ABSTRACT
A wide variety of pathogens have acquired antimicrobial resistance as an inevitable evolutionary response to the extensive use of antibacterial agents. In particular, one of the most widely used antibiotic structural classes is the beta-lactams, in which the most common and the most efficient mechanism of bacterial resistance is the synthesis of beta-lactamases. Class C beta-lactamase enzymes are primarily cephalosporinases, mostly chromosomally encoded, and are inducible by exposure to some beta-lactam agents and resistant to inhibition by marketed beta-lactamase inhibitors. In an ongoing effort to alleviate this problem a series of novel 4-substituted trinems was designed and synthesized. Significant in vitro inhibitory activity was measured against the bacterial beta-lactamases of class C and additionally against class A. The lead compound LK-157 was shown to be a potent mechanism-based inactivator. Acylation of the active site Ser 64 of the class C enzyme beta-lactamase was observed in the solved crystal structures of two inhibitors complexes to AmpC enzyme from E. cloacae. Structure-activity relationships in the series reveal the importance of the trinem scaffold for inhibitory activity and the interesting potential of the series for further development.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Azetidines/chemical synthesis , Bacterial Proteins/antagonists & inhibitors , Drug Resistance, Bacterial , Heterocyclic Compounds, 3-Ring/chemical synthesis , beta-Lactamase Inhibitors , Acylation , Anti-Bacterial Agents/chemistry , Azetidines/chemistry , Bacterial Proteins/chemistry , Binding Sites , Crystallography, X-Ray , Enterobacter cloacae/enzymology , Heterocyclic Compounds, 3-Ring/chemistry , Models, Molecular , Molecular Structure , Stereoisomerism , Structure-Activity Relationship , beta-Lactamases/chemistryABSTRACT
Phosphonate inhibitors of antigen 85C were prepared. The inhibitors, comprising a phosphonate moiety, mycolic acid mimetic and a trehalose surrogate, contain substituted benzyl alcohols, N-(omega-hydroxyalky)phthalimide, 2-phenylethanol or 4-(phthalimido)butanol as trehalose mimetics, and an alkyl chain of different lengths mimicking the mycolic acid side chain. The best compounds inhibited the mycolyltransferase activity of antigen 85C with IC(50) in the low micromolar range and inhibited the growth of Mycobacterium avium in culture. The best compounds in the 3-phenoxybenzyl- and omega-(phthalimido)alkoxy series, ethyl 3-phenoxybenzyl butylphosphonate (4a) and (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl ethyl heptylphosphonate (5c) displayed IC(50) values of 2.0 and 1.3 microM, respectively, in a mycolyltransferase inhibition assay. In a M. avium growth inhibition assay MIC of 4a and (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl ethyl nonylphosphonate (5d) were 248.8 and 84.5 microg/mL, respectively.
Subject(s)
Acyltransferases/antagonists & inhibitors , Antitubercular Agents/chemical synthesis , Organophosphonates/chemical synthesis , Acyltransferases/chemistry , Antigens, Bacterial/chemistry , Antitubercular Agents/chemistry , Antitubercular Agents/pharmacology , Cell Wall/metabolism , Drug Design , Mycobacterium avium/drug effects , Mycobacterium avium/metabolism , Organophosphonates/chemistry , Organophosphonates/pharmacology , Structure-Activity RelationshipABSTRACT
The first phosphonate inhibitors of antigen 85C--a major protein component of the Mycobacterium tuberculosis cell wall possessing mycolyltransferase activity were prepared using structure-based design. These potential novel antituberculosis agents, consisting of a phosphonate moiety, hydrophobic alkyl chain and a simple trehalose-mimicking aromatic structure, were designed as tetrahedral transition-state analogue inhibitors of antigen 85C, which catalyzes the key mycolyltransferase reaction involved in cell wall biosynthesis.
