[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to design, synthesize, and evaluate novel antibacterial agents, derivatives of aryl-4-guanidinomethylbenzoate and N-aryl-4-guanidinomethylbenzamide.
A total of 44 derivatives of aryl-4-guanidin-omethylbenzoate (series A) and N-aryl-4-guanidinomethylbenzamide (series B) were synthesized and their antibacterial activities were assessed in vitro against a variety of Gram-positive and Gram-negative bacteria by an agar dilution method.
Twelve compounds showed potent bactericidal effects against a panel of Gram-positive germs, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), vancomycin-intermediate Staphylococcus aureus (VISA), and methicillin-resistant coagulase-negative staphylococci (MRCNS), with minimum inhibitory concentrations (MIC) ranging between 0.5 and 8 microg/mL, which were comparable to the MIC values of several marketed antibiotics. They exhibited weak or no activity on the Gram-negative bacteria tested. In addition, these compounds displayed high inhibitory activities towards oligopeptidase B of bacterial origin.
In comparison with the previously reported MIC values of several known antibiotics, the derivatives of aryl-4-guanidinomethylbenzoate and N-aryl-4-guanidinomethylbenzamide showed comparable in vitro bactericidal activities against VRE and VISA as linezolid. Their growth inhibitory effects on MRSA were similar to vancomycin, but were less potent than linezolid and vancomycin against MRCNS. This class of compounds may have the potential to be developed into narrow spectrum antibacterial agents against certain drug-resistant strains of bacteria.
Full-text · Article · Mar 2008 · Acta Pharmacologica Sinica
[Show abstract][Hide abstract] ABSTRACT: Oligopeptidase B (OpdB) of Escherichia coli, previously called protease II, has a trypsin-like specificity, cleaving peptides at lysine and arginine residues and belongs to the prolyl oligopeptidase family of new serine peptidases. In this study, we report the fusion expression of E. coli oligopeptidase B with an N-terminal histidine tag using pET28a as the expression vector. Although most of the recombinant OpdB was produced as inclusion bodies, the solubility of the recombinant protease increased significantly when the expression temperature shifted from 37 to 30 degrees C. Recombinant OpdB (approximately 10 mg) could be purified from the soluble fraction of the crude extract of 1L log-phase E. coli culture containing 1.5 g wet bacterial cells. The purified OpdB has a molecular weight of approximately 80 kDa and a specific activity of 4.8 x 10(4) U/mg. OpdB could also be purified from the inclusion bodies with a lower yield. The recombinant enzyme was very stable under 40 degrees C. By comparison of the substrate specificity of the purified OpdB with that of OpdA, another trypsin-like protease in E. coli, we found that Boc-Glu-Lys-Lys-MCA is a specific substrate for E. coli OpdB. We also found that compared to OpdA, OpdB is much more sensitive to GMCHA-OPh(t)Bu, a synthetic trypsin inhibitor that can retard the growth of E. coli.
Full-text · Article · Jul 2006 · Protein Expression and Purification
[Show abstract][Hide abstract] ABSTRACT: The antibacterial activities of NE-2001 were tested against 24 clinical isolates of Helicobacter pylori and compared with those of amoxicillin, clarithromycin, metronidazole, and furazolidone. The MIC50 and MIC90 of this synthetic compound on the isolates were 8 and 16 μg/ml, respectively. This action was highly selective against Helicobacter pylori; there was a >4-fold difference between the concentration of NE-2001 required to inhibit the growth of Helicobacter pylori and that required to inhibit the growth of common aerobic and anaerobic bacteria. Exposure of Helicobacter pylori (ATCC43504) to NE-2001 at the MIC (4 μg/ml), or at a greater concentration, resulted in an extensive loss of viability. The
phenomenon was also observed at pH levels between 3.0 and 7.0. When two clinical Helicobacter pylori strains were successively cultured at subinhibitory concentrations of NE-2001, no significant changes in the bactericidal
effects were found. The morphological alterations of Helicobacter pylori cells (ATCC43504), exposed to NE-2001 at various concentrations for 6 h, were observed using transmission electron microcopy.
The bacterium displayed features such as swelling, vacuole-like structures in the cytoplasm, and cell destruction following
exposure to NE-2001. The efficacy of NE-2001 was maintained when evaluated in eight clinical isolates resistant to metronidazole
and five isolates resistant to both metronidazole and clarithromycin (MIC ranging between 4 and 16 μg/ml). The above-described
results suggest that NE-2001 may have the potential to be developed as a candidate agent for the treatment of Helicobacter pylori infection.
[Show abstract][Hide abstract] ABSTRACT: This study describes the cloning, genetic analysis and biochemical characterization of a leucyl aminopeptidase (LAP) from Helicobacter pylori. A gene encoding LAP was cloned from H. pylori and the expressed 55 kDa protein displayed homology to aminopeptidases from Gram-negative bacteria, plants and mammals. This LAP demonstrated amidolytic activity against L-leucine-p-nitroanilide. Optimal activity was observed at pH 8.0 and 45 degrees C, with V(max) of 232 mumol min(-1) (mg protein)(-1) and S(0.5) of 0.65 mM. The data suggest that LAP could be allosteric (n(H)=2.27), with regulatory homohexamers, and its activity was inhibited by ion chelators and enhanced by divalent manganese, cobalt and nickel cations. Bestatin inhibited both LAP activity (IC(50)=49.9 nM) and H. pylori growth in vitro. The results point to the potential use of LAP as a drug target to develop novel anti-H. pylori agents.
[Show abstract][Hide abstract] ABSTRACT: The synthesis and anti-Helicobacter pylori activity of a novel agent NE2001, 4-(4-methylbenzyl)-4'-[guanidinomethylbenzoyloxy] biphenyl-4-carboxylate hydrochloride, are described. NE2001 had a specific inhibitory effect on the growth of H. pylori preceded by the suppression DNA synthesis in the cell. The effects of NE2001 on RNA and protein syntheses in H. pylori were also examined.