Inhalation anthrax is a life-threatening disease that would result from the release of Bacillus anthracis spores into the environment. The economic impact of such an event, which would be secondary only to the resulting morbidity and mortality figures, would be in the billions. Although approved antibiotics are available for use against anthrax, they represent standard classes currently being used for other diseases. Resistant strains of B. anthracis exist for certain antimicrobials and development of resistant strains to all the available drugs is achievable with current molecular tools. There is only one new antimicrobial in late-stage development that is effective in preventing inhalation anthrax infections. The goal of this R01 proposal is to develop a new assemblage of antimicrobials for the treatment of inhalation anthrax that will inhibit a critical metabolic enzyme, dihydrofolate reductase (DHFR). The anthracis DHFR is inherently resistant to the only clinical drug for this target. Thus, if multiple-resistant B. anthracis were covertly created, DHFR would likely be unchanged and these new antimicrobials would be effective against those strains. Through an R21, several new parent compounds were identified that inhibit B. anthracis through selective activity against the bacterial DHFR (IC50s of 46-100 nM) but not human DHFR (IC50s >25,000 nM). This approach will involve a team of scientists from diverse disciplines, including biochemistry, microbiology &structural biology, in silico technology, protein chemistry, molecular biology, medicinal chemistry, and animal models. The application is a specific response to a RFA request to develop therapeutics for NIAID Category A, B, and C priority pathogens. This application will involve the following Milestones: Milestone 1: Synthesize 4 more parent compounds designed from crystallographic working model and from previous studies;Milestone 2: Propose 25 suggested 1st generation compounds using in silico drug design methods;Milestone 3: Begin PK and MTD studies;Milestone 4: Synthesize and assay 8 selected compounds from 1st generation derivatives;Milestone 5: Complete MTD/PK studies;Milestone 6: Evaluate 1st generation lead compounds for efficacy in mouse anthrax model;Milestone 7: Identify 1-3 lead compounds for preclinical development. This multidisciplinary effort will involve both academic and privately owned research organizations participating in a comprehensive team-based plan that will facilitate the advancement of a promising therapeutic through the product development pathway. The public health relevance is the development of a therapeutic countermeasure that will be effective against multidrug-resistant strains of anthrax.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Study Section
Special Emphasis Panel (ZAI1-LR-M (M1))
Program Officer
Franceschi, Francois J
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Oklahoma State University Stillwater
Veterinary Sciences
Schools of Veterinary Medicine
United States
Zip Code
Muddala, Nagendra Prasad; Nammalwar, Baskar; Selvaraju, Subhashini et al. (2015) Evaluation of New Dihydrophthalazine-Appended 2,4-Diaminopyrimidines against Bacillus anthracis: Improved Syntheses Using a New Pincer Complex. Molecules 20:7222-44
Nammalwar, Baskar; Bourne, Christina R; Wakeham, Nancy et al. (2015) Modified 2,4-diaminopyrimidine-based dihydrofolate reductase inhibitors as potential drug scaffolds against Bacillus anthracis. Bioorg Med Chem 23:203-11
Bourne, Christina R; Wakeham, Nancy; Webb, Nicole et al. (2014) The structure and competitive substrate inhibition of dihydrofolate reductase from Enterococcus faecalis reveal restrictions to cofactor docking. Biochemistry 53:1228-38
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Kobayashi, Maiko; Kinjo, Tomohiro; Koseki, Yuji et al. (2014) Identification of novel potential antibiotics against Staphylococcus using structure-based drug screening targeting dihydrofolate reductase. J Chem Inf Model 54:1242-53
Bourne, Christina R; Wakeham, Nancy; Nammalwar, Baskar et al. (2013) Structure-activity relationship for enantiomers of potent inhibitors of B. anthracis dihydrofolate reductase. Biochim Biophys Acta 1834:46-52
Nammalwar, Baskar; Bunce, Richard A; Berlin, K Darrell et al. (2013) Comparative Study of the Frech Catalyst with Two Conventional Catalysts in the Heck Synthesis of 2,4-Diaminopyrimidine-based Antibiotics. Org Prep Proced Int 45:66-71
Nammalwar, Baskar; Bunce, Richard A; Berlin, K Darrell et al. (2012) Synthesis and biological activity of substituted 2,4-diaminopyrimidines that inhibit Bacillus anthracis. Eur J Med Chem 54:387-96
Bourne, Christina R; Wakeham, Nancy; Bunce, Richard A et al. (2012) Classifying compound mechanism of action for linking whole cell phenotypes to molecular targets. J Mol Recognit 25:216-23
Nammalwar, Baskar; Bunce, Richard A; Berlin, K Darrell et al. (2012) Approaches to Iodinated Derivatives of Vanillin and Isovanillin. Org Prep Proced Int 44:146-152

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