An inhibitor of viral DNA and RNA polymerases and reverse transcriptase; inhibits DNA polymerase from HSV-1, HSV-2, CMV, and Epstein-Barr virus (IC50s = 0.3-22 μM); inhibits DNA polymerase α, but not β or γ, from HeLa cells (IC50 = 32 μM); inhibits RNA polymerase from influenza A and B (IC50s = 29 and 61 μM, respectively) and reverse transcriptase from avian myeloblastosis virus and murine leukemia virus (IC50s = 0.7-55 μM); inhibits replication of HSV-2 in Vero cells (IC100 = 1,000 μM) and laboratory and clinical isolates of CMV in MRC-5 cells (IC50s = 102.6-163.8 μM); reduces mortality in mouse models of infection with murine CMV or HSV-2 when administered alone (ED50s = 242 and 170 mg/kg, respectively) or in combination with ganciclovir (ED50s = 57 and <32 mg/kg, respectively)