A new synthesis and an antiviral assessment of the 4′-fluoro derivative of 4′-deoxy-5′-noraristeromycin

A synthetic route to (1S,2S,3R,5S)-3-(6-amino-9H-purin-9-yl)-5-fluorocyclopentane-1,2-diol (that is, the 4′-fluoro derivative of 4′-deoxy-5′-noraristeromycin, 3) is described via a fluorinated cyclopentanol, which is in contrast to existing schemes where fluorination occurred once the purine ring was present. Compound 3 was assayed versus a number of viruses. A favorable response was observed towards measles (IC₅₀ of 1.2 μg/mL in the neutral red assay and 14 μg/mL by the visual assay) but this was accompanied by cytotoxicity in the CV-1 host cells (21–36 μg/mL). Among the viruses unaffected by 3 were human cytomegalovirus and the poxviruses (vaccinia and cowpox), which are three viruses that were inhibited by the 4′,4′-difluoro analog of 3 (that is, 2).     

Synthesis of a Novel Aldehyde: 4-O-Methyl-5-formylmethyl- 2′-deoxyuridine

Abstract

The synthesis of the blocked nucleoside 3′,5′-di-O-p-toluoyl-4-O-methyl-5-formylmethyl-2′-deoxyuridine (19) was accomplishied in eleven steps from gamma-butyrolactone. This aldehyde, which should facilitate the synthesis of nucleosides containing ¹⁸F, was converted to the corresponding blocked dithianyl nucleoside (21), and also to 5-(2,2-difluoroethyl)-substituted derivatives of 2′-deoxyuridine and 2′-deoxycytidine.     

Inhibition of anion permeability of sarcoplasmic reticulum vesicles by 4-acetoamido-4′-isothiocyanostilbene-2,2′-disulfonate

The permeabilities of sarcoplasmic reticulum vesicle membrane for various ions and neutral molecules were measured by following the change in light scattering intensity due to the osmotic volume change of the vesicles. 4-Acetoamido-4′-isothiocyanostilbene-2,2′-disulfonate (SITS), which is a potent inhibitor for the anion permeability of red blood cells membrane, inhibited the permeability of sarcoplasmic reticulum for anions such as Cl^?, P_i and methanesulfonate, while it slightly increased that for cations and neutral molecules such as Na⁺, K⁺, choline and glycerol. Binding of 5μmol SITS/g protein was necessary for the inhibition of anion permeability. These results suggest the existence of a similar anion transport system in sarcoplasmic reticulum membrane as revealed in red blood cell membrane.     

Synthesis of 4′-Trifluoromethyl Nucleoside Analogs

Abstract

A strategy based on the use of (trifluoromethyl) trimethylsilane for introduction of the trifluoromethyl group at the C-4 of ribose has been developed and utilized in the synthesis of various novel 4′-trifluoromethylated nucleoside analogs. Screening of these analogs against HIV did not reveal significant biological activity.     

Synthesis of 4′-(Hydroxymethyl)Guanosine and a Phosphonate Analogue of Guanylic Acid

Abstract

The synthesis of 4′-(hydroxymethyl)guanosine (7) and the phosphonate analogue 8 of guanylic acid proceed from a common intermediate, 2′, 3′-O-isopropylidene-N ²-(monomethoxytrityl)-guanosine-5′-aldehyde (13).     

An Alternative Synthetic Method for 4′-C-Ethynylstavudine by Means of Nucleophilic Substitution of 4′-Benzoyloxythymine Nucleoside

For the synthesis of 2′,3′ -didehydro-3′ -deoxy-4′ -C-ethynylthymidine (8: 4′ -Ed4T), a recently reported promising anti-HIV agent, a new approach was developed. Since treatment of 1-(2,5-dideoxy-β-l-glycero-pent-4-enofuranosyl)thymine with Pb(OBz)₄ allowed the introduction of a 4′-benzoyloxy leaving group, nucleophilic substitution at the 4′ -position became feasible for the first time. Thus, reaction between the 4′-benzoyloxy derivative (11) and Me₃SiC ≡ CAl(Et)Cl as a nucleophile led to the isolation of the desired 4′-“down”-ethynyl derivative (15) stereoselectively in 62% yield.     

Nucleosides and Nucleotides. 232. Synthesis of 2′-C-Methyl-4′-thiocytidine: Unexpected Anomerization of the 2′-Keto-4′-thionucleoside Precursor

The synthesis of 2′-C-methyl-4′-thiocytidine (16) is described. Since the 2′-keto-4′-thiocytidine derivative 2β unexpectedly isomerized to 2α and the methylation of 2β proceeded predominantly from the less hindered α-face to give 7, the desired product 16 was synthesized via the Pummerer reaction of the sulfoxide 14 and N ⁴ -benzoylcytosine.     

Determination of albumin adducts of 4,4′-methylenediphenyl diisocyanate in workers of a 4,4′-methylenedianiline factory

Lung sensitization and asthma are the main health effects of 4,4′-methylenediphenyl diisocyanate (MDI). Albumin adducts (isocyanate specific adducts) of MDI might be involved in the etiology of sensitization reactions. Albumin adducts of MDI have been found in subjects classified as 4,4′-methylenedianiline (MDA) workers. The mean adduct levels in these MDA-workers were 1.5 times higher than in MDI-workers of the same company. MDA-specific hemoglobin adducts, were present ten times more in the MDA-workers than in the MDI-workers. MDA-workers with specific work task had significantly higher albumin adduct levels.     

2′,4′-BNA/LNA aptamers: CE-SELEX using a DNA-based library of full-length 2′-O,4′-C-methylene-bridged/linked bicyclic ribonucleotides

DNA-based aptamers that contain 2′-O,4′-C-methylene-bridged/linked bicyclic ribonucleotides (B/L nucleotides) over the entire length were successfully obtained using a capillary electrophoresis systematic evolution of ligands by exponential enrichment (CE-SELEX) method. A modified DNA library was prepared with an enzyme mix of KOD Dash and KOD mutant DNA polymerases. Forty 2′-O,4′-C-methylene bridged/locked nucleic acid (2′,4′-BNA/LNA) aptamers were isolated from an enriched pool and classified into six groups according to their sequence. 2′,4′-BNA/LNA aptamers of groups V and VI bound human thrombin with K_d values in the range of several 10 nanomolar levels.     

Inhibition of a novel subspecies of DNA polymerase α by 2′-deoxy-2′-azidoadenosine 5′-triphosphate

DNA polymerase α₁, a subspecies of DNA polymerase α of Ehrlich ascites tumor cells, was associated with a novel RNA polymerase activity and utilized poly(dT) and single-stranded circular fd DNA as a template without added primer in the presence of ribonucleoside triphosphates and a specific stimulating factor. DNA synthesis in the above system was inhibited by the ATP analogue, 2′-deoxy-2′-azidoadenosine 5′-triphosphate more than the DNA synthesis with poly(dT)·oligo(rA) by DNA polymerase α₁ and RNA synthesis by mouse RNA polymerases I and II. Kinetic analysis showed that the analogue inhibited DNA polymerase α₁ activity on poly(dT) competitively with respect to ATP, suggesting that the analogue inhibited RNA synthesis by the associated RNA polymerase activity.     

Efficient Synthesis of 4-Thio-D-ribofuranose and Some 4′-Thioribonucleosides

Abstract

A synthetic pathway to reach easily the 4-thio-D-ribofuranose is described. Some corresponding pyrimidine α and β 4′-thioribonucleosides have been synthesized and evaluated as antiviral agents against various viruses.     

Synthesis and evaluation of the anti-hepatitis B virus activity of 4′-Azido-thymidine analogs and 4′-Azido-2′-deoxy-5-methylcytidine analogs: structural insights for the development of a novel anti-HBV agent

Abstract

Hepatitis B virus (HBV) infection is a major worldwide health problem that requires the development of improved antiviral therapies. Here, a series of 4′-Azido-thymidine/4′-Azido-2′-deoxy-5-methylcytidine derivatives (6, 10–15) were synthesized, and their anti-HBV activities evaluated. Compounds 10–15 were synthesized via an S_NAr reaction of 18, in which the 4-position of the thymine moiety was activated as the 2,4,6-triisopropylbenzenesulfonate. Compounds 11–15 showed no antiviral activity. However, 4′-Azido thymidine (6) and 4′-Azido-2′-deoxy-5-methylcytidine (10) displayed significant anti-HBV activity (EC₅₀ = 0.63 and 5.99?µM, respectively) with no detectable cytotoxicity against MT-2 cells up to 100?µM.     

Microbial conversion of o-acetyltoluidide into 4′-hydroxy-o-acetyltoluidide

Summary Approximately 600 strains of various bacteria and actinomycetes were tested for their ability to hydroxylate o-acetyltoluidide (AT) at the 4'-position. Nocardia asteroides IFO 3384 and N. globerula IFO 13510 were selected as the best strains to catalyse the hydroxylation of AT. The product was isolated from culture] broth and identified as 4'-hydroxy-o-acetyltoluidide (4'-HAT). When AT was added during the course of cultivation of N. asteroides IFO 3384 and N. globerula IFO 13510, final concentrations of 1.0 mg/ml (a 23% molar conversion yield) and 1.5 mg/ml 4'-HAT (a 34% molar conversion yield) were obtained, respectively, from AT after 7 days cultivation. On the other hand, when resting cells of N. globerula IFO 13510 were used, the concentration of 4'-HAT attained was 4.4 mg/ml, a 69% molar conversion yield, after 4 days reaction. Offprint requests to: T. Nagasawa     

Deuteration and Tritiation of 2′-Deoxyribonucleosides in the 5′ and 4′ Positions

Abstract

The deuterations of 2′-deoxyguanosine in the 4′ and 5′ positions have been described elsewhere (1). The starting material is the 5′-aldehyde formed by mild oxidation with N,N-dicyclohexyl carbodiimide in dimethyl sulphoxide of the fully protected nucleoside with free 5′-alcoholic function. The 5′4euteration was achieved by reduction with deuterated sodium borohydride. Incorporation of deuterium in the 4′-position was achieved v i a an enhanced keto-enol tautomerim by heating the aldehyde in 50/50 D20/pyridine, with subsequent reduction of the aldehyde with NaBH4. The 6-furanoid form was isolated from the I-lyxo by-product by reverse phase HPLC. Applied to pyrimidine 2′-deoxyribonucleosides, this method was shown to give deuterated 2′-deoxycytidine and thymidine in good yield.     

Synthesis and Antiviral Activity of L-2′-Deoxy-2′-up-fluoro-4′-thionucleosides

Abstract

L-2′-Deoxy-2′-up-fluoro-4′-thionucleosides were efficiently synthesized from D-xylose via L-4-thioarabitol derivative as a key intermediate and evaluated for antiviral activities against HIV-1, HSV-1,2 and HBV.     

Synthesis of (±)-4′-Ethynyl and 4′-Cyano Carbocyclic Analogues of Stavudine (d4T)

The synthesis of (±)-4′-ethynyl (8) and 4′-cyano (9) carbocyclic analogues of the anti-HIV agent stavudine (5, d4T) is reported. The carbocyclic unit (16) was constructed from readily available β-keto ester 10. The ethynyl or cyano group of 8 and 9 were prepared, after the introduction of thymine base to 16, by manipulation of the ester function. Evaluation of the anti-HIV activity of 8 and 9 was also carried out.     

Reinvestigation of 4-Thiothymidine-5′-triphosphate Synthesis

Abstract

The 4-Thiothymidine-5′-triphosphate 1 (S⁴TTP) was known to be a substrate for polymerase, however a commercial sample of this compound failed to be incorporated into DNA. Mass spectrometry combined to alkaline phosphatase digestion and ³¹P-NMR showed that this sample was in fact 5′-chloro-5′-deoxy-4-thiothymidine-3′-triphosphate 2 . The desired S⁴TTP was synthesized by two alternate routes, was fully characterized and was shown to be incorporated in a DNA polymerase assay.