Synthesis, in vitro evaluation and cocrystal structure of 4-oxo-[1]benzopyrano[4,3-c]pyrazole Cryptosporidium parvum inosine 5'-monophosphate dehydrogenase (CpIMPDH) inhibitors.

Cryptosporidium inosine 5'-monophosphate dehydrogenase (CpIMPDH) has emerged as a therapeutic target for treating Cryptosporidium parasites because it catalyzes a critical step in guanine nucleotide biosynthesis. A 4-oxo-[1]benzopyrano[4,3-c]pyrazole derivative was identified as a moderately potent (IC50 = 1.5 mu M) inhibitor of CpIMPDH. We report a SAR study for this compound series resulting in 8k (IC50 = 20 +/- 4 nM). In addition, an X-ray crystal structure of CpIMPDH IMP 8k is also presented.