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A series of novel 2'-C-methylribonucleosides, involving 5-iodo and 5-alkynyl uridine analogues as well as related bicyclic furano- and pyrrolo[2,3-d]pyrimidinone compounds, has been synthesized and evaluated for their inhibitory effect on replication of the hepatitis C virus (HCV). The new nucleoside analogues did not show meaningful anti-HCV activity.
Unlike their +/+ and nu/+ littermates, homozygous athymic-nude (nu/nu) mice that had been sensitized with Bacillus Calmette-Guérin (BCG) failed to produce interferon (IFN) in response to purified protein derivative (PPD). Likewise, spleen cells derived from BCG-sensitized nu/nu mice failed to produce IFN when exposed to PPD in vitro. These findings suggest that the T-cell subset that responds to specific antigens (i.e., PPD) is absent in athymic-nude mice.
In view of recent developments, the structural determinants of the interferon inducing activity of polynucleotides have been (re)evaluated. To induce interferon, the polynucleotide should be sufficiently large and double-stranded, although not necessarily double-stranded over its whole length. It should be sufficiently stable to both thermal denaturation and hydrolysis by nucleases. It should also contain a particular steric conformation. This conformation is most regularly ensured by the presence of 2'-hydroxyl in the ribose moieties and intact purine-pyrimidine base pairs in the interior of the double helix. Other biologic activities of polynucleotides, such as anti-complement activity and inhibition of reverse transcriptase (RNA-directed DNA polymerase) activity, depend on structural requirements which are rather antagonistic to those governing the interferon response.
Novel analogues of the anti-HIV-1 lead compound [1-[2‘,5’-bis- O-( tert-butyldimethylsilyl)-β-D-ribofuranosyl]thymine]-3‘-spiro-5’-(4“-amino-1”,2“-oxathiole-2‘,2’-dioxide) (TSAO-T) bearing different amino acids at position N-3 of thymine were prepared and evaluated as inhibitors of HIV replication. The synthesis of the target compounds was accomplished by coupling of the appropriate TSAO intermediate with a conveniently protected (L) amino acid in the presence of BOP and triethylamine, followed by depro-tection of the amino acid moiety. Several TSAO derivatives, bearing at N-3 position of the thymine base an L-amino acid retaining the free carboxylic acid, acquired activity against HIV-2, in addition to their inhibitory effect on HIV-1.