11 research outputs found
Synthesis of trehalose-based chemical tools for the study of the mycobacterial membrane
Corynebacteriales including the causative agent of many diseases such as tuberculosis are known to be extremely resistant against external stress as well as to antibiotic treatments which is believed to be related to the singular architecture of their mycomembrane. Over the last decades, both bioorthogonal chemical reporters and fluorescent probes for the metabolic labeling of bacterial cell glycans were developed including several trehalose-based probes to study the dynamics of mycomembrane components. This review presents an exhaustive view on the reported syntheses of trehalose-based probes enabling the study of the mycomembrane biogenesis
2âČ-Modified thymidines with bioorthogonal cyclopropene or sydnone as building blocks for copper-free postsynthetic functionalization of chemically synthesized oligonucleotides
International audienceThe development of facile methods for conjugating relevant probes, ligands, or delivery agents onto oligonucleotides (ONs) is highly desirable both for fundamental studies in chemical biology and for improving the pharmacology of ONs in medicinal chemistry. Numerous efforts have been focused on the introduction of bioorthogonal groups onto phosphoramidite building blocks, allowing the controlled chemical synthesis of reactive ONs for postsynthetic modifications. Among these building blocks, alkyne, cyclooctynes, trans-cyclooctene, and norbornene have been proved to be compatible with automated solid-phase chemistry. Herein, we present the development of novel 2âČ-functionalized nucleoside phosphoramidite monomers comprising bioorthogonal methylcyclopropene or sydnone moieties and their introduction for the first time to ON solid-phase synthesis. Traceless ON postsynthetic modifications with reactive complementary probes were successfully achieved through either inverse electron-demand DielsâAlder (iEDDA) reactions or strain-promoted sydnoneâalkyne cycloaddition (SPSAC). These results expand the set of bioorthogonal phosphoramidite building blocks to generate ONs for postsynthetic labeling
Sequence-Specific Base Pair Mimics Are Efficient Topoisomerase IB Inhibitors
Topoisomerase IB controls DNA topology by cleaving DNA
transiently. This property is used by inhibitors, such as camptothecin,
that stabilize, by inhibiting the religation step, the cleavage complex,
in which the enzyme is covalently attached to the 3âČ-phosphate
of the cleaved DNA strand. These drugs are used in clinics as antitumor
agents. Because three-dimensional structural studies have shown that
camptothecin derivatives act as base pair mimics and intercalate between
two base pairs in the ternary DNAâtopoisomeraseâinhibitor
complex, we hypothesized that base pairs mimics could act like campthotecin
and inhibit the religation reaction after the formation of the topoisomerase
IâDNA cleavage complex. We show here that three base pair mimics,
nucleobases analogues of the aminophenyl-thiazole family, once targeted
specifically to a DNA sequence were potent topoisomerase IB inhibitors.
The targeting was achieved through covalent linkage to a sequence-specific
DNA ligand, a triplex-forming oligonucleotide, and was necessary to
position and keep the nucleobase analogue in the cleavage complex.
In the absence of triplex formation, only a weak binding to the DNA
and topoisomerase I-mediated DNA cleavage was observed. The three
compounds were equally active once conjugated, implying that the intercalation
of the nucleobase upon triplex formation is the essential feature
for the inhibition activity
Borinic Acids as New Fast-Responsive Triggers for Hydrogen Peroxide Detection.
Detection of hydrogen peroxide (H2O2), which is responsible for numerous damages when overproduced, is crucial for a better understanding of H2O2-mediated signalling in physiological and pathological processes. For this purpose, variousâoff-onâ small fluorescent probes relying on a boronate trigger have been developed. However, they suffer from low kinetics and do not allow forH2O2-detectionwith a short response time. Therefore, more reactive sensors are still awaited. To address this issue, we have successfully developed the first generation of borinic-based fluorescent probes containing a coumarin-scaffold. We determined the in vitrokinetic constants of the probe toward H2O2-promotedoxidation. We measured 1.9x104m-1.s-1as a second order rate constant, which is 10 000 faster than its boronic counterpart (1.8 m-1.s-1). This remarkable reactivity was also effective in a cellular context, rendering the borinic trigger an advantageous new tool for H2O2detection
Identification of Novel Inhibitors of DNA Methylation by Screening of a Chemical Library
In order to discover new inhibitors of the DNA methyltransferase
3A/3L complex, we used a medium-throughput nonradioactive screen on
a random collection of 1120 small organic compounds. After a primary
hit detection against DNA methylation activity of the murine Dnmt3A/3L
catalytic complex, we further evaluated the EC<sub>50</sub> of the
12 most potent hits as well as their cytotoxicity on DU145 prostate
cancer cultured cells. Interestingly, most of the inhibitors showed
low micromolar activities and little cytotoxicity. Dichlone, a small
halogenated naphthoquinone, classically used as pesticide and fungicide,
showed the lowest EC<sub>50</sub> at 460 nM. We briefly assessed the
selectivity of a subset of our new inhibitors against hDNMT1 and bacterial
Dnmts, including M. SssI and EcoDam, and the protein lysine methyltransferase
PKMT G9a and the mode of inhibition. Globally, the tested molecules
showed a clear preference for the DNA methyltransferases, but poor
selectivity among them. Two molecules including Dichlone efficiently
reactivated YFP gene expression in a stable HEK293 cell line by promoter
demethylation. Their efficacy was comparable to the DNMT inhibitor
of reference 5-azacytidine
Synthesis and Evaluation of Analogues of <i>N</i>âPhthaloylâlâtryptophan (RG108) as Inhibitors of DNA Methyltransferase 1
DNA
methyltransferases (DNMT) are promising drug targets in cancer provided
that new, more specific, and chemically stable inhibitors are discovered.
Among the non-nucleoside DNMT inhibitors, <i>N</i>-phthaloyl-l-tryptophan <b>1</b> (RG108) was first identified as
inhibitor of DNMT1. Here, <b>1</b> analogues were synthesized
to understand its interaction with DNMT. The indole, carboxylate,
and phthalimide moieties were modified. Homologated and conformationally
constrained analogues were prepared. The latter were synthesized from
prolinoÂhomotryptophan derivatives through a methodology based
aminoâzincâeneâenolate cyclization. All compounds
were tested for their ability to inhibit DNMT1 in vitro. Among them,
constrained compounds <b>16</b>â<b>18</b> and NPys
derivatives <b>10</b>â<b>11</b> were found to be
at least 10-fold more potent
than the reference compound. The cytotoxicity on the tumor DU145 cell
line of the most potent inhibitors was correlated to their inhibitory
potency. Finally, docking studies were conducted in order to understand
their binding mode. This study provides insights for the design of
the next-generation of DNMT inhibitors