Inhibition of herpes simplex virus type 1 DNA polymerase by [1R(1 alpha,2 beta,3 alpha)]-9-[2,3-bis(hydroxymethyl)cyclobutyl] guanine

Mol Pharmacol. 1991 Oct;40(4):591-6.


(+/-)-(1 alpha,2 beta,3 alpha)-9-[2,3-Bis(hydroxymethyl)cyclobutyl] guanine [(+/-)-BHCG] is a nucleoside analog with potent in vitro activity against herpesviruses [Tetrahedron Lett. 30:6453-6456 (1989)]. The two enantiomers have been synthesized, and their biochemical characterization is reported here. [1S(1 alpha,2 beta,3 alpha)]-9-[2,3-Bis(hydroxymethyl)cyclobutyl]guanine [(S)-BHCG] was phosphorylated by herpes simplex virus type 1 (HSV-1) thymidine kinase (Vmax = 8 nmol/hr/micrograms of enzyme), whereas [1R(1 alpha,2 beta,3 alpha)]-9-[2,3-bis(hydroxymethyl)cyclobutyl]guanine [(R)-BHCG] was a poor substrate for the viral thymidine kinase under these conditions. The triphosphate of each enantiomer was enzymatically synthesized, and both enantiomers competitively inhibited HSV-1 DNA polymerase with respect to dGTP. However, the potency of (R)-BHCG-TP was 4 orders of magnitude greater than that of (S)-BHCG-TP. (R)-BHCG-TP inhibited HeLa DNA polymerase alpha, but the inhibition constant was 30-fold higher than that for the viral DNA polymerase. In comparison, (S)-BHCG-TP was a very poor inhibitor of DNA polymerase alpha. (R)-[3H]BHCG-TP could be incorporated into a synthetic DNA template by HSV-1 DNA polymerase at 80% the extent of dGTP under the assay conditions used and, therefore, could act as an alternative substrate. Incorporation of (R)-BHCG-TP was similar to that observed for acyclovir triphosphate and ganciclovir triphosphate, based on maximal velocities. In contrast, HSV-1 DNA polymerase did not incorporate (S)-BHCG-TP into DNA. Compared with dGTP, only limited extension (10%) of the DNA primer by HSV-1 DNA polymerase occurred after incorporation of (R)-BHCG-TP and, therefore, (R)-BHCG-TP acts as a nonobligate chain terminator.

MeSH terms

  • Antiviral Agents / pharmacology*
  • Base Sequence
  • DNA Polymerase I / antagonists & inhibitors*
  • DNA, Viral / metabolism
  • Deoxycytosine Nucleotides / metabolism
  • Deoxyguanine Nucleotides / metabolism
  • Guanine / analogs & derivatives*
  • Guanine / pharmacology
  • Molecular Sequence Data
  • Phosphorylation
  • Simplexvirus / enzymology*
  • Simplexvirus / metabolism
  • Stereoisomerism
  • Viral Proteins / antagonists & inhibitors*


  • Antiviral Agents
  • DNA, Viral
  • Deoxycytosine Nucleotides
  • Deoxyguanine Nucleotides
  • Viral Proteins
  • 2'-deoxycytidine 5'-triphosphate
  • Guanine
  • deoxyguanosine triphosphate
  • lobucavir
  • DNA Polymerase I