title: Synthesis and anti-HSV-1 evaluation of new 3H-benzo[b]pyrazolo[3,4-h]-1,6-naphthyridines and 3H-pyrido[2,3-b]pyrazolo[3,4-h]-1,6-naphthyridines.
abstract: BACKGROUND
  Herpes simplex virus type-1 (HSV-1) is the primary cause of facial lesions (mouth, lips, and eyes) in humans. The widespread use of acyclovir and nucleoside analogues has led to emergence of HSV strains that are resistant to these drugs. Recently, non-nucleoside anti-HSV compounds have received considerable attention. 1,6-Naphthyridines are a class of heterocyclic compounds that exhibit a broad spectrum of biological activities such as inhibitor of HIV-1 integrase, HCMV, FGF receptor-1 tyrosine kinase, and the enzyme acetylcholinesterase. We previously reported the synthesis, SAR studies, and evaluation anti-HSV-1 activity of 3H-benzo[b]pyrazolo[3,4-h]-1,6-naphthyridines. In the course of our search for new 1,6-naphthyridines derivatives with potential activity against HSV-1, we have synthesized and evaluated new 3H-benzo[b]pyrazolo[3,4-h]-1,6-naphthyridines (1a-k) and 3H-pyrido[2,3-b]pyrazolo[3,4-h]-1,6-naphthyridines (2a-c).
  
  
  RESULTS
  A known synthetic approach was used for preparing new 3H-benzo[b]pyrazolo[3,4-h]-1,6-naphthyridines (1a-k) and 3H-pyrido[2,3-b]pyrazolo[3,4-h]-1,6-naphthyridines (2a-c), starting from ethyl 4-chloro-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (7). All compounds were identified by FTIR, 1H NMR, and mass spectrometry. The antiviral effect on HSV-1 virus replication was determined.
  
  
  CONCLUSIONS
  The compounds 1d, 1f, 1g, and 1h exhibited the highest anti-HSV-1 activity. In general, 3H-benzo[b]pyrazolo[3,4-h]-1,6-naphthyridines were more effective inhibitors than their corresponding 3H-pyrido[2,3-b]pyrazolo[3,4-h]-1,6-naphthyridines. The compound 1h reduced the virus yield in 91% at 50 μM and exhibited a low cytotoxicity (CC50 600 μM).
authors.affiliation: Departamento de Física e Química, Instituto de Ciências Exatas, Universidade Federal de Itajubá, 37500-903, Itajubá, MG, Brazil. mauriciounifei@yahoo.com.br.
authors.forename: Alice Mr
authors.initials: AM
authors.lastname: Bernardino
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Azevedo
authors.forename: Luiz Cs
authors.initials: LC
authors.lastname: Pinheiro
authors.forename: Júlio C
authors.initials: JC
authors.lastname: Borges
authors.forename: Izabel Cp
authors.initials: IC
authors.lastname: Paixão
authors.forename: Milene
authors.initials: M
authors.lastname: Mesquita
authors.forename: Thiago Ml
authors.initials: TM
authors.lastname: Souza
authors.forename: Maurício S
authors.initials: MS
authors.lastname: Dos Santos