Pathogens such as Plasmodium and Trypanosoma spp. are unable to synthesize purine nucleobases. They rely on the salvage of these purines and their nucleosides from the host cell to synthesize the purine nucleotides required for DNA/RNA production. The key enzymes in this pathway are purine phosphoribosyltransferases (PRTs). Here, we synthesized 16 novel acyclic nucleoside phosphonates, 12 with a chiral center at C-2', and eight bearing a second chiral center at C-6'. Of these, bisphosphonate (S,S)-48 is the most potent inhibitor of the Plasmodium falciparum and P. vivax 6-oxopurine PRTs and the most potent inhibitor of two Trypanosoma brucei (Tbr) 6-oxopurine PRTs yet discovered, with Ki values as low as 2 nM. Crystal structures of (S,S)-48 in complex with human and Tbr 6-oxopurine PRTs show that the inhibitor binds to the enzymes in different conformations, providing an explanation for its potency and selectivity (i.e., 35-fold in favor of the parasite enzymes).

Faculty of Science University of South Bohemia České Budějovice 37005 Czech Republic

Institute of Parasitology Biology Centre ASCR České Budějovice 37005 Czech Republic

School of Chemistry and Molecular Biosciences The University of Queensland Brisbane 4072 Australia

The Centre for Microscopy and Microanalysis The University of Queensland Brisbane 4072 Australia

The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Prague 6 CZ 16000 Czech Republic

References provided by Crossref.org

Development of Prolinol Containing Inhibitors of Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferase: Rational Structure-Based Drug Design