Inhibition of herpes simplex virus DNA polymerase by diphosphates of acyclic phosphonylmethoxyalkyl nucleotide analogues

The inhibition of HSV-1 DNA polymerase and HeLa DNA polymerases α and β by diphosphoryl derivatives of acyclic phosphonylmethoxyalkyl nucleotide analogues was studied and compared with the inhibition by ACV-TP, araCTP, ddTTP and AZT-TP. In the series of phosphonylmethoxyethyl (PME-) derivatives of heterocyclic bases, the inhibitory effect of their diphosphates on HSV-1 DNA polymerase decreased in the order 2-amino-PMEApp ( K i = 0.03 μM) ⪢ PMEGpp > PMEApp > PMETpp ⪢ PMECpp ⪢ n 8z 7PMEApp > PMEUpp. The diphosphate derivative of the antiherpes agent (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl) adenine (HPMPA) proved to be a relatively weak inhibitor of HSV-1 DNA polymerase ( K i = 1.4 μM). The inhibitors could be divided into three groups: (a) the diphosphoryl derivatives of acyclic nucleotide analogues (PME-type and HPMPA) and ACV-TP specifically inhibit HSV-1 DNA polymerase and DNA polymerase α and do not significantly inhibit DNA polymerase β; (b) AZT-TP and ddTTP are effective only against DNA polymerase β, and (c) araCTP inhibits all three enzymes. When dATP was omitted from the reaction mixture, the addition of HPMPApp stimulated DNA synthesis by HSV-1 DNA polymerase indicating that HPMPApp is an alternative substrate for in vitro DNA synthesis catalyzed by this enzyme.