No abstract

The effect of substitution in the tricyclic moiety of 3,9-dihydro-9-oxo-5H-imidazo[1,2-alpha]purine (1,N-2-ethenoguanine) analogues of acyclovir (1) and ganciclovir (2) on their physical properties and antiherpetic activity was investigated by synthesizing a series of compounds substituted in the 2, 6, or 7 position (6-14). Substitution in the 6-position with phenyl or 4-biphenylyl resulted in fluorescent compounds (7, 9, 13, 14). In general, the substituent in the 6 position potentiated the antiviral activity. The fluorescent 6-phenyl derivatives: 3,9-dihydro-3-[(2-hydroxyethoxy)methyl]-9-oxo-6-phenyl-5H-imidaxo[ 1,2-alpha]purine (7) and its 3-[(1,3-dihydroxy-2-propoxy)methyl] congener (13) were the most potent tricyclic analogues of 1 and 2, respectively. Compound 7 was inhibitory to TK+ HSV-1, TK+ HSV-2, and TK+ VZV within the concentration range of 0.2-2.0 micrograms/mL, well below the cytotoxicity threshold (50 to > 100 micrograms/mL). Compound 13 was inhibitory to TK+ HSV-1 and TK+ HSV-2 within the concentration range of 0.005-0.3 microgram/mL and to TK+ and TK- VZV within the concentration range of 0.4-3 micrograms/mL (cytotoxicity threshold > 200 micrograms/mL). Both 7 and 13 seem to be promising candidate compounds for the noninvasive diagnosis of herpesvirus infections.

Of a series of new guanine base modified tricyclic analogues of acyclovir (ACV, 1) and ganciclovir (GCV, 2), derivatives of the 3,9-dihydro-9-oxo-5H-imidazo[1,2-a]purine system, evaluated for activity against herpes simplex virus type 1 and 2, several fluorescent analogues, 6-(4-MeOPh)-TACV (8), 7-Me-6-Ph-TACV (17), 6-(4-MeOPh)-TGCV (27), and 7-Me-6-Ph-TGCV (28), were obtained that showed similar potency and selectivity as the parent compounds. The activity was found to be strongly dependent on the nature and steric demands of the substituents in the 6 and/or 7 position.