Discovery of 1,2,3-triazole-based pleuromutilin derivatives as potent gram-positive antibacterial agents

A novel class of pleuromutilin derivatives possessing 1,2,3-triazole as the linker connected to phenyl analogues were designed. The antibacterial properties of the prepared compounds were assessed in vitro against five strains (E. coli, S. aureus, S. epidermidis, and E. faecalis). Most of the tested compounds displayed potent antibacterial activities against gram-positive bacteria and 14-O-[2-(4-((2,4-dinitrophenoxy)-methyl-1H-1,2,3-triazol-1-yl) acetamide)-2-methylpropan-2-yl) thioacetyl]mutilin (7c) exerted antibacterial activities against S. aureus, MRSA and S. epidermidis with MIC values 0.0625 μg/mL, representing 64-fold, 4-fold and 8-fold higher than tiamulin respectively. Compound 6e, 7c and 8c were chosen to carry out killing kinetics, which exhibited concentration-dependent effect. Subsequently, molecular modeling was conducted to further explore the binding of compound 6e, 7a, 7c, 8c and tiamulin with 50S ribosomal subunit from deinococcus radiodurans. The investigation revealed that the main interactions between compound 7c and the ribosomal residues were three hydrogen bonds, π-π, and p-π conjugate effects. Additionally, the free binding energy and docking score of 7c with the ribosome demonstrated the lowest values of -11.90 kcal/mol and -7.97 kcal/mol, respectively, consistent with its superior antibacterial activities.