Imidazole-4-Carboxamide and 1,2,4-Triazole-3-Carboxamide Deoxynucleotides as Simplified DNA Building Blocks with Ambiguous Pairing Capacity

Abstract

2′-Deoxynucleosides of imidazole-4 (or 1,2,4-triazole-3)-carboxamide, ethyl imidazole-4 (or 1,2,4-triazole-3)-carboxylate were synthesized by enzymatic glycosylation using N-deoxyribosyltransferase from a lactobacterium. The base pairing properties of Y and V when placed opposite the natural DNA bases as well as their self were evaluated by thermal denaturation experiments. DNA templates containing imidazole-4-carboxamide base were used in elongation reaction catalysed by Klenow fragment.     

Synthesis and antiviral activity of amino acid esters of ribavirin

The synthesis and antiviral activity of amino acid esters of 1-(β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (ribavirin,1) is described.     

Chemoenzymatic method of 1,2,4-triazole nucleoside synthesis: Possibilities and limitations

Possibilities and limitations of chemoenzymatic synthesis of novel structural analogues of an antiviral preparation of Ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) were established. A synthesis of various amides of 1H-1,2,4-triazole-3-carboxylic acid and its 5-substituted analogues—potential substrates of purine nucleoside phosphorylase—has been described. Comparative efficiency of preparation methods of these amides, as well as the methods of introduction of functional groups to the C5 position of heterocyclic system, were investigated. Novel analogues of Ribavirin containing various substitutes in the carboxamide group were synthesized. A biotechnological method was developed for the preparation of 1-β-D-ribofuranozyl-1,2,4-triazole-3-carbonitryl, an intermediate in the synthesis of Viramidine, the modern analogue of Ribavirin.     

Compounds, similar to acyclovir V. Synthesis and antiviral activity of carbethoxyalkoxymethyl derivatives of nucleic bases

Ethyl esters and amides of carboxymethoxy-, alpha- and beta-carboxyethoxy- and gamma-carboxypropoxymethyl derivatives of adenine, guanine, cytosine, uracil, thymine, 1,2,4-triazole-3- and -5-carboxamide were synthesized and their antiviral activity was studied.     

Compounds similar to acyclovir. VII. Attempts to construct an anti-herpetic agent (6-hydroxy-2-oxa-4-hexenyl derivatives of nucleic bases

Based on the available data on the acyclovir's mechanism of action we attempted to predict the antiherpetic activity of 6-hydroxy-2-oxahexen-4-yl derivatives of nucleic bases. In terms of this model 9-(6-hydroxy-2-oxahexen-4-yl) guanine might be active. 6-Hydroxy-2-oxahexen-4-yl derivatives of adenine, guanine, cytosine, thymine, uracil, 1,2,4-triazole-3 and 1,2,4-triazole-5-carboxamide have been synthesized and their activity against herpes virus I investigated. The guanine derivative proved to possess rather high activity (chemotherapeutical index 8).     

Synthesis of carbocyclic 1-[4-(hydroxymethyl)cyclopent-2-enyl]-1,2,4-triazole-3-carboxamide and its derivatives

The synthesis of carbocyclic 1-[4-(hydroxymethyl)cyclopent-2-enyl]-1,2,4-triazole-3-carboxamide (6a) and its derivatives was achieved from triol 10 in excellent overall yield. This route involves a Pd(0)-catalyzed coupling reaction as a key step.     

Enzymatic Production of Ribavirin from Orotidine by Erwinia carotovora AJ 2992

Microorganisms that produce ribavirin (1-β-d-ribofuranosyl-1,2,4-triazole-3-carboxamide; virazole^®) directly from orotidine and 1,2,4-triazole-3-carboxamide (TCA) were screened from our stock cultures. Of the 425 strains, Erwinia carotovora AJ 2992 was found to possess potent ribavirin-producing ability, from orotidine and TCA. In the presence of intact cells of E. carotovora AJ 2992, 183 mm ribavirin was produced from 300 mm orotidine and 300 mm TCA on 48 hr reaction.     

Ribavirin cures cells of a persistent infection with foot-and-mouth disease virus in vitro.

Ribavirin (1-beta-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide) eliminates foot-and-mouth disease virus from persistently infected cell cultures. The latter are 10-fold more sensitive to ribavirin than lytically infected cells. In treated cells no viral RNA or proteins could be detected by dot-blot hybridization to cDNA probes, virus and RNA infectivity assays, or immunofluorescence. A potential application of the drug for the treatment of animals carrying the virus is suggested.     

Synthesis of homo-N-nucleoside with 1,2,4-triazole-3-carboxamide

On the basis of potent biological activities of ribavirin and homo-N-nucleosides, a novel homo-N-1,2,4-triazole-3-carboxamide derivative 1 was synthesized starting from 2,3,5-tri-O-benzoylribofuranosyl-1-acetate as a potential antiviral agent.     

Synthesis and properties of acyclic analogs of ribavirin

Acyclic analogues of ribavirine, viz. 1-(1-hydroxy-4-oxahex-3-yl)-, 1-(1-chloro-4-oxahex-3-yl)-, 1-(1,2-dihydroxy-4-oxahex-3-yl)-, 1-(1,6-dihydroxy-4-oxahex-3-yl)-, 1-(1-chloro-6-hydroxy-4-oxahex-3-yl)-, and 1-(1,2,6-trihydroxy-4-oxahex-3-yl)-1,2,4-triazole-3-carboxamide, with the C3'-C4' bond of the furanose ring cleaved, have been prepared by condensation of trimethylsilyl derivatives of 3-ethoxycarbonyl-1,2,4-triazole with alkylating agents in the presence of SnCl4 followed by treatment with methanolic ammonia. Convenient methods for synthesis of the alkylating agents were elaborated.     

Synthesis of Carbocyclic 1-[4-(Hydroxymethyl)cyclopent-2-enyl]-1,2,4-triazole-3-carboxamide and Its Derivatives

Abstract

The synthesis of carbocyclic 1-[4-(hydroxymethyl)cyclopent-2-enyl]-1,2,4-triazole-3-carboxamide (6a) and its derivatives was achieved from triol 10 in excellent overall yield. This route involves a Pd(0)-catalyzed coupling reaction as a key step.     

SYNTHESIS OF HOMO-N-NUCLEOSIDE WITH 1,2,4-TRIAZOLE-3-CARBOXAMIDE

On the basis of potent biological activities of ribavirin and homo-N-nucleosides, a novel homo-N-1,2,4-triazole-3-carboxamide derivative 1 was synthesized starting from 2,3,5-tri-O-benzoyl-ribofuranosyl-1-acetate as a potential antiviral agent.     

Elimination of eggplant mottled crinkle virus using virazole in explant cultures of Solanum melongena L

Virazole (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide; 100 and 150 mg/l) incorporated into brinjal explant culture medium induced in complete elimination of eggplant mottled crinkle virus - Indian isolate (EMCV-1) from infected explant cultures of S. melongena L. and production of virus free plant progeny. Acridine orange and ethidium bromide (150 ml/l) were also potent antiviral agents to some extent.     

Synthesis of 3'-deoxy-3'-C-methyl nucleoside derivatives

2',3'-Dideoxy-3'-C-methyl nucleosides bearing the five naturally occurring nucleic acid bases were synthesized. Additionally, the 3'-deoxy-3'-C-methyl nucleoside analogues bearing 5-aminoimidazole-4-carboxamide as well as 1,2,4-triazole-3-carboxamide moieties were prepared. The synthesis of the corresponding 2',3'-dideoxy-3'-C-methyl triazole derivative was also accomplished. The dideoxynucleoside derivatives were prepared by radical deoxygenation from their 3'-deoxy-3'-C-methyl parent ribonucleosides. When evaluated for their antiviral activity in cell culture experiments, none of these compounds showed any significant antiviral activity.     

Enzymatic Production of Ribavirin from Pyrimidine Nucleosides by Enterobacter aerogenes AJ 11125

Microorganisms that produce ribavirin(1-β-d-ribofuranosyl-1,2,4-triazole-3-carboxamide; virazole^®) directly from pyrimidine nucleosides and TCA (1,2,4-triazole-3-carboxamide) were screened from our stock cultures. Of the 400 strains tested, 16 were isolated as ribavirin-producers from uridine or cytidine. In particular, Enterobacter aerogenes AJ 11125, Bacillus brevis AJ 1282 and Sarcina lutea AJ 1212 were found to possess potent activities of ribavirin production from them. In the presence of intact cells of Enterobacter aerogenes AJ 11125, which was selected as the best strain, 110.2mm and 67.6 mm ribavirin were produced from uridine and cytidine, respectively, on 96 hr reaction at 60°C. In addition, this strain could also produce ribavirin from guanosine, but could not produce it from orotidine, which is also a pyrimidine nucleoside.     

The effect of 1-β-d-ribofuranosyl- 1,2,4-triazole-3-carboxamide on bud and shoot formation in tobacco petiole cultures

Ribavirin (1-β- d -ribofuranosyl- 1,2,4-triazole-3-carboxamide) increases starch accumulation in explants of Nicotiana tabacum L. ev. Xanthi nc and increases the number of meristematic zones; adventitious bud and shoot formation is significatntly increased. It overcomes auxin inhibition of bud and shoot formation in this system but studies on interaction with exogenous auxin and triiodobenzoic acid do not support the hypothesis that ribavirin acts directly on auxin metabolism. The results are discussed in relation to the induction and maintenance of permissive or receptive cell states in tobacco explant culture.     

In Search of New Inhibitors of HIV-1 Replication: Synthesis and Study of 1-(2′-Deoxy-β-D-Ribofuranosyl)-1,2,4-Triazole-3-Carboxamide as a Selective Viral Mutagenic Agent

With the emergence of HIV strains resistant or cross-resistant to nearly all antiretroviral regimen, novel therapy approaches have to be considered. As a part of our current work on viral mutagenic compounds, we prepared 1-(2′ -deoxy-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (2′ -deoxy-ribavirin) and its 5′ -triphosphate derivative. The nucleoside mutagenic activity was evaluated on HIV-1 NL4-3 in CEMx174 cell culture. After 2.5 months, no reduction on HIV-1 viability was observed. On the other hand, in vitro experiments with purified HIV-1 RT demonstrated that the triphosphate analog can be incorporated opposite to several natural nucleosides.     

In search of new inhibitors of HIV-1 replication: synthesis and study of 1-(2'-Deoxy-beta-D-Ribofuranosyl)-1,2,4-triazole-3-carboxamide as a selective viral mutagenic agent

With the emergence of HIV strains resistant or cross-resistant to nearly all antiretroviral regimen, novel therapy approaches have to be considered. As a part of our current work on viral mutagenic compounds, we prepared 1-(2' -deoxy-beta-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (2' -deoxy-ribavirin) and its 5' -triphosphate derivative. The nucleoside mutagenic activity was evaluated on HIV-1 NL4-3 in CEMx174 cell culture. After 2.5 months, no reduction on HIV-1 viability was observed. On the other hand, in vitro experiments with purified HIV-1 RT demonstrated that the triphosphate analog can be incorporated opposite to several natural nucleosides.     

Synthesis and characterization of a ribavirin-3'',5''-phosphate pentadecamer homoribopolymer bearing a 5''-amino tether group and a 3''-thymidine.

The synthesis of a pentadecamer of the 5'-phosphate of the antiviral nucleoside ribavirin (1'-beta-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide) has been achieved. This homoribopolymer is terminated at the 5'-position with an (6-aminohexyl)phosphate group to permit conjugation to a carrier and at the 3'-position by a thymidine-5'-phosphate. The synthesis was accomplished using the methyl phosphoramidite approach to oligoribonucleotides. The homoribopolymer was insensitive to ribonuclease A but was sensitive to ribonuclease T2 digestion.     

Synthesis of 2′,3′-Dideoxyribavirin

Abstract

A synthesis of 1-(2,3-dideoxy-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (2′,3′-dideoxyribavirin, ddR) is described. Glycosylation of the sodium salt of 1,2,4-triazole-3-carbonitrile (5) with 1-chloro-2-deoxy-3,5-di-0-p-toluoyl-α-D-erythro-pentofuranose (1) gave exclusively the corresponding N-1 glycosyl derivative with β-anomeric configuration (6), which on ammonolysis provided a convenient synthesis of 2′-deoxyribavirin (7). Similar glycosylation of the sodium salt of methyl 1,2,4-triazole-3-carboxylate (2) with 1 gave a mixture of corresponding N-1 and N-2 glycosyl derivatives (3) and (4), respectively. Ammonolysis of 3 furnished yet another route to 7. A four-step deoxygenation procedure using imidazolylthiocarbonylation of the 3′-hydroxy group of 5′-0-toluoyl derivative (9a) gave ddR (11). The structure of 11 was proven by single crystal X-ray studies. In a preliminary in vitro study ddR was found to be inactive against HIV retrovirus.