Parasites of the Plasmodium genus are unable to produce purine nucleotides de novo and depend completely on the salvage pathway. This fact makes plasmodial hypoxanthine-guanine-(xanthine) phosphoribosyltransferase [HG(X)PRT] a valuable target for development of antimalarial agents. A series of nucleotide analogues was designed, synthesized and evaluated as potential inhibitors of Plasmodium falciparum HGXPRT, P. vivax HGPRT and human HGPRT. These novel nucleoside phosphonates have a pyrrolidine, piperidine or piperazine ring incorporated into the linker connecting the purine base to a phosphonate group(s) and exhibited a broad range of Ki values between 0.15 and 72 μM. The corresponding phosphoramidate prodrugs, able to cross cell membranes, have been synthesized and evaluated in a P. falciparum infected human erythrocyte assay. Of the eight prodrugs evaluated seven exhibited in vitro antimalarial activity with IC50 values within the range of 2.5-12.1 μM. The bis-phosphoramidate prodrug 13a with a mean (SD) IC50 of 2.5 ± 0.7 μM against the chloroquine-resistant P. falciparum W2 strain exhibited low cytotoxicity in the human hepatocellular liver carcinoma (HepG2) and normal human dermal fibroblasts (NHDF) cell lines at a concentration of 100 μM suggesting good selectivity for further structure-activity relationship investigations.

• MeSH
• antimalarika chemická syntéza   metabolismus   farmakologie   MeSH
• buněčné linie MeSH
• erytrocyty cytologie   metabolismus   parazitologie   MeSH
• inhibitory enzymů chemie   metabolismus   MeSH
• léková rezistence účinky léků   MeSH
• lidé MeSH
• nukleotidy chemie   metabolismus   MeSH
• pentosyltransferasy antagonisté a inhibitory   metabolismus   MeSH
• piperazin chemie   MeSH
• piperidiny chemie   MeSH
• Plasmodium falciparum účinky léků   enzymologie   MeSH
• Plasmodium vivax enzymologie   MeSH
• preklinické hodnocení léčiv MeSH
• prekurzory léčiv chemická syntéza   chemie   metabolismus   farmakologie   MeSH
• protozoální proteiny antagonisté a inhibitory   metabolismus   MeSH
• pyrrolidiny chemie   MeSH
• viabilita buněk účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) is a recognized target for antimalarial chemotherapeutics. It synthesises all of the 6-oxopurine nucleoside monophosphates, IMP, GMP and XMP needed by the malarial parasite, Plasmodium falciparum (Pf). PfHGXPRT is also indirectly responsible for the synthesis of the adenosine monophosphate, AMP. The acyclic nucleoside phosphonates (ANPs) are a class of PfHGXPRT inhibitors. Prodrugs of these compounds are able to arrest the growth of Pf in cell culture. In the search for new inhibitors of PfHGXPRT, a series of sulfur containing ANPs (thia-ANPs) has been designed and synthesized. These compounds are based on the structure of 2-(phosphonoethoxy)ethylguanine (PEEG) and PEEHx which consist of a purine base (i.e. guanine or hypoxanthine) linked to a phosphonate group by five atoms i.e. four carbons and one oxygen. Here, PEEG and PEEHx were modified by substituting a sulfide, sulfoxide or a sulfone bridge for the oxygen atom in the linker. The effect of these substitutions on the Ki values for human HGPRT and PfHGXPRT was investigated and showed that most of the thia-ANPs distinctively favour PfHGXPRT. For example, the thia-analogue of PEEHx has a Ki value of 0.2 μM for PfHGXPRT, a value 25-fold lower than for the human counterpart. Prodrugs of these compounds have IC50 values in the 4-6 μM range in antimalarial cell-based assays, making them attractive compounds for further development as antimalarial drug leads.

• MeSH
• antimalarika chemická syntéza   farmakologie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• nukleosidy chemická syntéza   farmakologie   MeSH
• organofosfonáty chemická syntéza   farmakologie   MeSH
• oxidace-redukce MeSH
• pentosyltransferasy antagonisté a inhibitory   MeSH
• Plasmodium falciparum účinky léků   enzymologie   MeSH
• prekurzory léčiv chemická syntéza   farmakologie   MeSH
• sulfidy chemie   MeSH
• sulfony chemie   MeSH
• sulfoxidy chemie   MeSH
• termodynamika MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) are the foremost causative agents of malaria. Due to the development of resistance to current antimalarial medications, new drugs for this parasitic disease need to be discovered. The activity of hypoxanthine-guanine-[xanthine]-phosphoribosyltransferase, HG[X]PRT, is reported to be essential for the growth of both of these parasites, making it an excellent target for antimalarial drug discovery. Here, we have used rational structure-based methods to design an inhibitor, [3R,4R]-4-guanin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine, of PvHGPRT and PfHGXPRT that has Ki values of 8 and 7 nM, respectively, for these two enzymes. The crystal structure of PvHGPRT in complex with this compound has been determined to 2.85 Å resolution. The corresponding complex with human HGPRT was also obtained to allow a direct comparison of the binding modes of this compound with the two enzymes. The tetra-(ethyl l-phenylalanine) tetraamide prodrug of this compound was synthesized, and it has an IC50 of 11.7 ± 3.2 μM against Pf lines grown in culture and a CC50 in human A549 cell lines of 102 ± 11 μM, thus giving it a ∼10-fold selectivity index.

• MeSH
• antimalarika chemie   farmakologie   MeSH
• bisfosfonáty chemie   farmakologie   MeSH
• hypoxanthinfosforibosyltransferasa antagonisté a inhibitory   chemie   metabolismus   MeSH
• katalytická doména MeSH
• konformace proteinů MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• molekulární modely MeSH
• pentosyltransferasy antagonisté a inhibitory   chemie   metabolismus   MeSH
• Plasmodium vivax enzymologie   MeSH
• proteiny z Escherichia coli chemie   MeSH
• racionální návrh léčiv MeSH
• techniky syntetické chemie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Acyclic nucleoside bisphosphonates (ANbPs) have previously been shown to be good inhibitors of human hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and Plasmodium falciparum (Pf) hypoxanthine-guanine-xanthine phosphoribosyltransferase (PfHGXPRT). On the basis of this scaffold, a new series of ANbPs was synthesized. One of these new ANbPs, [3-(guanine-9-yl)-2-((2-phosphonoethoxy)methyl)propoxy]methylphosphonic acid, exhibited Ki values of 6 and 70 nM for human HGPRT and Pf HGXPRT, respectively. These low Ki values were achieved by inserting an extra carbon atom in the linker connecting the N(9) atom of guanine to one of the phosphonate groups. The crystal structure of this ANbP in complex with human HGPRT was determined at 2.0 Å resolution and shows that it fills three key pockets in the active site. The most potent phosphoramidate prodrugs of these compounds have IC50 values in the low micromolar range in Pf lines and low toxicity in human A549 cells, demonstrating that these ANbPs are excellent antimalarial drug leads.

• MeSH
• antimalarika chemie   farmakologie   MeSH
• bisfosfonáty chemie   farmakologie   MeSH
• lidé MeSH
• nukleosidy chemie   farmakologie   MeSH
• pentosyltransferasy antagonisté a inhibitory   metabolismus   MeSH
• Plasmodium falciparum účinky léků   enzymologie   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• tropická malárie farmakoterapie   enzymologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Two new series of symmetric acyclic nucleoside bisphosphonates (ANbPs) have been synthesised as potential inhibitors of the Plasmodium falciparum (Pf) and vivax (Pv) 6-oxopurine phosphoribosyltransferases. The structural variability between these symmetric ANbPs lies in the number of atoms in the two acyclic linkers connecting the N9 atom of the purine base to each of two phosphonate groups and the branching point of the acyclic moiety relative to the purine base, which occurs at either the alpha or beta positions. Within each series, six different 6-oxopurine bases have been attached. In general, the ANbPs with either guanine or hypoxanthine have lower Ki values than for those containing either the 8-bromo or 7-deaza 6-oxopurine bases. The lowest Ki values obtained for the two parasite enzymes were 0.1μM (Pf) and 0.2μM (Pv) for this series of compounds. Two phosphoramidate prodrugs of these inhibitors exhibited antimalarial activity against Pf in infected erythrocyte cell culture with IC50 values of 0.8 and 1.5μM. These two compounds exhibited low cytotoxicity in human A549 cells having CC50 values of >300μM resulting in an excellent selectivity index.

• MeSH
• antimalarika chemická syntéza   farmakologie   MeSH
• ATP-fosforibosyltransferasa antagonisté a inhibitory   MeSH
• inhibitory enzymů chemická syntéza   farmakologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• Plasmodium falciparum účinky léků   MeSH
• Plasmodium vivax účinky léků   MeSH
• prekurzory léčiv farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Acyclic nucleoside phosphonates (ANPs) are a promising class of antimalarial therapeutic drug leads that exhibit a wide variety of Ki values for Plasmodium falciparum (Pf) and human hypoxanthine-guanine-(xanthine) phosphoribosyltransferases [HG(X)PRTs]. A novel series of ANPs, analogues of previously reported 2-(phosphonoethoxy)ethyl (PEE) and (R,S)-3-hydroxy-2-(phosphonomethoxy)propyl (HPMP) derivatives, were designed and synthesized to evaluate their ability to act as inhibitors of these enzymes and to extend our ongoing antimalarial structure-activity relationship studies. In this series, (S)-3-hydroxy-2-(phosphonoethoxy)propyl (HPEP), (S)-2-(phosphonomethoxy)propanoic acid (CPME), or (S)-2-(phosphonoethoxy)propanoic acid (CPEE) are the acyclic moieties. Of this group, (S)-3-hydroxy-2-(phosphonoethoxy)propylguanine (HPEPG) exhibits the highest potency for PfHGXPRT, with a Ki value of 0.1 μM and a Ki value for human HGPRT of 0.6 μM. The crystal structures of HPEPG and HPEPHx (where Hx=hypoxanthine) in complex with human HGPRT were obtained, showing specific interactions with active site residues. Prodrugs for the HPEP and CPEE analogues were synthesized and tested for in vitro antimalarial activity. The lowest IC50 value (22 μM) in a chloroquine-resistant strain was observed for the bis-amidate prodrug of HPEPG.

• MeSH
• antimalarika chemická syntéza   chemie   farmakologie   MeSH
• hypoxanthinfosforibosyltransferasa antagonisté a inhibitory   metabolismus   MeSH
• inhibitory enzymů chemická syntéza   chemie   farmakologie   MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• nukleosidy chemická syntéza   chemie   farmakologie   MeSH
• organofosfonáty chemická syntéza   chemie   farmakologie   MeSH
• parazitické testy citlivosti MeSH
• Plasmodium falciparum účinky léků   enzymologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Acyclic nucleoside phosphonates (ANPs) that contain a 6-oxopurine base are good inhibitors of the human and Plasmodium falciparum 6-oxopurine phosphoribosyltransferases (PRTs), key enzymes of the purine salvage pathway. Chemical modifications, based on the crystal structures of several inhibitors in complex with the human PRTase, led to the design of a new class of inhibitors--the aza-ANPs. Because of the negative charges of the phosphonic acid moiety, their ability to cross cell membranes is, however, limited. Thus, phosphoramidate prodrugs of the aza-ANPs were prepared to improve permeability. These prodrugs arrest parasitemia with IC50 values in the micromolar range against Plasmodium falciparum-infected erythrocyte cultures (both chloroquine-sensitive and chloroquine-resistant Pf strains). The prodrugs exhibit low cytotoxicity in several human cell lines. Thus, they fulfill two essential criteria to qualify them as promising antimalarial drug leads.

• MeSH
• antimalarika metabolismus   MeSH
• hypoxanthinfosforibosyltransferasa antagonisté a inhibitory   MeSH
• inhibitory enzymů metabolismus   MeSH
• lidé MeSH
• malárie farmakoterapie   MeSH
• molekulární modely MeSH
• nukleotidy metabolismus   MeSH
• organofosfonáty chemie   MeSH
• prekurzory léčiv MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH