Le principal objectif de cette thèse, au caractère interdisciplinaire, concernait l'étude de l'éponge Biemna laboutei de Madagascar, connue pour sa toxicité (causant notamment des dermatites). Les travaux entrepris comprenaient en premier lieu, l'étude chimique de cette éponge incluant l'extraction, l'isolement et l'identification des métabolites secondaires par différentes techniques chromatographiques (CLMP, CLHP…) et spectroscopiques (UV-visible, HRMS, RMN 1D et 2D…). Dix-huit alcaloïdes appartenant à la classe rare des hétérocycles tricycliques (5,6,8b)-triazaperhydroacénaphtylène (i.e. ptilocaulines, mirabilines, nétamines) ont été isolés et identifiés. Douze de ces alcaloïdes tricycliques guanidiniques, de structures nouvelles, ont été nommées nétamines H-S. Ces composés ont été classés en fonction des insaturations de leur noyau tricyclique : type pyrimidine, insaturés en Δ8,8a et insaturés en Δ8a,8b. Pour deux des composés isolés, les nétamines I (58) et J (59), une étude configurationnelle reposant sur la comparaison de spectres UV et DCE, expérimentaux et théoriques (théorie de la fonctionnelle et de la densité), a permis la détermination de leurs configurations absolues : 5aS, 7R, 8R pour la nétamine I et 5aS, 7R, 8S pour la nétamine J. La valorisation des molécules isolées a ensuite été envisagée via d'une part la réalisation d'une étude chimiotaxonomique et d'autre part, l'évaluation de leurs activités biologiques (cytotoxicité, activité antipaludique, …). La nétamine M (62) a présenté une activité cytotoxique sur les cellules cancéreuses KB (CI50 = 1,0 μg/mL) et les nétamines O (64), Q (66) et K (60) se sont montrées actives contre le parasite Plasmodium falciparum, responsable du paludisme avec respectivement une CI50 de 4,66 ; 2,53 et 0,62 μg/mL. Enfin, au cours de ces travaux de thèse, ont été explorées trois nouvelles stratégies de synthèse conduisant au squelette des alcaloïdes guanidiniques tricycliques, suivant une approche biomimétique. / The main purpose of this interdisciplinary thesis was to study Biemna laboutei, a sponge from Madagascar, known to have toxic properties (dermatitis-producing). The chemical investigation of this sponge including extraction, isolation and identification of secondary metabolites was first undertaken using several chromatographic (HPLC, MPLC…) and spectroscopic (UV-visible, HRMS, NMR 1D et 2D…) techniques. Eighteen alkaloids belonging to the rare class of tricyclic (5,6,8b)-triazaperhydroacenaphtylene heterocycles (i.e. ptilocaulins, mirabilins, netamines) were isolated and identified. Twelve new alkaloids from this group of guanidine derivatives were named netamine H-S. These compounds were grouped on the basis of unsaturation and double bond regiochemistry, with pyrimidine, Δ8,8a and Δ8a,8b heterocycles. For two compounds, netamine I (58) and J (59), a joint theoretical (Density functional theory) and experimental study of UV and ECD spectra allowed the determination of their absolute configuration: 5aS, 7R, 8R for netamine I and 5aS, 7R, 8S for netamine J. The chemotaxonomic meaning of these alkaloids was discussed. Their biological activities were also evaluated. Netamine M (62) exhibited a cytotoxic activity towards KB cells (IC50 = 1,0 μg/mL) while netamine O (64), Q (66) and K (60) were active against the malaria parasite Plasmodium falciparum with IC50 value of 4,66; 2,53 and 0,62 μg/mL respectively. Finally, this work was also dedicated to the biomimetic synthesis of the tricyclic guanidine skeleton. Three new synthesis routes were explored.

Irritable bowel syndrome (IBS) is a functional disorder that affects the gastrointestinal tract and especially the large intestine. The pathogenesis of the disease is not fully understood, for that reason there is still no cure and current therapy focuses on symptom relief. The disease manifests itself in the form of abdominal pain, bloating, constipation or diarrhoea. New studies have shown a link between IBS and communication between the central nervous system and the gut. Serotonin and norepinephrine seem to be important for the course of the disease. The purpose of this literature review was to study the efficacy and safety of certain antidepressant preparations belonging to tricyclic antidepressants and selective serotonin reuptake inhibitors in the treatment of IBS. This work focused on the effect of preparations and how tolerable they are with respect to their side effects. Articles presented in this work were found in the PubMed database with the keywords "irritable bowel syndrome", "serotonin reuptake inhibitor", " tricyclic antidepressants ". Amitriptyline 10 mg and imipramine 25 mg provided a statistically significant symptom relief in IBS with diarrhoea (IBS-D) compared to placebo. In addition, tianeptine 12.5 mg 3 times / day, which belongs to the selective serotonin reuptake enhancer (SSRE) group, gave a corresponding symptom relief as amitriptyline 10 mg once / day. The difference between the two was not statistically significant, but the study was open label and non-placebo-controlled, which made it difficult to draw any conclusions. Fluoxetine, which belongs to the selective serotonin reuptake inhibitor (SSRI) group, produced a statistically significant effect compared to placebo in the treatment of constipation IBS (IBS-C). In contrast, paroxetine-CR did not have any statistically significant effect on abdominal pain in IBS-C compared with placebo. However, more patients in the paroxetine group achieved the secondary outcome (clinical global improvement) with scores of 1-2 on the scale Clinical Global Impressions-Improvement (CGI-I). Based on the studies presented in this literature study, it is concluded that a low dose of TCA is an effective and safe treatment for IBS-D while SSRIs are effective and safe in the treatment of IBS-C compared to placebo. / Irritable bowel syndrome (IBS), är funktionella störningar som drabbar gastrointestinalkanalen och framför allt kolon. Patogenesen till sjukdomen är inte helt klarlagd, av den anledningen saknas fortfarande någon botande behandling och dagens terapi fokuserar på symtomlindring. Sjukdomen yttrar sig i form av buksmärta, uppblåsthet, förstoppning eller diarré. Senaste studier har visat en koppling mellan IBS och kommunikation mellan centrala nervsystemet och tarmen. Serotonin och noradrenalin verkar ha betydelse för sjukdomsförlopp. Syftet med detta litteraturarbete var att studera effektivitet och säkerhet för några antidepressiva preparat som tillhör tricykliska antidepressiva och selektiva serotonin återupptagshämmare vid behandling av IBS. Detta arbete fokuserade på effekten av preparaten och hur tolererbara de är med avseende på deras biverkningar. Artiklar som presenteras i detta arbete söktes i databasen Pubmed med sökord ”irritable bowel syndrome”, ”serotonin reuptake inhibitors”, ” tricyclic antidepressants”. Amitriptylin 10mg och imipramin 25mg gav en statistiskt signifikant symtomlindring vid IBS med diarré (IBS-D) jämfört med placebo. Dessutom gav tianeptin 12,5mg 3 gånger/dag, som tillhör läkemedelsgruppen selektiv serotonin återupptagsenhancer (SSRE), en likvärdig symtomlindring som amitriptylin 10mg en gång/dag. Skillnaden mellan de två var inte statistiskt signifikant, däremot var studien openlabel och icke-placebokontrollerad vilket gör det svårt att dra någon slutsats. Fluoxetin, som tillhör läkemedelsgruppen selektiva serotonin återupptagshämmare SSRI, gav en statistiskt signifikant effekt jämfört med placebo vid behandling av IBS med förstoppning (IBS-C). Däremot gav paroxetin-CR ingen statistiskt signifikant effekt på buksmärta vid IBS-C jämfört med placebo, dock uppnådde fler i paroxetingruppen den sekundära utfallsvariabeln (global klinisk förbättring) och fick poäng mellan 1 – 2 på skalan Clinical Global Impressions-Improvement (CGI-I).  Baserat på studierna som presenteras i denna litteraturstudie dras slutsatsen att en låg dos TCA är en effektiv och säker behandling vid IBS-D medan SSRI är effektiva och säkra vid behandling av IBS-C jämfört med placebo.

Cette thèse décrit deux thèmes principaux: 1) la conception, la synthèse, et l'évaluation biophysique des nucléosides tricycliques, et 2) la synthèse de nagilactone B, un produit naturel norditerpenoïde dilactone de la famille de produits naturels “podolactone”. Le premier chapitre décrit la stratégie de design rationnel des nucléosides nommé “restriction conformationnelle double” basée sur les études de modélisation structurales des duplex ADN–ARN modifiés. Cette stratégie implique un blocage du cycle furanose dans une configuration de type N- ou S, et une restriction de la rotation torsionelle autour de l’angle γ. La première contrainte a été incorporée avec un pont méthylène entre l’oxygène en position 2′ et le carbone 4′ du nucléoside. Cette stratégie a été inspirée par les acides nucléiques bloqués (ou “locked nucleic acid”, LNA). La deuxième contrainte a été réalisée en ajoutant un carbocycle supplémentaire dans l'échafaud de l’acide nucléique bloqué. Les défis synthétiques de la formation des nucléotides modifiés à partir des carbohydrates sont décrits ainsi que les améliorations aux stabilités thermiques qu’ils apportent aux duplex oligonucléïques dont ils font partie. Chapitres deux et trois décrivent le développement de deux voies synthétiques complémentaires pour la formation du noyau de nagilactone B. Ce produit naturel a des implications pour le syndrome de Hutchinson–Gilford, à cause de son habilité de jouer le rôle de modulateur de l’épissage d’ARN pré-messager de lamine A. Ce produit naturel contient sept stereocentres différents, dont deux quaternaires et deux comprenant un syn-1,2-diol, ainsi que des lactones à cinq ou six membres, où le cycle à six ressemble à un groupement α-pyrone. La synthèse a débuté avec la cétone de Wieland-Miescher qui a permis d’adresser les défis structurels ainsi qu’explorer les fonctionnalisations des cycles A, B et D du noyau de nagilactone B. / The present thesis comprises two major themes: 1) the design, synthesis, and biophysical evaluation of conformationally restricted tricyclic nucleosides for antisense applications, and 2) strategic approaches for synthesizing the core of nagilactone B, a norditerpenoid dilactone from the podolactone family of natural products. Guided by structural studies of modified DNA–RNA duplexes, Chapter One focuses on a proposed dual-conformational-restriction strategy, in which two modes of conformational restriction are incorporated into a single nucleotide modification: 1) locking the furanose ring in an N- or S-type configuration and 2) restricting rotation around backbone torsion angle γ. The first constraint was incorporated by way of a 2′,4′-anhydro bridge that is found in the scaffold of locked nucleic acid (LNA), while the second was realized by annealing an additional carbocyclic ring to the modified nucleoside. The synthetic challenges associated with preparing these highly constrained molecules from carbohydrate-derived starting materials are described, in addition to the corresponding improvements in duplex thermal stability they provide to oligonucleotide sequences containing them. Chapters Two and Three describe complementary approaches for the synthesis of the core of nagilactone B, a natural product with implications for Hutchinson–Gilford progeria syndrome, as a consequence of its ability to act as a modulator of splicing events leading to lamin A. This natural product contains seven stereogenic centers overall, including a syn-1,2-diol moiety, a γ-lactone, and a pair of quaternary stereocenters, which are complemented by the presence of an α-pyrone moiety. To address the synthesis of these structural features, the utility of the Wieland–Miescher ketone was explored with an emphasis on synthesizing rings A, B, and D of the core of nagilactone B.

No description available.

No / A novel series of 1,4-disubstituted aminoanthraquinones were prepared by ipso-displacement of 1,4-difluoro-5,8-dihydroxyanthraquinones by hydroxylated piperidinyl- or pyrrolidinylalkyl-amino side chains. One aminoanthraquinone (13) was further derivatized to a chloropropyl-amino analogue by treatment with triphenylphosphine-carbon tetrachloride. The compounds were evaluated in the A2780 ovarian cancer cell line and its cisplatin-resistant variants (A2780/ cp70 and A2780/MCP1). The novel anthraquinones were shown to possess up to 5-fold increased potency against the cisplatin-resistant cells compared to the wild-type cells. Growth curve analysis of the hydroxyethylaminoanthraquinone 8 in the osteosarcoma cell line U-2 OS showed that the cell cycle is not frozen, rather there is a late cell cycle arrest consistent with the action of a DNA-damaging topoisomerase II inhibitor. Accumulative apoptotic events, using time lapse photography, indicate that 8 is capable of fully engaging cell cycle arrest pathways in G2 in the absence of early apoptotic commitment. 8 and its chloropropyl analogue 13 retained significant activity against human A2780/cp70 xenografted tumors in mice.