overall rate of loss for each nucleoside. These data indicated that the 6-methyl nucleosides underwent partial or complete hydrolysis to yield their corresponding sugars and 6-methylcytosine, which then deaminated to 6-methyluracil. An increase in the reactivity and a change in the reaction products of the 6-methyl nucleosides were attributed to an alteration in conformation. In addition, the 6-methyl arabinosyl nucleoside reacted much faster than the 6-methyl ribosyl nucleoside, presumably due to 2'-OH participation. Degradation of 5-methyl deoxycytidine was also re-examined since its degradation was previously attributed solely to N-glycosyl hydrolysis. In the present study, simultaneous deamination and hydrolysis were measured, although N-glycosyl hydrolysis was found to predominate.
- Nguyen,Notari
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p. 802 - 806
(2007/10/02)
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- Hydrolysis of Tosyl Esters Initiated by an Electron Transfer from Photoexcited Electron-Rich Aromatic Compounds
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Selective hydrolysis of tosyl esters was realized by irradiation of Uv light (>300 nm) in the presence of electron-rich aromatic compounds and the reaction proceeds via en electron-transfer process.
- Nishida, Atsushi,Hamada, Tatsuo,Yonemitsu, Osamu
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p. 3386 - 3387
(2007/10/02)
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- THE RAPID CHEMICAL SYNTHESIS OF ARABINONUCLEOTIDES
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A fast and convenient procedure for the chemical synthesis of arabinonucleotides which eliminates the multistep protection of the arabinonucleoside building blocks is described.Both solution and solid phase phosphite triester procedures are described.
- Damha, Masad J.,Usman, Nassim,Ogilvie, Kelvin K.
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p. 1633 - 1636
(2007/10/02)
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- Reactions of pyrimidine nucleosides with aqueous alkalies: kinetics and mechanisms.
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Kinetics for the reactions of various cytosine and uracil nucleosides and their alkyl derivatives with aqueous sodium hydroxide have been studied by liquid chromatography. Blocking of the glycosyl hydroxyl groups with alkyl groups and changes in the glycon moiety configuration have been observed to exert only moderate effects on the rate of deamination of cytosine nucleosides. Methylation of the 4-amino group retards deamination considerably, while a methyl substituent at C5 is rate accelerating and at C6 only moderately rate retarding. These findings have been accounted for by a mechanism involving a rate limiting bimolecular displacement of the 4-amino group by a hydroxide ion. Analogous comparisons with uracil nucleosides suggest that the decomposition of uridine is initiated by an intermolecular attack of hydroxide ion on the C5 atom of the base moiety. In contrast, beta-D-arabino- and beta-D-lyxo-furanosyl derivatives appear to be cleaved via an intramolecular nucleophilic attack of the ionized 2'-hydroxyl group.
- L?nnberg,Suokas,K?ppi,Darzynkiewicz
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p. 798 - 805
(2007/10/02)
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- 17O NMR of Nucleosides. 3 - Chemical Shifts of Substituted Uridines and Ribothymidines
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Uridine and ribothymidine derivatives, bearing different substituents at C-5 and enriched (Ca 50percent) with 17O in the O-4 and O-2 carbonyls, have been studied via 17O NMR in both acetonitrile and aqueous solvents.The solvent shift differences between acetonitrile and water at O-4 (30-42 ppm) and O-2 (13-16 ppm) vary significantly from each other, but the chemical shift changes induced by changing the substituent at C-5 correlated well only with the O-4 shifts and the electron-withdrawing ability of the substituent.Examination of the 17O shifts of model compounds reconfirms the predominance of keto tautomers for both carbonyls.The significance of the solvent shifts and substituent shifts are discussed with respect to the electronic structure of the nucleoside base rings, and with respect to the hydrogen-bonding abilities of the carbonyl groups.Other nucleoside derivatives studied include those in which the 17O enrichment is in the ring linking the base to the sugar moiety in a pyrimidine cyclonucleoside, in the sugar hydroxy groups and in the phosphodiester linkage of a highly strained ring system in a nucleoside cyclic monophosphate.
- Schwartz, Herbert M.,MacCoss, Malcolm,Danyluk, Steven S.
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p. 885 - 894
(2007/10/02)
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- Reaction of Uridine and Uridine 5'-Phosphate with Diiminosuccinonitrile and Cyanogen Bromide in Aqueous Solution. Direct Synthesis of the 2,2'-Anhydronucleoside Linkage at 2 deg C
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Reaction of uridine with diiminosuccinonitrile (DISN) at 2 deg C in aqueous solution yields 2,2'-anhydrouridine 3-carbamate (7) (54percent) along with 2,2'-anhydrouridine (8) (10percent), arabinofuranosyluracil (9) (9percent), uridine 2',3'-carbonate (10) (5percent), uridine 2'-carbamate (11) (3percent), and uridine 3'-carbamate (12) (9percent).A similar distribution of reaction products was obtained when BrCN was used in place of DISN.The same reaction products were isolated from the reaction of DISN or BrCN with uridine 5'-phosphate after the phosphate grouping was cleaved from the initial reaction product mixture with alkaline phosphatase.A reaction pathway is proposed in which the imidocarbonate derivative 6 is a common intermediate for product formation.The vicinal 2',3'-hydroxyl groups are essential for reaction as shown by the failure to form stable reaction products with thymidine (17).Adenosine (13), which has vicinal 2',3'-hydroxyl groups, is converted to a mixture of the 2'- and 3'-carbamates (15 and 16) via an imidocarbonate (14) intermediate with DISN or BrCN.The relevance of these studies to chemical evolution is discussed.
- Ferris, J. P.,Yanagawa, H
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p. 2121 - 2125
(2007/10/02)
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- Aqueous conversion kinetics and mechanisms of ancitabine, a prodrug of the antileukemic agent cytarabine
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The kinetics of conversion of the prodrug ancitabine to the anti-cancer drug cytarabine have been studied in aqueous solutions in the pH range of 1.5-10.7, temperature range of 19.5-80.0°C, ionic strength range of 10-4 to 1.5, and in the presence of several general-base catalysts. Under all conditions ancitabine was quantitatively converted to cytarabine. The pH-rate profiles were linear with slope = 1 in alkaline pH, becoming pH independent in the region of maximum stability at pH ≤4, where buffer catalysis was found to be insignificant and k(obs) ? (1.12 x 1011 h-1)·exp {-10121 deg/T}. At 30°C, pH ≤4, it is calculated that an aqueous ancitabine solution will maintain 90% of its initial concentration for 12 d. A novel method for measuring general-base catalysis in competition with predominating a specific-base catalysis and in the presence of secondary salt effects a constant ionic strength was developed. Three mechanisms of hydrolytic prodrug conversion are proposed: nucleophilic hydroxide addition, general base-assisted nucleophilic water attack, and spontaneous water attack.
- Kirsch,Notari
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p. 896 - 902
(2007/10/02)
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- Syntheses of 1-(β-D-Arabinofuranosyl)-pyrimidines
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New synthetic methods of 1-(β-D-arabinofuranosyl)-pyrimidines are described. 1-(β-D-arabinofuranosyl)-uracil, 1-(β-D-arabinofuranosyl)-5-fluorouracil, 1-(β-D-arabinofuranosyl)-thymine, and 1-(β-D-arabinofuranosyl)-cytosine can be obtained in a high yield by the splitting of the anhydrobond in 2,2'-anhydropyrimidines in dipolar aprotic solvents, such as HMPT, DMF, and DMSO, respectively, in the presence of activated elemental copper.Unlike the formation of cyclopyrimidines ribonucleosides are directly transformed to the corresponding arabinofuranosyl derivatives by the reaction with diphenylcarbonate and NaHCO3 in the presence of copper.The reaction proceeds probably via an intermediate formation of the cycloproduct.Further aspects on the mechanism are described.
- Cech, D.,Schwarz, B.,Pein, C. D.
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p. 387 - 392
(2007/10/02)
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- 4-(1,2,4-Triazol-1-yl)- and 4-(3-Nitro-1,2,4-triazol-1-yl)-1-(β-D-2,3,5-tri-O-acetylarabinofuranosyl)pyrimidin-2(1H)-ones. Valuable Intermediates in the Synthesis of Derivatives of 1-(β-D-Arabinofuranosyl)cytosine (Ara-C)
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Treatment of the acetylated derivative (3b), which was prepared from uridine in 86 percent overall yield, with tri(1H-1,2,4-triazol-1-yl)phosphine oxide gave compound (6a) in high yield, and with 3-nitro-1,2,4-triazole and diphenyl phosphorochloridate it gave compound (6b) in high yield.When the former product (6a) was allowed to react with ammonia, methylamine, dimethylamine, and morpholine at room temperature, and the products further deacetylated if necessary, ara-C (1; R1=R2=H) and its corresponding 4-N-alkyl derivatives (1; R1=H, R2=Me), (1: R1=R2=Me), and 1,R2= -(CH2)2O(CH2)2-> were obtained in very high yields. 4-N-Phenyl-ara-C (1; R1=H, R2=Ph) was obtained in high yield when compound (6a) or (6b) was heated with aniline in pyridine solution and the products then deacetylated.The nitro-compound (6b) was converted into the ara-C derivative (1; R1=H, R2=CH2CO2Me), and the sulphide (7) was obtained following the deacetylation of the products of the reaction between the 1,2,4-triazolyl derivative (6a), toluene-p-thiol, and triethylamine.
- Divakar, K.J.,Reese, Colin B.
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p. 1171 - 1176
(2007/10/02)
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- AN ENZYMIC SYNTHESIS OF PURINE D-ARABINONUCLEOSIDES
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A method is described for the synthesis of purine D-arabinonucleosides that uses purine bases and 2,2'-anhydro-(1-β-D-arabinofuranosylcytosine), AraC-an, as the starting materials.AraC-an was chosen as the precursor to the D-arabinosyl donor, because it is more readily available than any of the products that may be sequentially derived from it, namely, 1-β-D-arabinofuranosylcytosine ( AraC ), 1-β-D-arabinofuranosyluracil ( AraU ), and α-D-arabinofuranosyl-1-phosphate ( Araf 1-P ), a D-arabinofuranosyl donor.Four reactions were involved in the ovarall procass; ( a ) AraC-an was nonenzymically hydrolyzed at alkaline pH to AraC which was then ( b ) deaminated by deaminase to AraU, a nucleoside, ( c ) phosphorylyzed by uridine phosphorylase to Araf 1-P, and ( d ) this ester caused to react with a purine base to afford a purine D-arabinonucleoside, the reaction being catalyzed by purine nucleoside phosphorylase.All four rections occured in situ, the first and second being performed sequentially, whereas the third and fourth were combined in a single step.The three enzyme catalysts were purified from Escherichia coli.The efficiency of the method is exemplified by the synthesis of the D-arabinonucleosides of 2,6-diaminopurine and adenine; the overall yields, based on AraC-an, were 60 and 80 percent respectively.
- Krenitski, Thomas A.,Koszalka, George, W.,Tuttle, Joel V.,Rideout, Janet L.,Elion, Gertrude B.
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p. 139 - 146
(2007/10/02)
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