123242-02-4Relevant articles and documents
Dicyclic and tricyclic diaminopyrimidine derivatives as potent inhibitors of Cryptosporidium parvum dihydrofolate reductase: Structure-activity and structure-selectivity correlations
Nelson,Rosowsky
, p. 3293 - 3303 (2007/10/03)
A structurally diverse library of 93 lipophilic di- and tricyclic diaminopyrimidine derivatives was tested for the ability to inhibit recombinant dihydrofolate reductase (DHFR) cloned from human and bovine isolates of Cryptosporidium parvum (J. R. Vasquez et al., Mol. Biochem. Parasitol. 79:153-165, 1996). In parallel, the library was also tested against human DHFR and, for comparison, the enzyme from Escherichia coli. Fifty percent inhibitory concentrations (IC50s) were determined by means of a standard spectrophotometric assay of DHFR activity with dihydrofolate and NADPH as the cosubstrates. Of the compounds tested, 25 had IC50s in the 1 to l0 μM range against one or both C. parvum enzymes and thus were not substantially different from trimethoprim (IC50s, ca. 4 μM). Another 25 compounds had IC50s of 50s of 50s, 50s of 50s of 0.3 μM and thus were comparable in potency to trimetrexate. The finding that submicromolar concentrations of several of the compounds in the library could inhibit in vitro growth of C. parvum in host cells in the presence of thymidine (dThd) and hypoxanthine (Hx) suggests that lipophilic DHFR inhibitors, in combination with leucovorin, may find use in the treatment of intractable C. parvum infections.
