Synthesis of 2′,3′-Dideoxynucleoside Phosphoesters Using H-Phosphonate Chemistry on Soluble Polymer Support

International audiencePhosphorylation of ddC and 3TC was efficiently performed on soluble poly(ethylene glycol) support. The corresponding 5′-monophosphate derivatives were obtained by oxidation of the support bound 5′-H-phosphonate intermediates. Then, di- and triphosphorylations were carried out using a carbonyldiimidazole activation step followed by nucleophilic substitution with suitable phosphate salts. Trivalent phosphorus chemistry appeared as a good alternative for monophosphate synthesis of acid-sensitive 2′,3′-dideoxynucleosides

Insights into the Soluble PEG-Supported Synthesis of Cytosine-Containing Nucleoside 5′-Mono-, Di-, and Triphosphates

International audienceNucleoside phosphoesters (nucleotides) have crucial roles in a large variety of biological processes including nucleic acid biosynthesis and their corresponding analogues are extensively used as biological tools. Herein, we describe a new and efficient synthetic procedure involving polyethylene glycol (PEG) as soluble support and regioselective mono-, di-, and triphosphorylation steps. Applied to natural and synthetic cytosine containing nucleosides, this methodology allowed the preparation of various phosphorylated forms in high yields and good purity

Plasmodium Purine Metabolism and Its Inhibition by Nucleoside and Nucleotide Analogues

International audienceMalaria still affects around 200 million people and is responsible for more than 400,000 deaths per year, mostly children in subequatorial areas. This disease is caused by parasites of the Plasmodium genus. Only a few WHO-recommended treatments are available to prevent or cure plasmodial infections, but genetic mutations in the causal parasites have led to onset of resistance against all commercial antimalarial drugs. New drugs and targets are being investigated to cope with this emerging problem, including enzymes belonging to the main metabolic pathways, while nucleoside and nucleotide analogues are also a promising class of potential drugs. This review highlights the main metabolic pathways targeted for the development of potential antiplasmodial therapies based on nucleos(t)ide analogues, as well as the different series of purine-containing nucleoside and nucleotide derivatives designed to inhibit Plasmodium falciparum purine metabolism.

Structural Insights into the Inhibition of Cytosolic 5′-Nucleotidase II (cN-II) by Ribonucleoside 5′-Monophosphate Analogues

Cytosolic 5′-nucleotidase II (cN-II) regulates the intracellular nucleotide pools within the cell by catalyzing the dephosphorylation of 6-hydroxypurine nucleoside 5′-monophosphates. Beside this physiological function, high level of cN-II expression is correlated with abnormal patient outcome when treated with cytotoxic nucleoside analogues. To identify its specific role in the resistance phenomenon observed during cancer therapy, we screened a particular class of chemical compounds, namely ribonucleoside phosphonates to predict them as potential cN-II inhibitors. These compounds incorporate a chemically and enzymatically stable phosphorus-carbon linkage instead of a regular phosphoester bond. Amongst them, six compounds were predicted as better ligands than the natural substrate of cN-II, inosine 5′-monophosphate (IMP). The study of purine and pyrimidine containing analogues and the introduction of chemical modifications within the phosphonate chain has allowed us to define general rules governing the theoretical affinity of such ligands. The binding strength of these compounds was scrutinized in silico and explained by an impressive number of van der Waals contacts, highlighting the decisive role of three cN-II residues that are Phe 157, His 209 and Tyr 210. Docking predictions were confirmed by experimental measurements of the nucleotidase activity in the presence of the three best available phosphonate analogues. These compounds were shown to induce a total inhibition of the cN-II activity at 2 mM. Altogether, this study emphasizes the importance of the non-hydrolysable phosphonate bond in the design of new competitive cN-II inhibitors and the crucial hydrophobic stacking promoted by three protein residues

New Series of Acyclic Nucleoside Phosphonates as Potent Antimalarials

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New Series of Acyclic Nucleoside Phosphonates as Potent Antimalarials

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Synthèse et étude d'inhibiteurs potentiels de la 5'-nucléotidase cytosolique II (Analogues de mononucléotides en série phosphonate et leurs prodrogues)

Les analogues de nucléosides représentent une famille d'agents thérapeutiques très largement utilisée en chimiothérapie anticancéreuse. Cependant, des phénomènes de résistance d'origine multifactorielle apparaissent et il semble que la surexpression d'une enzyme, la 5'-nucléotidase cytosolique II (cN-II) soit un des facteurs impliqués. Nous nous sommes donc intéressés à son étude ainsi qu'à la synthèse d'inhibiteurs potentiels de type analogues de nucléosides phosphonates modifiés en position á/â. Ce manuscrit rapporte dans un premier temps aux particularités de la cN-II puis l'élaboration d'un test d'évaluation efficace. Suite à la mise en oeuvre de différentes techniques d'enzymologie, le dosage colorimétrique au vert de Malachite a été retenu. Le second chapitre décrit l'optimisation et la synthèse d'analogues de type alcyne phosphonate selon deux approches puis l'évaluation de leur capacité à inhiber la cN-II. La troisième partie traite d'une nouvelle approche synthétique de nucléosides phosphonates â-modifiés via l'utilisation d'un intermédiaire â-cétophosphonate. Des dérivés de type â-hydroxyphosphonate et â-oximephosphonate ont été obtenus et testés. Enfin, la mise au point d'une stratégie inédite pour la synthèse de prodrogues bisSATE de â-hydroxyphosphonates (têtes de série) via l'ouverture d'un époxyde par un phosphite a été réaliséeNucleosidic analogs are widely used as therapeutic agents in antitumoral chemotherapy. However, cellular resistance appears in a multifactorial manner and it seems that overexpression of an enzyme, the 5'-cytosolic nucleotidase (cN-II) may be involved in this phenomenon. We were interested in the study of this enzyme in order to design and synthesize potential inhibitors belonging to the family of nucleoside analogs in the á/â-modified phosphonate series. First, we reviewed literature data on the nucleotidase family and particularly on cN-II, then we engaged in the setting up of an evaluation test using various enzymological techniques. Thus, green malachite colorimetric assay was successful and efficient for the evaluation of the inhibitor capacity of our different derivatives. Secondly, we described the optimisation and the synthesis of alkynylphosphonate nucleoside analogs using two different pathways. These latter were tested and the cytosine analog inhibited 65% of the enzyme activity. Then, a new synthetic approach to â-modified nucleoside phosphonates was reported using a â-ketophosphonate as key intermediate. â-hydroxyphosphonate et â-oximephosphonate analogs were obtained and inhibited 50% of the enzyme activity. Finally, a novel prodrug stategy for the synthesis of bisSATE ester of â-hydroxyphosphonates (our leading series) was designed and developpedMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Nouveaux anti-viraux pour le traitement des affections associées aux virus émergents

Dans un premier chapitre, nous avons présenté un historique succinct de la chimiothérapie antivirale et l'utilisation d'analogues nucléos(t)idiques. Nous nous sommes focalisés en particulier sur les nucléosides phosphonates acycliques (ANP) en tant qu'antiviraux potentiels. Dans un second chapitre, nous avons décrit la synthèse de b-céto, b-hydroxylamino et b-O-(benzyl)hydroxylamino ANP dérivés de l'adénine et de la cytosine. Les isomèrs (R) et (S)-b-hydroxy-ANP ont été préparés par dédoublement du racémique correspondant avec le (S)-MPA et l'attribution des configurations absolues a été effectuée par RMN et calculs de modélisation moléculaire. Nous avons aussi développé une méthodologie de synthèse de b-azido-ANP, ces derniers étant utilisés pour la préparation de b-amino-ANP par hydrogénation catalytique. Dans un troisième chapitre, nous avons présenté la synthèse des 2H-azirine et cis-aziridne-ANP et examiné lʹ ouverture de cycle comme voie d'accès à des ANP a,b-fonctionnalisés. Les propriétés biologiques de ces nouveaux ANP ont été évaluées en culture cellulaire sur un certain nombre de virus à ADN et ARN.In the first chapter, we presented a brief history of antiviral chemotherapy and use of nucleos(t)ide analogues, especially acyclic nucleoside phosphonates as potential antiviral agents. In the chapter-II we have successfully synthesized Â-keto, Â-hydroxylamino and Â-O-(benzyl)hydroxylamino ANPs of adenine and cytosine derivatives. Then (R) and (S)- Â-hydroxy-ANPs were prepared via chiral resolution of racemic Â-hydroxy-ANPs with (S)-MPA and assignment of absolute configuration was achieved using NMR and molecular modeling studies. We also developed a methodology for the synthesis of Â-azido-ANPs and those were used for the preparation of Â-amino-ANPs by catalytic hydrogenation. In third chapter, we synthesized 2H-azirine and cis-aziridine-ANPs and explored their ring opening to functionalized Á, Â-ANPs. The novel ANPs obtained during this study were evaluated for their inhibitory effect on a number of DNA and RNA viruses in cell culture experiments.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

One-pot synthesis of nucleotides in water-medium

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Synthesis of N-methylene phosphonate aziridines: Reaction scope and mechanistic insights

International audienceA series of N-carbamoyl aziridines has been treated by diethyl phosphite in presence of n-BuLi to afford α-methylene phosphonate aziridines in modest yields. The study of the reaction's scopes and the analysis of byproducts indicated that this transformation proceeds via a unique mechanism. The mechanism that produces the α-methylene phosphonate relies in the use of BuLi, where both the lithium ion and then the presence of the nucleophilic butyl is essential. In addition, the nature of the final compound, either α-methylene phosphonate or α-methylene-gem-bisphosphonate derivatives containing an aziridine motif, is highly dependent on the nature of the base used