Summer 2012-Spring 2014: Investigating Propargyl-Linked Antifolates in Inhibiting Bacterial and Fungal Dihydrofolate Reductase

By Joshua Andrade, Dr. Amy Anderson’s Lab, and Dr. Dennis Wright’s Lab

Antimicrobial agents have been invaluable in reducing illness and death associated with bacterial infection. However, over time, bacteria have evolved resistance to all major drug classes as a result of selective pressure. The advancement of new drug compounds is therefore vital.  The Anderson-Wright Lab has focused on developing potent and selective inhibitors of dihydrofolate reductase (DHFR), an enzyme key in cell proliferation and survival, in several pathogenic species.  The lab has found that a set of compounds, known as propargyl-linked antifolates, are DHFR inhibitors that are both biologically effective and have strong pharmacokinetic properties.

The efficacy of novel propargyl-linked antifolates in inhibiting DHFR was tested with enzymatic assays in three species: Candida albicans, Candida glabrata, and Klebsiella pneumoniae. In order to gauge the potency of the novel compounds, the results of the tests were referenced against assay results using trimethoprim, which is a known, powerful inhibitor of DHFR. Additionally, x-ray crystallography was employed to generate a three dimensional representation of inhibitor:pathogen DHFR interactions. The data from the enzymatic assay and x-ray crystallography were utilized to deduce the structural analogs of the propargyl-linked antifolates most effective in inhibiting DHFR in the given pathogens. Knowing what specific molecular features comprise an effective inhibitor allows the lab to strive towards more ideal drug compounds and allows for future development of increasingly powerful antimicrobials.

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