Novel Benzo[d]imidazole-based Heterocycles as Broad Spectrum Anti-viral Agents: Design, Synthesis and Exploration of Molecular Basis of Action.

The design and synthesis of a novel series of benzo[d]imidazole-based heterocycles and their biological evaluation as antiviral agents are reported herein. 1-(1-Methyl-1H-benzo[d]imidazol- 2-yl)-2-thiocyanatoethanone 2 was used as a key intermediate for the synthesis of the thiazolylhydrazine 4, the thiazolylamine 5 and the methylthiazole 7. Coupling of compounds 5 or 7 with the appropriate diazotized aromatic amines gave the diazenyl derivatives 6a-c and 8a-c, respectively. The quinazoline derivative 12 was also synthesized. On the other hand, the phenylthio 20 and the phenylsulphonyl 22 bioisosteresand their respective diazenyl derivatives 21a-c and 23a-c were prepared. The synthesized compounds were evaluated for their HIV-1, HCV, SSPE and H1N1 inhibitory activities and were found to display very promising results. Furthermore, to investigate the underlying possible mechanism of action, in vitro and in silico screening of this series of benzo[d]imidazoles was performed against the viral enzymes HIV-1 RT, HCV NS3/4A serine protease and H1N1 NA1. Overall findings of the executed investigations highlight these novel compounds as very promising potent, broad spectrum antiviral agents.