Synthesis, antibacterial activities, and theoretical studies of dicoumarols

Four dicoumarols (DC, 2-PyDC, 3-PyDC and 4-PyDC) were synthesized and characterized via IR, H-1 NMR, HRMS, and single crystal X-ray crystallography. Two classical intramolecular O-H center dot center dot center dot O hydrogen bonds (HBs) stabilized their structures. The total HB energies in DC, 2-PyDC, 3-PyDC and 4-PyDC were calculated with the density functional theory (DFT) [B3LYP/6-31G*] method. The in vitro antibacterial activity of DC, 2-PyDC, 3-PyDC and 4-PyDC against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC) was evaluated by observing the minimum inhibitory concentration and time-kill curves. The results showed that among all the compounds, 2-PyDC exhibited the most potent antibacterial activity.