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

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

Asymmetric Synthesis of New β-Lactam Lipopeptides as Bacterial Signal Peptidase I Inhibitors

International audienceThe transmembrane bacterial enzyme, signal peptidase I, is recognized as being a promising target for reducing the emergence of drug resistance. The asymmetric synthesis and the biological evaluation of original β-lactam lipopeptides have been performed to discover potent signal peptidase inhibitors. The importance of the azetidinone motif of these lipopeptides has been demonstrated and can serve as a starting point to exploit and improve the reactivity of the β-lactam in peptidomimetics

Unconventional surface plasmon resonance signals reveal quantitative inhibition of transcriptional repressor EthR by synthetic ligands

International audienceEthR is a mycobacterial repressor that limits the bioactivation of ethionamide, a commonly used anti-tuberculosis second-line drug. Several efforts have been deployed to identify EthR inhibitors abolishing the DNA-binding activity of the repressor. This led to the demonstration that stimulating the bioactivation of ETH through EthR inhibition could be an alternative way to fight Mycobacterium tuberculosis. We propose a new SPR methodology to study the affinity between inhibitors and EthR. Interestingly, the binding between inhibitors and immobilized EthR produced a dose dependent negative SPR signal. We demonstrated that this signal reveals the affinity of the small molecules for the repressor. The affinity constants (KD) correlated with their capacity to inhibit the binding of EthR to DNA. We hypothesize that conformational changes of EthR during ligand interaction could be responsible for this SPR signal. Practically, this unconventional result open perspectives to the development of SPR assay that would at the same time tough on the structural changes of the target upon binding with an inhibitor and on the binding constant of this interaction

Synthèse supportée et dosage par LC-MS-MS en milieu biologique de nucléotides de la cytidine et analogues

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Omega-3 polyunsaturated lipophenols, how and why?

International audiencePolyphenols and n-3 polyunsaturated fatty acids (PUFAs) are two classes of natural compounds, which have been highlighted in epidemiological studies for their health benefits. The biological activities of those two families of metabolites on oxidation, inflammation, cancer, cardiovascular and degenerative diseases have been reported in vitro and in vivo. On the other hand, chemical bonding between the two structures leading to n-3 lipophenol derivatives (or phenolipids) has been studied in numerous works over the last decade, and some examples could also be found from natural sources. Interest in lipophilization of phenolic structures is various and depends on the domain of interest: in food industry, the development of lipidic antioxidants could be performed to protect lipidic food matrix from oxidation. Whereas, on pharmaceutical purpose, increasing the lipophilicity of polar phenolic drugs could be performed to improve their pharmacological profile. Moreover, combining both therapeutic aspects of n-3 PUFAs and of polyphenols in a single lipophenolic molecule could also be envisaged. An overview of the synthesis and of the natural sources of n-3 lipophenols is presented here, in addition to their biological activities which point out in several cases the benefit of the conjugated derivatives

New Lipophenol Antioxidants Reduce Oxidative Damage in Retina Pigment Epithelial Cells

International audienceAge-related macular degeneration (AMD) is a multifactorial pathology and its progression is exacerbated by oxidative stress. Oxidation and photo-oxidation reactions modify lipids in retinal cells, contribute to tissue injury, and lead to the formation of toxic adducts. In particular, autofluorescent pigments such as N-retinylidene-N-retinylethanolamine (A2E) accumulate as lipofuscin in retinal pigment epithelial cells, contribute to the production of additional reactive oxygen species (ROS), and lead to cell degeneration. In an effort to develop efficient antioxidants to reduce damage caused by lipid oxidation, various natural polyphenols were structurally modified to increase their lipophilicity (lipophenols). In this study, resveratrol, phloroglucinol, quercetin and catechin were selected and conjugated to various polyunsaturated fatty acids (PUFAs) using classical chemical strategies or enzymatic reactions. After screening for cytotoxicity, the capacity of the synthesized lipophenols to reduce ROS production was evaluated in ARPE-19 cells subjected to H 2 O 2 treatment using a dichlorofluorescein diacetate probe. The positions of the PUFA on the polyphenol core appear to influence the antioxidant effect. In addition, two lipophenolic quercetin derivatives were evaluated to highlight their potency in protecting ARPE-19 cells against A2E photo-oxidation toxicity. Quercetin conjugated to linoleic or α-linolenic acid were promising lipophilic antioxidants, as they protected ARPE-19 cells from A2E-induced cell death more effectively than the parent polyphenol, quercetin

Tuberculosis: The drug development pipeline at a glance

International audienceTuberculosis is a major disease causing every year 1.8 million deaths worldwide and represents the leading cause of mortality resulting from a bacterial infection. Introduction in the 60's of first-line drug regimen resulted in the control of the disease and TB was perceived as defeating. However, since the progression of HIV leading to co-infection with AIDS and the emergence of drug resistant strains, the need of new anti-tuberculosis drugs was not overstated. However in the past 40 years any new molecule did succeed in reaching the market. Today, the pipeline of potential new treatments has been fulfilled with several compounds in clinical trials or preclinical development with promising activities against sensitive and resistant Mycobacterium tuberculosis strains. Compounds as gatifloxacin, moxifloxacin, metronidazole or linezolid already used against other bacterial infections are currently evaluated in clinical phases 2 or 3 for treating tuberculosis. In addition, analogues of known TB drugs (PA-824, OPC-67683, PNU-100480, AZD5847, SQ609, SQ109, DC-159a) and new chemical entities (TMC207, BTZ043, DNB1, BDM31343) are under development. In this review, we report the chemical synthesis, mode of action when known, in vitro and in vivo activities and clinical data of all current small molecules targeting tuberculosis

Magnesium(II)-coordinated Claisen rearrangement: a direct approach towards ulosonic acid derivatives

International audienceUnprecedented magnesium dihalide-catalysed Claisen rearrangement of 2-alkoxycarbonyl allyl vinyl ethers derived from α-chloroglycidic esters is reported in the glucidic series. A first application of this reaction concerns the stereoselective construction of a disaccharide analogue including a galactosyl and an ulosonic isopropyl ester moieties

Deciphering the physiological role of serine enzymes involved in mycobacterial lipid metabolism using activity-based protein profiling

International audienceThe importance of lipids as key players in the physiology, life cycle and virulence of mycobacterial-related diseases, such as tuberculosis caused by the pathogenic bacteria M. tuberculosis, has been well established. These lipids participate in the host-pathogen crosstalk and play crucial roles in key cellular processes, including bacterial growth, virulence (reactivation and propagation), dormancy, cell wall biosynthesis, as well as in lipid storage and degradation. In this context, activity-based protein profiling has emerged as a powerful chemoproteomic strategy to identify and characterize the mycobacterial enzymes responsible for the synthesis and degradation of these lipids. Herein, we highlight the use of serine enzyme inhibitors as activity-based probes for the identification and characterization of the functional state of mycobacterial serine enzymes within the bacteria