European Journal of Medicinal Chemistry 44 (2009) 3777–3783
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Antiviral evaluation of N-amino-1,2,3-triazoles against Cantagalo virus replication in cell culture Alessandro K. Jorda˜o a, Priscila P. Afonso b, Vitor F. Ferreira a, Maria C.B.V. de Souza a, Maria C.B. Almeida a, Cristiana O. Beltrame b, Daniel P. Paiva b, Solange M.S.V. Wardell c, James L. Wardell d, e, Edward R.T. Tiekink f, Clarissa R. Damaso b, Anna C. Cunha a, * a
ˆnica, Instituto de Quıı´mica, Outeiro de Sa ˜o Joa ˜o Baptista, 24020-141 Nitero ´i, RJ, Brazil Universidade Federal Fluminense, Departamento de Quı´mica Orga ´rio de Biologia Molecular de Vı´rus, Instituto de Biofı´sica Carlos Chagas Filho, CCS, 21949-900 Rio de Janeiro, RJ, Brazil Universidade Federal do Rio de Janeiro, Laborato FAR-MANGUINHOS, Rua Sizenando Nabuco 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil d Department of Chemistry, University of Aberdeen, Old Aberdeen, AB24 3UE, Scotland, UK e ´ gico em Sau ´ de (CDTS), Fundaça ˜o Oswaldo Cruz (FIOCRUZ), Casa Amarela, Campus de Manguinhos, Av. Brasil 4365, Centro de Desenvolvimento Tecnolo 21040-900 Rio de Janeiro, RJ, Brazil f Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78248-0698, USA b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 22 July 2008 Received in revised form 14 April 2009 Accepted 23 April 2009 Available online 8 May 2009
This paper describes the antiviral evaluation of new N-amino-1,2,3-triazole derivatives, 1-(substitutedphenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl esters, 3 and 1-(4-substituted-phenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid hydrazides, 4, on Cantagalo virus replication. 1-(4-Fluoro-phenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid hydrazide, 4e, exhibited a significant antiviral effect. Characterization of all compounds was confirmed by IR, 1H and 13C spectroscopies and elemental analysis. In addition, molecular structure of 4e was also reported. Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords: 1,2,3-Triazole derivatives Diazo compounds Cantagalo virus Anti-poxvirus agents Molecular structure X-ray crystallography
1. Introduction The poxviruses present a complex morphology, a doublestranded DNA genome and replication in the cytoplasm of the host cells [1]. The family Poxviridae includes eight genera, four of which are of greater importance to humans: Orthopoxvirus (variola, vaccinia, cowpox and monkeypox viruses), Parapoxvirus (orf, Milker’s nodules and pseudocowpox viruses), Yatapoxvirus (yatapox and tanapox viruses) and Molluscipoxvirus (molluscum contagiosum virus) [2]. The Orthopoxvirus is by far the most studied genus, with species of particular importance clinically and historically, especially variola virus (VARV) and vaccinia virus (VACV). VARV is the causative agent of smallpox, a disease that ravaged the human population until its eradication in 1977 by a worldwide vaccination campaign with VACV [1,2].
* Corresponding author. Tel.: þ55 21 2629 2148; fax: þ55 21 2629 2364. E-mail address:
[email protected] (A.C. Cunha). 0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ejmech.2009.04.046
It is a general consensus in the literature that VACV has no natural host. Nevertheless, vaccinia-like viruses (VACV-like) have been frequently isolated from dairy cattle and humans in different states of Brazil for the last 7 years [3–7]. Cantagalo virus (CTGV) was the first sample isolated during a poxvirus outbreak in 1999 in Rio de Janeiro State, and it was characterized as a VACV strain [1]. In recent years, the potential use of VARV or another orthopoxvirus, such as monkeypox virus, as a biological weapon has heightened our awareness as to our vulnerability to smallpox since routine vaccination was discontinued in 1980 [8]. A few drugs [9,10], that have approval for other uses, have been identified as anti-poxvirus agents, and efforts have been intensified to discover and develop potentially active compounds against smallpox and other diseases caused by orthopoxviruses. As already mentioned, outbreaks of CTGV infection and other VACV-like viruses have been frequently notified all over Brazil, leading to major agricultural losses, but no treatment is yet available [5] (Fig. 1). Among the known drugs, the most studied agent against orthopoxviruses is the cidofovir, an acyclic nucleoside phosphonate
˜o et al. / European Journal of Medicinal Chemistry 44 (2009) 3777–3783 A.K. Jorda
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phenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl ester, 3e, and 1-(4-fluoro-phenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid hydrazide, 4e (Fig. 2). In designing these compounds, a para-fluoro substituent was introduced into the Nphenyl rings of the parent compounds 3a and 4a in order to increase the structural similarity to 5.
NH2 NH2
N
N O O
15
3 O
O
P
O N
17
O
2 O
O
P
N
O
HO
O
HO
OH OH
2. Results and discussion
1,HDP-CDV
2,ODE-CDV 2.1. Chemistry
Fig. 1. Potential antiviral drugs against orthopoxvirus replication.
Compounds 3–4 were prepared according to the synthetic pathways described in Scheme 1. Ethyl 2-diazoacetoacetate 6 prepared in a 70% yield by the method of Danheiser and co-workers [38] was condensed with the desired phenylhydrazine (7a) or with phenylhydrazine hydrochlorides (7b–e), giving the corresponding diazo-hydrazone intermediates 8a–e, which underwent 1,5-electrocyclization leading to the 4-carbethoxy-triazoles 3a–e (Scheme 1). The 1,5-electrocyclization reaction using phenylhydrazine 7a was carried out in MeOH/AcOH. Those using 7b–d in MeOH, and that using 7e in MeOH/DMSO (4:1), as illustrated in Scheme 1. The choice of solvent was determined by the solubilities of 7. The yields of the reactions and the melting points of triazole derivatives 3a–e are listed in Table 1. A good yield was obtained from 7a, while compounds having moderate electron withdrawing substituents, i.e. 7b, 7c and 7d, gave the corresponding 1,2,3-triazoles 3b, 3c and 3d in reasonable yields. Compound 7e having strong electron withdrawing group produced the triazole product 3e in low yield. Finally, the 4-carbethoxy-triazole derivatives 3a–e were easily converted into the corresponding acylhydrazides 4a–e in moderated yields (Table 1), on treatment with hydrazine hydrate in refluxing ethanol (Scheme 1).
[9,11] approved for intravenous use in the treatment of cytomegalovirus (CMV) retinitis in HIV-infected patients. However, its oral bioavailability is the major limitation for use in a large-scale emergency situation such as a smallpox outbreak [10,12]. The alkoxyalkyl esters of cidofovir, such as hexadecyloxypropyl-cidofovir (1, HDP-CDV) and octadecyloxyethyl-cidofovir (2, ODE-CDV) were designed and developed as potential oral drugs for the prophylaxis and treatment of variola virus infection [13]. 1,2,3-Triazoles have a wide range of applications as antimicrobial [14], cytostatic [15], anti-HIV [16], antineoplastic [17], and antiinflammatory agents [18] and as potassium channel activators [19]. Two general methods are available for the construction of 1,2,3triazole rings: Huisgen’s [1,3]-dipolar cycloaddition reactions [20], in particular the copper(I)-catalyzed cycloaddition [21], and the intramolecular 1,5-electrocyclization of b-substituted-a-diazocarbonyl compounds [22,23]. Wolff [24], in 1912, reported the synthesis of ethyl 1-(phenylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylate, 3a, from ethyl 2-diazoacetoacetate 6 and phenylhydrazine 7a (Scheme 1) and then Shukla and co-workers [25] and Sezer and workgroup [26] prepared other NH-triazoles by variation of this methodology. Following our interest in triazoles [27–34] with potential pharmacological activity, we have developed this methodology to produce triazole derivatives 3a–d, from substituted phenylhydrazines 7b–e and ethyl 2-diazoacetoacetate 6. The structural similarity of these compounds to ST-246 5 [35] (Fig. 2) led us to investigate their antiviral potential as poxvirus inhibitors. Compound 5 is an anti-poxvirus agent that exhibits activity against vaccinia virus and cowpox virus with EC50 values of
