Antibacterial and antibiofilm potential of ferrocenyl acetylaniline regioisomers supported by DFT, molecular docking, molecular dynamics, MM/PBSA and ADMET studies

Three previously reported ferrocenyl acetylaniline regioisomers, N-[(ferrocenyl)methyl]-2-acetylaniline (FcMe2Ac), N-[(ferrocenyl)methyl]-3-acetylaniline (FcMe3Ac) and N-[(ferrocenyl)methyl]-4-acetylaniline (FcMe4Ac), were evaluated for antibacterial activity and inhibition of biofilm formation, supported by DFT, molecular docking, molecular dynamics, MM/PBSA and ADMET prediction. The compounds showed concentration-dependent activity against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Klebsiella pneumoniae. FcMe2Ac produced the largest inhibition zones in the disc-diffusion assay, whereas FcMe3Ac showed the best relative activity in broth, with IC50 values of 1.60 ± 0.10, 0.80 ± 0.07, 7.24 ± 0.65, 0.76 ± 0.06 and 2.95 ± 0.73 mg mL−1, respectively. FcMe3Ac also showed the strongest inhibition of biofilm formation against S. epidermidis (MBIC50 = 2.52 ± 1.26 mg mL−1). DFT, docking, 100 ns molecular dynamics and MM/PBSA analyses supported the relative behavior of FcMe3Ac. Overall, FcMe3Ac was the most active regioisomer, although its activity remained in the mg mL−1 range.