Synthesis and Anti-Picornaviridae In Vitro Activity of a New Class of Helicase Inhibitors the N,N-bis[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl] alkyldicarboxamides

A.      Carta; M.      Loriga; S.      Piras; G.      Paglietti; M.      Ferrone; M.      Fermeglia; S.      Pricl; P.   La   Colla; G.      Collu; T.      Sanna; R.      Loddo

Abstract

A series N,N-bis[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl]alkyldicarboxamides (3a-f and 5a-j) were prepared starting from their already known (1a-d) and (4a-c) or new (4d) amine parents. Because of the antiviral activity of several N-[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl]alkylcarboxamides previously reported, title compounds were evaluated in vitro for cytotoxicity and antiviral activity against viruses representative of Picornaviridae, [i.e. Enterovirus Coxsackie B2 (CVB-2) and Polio (Sb-1)] and of two of the three genera of the Flaviviridae [Bovine Viral Diarrhea Virus (BVDV) and Yellow Fever Virus (YFV)]. Furthermore, because of the in silico activity against the RNA-dependent RNA-helicase of Polio 1 previously reported, title compounds were evaluated against the 3D model of the Sb-1 helicase and against the 2D model of the CVB-2 helicase. As a reference we used the antiviral and in silico activities of an imidazo counterpart of the title compounds, N,N-bis[4-(2-benzimidazolyl)phenyl]alkyldicarboxamides (III) that other authors reported to be able to inhibit the corresponding enzyme of Hepatitis C Virus (HCV). In cell-based antiviral assays, N,N-bis[4-(1H-benzotriazol- 1-yl)phenyl]alkyldicarboxamides (3a-f) resulted completely inactive whereas the bis-5,6-dimethyl-benzotriazol-2-yl derivatives (5d-f) exhibited good activity against the Enteroviruses, (EC50s ranged between 7 and 11 μM against CVB-2 and 19-52 against Sb-1). Interestingly, bis-5,6-dichloro-benzotriazol-2-yl derivatives (5h-j) showed very selective activity against CVB-2 (EC50s = 4-11 μM) whereas they resulted completely inactive against all the other viruses screened. In general, all title compounds showed a good cytotoxicity profile in MT-4 cells. Molecular modeling investigations showed that active compounds may interact with the binding site of the Sb-1 helicase and that their free binding energy values are in agreement with their EC50s values.

Keywords: Benzotriazol-1(2)-yl-phenylalkyldicarboxamides, anti-viral activity, picornaviridae, flaviviridae, helicase, in silico evaluation, cytotoxicity, SAR