Bacteria synthesize the cellular growth factor putrescine through a number of pathways. One pathway involves the decarboxylation of arginine by arginine decarboxylase to produce agmatine, which is then degraded to putrescine. While important for various cellular processes (e.g., cell division, differentiation, environmental stress responses) in all living organisms, including plants, high levels of this polyamine can be toxic. α-(difluoromethyl)-DL-Arginine (DFMA) is an enzyme-activated, irreversible inhibitor of the arginine decarboxylases of E. coli (Ki = 800 μM), P. aeruginosa, and K. pneumoniae. At 0.01 mM, it has been shown to prevent the osmotic stress-induced increase in arginine decarboxylase activity and putrescine synthesis in oat leaf cells. DFMA can also reduce the growth of T. cruzi in mammalian host cells at a minimal concentration of 10 mM and prevent the growth of C. parvum in a T cell receptor alpha-deficient mouse model when combined with various polyamine analogs.
