Au cours de ce travail, nous avons abordé la synthèse biomimétique sous des angles variés. Une déclinaison des approches bio-inspirées a en effet permis de réaliser plusieurs synthèses totales d'alcaloïdes polycycliques complexes. La biogenèse des substances naturelles considérées est placée au centre de la démarche. Au départ, pour définir la stratégie de synthèse puis, en conclusion, lorsque les synthèses réalisées mènent a des hypothèses biosynthétiques plus abouties.Le squelette des drimentines, alcaloïdes hybrides possédant une partie sesquiterpénique, a été obtenu grâce à une séquence de désaromatisation-cyclisation qui mime l'étape-clé de la biogenèse de ces métabolites spécialisés.Une stratégie d'auto-assemblage par dimérisation a été adoptée afin d'étudier les liens synthétiques et biosynthétiques qui unissent les alcaloïdes marins de la famille des aplysinopsines. Au cours de cette étude, les premières synthèses totales du dictazole B et du tubastrindole B ont été réalisées. De plus, l'obtention d'analogues proches des substances décrites et d'un intermédiaire biogénétique supposé a permis de développer une hypothèse de biogenèse se fondant sur la spontanéité et les réactivités chimiques observés au cours de l'étude. L'application de la catalyse à l'ADN à ces travaux a également conduit à des résultats prometteurs.Enfin, une méthode bio-informatique récente appelée "molecular networking" peut être mise à profit afin d'exploiter la diversité de mélanges synthétiques complexes générés par la mise en présence de quelques précurseurs simples. La démarche s'applique à des mélanges connus dans lesquels la nitraramine ou la nitrarine se forment ainsi qu'à des mélanges inédits pouvant conduire, par exemple, au myrifabral A.Ces études montrent encore une fois que la synthèse biomimétique est un outil puissant pour la synthèse totale de substances naturelles polycycliques complexes et ce de bien des manières. On peut retenir que ces stratégies permettent d'accéder à des cibles extrêmement complexes avec simplicité, sobriété et élégance. / This work features various approaches of biomimetic organic syntheses. Biosynthetic considerations have been placed at the center of our analysis in order to define the synthetic plans and later to propose biosynthetic hypotheses.First, the skeleton of drimentines, hybrid alkaloids containing a sesquiterpenic unit, has been obtained by mimicking the main event of their postulated biosynthesis.In a wider study, the marine alkaloid family of the aplysinopsins has been treated with two total syntheses, of dictazole B and tubastrindole B, as well as a full bio-relevant aplysinopsins’ cascade and the application of DNA catalysis principles to the series.Finally, novel dereplication techniques relying on "molecular networking are currently tested on complex synthetic mixtures to merge one step total syntheses and diversity oriented synthesis.

Le but de ce travail de doctorat est l’étude chimique et biosynthétique de familles d’alcaloïdes guanidiniques d’origine marine provenant d’éponges de Méditerranée.Le travail est divisé en trois parties successives : 1) l’isolement d’alcaloïdes produits par des éponges marines de l’ordre des Poeciloscerida; 2) l’élucidation de la biosynthèse de la crambescine C1 par des études in vivo d’incorporation de précurseurs marqués au 14C; 3) la synthèse biomimétique de la crambescine A2 448 et de dérivés proches.La famille des alcaloïdes guanidiniques cycliques des crambescines est au coeur de la thèse, ces substances naturelles sont produites par l’éponge incrustante Crambe crambe. Ces alcaloïdes ont été découverts dans les années 1990 et ont suscité beaucoup d’intérêt pour leurs propriétés biologiques et écologiques et leurs synthèses totales. Par contre, leur biosynthèse était encore inconnue à ce jour. La seule synthèse biomimétique disponible était basée sur une hypothèse d’origine polyacétique. Les hypothèses récentes de nos groupes ont permis de mettre en avant une origine mixte: la partie cyclique guanidinique proviendrait d’un pyrrolidinium issu de l’arginine et d’un précurseur “céto-acide” proche des acides gras. Sur la base de cette hypothèse, nous avons mis au point une expérience d’incorporation qui a ensuite inspirée une voie de synthèse biomimétique pour l’accès aux crambescines et dérivés. Les premières conclusions quant à l’origine biosynthétique de ces molécules sont les faits les plus marquants de ce travail. Nous apportons une meilleure compréhension de la biochimie des alcaloïdes guanidiniques marins de structures complexes. / This thesis aims at the study of the chemical and biogenetic origin of specialized guanidine-alkaloid metabolites produced by sponges from the Mediterranean Sea.The work is divided into three main parts: 1) isolation of alkaloids produced by sponges of the Poeciloscerida order; 2) biosynthesis of crambescin C1 by in-vivo 14C-feeding experiments with Crambe crambe sponge; 3) biomimetic synthesis of crambescin A2 448 and derivatives. The main focus of the thesis will be the family of cyclic-guanidine alkaloids "crambescins", produced by the red incrusting sponge Crambe crambe.These alkaloids were discovered in the early 90s and despite the large interest on their biological activities, ecological roles, and synthesis, their biosynthesis is still unknown.The only available biomimetic synthesis of crambescins was based on a fully polyketide origin hypothesis. Recently our groups suggested an alternative biosynthetic hypothesis in which the guanidine-core would be originated from a condensation between a guanidinated pyrrolidinium derived from arginine and a beta-keto fatty acid. Based on this hypothesis, we designed a biosynthesis experiment that inspired a biomimetic synthesis route to access the crambescins and derivatives. The insights from these studies are the first experimental conclusions about the biosynthesis of crambescins. Finally, this work leads to a better comprehension of the biochemistry involved in guanidine marine alkaloids of complex structures.

Cette thèse est fondée sur le développement de nouvelles méthodes de criblage et d’analyse appliquées aux extraits naturels. Le premier axe de ce travail a consisté à isoler une molécule très minoritaire dans un mélange réactionnel de synthèse biomimétique en utilisant entre autre la chromatographie de partage centrifuge (CPC) en mode pH-zone refining. Nous avons pu isoler la nitrarine avec un rendement de 0,04% en permettant de valider le mécanisme proposé pour sa synthèse biomimétique.Le deuxième axe de ce projet est consacré à l’identification par fractionnement bioguidé, dans les graines de Mucuna pruriens (une plante de la pharmacopée traditionnelle indienne), des molécules responsables de la synergie thérapeutique antiparkinsonienne mise en évidence dans la littérature par des essais in vivo et cliniques. L’extrait hydro-alcoolique de graines de Mucuna pruriens a été fractionné par chromatographie sur colonne de gel de silice, puis les fractions obtenues ont été évaluée in vitro sur plusieurs cibles biologiques : enzymes de dégradation de la dopamine (MAO, COMT), et une enzyme de sa synthèse endogène (DDC). Nous avons développé une méthodes de détection d’une activité d’inhibition de ces enzymes par spectrométrie de masse. À partir des fractions identifiées comme étant actives, nous avons isolé et identifié une vingtaine de molécules, parmi lesquelles une dizaine sont nouvellement décrites. Il a été nécessaire de synthétiser certaines d'entre elles en raison de la quantité nécessaire aux essais biologiques. Certaines de ces molécules ont montré une activité inhibitrice intéressante sur la COMT / This thesis is based on the development of new methods of screening and analysis applied to natural extracts.The first axis of this work consisted in isolating a minoritary molecule in a reaction mixture of a biomimetic synthesis using different techniques including centrifugal partition chromatography (CPC) in pH-zone refining mode. We were able to isolate the nitrarine with a yield of 0.04%, thus allowing to validate the proposed mechanism of its biomimetic synthesis.The second axis of this project is dedicated to the identification in the seeds of Mucuna pruriens (a plant of Indian traditional pharmacopoeia), by bioguided fractionation, the molecules responsible for the antiparkinsonian synergy demonstrated by in vivo studies and clinical trials. For this purpose, the hydroalcoholic extract of M. pruriens seeds was fractionated by chromatography on a silica gel column and the obtained fractions were evaluated in vitro on various biological targets: the dopamine-degrading enzymes (MAO, COMT) and an enzyme implicated in its endogenous synthesis (DDC). Moreover, we have developed a method to detect by mass spectrometry fractions or compounds having an inhibitory activity on these enzymes. From fractions identified as active, we isolated and identified about twenty molecules, from which a dozen are newly described. On the other hand, it was necessary to synthetize some of them due to the amount required by bioassays. Some of these molecules have shown an interesting inhibitory activity against the COMT enzyme

Miklová V.: Cytotoxic and cholinesterase inhibitory activity of extracts from selected species of the Centaurea L. genus II. Diploma thesis, Charles University, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany, Hradec Králové, 2020. This Diploma Thesis was carried out at the Department of Pharmaceutical Botany FAF UK and it is a part of a screening of biologically active secondary metabolites of selected on taxa of the genera Centaurea L. and Psephellus L. in the family Asteraceae. Secondary metabolites are responsible for various effects on the human body. The study is focused on the phytochemical research of extracts prepared from aerial parts (cauloms with leaves) of Centaurea cyanus L., Centaurea stoebe L., Cyanus montanus (L.) Hill, Centaurea benedicta L., Centaurea jacea L., Centaurea macrocephala Muss. Puschk. ex. Willd, Centaurea solstitialis L., Centaurea nigra L., Centaurea scabiosa L., Psephellus bellus (Trautv.) Wagenitz, Centaurea pannonica (Heuff.) Hayek and Psephellus dealbatus (Willd) K. Koch. Both ethyl acetate and summary ethanolic extracts were prepared for detection of individual groups of secondary metabolites by thin-layer chromatohraphy. Consistently with previously published results, sesquiterpenes, flavonoids, coumarins, phenolic compounds,...

Charles University, Faculty of Pharmacy in Hradec Králové Department: Department of Pharmaceutical Botany (16-16130) Author: Tkáčová Beáta Supervisor: PharmDr. Kateřina Breiterová, Ph.D. Title of thesis: Alkaloids of Narcissus species cultivars and their biological activity I. Key words: Narcissus, alkaloids, biological activity, Alzheimer's disease. The main aim of this diploma thesis was to obtain summary alkaloid extracts from bulbs of five species cultivars (Narcissus cv. Acropolis, Delta, White Marvel, Kedron, Scarlet Gem) and one variety (Narcissus albus var. plenus odoratus), labeled as AL-450, AL-457, AL-460, AL-463, AL-467 and AL-508, from which samples were subsequently prepared for GC-MS analysis and screening of biological activities (cholinesterase inhibitory activity and cytotoxicity). Totally, 18 alkaloids were identified by GC-MS analysis, comparing their mass spectra. Identified alkaloids include 3-O-demethylmaritidine, 11,12-dehydroanhydrolycorine, assoanine, dehydroassoanine, galanthamine, galanthine, haemanthamine, hippeastrine, incartine, lycoramine, lycorine, narwedine, norpluvine, pancracine, pluvine, pseudolycorine and tazettine. Samples of cultivars AL-457, AL-460, AL-463 and AL-508, showed relatively promising hAChE inhibitory activity in screening assay (c = 50 µg/ml),...

Synthesis of cyclodextrin derivatives for organocatalysis This doctoral thesis examines the preparation of new cyclodextrin (CD) derivatives suitable for organocatalysis. The aim of this work is to prepare monosubstituted and disubstituted CD derivatives as organocatalysts for different types of enantioselective reactions potentially performed in water. In addition, disubstituted CD derivatives require considering the potential mixture of regioisomers and pseudoenantiomers. Thus, this thesis is divided into several sections - preparation of CD precursors and derivatives for organocatalysis, preparation of pure regioisomers and pseudoenantiomers of disubstituted CDs and final application of CD derivatives in enantioselective reactions. Furthermore, this thesis also focuses on the molecular modeling of the prepared CD derivatives and on their catalytic activity in silico. The first section covers the preparation of new disubstituted CD precursors as pure regioisomers for organocatalysts, specifically to develop a new method for the preparation of heterodisubstituted AC regioisomers on the primary rim of α-CD. This section also includes the determination of the regioisomer ratios of common α-CD intermediates disubstituted on the primary rim to evaluate their potential as precursors in organocatalysis....

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy Candidate: Iva Valachová Supervisor: Pharm.Dr. Daniela Hulcová, Ph.D. Title of diploma thesis: Derivatives of Amaryllidaceae alkaloids as potential drugs in the treatment of tumor diseases Twelve aromatic derivatives were prepared. The substitutions were performed on the hydroxyl group at C-3. This was acylated with differently substituted benzoyl chlorides affording the corresponding esters. Structural identification was performed by 1D- and 2D- NMR, ESI-HRMS spectroscopic techniques and optical rotation measurement. The yield of all reactions was more than 60 %. After converting these derivatives to hydrochlorides, their biological activity was tested. The Amaryllidaceae alkaloid vittaine itself exhibits cytotoxic activity and therefore its derivatives have been investigated in this respect. It has been tested against 9 cancerous and 1 non-cancerous cell lines. 3-O-(4-Chloro-3-nitrobenzoyl)vittatine showed the highest cytotoxic activity, unfortunatelly, it does not selectively affect only cancerous cells. Conversely, 3-O-(2-naphthoyl)vittatine has a selective effect on the HT-29 cancerous cell line (colorectal carcinoma) with a viability value of 32 ± 3 %, potentially being the subject of further studies of cytotoxicity...

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Dušan Zelina Supervisor: doc. Ing. Lucie Cahlíková, Ph.D. Title of diploma thesis: Derivates of Amaryllidaceae alkaloids and their biological activity: Derivates of tazettine II Plants of family Amaryllidaceae are a rich source of alkaloids that are characterized by a broad biological activity. Perhaps the world's best-known member of this family has become galanthamine, which, because of its potent inhibitory potential, has found a place in the treatment of Alzheimer's disease. Based on the conducted studies, the alkaloid tazettine has been chosen for this thesis. The main purpose was to prepare more active derivatives of tazettine and to test the biological activity for potential use in the treatment of cancer and Alzheimer's disease. Ten aromatic esters of tazettine were prepared. Reaction yields ranged from 33,5-69,3 %. Derivatives were identified by MS, NMR and optical rotation. Prepared compounds were tested for their inhibitory potential against human cholinesterases - AChE and BuChE. Unfortunately, it has not been possible to prepare derivatives, which exhibit significant activity in inhibiting AChE or BuChE. Anti-tumor activity of the derivates has been tested on the panel of selected...

Muchová, A.: Antiplatelet activity of alkaloids and its potential use in the Alzheimer's disease therapy. Diploma thesis, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany, Hradec Králové, 2020. According to recent studies, the pathophysiology of Alzheimer's disease, as a neurodegenerative disease, has been implicated in platelets and the associated haemostasis disorder, the release of inflammatory cells, which may result in the facilitation of amyloid plaque formation. Alkaloids as alkaline nitrogen compounds, which have many effects on humans or animals. In connection with this issue, researchers are investigating the antiplatelet effect of many structural types of alkaloids. The isoquinoline alkaloids of the families Lauraceae, Annonaceae, Piperaceae, Magnoliaceae and Papaveraceae are perpective for the study. In addition to their antiplatelet effects, they also have an antioxidant and inhibitory effect on acetylcholinesterase, which is also used in Alzheimer's disease therapy. Another promising substance is the pyrrolidinoindoline alkaloid Psm2, which was isolated from the plant Selaginella moellendorffii Hieron. It has an antiplatelet effect higher than the reference substance acetylsalicylic acid and is also associated with a lower risk...

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Filip Pidaný Supervisor: Assoc. Prof. Ing. Lucie Cahlíková, Ph.D. Title of diploma thesis: Derivatives of Amaryllidaceae alkaloids and their their biological activity: Derivatives of tazettine I A study conducted between 1981 and 2014 found that 65% of small molecule based drugs are related to natural substances. The plants of the family Amaryllidaceae contain a particular and still not fully investigated group of alkaloids called Amaryllidaceae alkaloids. Their important biological effects include, for example, antiviral, antibacterial, antifungal, antiparasitic, cytotoxic and, in particular, motor-neuronal system-mediated effects mediated by inhibition of cholinesterases. A widespread Amaryllidaceae alkaloid is tazettine, a structural type alkaloid of tazettine that has increased interest in the early 1970s due to its cytotoxic acitivity, but appears less interesting in the studies conducted. The subject of this thesis was the preparation of tazettin alkaloid derivatives. The cholinesterase inhibitory activity was then tested. Cytotoxic activity in a panel of selected tumor and healthy cell lines was studied by screening. Unfortunately, none of the derivatives prepared by us showed an...