Development of new methods of synthesis in fluorine chemistry and preparation of bioactive molecules

Ce travail s'inscrit dans le cadre d'un programme de collaboration entre l'Université Libanaise et l'université de Rennes 1. La thèse est divisée en deux parties :Chimie du fluor : synthèse de nouveaux hétérocycles portant des chaînes latérales fluorées ; chimie médicinale : recherche de nouvelles molécules à visées anticancéreuses. La première partie se compose de trois chapitres : dans le premier chapitre, des intermédiaires de synthèse de type énones fluorées ont été synthétisés par une voie originale, et leur réactivité en cyclocondensation a été étudiée pour obtenir de pyrazolines et de pyrrolines avec des chaînes latérales fluorés. Dans le deuxième chapitre, nous nous sommes intéressés à la préparation d'hétérocycles de type chroman-4-one, en utilisant les intermédiaires difluorés précédents. Dans le dernier chapitre, la réaction de Kinugasa a été appliquée pour la première fois sur des dérivés propargyliques gem-difluorés. Cette réaction nous a permis de découvrir une voie de synthèse originale à une famille de composés nouveaux, à savoir des exoalkylidène b-lactames portant un fluor en position vinylique. Dans la seconde partie, notre objectif était de restaurer les propriétés apoptotiques au sein des cellules cancéreuses afin d'obtenir de nouveaux composés à activité antitumorale. A partir de données obtenues par modélisation moléculaire, nous avons fait le design de plusieurs séries d'analogues d'un inhibiteur connu (MIM-1) de la protéine anti-apoptotique Mcl-1. Plus de 40 analogues ont été préparés et testés sur trois variétés de cellules cancéreuses (sein, ovaire et mélanome). Un certain nombre de ces composés ont présenté des activités prometteuses dans ces différents domaines.This work is a part of a collaboration program between Lebanese University and University of Rennes 1. The thesis is divided into two parts: fluorine chemistryv : synthesis of new heterocycles bearing fluorine-containing side chains ; medicinal chemistry : research towards new anticancer molecules. The first part consists of three chapters: in the first chapter, gem-difluoro enone-type intermediates were synthesized through a new route and their cyclocondensation reactions were studied to get pyrazolines and pyrrolines with fluorinated side chains. In the second chapter, type-chroman-4-one heterocycles were prepared using the previous difluorinated intermediates. In the third chapter, the Kinugasa reaction was applied for the first time on gem-difluoro propargylic derivatives. This reaction has allowed us to discover a pathway to a new family of molecules, the fluorine-containing exoalkylidene β-lactames. In the second part, our goal was to reinduce the proapoptotic properties in cancer cells in order to obtain new antitumor compounds. Starting from data obtained through molecular modeling studies, we designed and prepared several series of analogs for a known inhibitor (MIM-1) of the anti-apoptotic protein Mcl-1. Over 40 analogs have been synthetized and screened towards three types of cancer cells (breast, ovarian and melanoma). Some of these derivatives have demonstrated promising data in these areas

A new direct synthesis of α-methylene- and α-alkylidene-β-lactams

International audienceThe Kinugasa reaction applied to alkynes bearing a nucleofuge in propargylic position affords directly, and in fair yields, α-methylene- or α-alkylidene- β-lactam

Synthesis of Chroman-4-ones with gem-Difluoroalkyl Side Chains in Position 2

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Synthesis of enones, pyrazolines and pyrrolines with gem-difluoroalkyl side chains

International audienceStarting from easily accessible gem-difluoropropargylic derivatives, a DBU-mediated isomerisation affords enones in fair yields with a gem-difluoroalkyl chain. These derivatives were used to prepare pyrazolines and pyrrolines with the desired gem-difluoroalkyl side chain by cyclocondensations in good yields and with excellent stereoselectivity. A one-pot process was also successfully developed for these sequential reactions. By carrying out various types of Pd-catalyzed coupling reactions for compounds with a p-bromophenyl substituent a route to focused chemical libraries was demonstrated

A thiosemicarbazone derivative induces triple negative breast cancer cell apoptosis possible role of miRNA-125a-5p and miRNA-181a-5p

International audienceBackground - Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Triple negative breast cancer (TNBC), lacking the expression of estrogen, progesterone and HER2 receptors, has an aggressive clinical phenotype and is susceptible to chemotherapy but not to hormonal or targeted immunotherapy. In an attempt to identify potent and selective anti-TNBC agents, a set of thiosemicarbazone derivatives were screened for their cytotoxic activity against MDA-MB 231 breast cancer cell line. Methods - MTT assay was used to examine cell viability. P53 phosphorylation status, poly (ADP-ribose) polymerase (PARP) cleavage as well as Bcl2 and Bax protein levels were assessed by Western blot. Quantitative Real Time-PCR was carried out to characterize miRNAs expression levels. Results - Combining Cisplatin + thiosemicarbazone compound 4 showed potent anti-TNBC potential. Cisplatin + compound 4 significantly enhanced p53 phosphorylation, induced Bax amount, reduced Bcl2 protein levels, enhanced PARP cleavage and modulated miRNAs expression profile in TNBCs, with a particular overexpression of miR-125a-5p and miR-181a-5p. Intriguingly, miR-125a-5p and miR-181a-5p could significantly downregulate BCL2 expression by binding to their target sites in the 3'UTR. Conclusions - Collectively, our results demonstrate an anti-TNBC activity of Cisplatin + thiosemicarbazone compound 4 combination mediated via induction of apoptosis

Structural revision of the Mcl-1 inhibitor MIM1: synthesis and biological studies on ovarian cancer cells with evaluation of designed analogues

International audienceIn the area of cancer research, the development of new and potent inhibitors of anti-apoptotic proteins is a very active and promising topic. The small molecule MIM1 has been reported earlier as one of the first selective inhibitors of the anti-apoptotic protein Mcl-1. In the present paper, we first revised the structure of this molecule based on extensive physicochemical analyses. Then we designed and synthesized a focused library of analogues for the corrected structure of MIM1. Next, these molecules were subjected to a panel of in cellulo biological studies, allowing the identification of dual Bcl-x(L)/Mcl-1 inhibitors, as well as selective Mcl-1 inhibitors. These results have been complemented by fluorescence polarization assays with the Mcl-1 protein. Preliminary structure-activity relationships were discussed and extensive molecular modelling studies allowed us to propose a rationale for the biological activity of this series of new inhibitors, in particular for the selectivity of inhibition of Mcl-1 versus Bcl-x(L)