Structure and Conformation of the Antiviral Agent 5-Methoxymethyl-2′-deoxyuridine

Abstract

The three dimensional structure of the activiral agent, 5-methoxymethyl-2′-deoxyuridine (MmdUrd) was determined by x-ray diffraction methods. MMdUrd crystallized in space group P2₁2₁2₁ of the orthorhombic system with a = 9.166(1)A, b, = 25.348(1)Amm c = 5.270(1)A and Z = 4. The conformation of the glycosyl bond is anti (χ = 233.30), the deoxyribose ring has the C(2′)-endo envelope conformation (²E), the CH₂OH side chain has the g⁺ conformation and the methoxy group at the C(5) position is on the same side of pyrimidine plane as the 0(4′) oxygen. NMR spectroscopy was used to determine the conformation in solution. The spectra indicate that the sugar ring exists in a 60:40 equilibrium of the S- and N-states. The population of the three rotamers about the exocyclic c(4′)–C(5′) bond were estimated to be g⁺:t:g::61%:31%:8%. The correlaiton of molecular conforation with antiviral activity is discussed.     

Synthesis and Anti-Hiv Activity of 3′-0-Formyl Derivatives of Thymidine and 2′-Deoxyuridine

Abstract

Reaction of the 5′-O-t-butyldimethylsilyl derivatives of thymidine and 2′-deoxyuridine with the Vilsmeier reagent (POCI₃/DMF), and removal of the t–butyldimethylsilyl protecting group, afforded 3′-O-formylthymidine (5) and 3′-O-formyl-2′-deoxyuridine (6), respectively. In vitro evaluation, determined as the ability of the test compound to inhibit HIV induced cytopathogenicity in CEM cells, indicated that 5 was moderately active, whereas 6 was inactive.     

Mechanism of Antiviral Activity of 5-Ethyl-2′-Deoxyuridine

Abstract

5-Ethyl-2′-deoxyurldine (EDU) is phosphorylated to a much greater extent by herpes simplex virus (HSV)-infected Vero cells than by mock-infected cells. Within the infected cells, EDU is preferentially incorporated into viral DNA and more inhibitory to viral than cellular DNA synthesis     

Synthesis and Antiviral Activity of New 5-Substituted 2′-Deoxyuridine Derivatives

New 5-azole- and 5-oxime-substituted analogues of 2′-deoxyuridine are synthesized. The analogues with azole ring manifest low toxicities and antiherpetic activities on Vero cell culture, the imidazole derivative being the most active. The inhibitory effects of oximes of 5-formyl-deoxyuridine are comparable with those of the azole-containing nucleoside analogues, although their cytotoxicities are found to be higher; oxime of 5-formyldeoxyuridine is particularly toxic. The nucleoside analogues synthesized exhibit no marked activity on cell cultures infected with various variants of poxvirus.     

Biological Activity and Phosphorylation of 2′-Azido-2′-Deoxyuridine and 2′-Azido-2′-Deoxycytidlne

Abstract

2′-Azido-2′-deoxyuridine and 2′-azido-2′-deoxycytidine were evaluated for their inhibitory activity against ribonucleotide reductase and for subsequent cell growth inhibition. Their mono-and di-phosphates were synthesized and their inhibitory activities against the reductase were also determined in a permeabilized cell system, along with the two nucleosides. The results of the present study identify the first phosphorylation step involved in the conversion of the two azidonucleosides to the corresponding diphosphates to be rate-limiting in the overall activation.     

Synthetic Nucleosides and Nucleotides. XXX.1 Synthesis and Antiviral Activity of 3′-Azido, 2′,3′-Unsaturated and 2′,3′-Dideoxy Derivatives of E-5-Styryl-2′-Deoxyuridine on Human Immunodeficiency Virus

Abstract

Some new 3′-azido, 2′,3′-unsaturated and 2′,3′-dideoxy 5-styryl analogs of deoxyuridine-related compounds have been synthesized and evaluated against human immunodeficiency virus in vitro. Among these compounds, 3′-azido-2′,3′-dideoxy-5-E-styryluridine (6) and 2′,3′-dideoxy-E-5-styryluridine (9) were found to be active, with ED₅₀ values of 5 and 10 μg/ml respectively.     

Synthesis,Molecular Conformation and Activity Against Herpes Simplex Virus of (E)-5-(2-Bromovinyl)-2′-Deoxycytidine Analogs

Analogs of (E)-5-(2-bromovinyl)-2 ′-deoxycytidine (BrVdCyd) (1) by substitution at N⁴ were synthesized to impart resistance against deamination. The anti-HSV-1 activity and solution conformation of these analogs were determined. N⁴-Acetyl-BrVdCyd (2) was a potent inhibitor of HSV-1 replication whereas N⁴-propanoyl-BrVdCyd (3) had good activity and N⁴-Butanoyl-BrVdCyd (4) had only low activity against HSV-1 replication. N⁴-Methyl-BrVdCyd (5) was devoid of activity against HSV-1.     

Synthesis and Biological Activity of BIS(Pivaloyloxymethyl) Ester of 2′-Azido-2′-Deoxyuridine 5′-Monophosphate

Abstract

Bis(pivaloyloxymethyl) ester of 2′-azido-2′-deoxyuridine 5′-monophosphate was prepared as a prodrug to generate 2′-azido-2′-deoxyuridine 5′-diphosphate inside the cell. A synthetic route utilizing stannyl phosphate was adopted in the preparation. The prodrug was evaluated for cell growth inhibition against a variety of tumor cell lines along with 2′-azido-2′-deoxyuridine and 2′-azido-2′-deoxycytidine.     

Synthesis and Biological Activity of 3′-Modified 2′-5′ Adenylate Trimers

Abstract

One of the most important mediators in the mode of action of interferon is the (2′-5′)(A)n synthetase-RNase L pathway. The 2′-5′oligoadenylates (2–5A), synthesized from ATP, activate a pre-existing endonuclease that cleaves single-stranded RNA. The biological activity of 2–5A is rapidly lost due to cleavage of the 2′-5′ internucleotide bond by a specific 2′-5′-phosphodiesterase starting at the 3′end. This rapid cleavage and the poor uptake of 2–5A in intact cells limit the use of 2–5A as an antiviral or antineoplastic agent. Although several modified 2–5A analogues have been synthesized in order to improve the enzymatic stability, only few have proven to be resistant to degradation and still able to activate the 2–5A dependent endonuclease. 1-4 On the other hand, relative drastic methodology such as calcium coprecipitation, microinjection and liposome encapsulation5 has been used to introduce 2–5A into intact cells. Here, we present the synthesis and biological activity of oligoadenylates in which one or more adenosine residues were replaced by 9-(3-azido-3-deoxy-6-D-xylofuranosyl)adenine or 9-(3-amino-3-deoxy-D-xylofuranosyl)adenine. The oligonucleotides were synthesized by the phosphotriester method with triisopropylbenzenesulfonyl-chloride in the presence of N-methylimidazole as the condensing agent. The p-nitrophenylethyl group was used as the protecting group for the 2′-hydroxylfunction .(carbonate), the internucleotide linkage (phosphate ester) and the exocyclic amino groups of the heterocyclic base (carbamate). Bis(p-nitrophenylethy1)phosphoromonochloridate was used to phosphorylate the 5′-hy-droxyl group. All these blocking groups were removed with DBU in pyridine.     

2′5′-Phosphodiesterase Activity Studies with Xyloadenosine Analogs of 2–5A Cores

Abstract

Sequential substitution of xyloadenosine into the trimeric and tetrameric 2–5A cores¹ allows evaluation of the importance of the 3′ hydroxyl groups to 2′5′-phosphodiesterase (PDE) activity.     

The Carbocyclic Analogue of 5-(1-Propenyl)-2′-Deoxyuridine; Synthesis and Anti-Herpes Activity

Abstract

The title compound was synthesised and tested against HSV-1 in cell culture. Like related compounds, it was less active than the parent nucleoside.     

Synthesis and Antiviral Activity Evaluation of 2′,5′,5′-Trifluoro-Apiosyl Nucleoside Phosphonic Acid Analogs

Racemic synthesis of novel 2′,5′,5′-trifluoro-apiose nucleoside phosphonic acid analogs were performed as potent antiviral agents. Phosphonation was performed by direct displacement of triflate intermediate with diethyl (lithiodifluoromethyl) phosphonate to give the corresponding (α,α-difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor with persilylated bases to yield the nucleoside phosphonate analogs. Deprotection of diethyl phosphonates provided the target nucleoside analogs. An antiviral evaluation of the synthesized compounds against various viruses such as HIV, HSV-1, HSV-2, and HCMV revealed that the pyrimidine analogues have significant anti-HCMV activity.     

Relationship Between Conformation and Antiviral Activity -IV. 5-Ethyl-2′-Deoxyurldine and 5-Ethyl-2′-Deoxycytidine +

Abstract

5-Ethyl-2′-deoxyuridine(EtdUrd), though a potent inhibitor of herpes simplex virus (HSV) replication, is rapidly catabolized to produce an inactive pyrimidine base by thymidine and/or uridine phosphorylases. 5-Ethyl-2′-deoxycytidine (EtdCyd) was synthesized to confer metabolic stability and thus improve efficacy against systemic HSV infections. EtdCyd was inactive against HSV in the presence or absence of deaminase inhibitors in VERO cells up to 2 mM. The relationship between molecular conformation and antiherpes activity for EtdUrd and EtdCyd is discussed.

     

Highly Efficient and Facile Synthesis of 5-Azido-2′-Deoxyuridine

Previously reported syntheses of the photoaffinity label 5-azido-2′-deoxyuridine are rather inefficient and involve the tedious preparation of a 5-nitro intermediate. To overcome these inconveniences, we have developed a new approach from the commercially available 5-bromo-2′-deoxyuridine nucleoside. Our synthetic route makes use of a benzylamination reduction sequence. Using this strategy, the 5-azido-2′-deoxyuridine photolabel is prepared in three steps and quantitative yields.     

Synthesis of Two 2′-Deoxyuridine Analogs Substituted in Position 5 with 2-Atom Tethered Nitroxide Radicals

Abstract

The synthesis of two novel spin labeled 2′-deoxyuridine analogs is described. The nucleic acid building block is substituted in position 5 with a short methylamino tether, which bears either a six- or five-membered nitroxide ring.     

Synthesis and Antiretroviral Activity of Novel 4′-Fluoro-5′-Deoxyphosphonic Acid Carbocyclic Nucleoside Analogs

Novel 5′-deoxycarbocyclic purine phosphonic acid analogs with the 4′-electropositive moiety, fluorine were designed, and synthesized from glyceraldehyde. The cyclopentenol intermediate, 9, was successfully synthesized by the ring-closing metathesis of divinyl 8. The condensation reaction of cyclopentanol 15 with purine bases under Mitsunobu conditions successfully afforded the desired phosphonate analogs. The synthesized nucleoside phosphonic acid analogs, 19, 22, 26, and 29, were subjected to antiviral screening against human immunodeficiency virus (HIV)-1. Guanine phosphonic acid analog 29 showed significant anti-HIV activity (EC₅₀ = 10.3 μM).     

Effect of 2-Amino Substitution on the Antiviral Effects of 5-Ethyl-2′-Deoxyuridine and (E)-5-(2-bromovinyl)-2′-Deoxyuridine and Their Incorporation into DNA

Abstract

The 2-amino derivatives of 5-ethyl-2′-deoxyuridine (EDU) and (E)-5-(2-bromovinyl)-2′-deoxyuridine (BVDU) have been synthesized and evaluated for anti-herpesvirus activity. They were at least 1000-fold less effective against herpes simplex virus replication than the parent compounds EDU and BVDU. The 5′-triphosphates of the 2-amino substituted EDU, BVDU and thymidine derivatives were also synthesized and examined on their substrate/inhibitor properties against different DNA polymerases. None of the compounds proved markedly inhibitory to HSV-1 DNA polymerase or cellular DNA polymerase a. Nor were they incorporated into the growing DNA chain.     

3′-O- and 5′-O-Propargyl Derivatives of 5-Fluoro-2′-Deoxyuridine: Synthesis,Cytotoxic Evaluation and Conformational Analysis

A series of new 3′-O- and 5′-O-propargyl derivatives of 5-fluoro-2′-deoxyuridine (1–4) was synthesized by means of propargyl reaction of properly blocked nucleosides (2,4), followed by the deprotection reaction with ammonium fluoride. The synthesized propargylated 5-fluoro-2′-deoxyuridine analogues (1–4) were evaluated for their cytotoxic activity in three human cancer cell lines: cervical (HeLa), oral (KB) and breast (MCF-7), using the sulforhodamine B (SRB) assay. The highest activity and the best SI coefficient in all of the investigated cancer cells were displayed by 3′-O-propargyl-5-fluoro-2′-deoxyuridine (1), and its activity was higher than that of the parent nucleoside. The other new compounds exhibited moderate activity in all of the used cell lines.     

Synthesis and Biological Activity of 5-halo-2-Pyrimidinone 3′-Azido-2′,3′-Dideoxyribosides

Abstract

The synthesis of two nucleosides, 1-(3-azido-2,3-dideoxy-β-D-ribofuranosyl)-5-iodo- and -5-bromo-2(1H)-pyrimidinone, 1a and 1b, is described. Neither 1a nor 1b exhibited significant inhibition of T, lymphocyte growth. However, both compounds were unable to protect T, lymphocytes from the cytopathic effects of HIV.