Dual-targeting potential of active constituents of Nigella sativa against FimH and CTX-M-15: A plausible therapeutic strategy against drug-resistant uropathogenic strains.

Uropathogenic strains belonging to the Enterobacteriaceae family are considered one of factors for urinary tract infections, and type 1 pilus fimbrial adhesin (FimH) and beta lactamase CTX-M-15 play crucial roles in their pathogenesis and resistance. Thus, a promising approach is to explore dual-targeting therapeutic agents that act against both FimH and CTX-M-15. In the present study, active constituents of Nigella sativa were selected on the basis of significant ‎activity against UTIs. Molecular docking was used to target active constituents of Nigella sativa to the active sites of FimH and CTX-M-15; these included thymoquinone, dithymoquinone, carvacrol, p-cymene, thymol, thymohydroquinone and longifolene. Dithymoquinone was found to be the most potent dual inhibitor, with binding energy of -7.01 and -5.38kcal/mol against CTX-M-15 and FimH, respectively; In addition, Dithymoquinone exhibited superior activity compared to positive controls avibactam and heptyl α-D-mannopyranoside. Further molecular dynamic simulation studies were carried out to assess the stability of dithymoquinone-target protein complexes via RMSD, Rg, SASA, hydrogen bond number, and RMSF analysis. Both protein-ligand complexes were conserved and attained equilibrium at around 2.0 to 2.5 ns during‎10 ns runs. These results suggest that active constituents of Nigella sativa, particularly dithymoquinone, might represent a plausible therapeutic strategy against resistant uropathogenic bacteria.