A series of 13 acyclic nucleoside phosphonates (ANPs) as bisamidate prodrugs was prepared. Five compounds were found to be non-cytotoxic and selective inhibitors of Bordetella pertussis adenylate cyclase toxin (ACT) in J774A.1 macrophage cell-based assays. The 8-aza-7-deazapurine derivative of adefovir (PMEA) was found to be the most potent ACT inhibitor in the series (IC50 =16 nm) with substantial selectivity over mammalian adenylate cyclases (mACs). AC inhibitory properties of the most potent analogues were confirmed by direct evaluation of the corresponding phosphonodiphosphates in cell-free assays and were found to be potent inhibitors of both ACT and edema factor (EF) from Bacillus anthracis (IC50 values ranging from 0.5 to 21 nm). Moreover, 7-halo-7-deazapurine analogues of PMEA were discovered to be potent and selective mammalian AC1 inhibitors (no inhibition of AC2 and AC5) with IC50 values ranging from 4.1 to 5.6 μm in HEK293 cell-based assays.

• Keywords
• Bacillus anthracis, Bordetella pertussis, adefovir, adenylate cyclase, inhibitors,
• MeSH
• Adenine analogs & derivatives   chemical synthesis   chemistry   pharmacology   MeSH
• Adenylyl Cyclases metabolism   MeSH
• Bacillus anthracis enzymology   MeSH
• Bordetella pertussis enzymology   MeSH
• Enzyme Inhibitors chemical synthesis   chemistry   pharmacology   MeSH
• Molecular Structure MeSH
• Organophosphonates chemical synthesis   chemistry   pharmacology   MeSH
• Dose-Response Relationship, Drug MeSH
• Structure-Activity Relationship MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• adefovir MeSH Browser
• Adenine MeSH
• Adenylyl Cyclases MeSH
• Enzyme Inhibitors MeSH
• Organophosphonates MeSH

Bordetella pertussis adenylate cyclase toxin (ACT) and Bacillus anthracis edema factor (EF) are key virulence factors with adenylate cyclase (AC) activity that substantially contribute to the pathogenesis of whooping cough and anthrax, respectively. There is an urgent need to develop potent and selective inhibitors of bacterial ACs with prospects for the development of potential antibacterial therapeutics and to study their molecular interactions with the target enzymes. Novel fluorescent 5-chloroanthraniloyl-substituted acyclic nucleoside phosphonates (Cl-ANT-ANPs) were designed and synthesized in the form of their diphosphates (Cl-ANT-ANPpp) as competitive ACT and EF inhibitors with sub-micromolar potency (IC50 values: 11-622 nm). Fluorescence experiments indicated that Cl-ANT-ANPpp analogues bind to the ACT active site, and docking studies suggested that the Cl-ANT group interacts with Phe306 and Leu60. Interestingly, the increase in direct fluorescence with Cl-ANT-ANPpp having an ester linker was strictly calmodulin (CaM)-dependent, whereas Cl-ANT-ANPpp analogues with an amide linker, upon binding to ACT, increased the fluorescence even in the absence of CaM. Such a dependence of binding on structural modification could be exploited in the future design of potent inhibitors of bacterial ACs. Furthermore, one Cl-ANT-ANP in the form of a bisamidate prodrug was able to inhibit B. pertussis ACT activity in macrophage cells with IC50 =12 μm.

• Keywords
• adenylate cyclase, anthrax, antibacterial agents, fluorescence, whooping cough,
• MeSH
• Adenylyl Cyclases metabolism   MeSH
• Bordetella pertussis enzymology   MeSH
• Fluorescent Dyes chemical synthesis   chemistry   pharmacology   MeSH
• Adenylyl Cyclase Inhibitors chemical synthesis   chemistry   pharmacology   MeSH
• Macrophages drug effects   MeSH
• Molecular Structure MeSH
• Mice MeSH
• Nucleosides chemical synthesis   chemistry   pharmacology   MeSH
• Organophosphonates chemical synthesis   chemistry   pharmacology   MeSH
• Drug Design * MeSH
• Dose-Response Relationship, Drug MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Adenylyl Cyclases MeSH
• Fluorescent Dyes MeSH
• Adenylyl Cyclase Inhibitors MeSH
• Nucleosides MeSH
• Organophosphonates MeSH