Theaflavin‐3,3´‐digallate increases the antibacterial activity of β‐lactam antibiotics by inhibiting metallo‐β‐lactamase activity

Abstract

Metallo‐β‐lactamases (MBLs) are some of the best known β‐lactamases produced by common Gram‐positive and Gram‐negative pathogens and are crucial factors in the rise of bacterial resistance against β‐lactam antibiotics. Although many types of β‐lactamase inhibitors have been successfully developed and used in clinical settings, no MBL inhibitors have been identified to date. Nitrocefin, checkerboard and time‐kill assays were used to examine the enzyme behaviour in vitro. Molecular docking calculation, molecular dynamics simulation, calculation of the binding free energy and ligand‐residue interaction decomposition were used for mechanistic research. The behaviour of the enzymes in vivo was investigated by a mouse infection experiment. We showed that theaflavin‐3,3´‐digallate (TFDG), a natural compound lacking antibacterial activities, can inhibit the hydrolysis of MBLs. In the checkerboard and time‐kill assays, we observed a synergistic effect of TFDG with β‐lactam antibiotics against methicillin‐resistant Staphylococcus aureus BAA1717. Molecular dynamics simulations were used to identify the mechanism of the inhibition of MBLs by TFDG, and we observed that the hydrolysis activity of the MBLs was restricted by the binding of TFDG to Gln242 and Ser369. Furthermore, the combination of TFDG with β‐lactam antibiotics showed effective protection in a mouse Staphylococcus aureus pneumonia model. These findings suggest that TFDG can effectively inhibit the hydrolysis activity of MBLs and enhance the antibacterial activity of β‐lactam antibiotics against pathogens in vitro and in vivo.

<p>Palmatine Is a Plasmid-Mediated Quinolone Resistance (PMQR) Inhibitor That Restores the Activity of Ciprofloxacin Against QnrS and AAC(6ʹ)-Ib-cr-Producing <em>Escherichia coli</em></p>

“…Traditional Chinese medicines have found uses as antibiotic replacement therapies. 54,[64][65][66] For instance, the isoquinoline alkaloid palmatine has been widely used for clinical treatments. 50,51 In this study, we found that palmatine enhanced the ciprofloxacin susceptibility of E. coli strains containing qnrS or aac(6ʹ)-Ib-cr and the effect was synergistic.…”

“…The fractional inhibitory concentration index (FICI) values were calculated to evaluate the combination effect as described previously. 54 Synergistic effects were interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) as follows: FICI ≤ 0.5 represents synergy; 0.5 < FICI ≤ 4 represents no interaction; and FICI > 4 represents antagonism.…”

“…Timekill curves were established by plotting mean colony counts (log 10 CFU/mL) versus time. 54 Cytotoxicity Assays…”

Isoalantolactone Enhances the Antimicrobial Activity of Penicillin G against Staphylococcus aureus by Inactivating β-Lactamase during Protein Translation

“…In brief, 5 × 10 5 CFUs/mL of mid-logarithmic-phase bacterial cells in TSB (trypticase soy broth) broth were supplemented with different concentrations of IAL and then shaken under aerobic conditions at 37 • C for 4 h, and the culture supernatant was collected by centrifugation. E. coli BL21 cells carrying a β-lactamase-1 or β-lactamase-7 expression vector [24] were cultured with isopropyl-β-D-thiogalactoside to induce the expression of β-lactamases and then ultrasonicated. Then, the supernatant was collected by centrifugation and 100 µL of this supernatant was mixed with 75 µL of phosphate-buffered saline (PBS) in a 96-well microtiter plate, followed by the addition of 25 µL of nitrocefin and incubation at 37 • C for 30 min.…”

Specific NDM-1 Inhibitor of Isoliquiritin Enhances the Activity of Meropenem against NDM-1-positive Enterobacteriaceae in vitro

“…The β-lactamases of NDM-1, NDM-5 and VIM-1 were expressed and purified as described previously [20]. Briefly, the DNA sequences of NDM-1 and NDM-5 were obtained from genomic DNA of the NDM-1-positive isolates E. coli ZC-YN3 and E. coli ZC-YN5, respectively.…”