Several new pyrazolo[4,3-c]quinolin-3-one ribonucleosides (5a-g) and their corresponding heterocycle moieties (3a-g) were synthesized and evaluated against vaccinia virus (VV) and herpes simplex virus type 1 (HSV-1). The derivatives 3c and 3d showed modest inhibitory activity against vaccinia virus reaching 70% at a concentration of 100 microM. All heterocyclic compounds (3a-f) showed a modest inhibition against HSV-1, reaching the maximal inhibitory effect around 20-30%. The antiviral effects of most of the pyrazolo[4,3-c]quinolin-3-one ribonucleosides (5a-f) on VV and HSV were not impressive.

Synthesis and Antiviral Activities of New Pyrazolo[4,3-c]quinolin-3-ones andTheir Ribonucleoside Derivatives. -Several ribonucleoside derivatives of type (VI) and the corresponding heterocyclic bases (III) are synthesized and evaluated against vaccinia virus (VV) and herpes simplex virus type 1 (HSV-1). Derivatives (IIIa) and (IIIb) show modest inhibitory activity against VV. All compounds (III) show a modest inhibition of HSV-1. -(DE OLIVEIRA, M. R. P.; ALVES, T. R.; PINTO, A. C.; PEREIRA, H. D. S.; LEAO-FERREIRA, L. R.; MOUSSATCHE, N.; FRUGULHETTI, I. C. D. P. P.; FERREIRA, V. F.; DE SOUZA*, M. C. B. V.; Nucleosides, Nucleotides Nucleic Acids 23 (2004) 5, 735-748; Dep. Quim. Org., Inst. Quim., Univ. Fed. Rio de Janeiro,

A series of novel substituted isatin ribonucleosides 3b-3f were synthesized in good yields by a TMSOTf catalysed coupling reaction between the silylated nitrogenated base (1b-1f) and 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose (2). Isatin nucleoside 3a previously reported was also prepared using this method giving high yield. From the compounds tested, ribonucleoside 3f proved to be the most active one when assayed for antiviral activitiy on HSV-1 infected cells, leading to 66% of inhibition of virus yield. All the isatin derivatives tested did not inhibit HIV-1 Reverse Transcriptase (RT) activity.