RESUMEN
The homogeneous/heterogeneous catalyst combination of VO2+ in anolyte with Pd/C at the anode is first introduced in a formic acid fuel cell to enhance HCOOH electrooxidation. The VO2+/Pd catalyst combination establishes a stepwise reaction pathway involving HCOOH dehydrogenation to form V3+ from VO2+ reduction and subsequent V3+ electrooxidation to regain VO2+. The fuel cell with the VO2+/Pd combination presents a peak power density of 341.3 mW cm-2 and stable power density higher than 30 mW cm-2.
RESUMEN
OBJECTIVES: Due to the increasing prevalence of drug-resistant Staphylococcus aureus infection, we develop novel 4-hydroxycoumarin derivatives as antimicrobials. METHODS: The antibacterial activity of 4-hydroxycoumarin derivatives against drug-susceptive S. aureus (ATCC 29213) and methicillin-resistant S. aureus (MRSA) were evaluated using minimal inhibitory concentration (MIC) assay; the activity of favourable compound was further observed using bacterial growth curves assay and in the MRSA infection mice. KEY FINDINGS: Compared with dihydropyran derivatives, compound 1 as one of biscoumarins showed most potent activity with MIC values of 4-8 µg/ml and apparently inhibited the growth rate of S. aureusâ ATCC 29213 and USA300 strain in concentrations of both 16 and 32 mg/ml. In the mice infected with MRSA USA300, administration of 5 mg/kg compound 1 improved the animal survival rate to 66.7%, and improved the pathological change in lung tissue compared with the infection model animals. No significant cytotoxicity of compound 1 was observed on the umbilical vein endothelial cells (HUVECs) under the concentration of 800 µg/ml. CONCLUSION: Compared with the dihydropyran derivatives, biscoumarins exhibited more promising activity against both drug-sensitive and drug-resistant S. aureus, and it is efficacious in treating MRSA infections in mouse models with a favourable safety in human cells.
Asunto(s)
4-Hidroxicumarinas/uso terapéutico , Antibacterianos/uso terapéutico , Enfermedades Pulmonares/tratamiento farmacológico , Pulmón/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Infecciones Estafilocócicas/tratamiento farmacológico , 4-Hidroxicumarinas/biosíntesis , 4-Hidroxicumarinas/farmacología , Animales , Antibacterianos/farmacología , Células Endoteliales de la Vena Umbilical Humana , Pulmón/microbiología , Pulmón/patología , Enfermedades Pulmonares/microbiología , Enfermedades Pulmonares/patología , Ratones , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Infecciones Estafilocócicas/microbiología , Staphylococcus aureusRESUMEN
Four dicoumarols (DC, 2-PyDC, 3-PyDC and 4-PyDC) were synthesized and characterized via IR, (1)H NMR, HRMS, and single crystal X-ray crystallography. Two classical intramolecular O-H···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.