Structure‐activity relationships of fragment‐based inhibitors of Trichomonas vaginalis adenosine/guanosine preferring nucleoside ribohydrolase

Abstract

Trichomoniasis is a sexually transmitted infection caused by the parasite, Trichomonas vaginalis. Infections are currently treated with 5‐nitroimidazole drugs, such as metronidazole and tinidazole. However, strains of the parasite with resistance to these drugs have emerged, indicating the need for new treatments with novel mechanisms. Since the parasite is unable to perform de novo synthesis of nucleobases, it must obtain them from its host using salvage pathway enzymes including adenosine/guanosine preferring nucleoside ribohydrolase (AGNH), an essential enzyme involved in the pyrimidine salvage pathway. We previously used fragment screening to identify ligand‐efficient fragment inhibitors of AGNH. Medicinal chemistry efforts were then focused on several fragment scaffolds including benzimidazoles and phenyl pyridines. IC50 values were determined using the same 1H NMR‐based activity assays as the fragment screens. The resulting structure‐activity relationships suggest that the fragment scaffolds interact primarily with the nucleobase regions of the active site rather than the ribose pocket. Collectively, the data define emerging structure‐activity relationships that suggest likely vectors and chemical modifications for improving inhibition potency while maintaining ligand efficiency. The data establishes a platform for ongoing medicinal chemistry development of compounds with nM potency that will provide the tools for in vitro target validation against both 5‐nitroimidazole‐sensitive and 5‐nitroimidazole‐resistant T. vaginalis strains.Support or Funding InformationResearch was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under Award Number R15AI128585 to BJS and MAVP. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.