ABSTRACT
Enzyme-catalyzed therapeutic activation (ECTA) is a novel prodrug strategy to overcome drug resistance resulting from enzyme overexpression. β-Lactamase overexpression is a common mechanism of bacterial resistance to β-lactam antibiotics. We present here the results for one of the β-lactamase ECTA compounds, NB2001, which consists of the antibacterial agent triclosan in a prodrug form with a cephalosporin scaffold. Unlike conventional β-lactam antibiotics, where hydrolysis of the β-lactam ring inactivates the antibiotic, hydrolysis of NB2001 by β-lactamase releases triclosan. Evidence supporting the proposed mechanism is as follows. (i) NB2001 is a substrate for TEM-1 β-lactamase, forming triclosan with a second-order rate constant (
k
cat
/
K
m
) of greater than 77,000 M
−1
s
−1
. (ii) Triclosan is detected in NB2001-treated, β-lactamase-producing
Escherichia coli
but not in
E. coli
that does not express β-lactamase. (iii) NB2001 activity against β-lactamase-producing
E. coli
is decreased in the presence of the β-lactamase inhibitor clavulanic acid. NB2001 was similar to or more potent than reference antibiotics against clinical isolates of
Staphylococcus aureus
(including MRSA),
Staphylococcus epidermidis
,
Streptococcus pneumoniae
, vancomycin-resistant
Enterococcus faecalis
,
Moraxella catarrhalis
and
Haemophilus influenza
e. NB2001 is also active against
Klebsiella pneumoniae
,
Enterobacter aerogenes
, and
Enterobacter cloacae
. The results indicate that NB2001 is a potent, broad-spectrum antibacterial agent and demonstrate the potential of ECTA in overcoming β-lactamase-mediated resistance.
摘要
酶催化治疗活化(ECTA)是一种新型原药策略,可克服酶过度表达导致的耐药性。β-内酰胺酶过表达是细菌对β-内酰胺类抗生素产生耐药性的常见机制。我们在此介绍其中一种β-内酰胺酶 ECTA 化合物 NB2001 的研究结果,该化合物由抗菌剂三氯生以原药形式与头孢菌素支架组成。与传统的β-内酰胺类抗生素不同,β-内酰胺环水解会使抗生素失活,而 NB2001 被β-内酰胺酶水解后会释放出三氯生。支持拟议机制的证据如下。(i) NB2001 是 TEM-1 β-内酰胺酶的底物,它以二阶速率常数 (
k
cat
/
K
m
)大于 77,000 M
-1
s
-1
(ii) 在经 NB2001 处理的产β-内酰胺酶大肠埃希氏菌中检测到三氯生。
大肠杆菌
但在
大肠杆菌
大肠杆菌中检测到三氯生。(iii) NB2001 对产β-内酰胺酶大肠杆菌的活性
大肠杆菌
内酰胺酶抑制剂克拉维酸存在时,NB2001 对产 β-内酰胺酶大肠杆菌的活性降低。NB2001 对临床分离的金黄色葡萄球菌的作用与参考抗生素相似或更强。
金黄色葡萄球菌
(包括 MRSA)、
表皮葡萄球菌
,
肺炎链球菌
耐万古霉素
耐万古霉素肠球菌
,
白喉莫拉菌
和
流感嗜血杆菌
e. NB2001 对以下细菌也有活性
肺炎克雷伯菌
,
产气肠杆菌
和
肠杆菌
.结果表明,NB2001 是一种强效、广谱的抗菌剂,并证明了 ECTA 在克服 β-内酰胺酶介导的耐药性方面的潜力。