Synthesis and evaluation of 9-deazaguanine derivatives as multi-substrate analogue inhibitors of PNP.

9-(5',5'-Difluoro-5'-phosphonopentyl)-9-deazaguanine (DFPP-DG) and its related analogues were designed as multi-substrate analogue inhibitors against purine nucleoside phosphorylase (PNP) on the basis of the X-ray crystallographic data obtained for the binary complex of 9-(5',5'-difluoro-5'-phosphonopentyl)guanine (DFPP-G) with calf-spleen PNP. One of these analogues, homo-DFPP-DG was found to be a very potent PNP inhibitor at an intracellular P(i) concentration (about 1 mM phosphate).