Chemical compounds are provided that are useful in the treatment of diseases associated with an activity of a 5,10-methylenyltetrahydrofolate cyclohydrolase/5,10-methylene tetrahydrofolate dehydrogenase enzyme in pathological eukaryotic cells. In particular, compounds that exhibit inhibitory activity upon 5,10-methylenyltetrahydrofolate cyclohydrolase/5,10-methylene tetrahydrofolate dehydrogenase enzymes and their use in the treatment of cancer and/or parasitic diseases are provided.