AUTHOR=Na Jung-Hyun , Lee Tae Hee , Park Soo-Bong , Kim Min-Kyu , Jeong Bo-Gyeong , Chung Kyung Min , Cha Sun-Shin 

TITLE=In vitro and in vivo Inhibitory Activity of NADPH Against the AmpC BER Class C β-Lactamase

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=8

YEAR=2018

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2018.00441

DOI=10.3389/fcimb.2018.00441

ISSN=2235-2988

ABSTRACT=<p>β-Lactamase-mediated resistance to β-lactam antibiotics has been significantly threatening the efficacy of these clinically important antibacterial drugs. Although some β-lactamase inhibitors are prescribed in combination with β-lactam antibiotics to overcome this resistance, the emergence of enzymes resistant to current inhibitors necessitates the development of novel β-lactamase inhibitors. In this study, we evaluated the inhibitory effect of dinucleotides on an extended-spectrum class C β-lactamase, AmpC BER. Of the dinucleotides tested, NADPH, a cellular metabolite, decreased the nitrocefin-hydrolyzing activity of the enzyme with a <italic>K</italic><sub><italic>i</italic></sub> value of 103 μM in a non-covalent competitive manner. In addition, the dissociation constant (<italic>K</italic><sub>D</sub>) between AmpC BER and NADPH was measured to be 40 μM. According to our <italic>in vitro</italic> susceptibility study based on growth curves, NADPH restored the antibacterial activity of ceftazidime against a ceftazidime-resistant <italic>Escherichia coli</italic> BER strain producing AmpC BER. Remarkably, a single dose of combinatory treatment with NADPH and ceftazidime conferred marked therapeutic efficacy (100% survival rate) in a mouse model infected by the <italic>E. coli</italic> BER strain although NADPH or ceftazidime alone failed to prevent the lethal bacterial infection. These results may offer the potential of the dinucleotide scaffold for the development of novel β-lactamase inhibitors.</p>