Novel stilbene scaffolds efficiently targetMycobacterium tuberculosisnucleoid-associated protein, HU

Novel scaffolds of stilbene were identified as inhibitors ofMycobacterium tuberculosisby targeting the nucleoid-associated protein, HU, using molecular docking. Based on the proposed combinatorial libraries I to VI, structures I and III had significantly greater docking binding energy that was comparable to that of the reference ligand, protein HU, fromMycobacterium tuberculosis.Using these docking results, 18 compounds were synthesized, characterized and evaluated forin vitroantitubercular (anti-TB) efficacy in theMycobacterium tuberculosisstrain, H37Rv. Thein vitroscreening results indicated a significant positive correlation between the docking binding efficacy (r²> 0.5) and clogp. Compounds3f,3dand4fwere ranked as top scoring ligands that interacted with amino acids ARG 53, ARG 55, PRO 81, PHE 79, and LYS 13, where the -NO₂or -Cl substitution at theparaposition of the 3-phenyl ring was essential for interacting of the HU protein. The hydrogen bonding with ARG 55 and LYS 13 of these compounds was similar to that with the reference ligand that inhibits the HUM_tbprotein. Compounds3d,3f, and4fwere evaluated as active leads, with MIC90 values of 21.3, 23.2 and 44.1 μM, respectively. The above mentioned compounds were also evaluated for antibacterial and antifungal efficacy in a panel of selected bacteria and fungi. Compound3dhad efficacy (MIC90: 6.82 μM) inS. aureusandE. coli. Compound3fwas also efficacious inE. coliandA. Niger, with an MIC90 value of 7.42 μM for both microorganisms. The fluoro-phenyl derivatives,3iand4i, were efficacious inC. albicans(MIC90 values of 8.2 and 7.8 μM, respectively) andA. niger(MIC90 values of 4.1 and 3.1 μM, respectively). Our results suggest that substitutions at theparaposition of 3-phenyl acryl derivatives with -NO₂and -Cl significantly affected the binding interactions with the HUMtb protein in the docking studies. Furthermore these compounds had antitubercular and antimicrobial efficacy. The substituted phenyl acrylic acid and hydrazides could be inhibitors of the HUMtb protein ofMycobacterium tuberculosis.