Nos tutelles

CNRS

Nos partenaires

Rechercher







Accueil > La recherche > Thematiques > Chimie

Nucléosides & Effecteurs Phosphorylés

par Bergogne Marie-Christine - publié le , mis à jour le

Equipe 3 : Nucléosides & Effecteurs Phosphorylés

Résumé

Les activités de l’équipe « Nucléosides & Effecteurs Phosphorylés », se situent à l’interface chimie/biologie. Les thèmes développés concernent la recherche de nouvelles cibles thérapeutiques et de modes d’action inédits dans le traitement de cancers ou d’infections pathogènes (virus, parasites). Ces aspects impliquent notamment la recherche de nouvelles méthodologies de synthèse dans le domaine de la chimie des constituants des acides nucléiques (hétérocycles, nucléosides et nucléotides) comme la mise en œuvre d’approches de ciblage et de vectorisation. Parallèlement, des méthodologies analytiques se substituant à l’utilisation de produits radiomarqués en pharmacologie cellulaire et métabolomique sont développées. L’ensemble de ces activités de recherche est associé depuis de nombreuses années à des partenariats industriels.

Major topics

New targets for the treatment of cancers and infectious diseases
Prodrug strategies. Site-specific activation or site-directed drug delivery
Analytical methodologies in biological media. Metabolomic approach
Nucleosides and nucleotides as therapeutic agents
Substrates/inhibitors of enzymes involved in the nucleic acid biosynthesis

Keywords

Therapeutics, Chemotherapy, Cancer and Infectious Diseases
Nucleoside and Nucleotide Analogues, Prodrugs
Fragment-Based Drug Design (FBDD), Soluble-Supported Synthesis
Sugar, Heterocycles, Phosphorus Chemistry
UPLC, LC-MS-MS, Metabolomics

Research Projects

1. New therapeutic targets & New modes of action.

Owing to the fundamental roles of nucleosides and nucleotides in cellular life, the design of analogues constitutes an attractive approach in chemotherapy, especially for cancer and viral infections treatments. Usually, their therapeutic efficacy requires a complex metabolisation into their corresponding phosphorylated (nucleotides) forms involving kinases and/or other activating enzymes virally encoded or naturally occurring in cells ; thus the resulting nucleoside 5’-triphosphates act as substrates and/or chain terminators of DNA/RNA synthesis.

1.1. Cancer.
Cytosolic 5’-nucleotidase II (cN-II).
Our main objective is to design and to study inhibitors of this enzyme to better understand its role in the nucleic acids biosynthesis, and later on to be able to increase the efficiency of cytotoxic nucleoside analogues currently used in clinic. On the basis of our previous studies related to this research project, the rational design of cN‐II inhibitors, such as allosteric effectors and substrate analogues is performed using molecular modelling, x‐ray crystallography and a novel B : heterocycles NMR fragment based drug‐design approach. In the meantime, we also study : (i) the specificity of our derivatives towards the other human 5’‐nucleotidases ; (ii) the implication of cN‐II in the activation and/or the catabolism of therapeutic nucleoside analogues ; (iii) the impact of cN‐II inhibition on the cellular metabolism of natural nucleotides through the quantification of related pools (LC/MS/MS methods).

  • Financial supports : « cN-II Focus » ANR (2012-2014) ; ARC (2014-2015) ; USTH (2013-2016, PhD).

1.2. Viral infections.
Conformationally constrained nucleosides. The ambitious objective of this research program is to elaborate a new generation of antiviral nucleosides analogues having structural and conformational parameters to confer a mode of action different than that of compounds currently used in antiviral chemotherapy.
Novel nucleos(t)ide analogues. In parallel, we pursued our efforts towards the synthesis of carbocyclic nucleosides, such as derivatives of the neplanocin family. Besides their potentiality as anti-HIV compounds, this type of compounds may also interact with other potential targets, such as cellular SAH hydrolase and in this case their mechanism of action will not be dependant on cellular metabolism. In this respect, we have reported the first enantioselective synthesis of (-)-neplanocin F to re-evaluate its antiviral activities against emerging pathogens. We opted for a strategy involving the use of a cyclopentenone precursor.

  • Financial supports : Infectiopôle Sud IHU Méditerrannée Infection (2013-2016, PhD) ; UM Conseil Scientifique (2014-2015).

1.3. Malaria.
Choline transport and phospholipids biosynthesis. Phospholipid biosynthesis in Plasmodium is an original target for a novel chemotherapeutic approach because of its crucial importance considering the high degree of membrane parasite biogenesis. Indeed, phospholipid metabolism is absent from normal mature human erythrocytes, whereas after malarial infection, the erythrocyte phospholipid content dramatically increases. In the de novo PC pathway, the main plasmodial phospholipid precursor, choline, first enters infected erythrocytes by a transport-mediated process. In relation to our previous works carried out within a European network, we are involved in the design, the synthesis and the study of potential inhibitors of the phospholipids biosynthesis in Plasmodium.

2. New synthetic methodologies
Supported synthesis.

Owing to the crucial role of nucleotides in a variety of biological processes, their corresponding polyphosphorylated analogues constitute useful biological tools. However, their classical solution syntheses usually led to complex crude mixtures that require tedious purification steps, often including preparative HPLC. Thus, fastidious and long purification procedures induce a decrease in yields and open the way to the development of new methodologies. We have settled up a new approach for the supported synthesis of nucleoside phosphorylated forms using polyethylene glycol (PEG) as soluble support. This methodology allowed the preparation of various nucleotides in high yields and good purity. Compared to classical solution procedures, our methodology is efficient, scalable, easy to handle and led to reduce the overall process-time. Our innovative methodology using soluble support for the synthesis of (poly)phosphorylated entities is currently developed and extended to obtain several libraries of nucleotide derivatives. In this respect, we started a project related to the study of the mechanisms involved in phosphoantigen recognition by some specific lymphocytes, especially in the course of the immune response to viral infections.

  • Financial supports : FRM (2013-2015) ; UM (2014-2017, PhD).

3. Site-specific activation or site-directed delivery
Targeted delivery of nanoparticles for scintigraphy.

Coordination polymers’ nanoparticles and particularly cyano-bridged coordination polymers, with Prussian blue (PB) being one of the best-known compound of this family, are the object of special attention from the scientific community working in the field of metal-based nanoparticles. More specifically, in recent years, the use of these nanoparticles is increasingly considered for applications in the biomedical field. The primary objective of this project is to elaborate new multi-functional nanoparticle systems. Such constructs will be considered as versatile and adaptable platforms that can carry imaging tools and site-directed their delivery by passive and/or active targeting. These nanoparticles are functionalized with an organic surrounding for their delivery in the vicinity of tumour cells and/or solid tumours.

4. Analytical tools for chemotherapy improvement
4.1. Cancer
A major challenge in oncology is the selection of the most effective chemotherapeutic agents for individual patients, while the administration of ineffective chemotherapy increases mortality and decreases quality of life in cancer patients. This emphasizes the need to evaluate every patient’s probability of responding to each chemotherapeutic agent and limiting the agents used to those most likely to be effective. In this context, we develop analytical methods leading to the determination of intracellular concentrations of endogenous nucleosides/nucleotides and cytotoxic analogues. Quantification of selected nucleosides and the corresponding nucleotides constitutes an analytical challenge since it requires both highest sensitivity and selectivity to detect, in a complex biological matrix, small amounts of analytes present among the myriad of endogenous derivatives. Based on the development of a priori simple tools, our current projects focus on : (i) the study of the cellular impact induced by deregulation of physiological nucleoside/nucleotide pools ; (ii) identify best-tolerated and most effective treatment regimen using cytotoxic nucleosides ; (iii) predict the emergence of resistance to this therapeutic class.

  • Financial support : ARC (2014-2015).

4.2. Malaria
Our multi-disciplinary project on malaria (1.3) is associated with a metabolomic approach and therefore we develop LC-MS/MS methods to quantify the intracellular concentration of some metabolites. Such integrated program coupling synthesis and analysis has the purpose of : (i) identifying the respective contributions of the different metabolic pathways and understanding their regulation in the parasite development ; (ii) within these pathways, identifying limiting steps as potential targets for chemotherapy ; (iii) studying pharmacological effects of potential drugs.

  • Financial supports : Infectiopôle Sud IHU Méditerranée Infection (2012-2014, PhD) ; EVIMalaR FP7 Network of Excellence funded by the European Commission (2010-2015).

Voir en ligne : L’équipe Nucléosides & Effecteurs Phosphorylés