The research focus of the proposed work is to develop second generation broad spectrum 5-nitrothiazolide therapeutics against Category B priority food and water borne pathogens Cryptosporidium parvum, Entamoeba histolytica, Giardia intestinalis, Campylobacter jejuni and Clostridium spp. All of these human pathogens share a common and essential metabolic enzyme of central metabolism, pyruvate ferredoxin oxidoreductase (PFOR) that is recognized as a good druggable target. Our published and preliminary studies establish that generic drug nitazoxanide (NTZ), a 5-nitrothiazolide which is FDA approved for treatment of infections caused by C. parvum and G. intestinalis, selectively inhibits PFOR in all of the target pathogens by a novel mechanism. Mechanistic studies show that the nitrothiazolide anion dissociates the pyruvate-thiamine pyrophosphate transition intermediate and thereby blocking formation of acetyl-CoA and reducing power. In the process, NTZ is protonated to an inactive form. The biological activity of nitazoxanide is highly pH dependent and the goal of the proposed studies is to develop derivatives which are more potent at lower pH. The pipeline approach to developing second generation broad spectrum therapeutics includes the following specific aims: (i) synthesize new lead compounds driven by knowledge of pKa and structural data from X-ray crystallography and screen for inhibitory activity in medium throughput PFOR 96 well assay (IC50 and Ki);(ii)screen active leads for biological activity against target pathogens in vitro (MIC, MBC, MLC);(iii) determine therapeutic efficacy of potent leads in animal infection models;and (iv) progress viable candidate drugs through product development, toxicology and scale up for clinical trials. Two unexpected caveats of this novel target and inhibitory mechanism are (i) low likelihood for development of drug resistance and (ii) weak activity against the NAD-pyruvate dehydrogenase of enteric pathogens - loss of fitness and colonization efficiency. Successful completion of these studies will produce second generation broad spectrum nitrothiazolide therapeutics with increased bioavailability and potency against Category B intestinal parasites and bacteria (broad spectrum anti-diarrheal agent) that can be evaluated clinically for prophylaxis against and primary treatment of infections caused by bioterrorism activities or natural events.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project--Cooperative Agreements (U01)
Project #
5U01AI075520-05
Application #
8115981
Study Section
Special Emphasis Panel (ZAI1-MH-M (M2))
Program Officer
Rogers, Martin J
Project Start
2007-08-01
Project End
2012-07-31
Budget Start
2011-08-01
Budget End
2012-07-31
Support Year
5
Fiscal Year
2011
Total Cost
$534,930
Indirect Cost
Name
University of Virginia
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
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Warren, Cirle A; van Opstal, Edward J; Riggins, Mary S et al. (2013) Vancomycin treatment's association with delayed intestinal tissue injury, clostridial overgrowth, and recurrence of Clostridium difficile infection in mice. Antimicrob Agents Chemother 57:689-96
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Warren, Cirle A; van Opstal, Edward; Ballard, T Eric et al. (2012) Amixicile, a novel inhibitor of pyruvate: ferredoxin oxidoreductase, shows efficacy against Clostridium difficile in a mouse infection model. Antimicrob Agents Chemother 56:4103-11
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Ballard, T Eric; Wang, Xia; Olekhnovich, Igor et al. (2011) Synthesis and antimicrobial evaluation of nitazoxanide-based analogues: identification of selective and broad spectrum activity. ChemMedChem 6:362-77
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Shamir, Eliah R; Warthan, Michelle; Brown, Sareena P et al. (2010) Nitazoxanide inhibits biofilm production and hemagglutination by enteroaggregative Escherichia coli strains by blocking assembly of AafA fimbriae. Antimicrob Agents Chemother 54:1526-33
Ballard, T Eric; Wang, Xia; Olekhnovich, Igor et al. (2010) Biological activity of modified and exchanged 2-amino-5-nitrothiazole amide analogues of nitazoxanide. Bioorg Med Chem Lett 20:3537-9
Devasahayam, Gina; Scheld, William M; Hoffman, Paul S (2010) Newer antibacterial drugs for a new century. Expert Opin Investig Drugs 19:215-34

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