Benzimidazole-2-Phenyl-Carboxamides as Dual-Target Inhibitors of BVDV Entry and Replication

Figure 1. Isosteric substitution of benzotriazole scaffold with benzimidazole scaffold.

Scheme 1. Synthetic route for derivatives 1–7c, 1–7d and 1–7e. i: when R1 or both R1 and R2 = Cl, reaction conditions: CH3NHNH2/EtOH in an autoclave at 100 °C for 48 h; ii: all the other derivative reaction conditions: NH2NH2 and Pd/C in EtOH at 80 °C for 1 h.

Figure 2. Effect of the time of drug addition on antiviral activity with SD of derivatives 2c (0.09 µM), 6c (0.23 µM) and 7c (0.3 µM) (green). Parallel experiments were performed using reference compounds NM 108 (1.5 µM) (blue) and Ribavirin (16 µM) (purple) for comparison. We show the untreated control in red.

Figure 3. Virucidal activity of the 2c, 6c and 7c compounds. BVDV suspensions were incubated with the title compound at 4 °C for 1 h, and then the remaining infectivity was determined. Results are expressed as a titer reduction in compound-treated samples compared to non-treated ones.

Figure 4. Conformational representation of the best-docked pose of compound 2c. (A) Protein–ligand polar interactions between 2c and the exposed amino acids of E2, investigated in PyMOL. Protein is depicted in a light-pink tint, compound 2c is in blue marine. Polar contacts are reported as yellow dashes. (B) Non-polar interactions between 2c and E2, generated through LigPlot+. Colors: black (carbon), blue (nitrogen) and red (oxygen).

Figure 5. PyMOL (3D) and LigPlot+ (2D) representations showing polar and nonpolar interactions between the E2 protein and (A) compounds 6c and (B) 7c. Compounds 6c and 7c are colored in yellow and white, respectively.

Figure 6. Electrostatic and hydrophobic contacts between E2 protein and compounds (A) 2d and (B) 2e, colored in gold and purple, respectively.

Figure 7. Tri- and bidimensional representation of the spatial conformation of compound 2c docked at the RdRp surface binding site.