Recentemente foram isolados da esponja marinha Axinella cf. corrugata dois compostos derivados da esculetina: o éster metílico do ácido 4-esculetínico e o éster etílico do ácido 4-esculetínico. Este último apresentou importante atividade contra o vírus da SARS. Este projeto teve como meta isolar e cultivar as linhagens de fungos associadas à esponja Axinella cf. corrugata, bem como analisar seus extratos por HPLC-PDA-MS, objetivando a possível detecção desses compostos (ou derivados) nesses extratos. Avaliações preliminares levaram à obtenção de 11 amostras potencialmente relacionadas a esses compostos. Dentre elas, uma apresentou espectros no UV e de massas muito similares aos obtidos para o aduto de sódio do éster metílico do ácido 4-esculetínico. No entanto análises espectroscópicas mais detalhadas por RMN - 1H, RMN - 13C, HSQC, HMBC e COSY da amostra purificada permitiram identificar o composto isolado, a 1,3,6-trihidroxi-8-metil-9H-xanten-9-ona. Simultaneamente às análises químicas, os extratos obtidos a partir das linhagens fúngicas isoladas da esponja Axinella cf. corrugata tiveram suas atividades biológicas avaliadas frente a microrganismos e células tumorais humanas, resultando em mais de 20% dos extratos com alguma atividade biológica. / Recently two compounds derived from esculetin have been isolated from the marine sponge Axinella cf. corrugata: the methyl ester of esculetin-4-carboxylic acid and the ethyl ester of esculetin-4-carboxylic acid. The latter displayed antiviral activity against the SARS virus. This project aimed the isolation and the growth of fungal strains associated to the sponge Axinella cf. corrugata, and the subsequent analysis of the fungal extracts by HPLC-PDA-MS, aiming the possible detection of the esculetin compounds (or derivatives) in those extracts. Preliminary analysis yielded 11 samples potentially related to these compounds. Among these extracts, one presented UV and MS spectra very similar to the spectra obtained for the sodium adduct of the methyl ester of esculetin-4-carboxylic acid. However, a detailed spectroscopic analysis of a pure compound isolated by RMN - 1H, RMN - 13C, HSQC, HMBC e COSY allowed the identification of the compound, which is 1,3,6-trihydroxy-8-methyl-9H-xanthen-9-one. Simultaneously to the chemical analysis of the fungal crude extracts, the biological activities of the obtained extracts were evaluated against microrganisms and human tumoral cell lines. More than 20% of the extracts displayed some biological activity.

Poon Wing Ming Jodie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 207-233). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 論文摘要 --- p.iv / Abbreviations --- p.v / List of Figures --- p.x / List of Tables --- p.xiii / Contents --- p.xiv / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1. --- Severe Acute Respiratory Syndrome (SARS) --- p.1 / Chapter 1.1.1. --- Background of SARS --- p.1 / Chapter 1.1.2. --- Etiology and pathology of SARS --- p.3 / Chapter 1.1.3. --- Genome organization and expression of SARS-CoV --- p.5 / Chapter 1.1.4. --- Current molecular advances of SARS-CoV --- p.13 / Chapter 1.1.5. --- Current research advances on SARS-CoV nucleocapsid --- p.18 / Chapter 1.1.6. --- Current diagnostic assays of SARS-CoV infection --- p.23 / Chapter 1.1.7. --- Current treatment --- p.25 / Chapter 1.1.8. --- Vaccine development --- p.27 / Chapter 1.2. --- Aims of study --- p.30 / Chapter CHAPTER TWO --- MATERIALS AND METHODS --- p.33 / Chapter 2.1. --- Subcellular localization study of the SARS-CoV nucleocapsid protein --- p.33 / Chapter 2.1.1. --- "Cloning of SARS-CoV nucleocapsid cDNA into the green fluorescence protein (GFP) mammalian expression vector, pEGFP-C1" --- p.33 / Chapter 2.1.1.1. --- Amplification of SARS-CoV nucleocapsid gene by polymerase chain reaction (PCR) --- p.33 / Chapter 2.1.1.2. --- Purification of PCR products --- p.35 / Chapter 2.1.1.3. --- Restriction digestion of purified PCR products and the circular pEGFP-C 1 vector --- p.36 / Chapter 2.1.1.4. --- Ligation --- p.36 / Chapter 2.1.1.5. --- Preparation of chemically competent bacterial cell E.coli strain DH5a for transformation --- p.37 / Chapter 2.1.1.6. --- Transformation of ligation product into chemically competent bacterial cells --- p.38 / Chapter 2.1.1.7. --- Small-scale preparation of bacterial plasmid DNA --- p.39 / Chapter 2.1.1.8. --- Screening for recombinant clones --- p.40 / Chapter 2.1.1.9. --- DNA sequencing of cloned plasmid DNA --- p.41 / Chapter 2.1.1.10. --- Midi-scale preparation of recombinant plasmid DNA --- p.42 / Chapter 2.1.2. --- Cell culture --- p.44 / Chapter 2.1.2.1. --- Sub-culture of VeroE6 and HepG2 cell lines --- p.44 / Chapter 2.1.2.2. --- Transient transfection of GFP fusion construct --- p.45 / Chapter 2.1.3. --- Epi-fluorescent microscopy --- p.46 / Chapter 2.2. --- Study on differential gene expression patterns upon SARS-CoV nucleocpasid induction by cDNA microarray analysis --- p.48 / Chapter 2.2.1. --- Cloning of SARS-CoV N gene into mammalian expression vector pCMV-Tagl --- p.48 / Chapter 2.2.2. --- Cell culture --- p.50 / Chapter 2.2.2.1. --- Sub-culture of VeroE6 cell line --- p.50 / Chapter 2.2.2.2. --- Transient transfection of pCMV-Tag1 -SAR-CoV N construct --- p.50 / Chapter 2.2.3. --- Total RNA isolation --- p.51 / Chapter 2.2.3.1. --- Total RNA isolation by RNeasy Mini Kit --- p.51 / Chapter 2.2.3.2. --- Checking of RNA integrity --- p.53 / Chapter 2.2.3.3. --- Checking of RNA purity --- p.54 / Chapter 2.2.3.4. --- Determinations of total RNA concentrations and precipitation --- p.54 / Chapter 2.2.4. --- cDNA microarray (done by Affymetrix Inc. as a customer service) --- p.55 / Chapter 2.2.4.1. --- Precipitation of RNA --- p.55 / Chapter 2.2.4.2. --- Quantification of RNA --- p.56 / Chapter 2.2.4.3. --- Synthesis of double-stranded cDNA from total RNA --- p.56 / Chapter (i) --- First stand cDNA synthesis --- p.56 / Chapter (ii) --- Second cDNA synthesis --- p.57 / Chapter 2.2.4.4. --- Clean-up of double stranded cDNA --- p.58 / Chapter (i) --- Phase lock gel-phenol/ chloroform extraction --- p.58 / Chapter (ii) --- Ethanol precipitation --- p.58 / Chapter 2.2.4.5. --- Synthesis of biotin-labeled cRNA --- p.59 / Chapter 2.2.4.6. --- Clean-up and quantification of in vitro transcription (IVP) products --- p.59 / Chapter (i) --- In vitro transcription clean-up --- p.59 / Chapter (ii) --- Ethanol precipitation --- p.60 / Chapter (iii) --- Quantitation of cRNA --- p.60 / Chapter (iv) --- Sample checking --- p.60 / Chapter 2.2.4.7. --- cRNA fragmentation for target preparation --- p.60 / Chapter 2.2.4.8. --- Eukaryotic target hybridization --- p.61 / Chapter 2.2.4.9. --- "Probe array washing, staining and scanning" --- p.62 / Chapter 2.2.5. --- Confirmation of results by RT-PCR --- p.62 / Chapter 2.2.5.1. --- First-strand cDNA synthesis --- p.62 / Chapter 2.2.5.2. --- RT-PCR of candidate gene --- p.63 / Chapter 2.3. --- In vitro RNA interference of SARS-CoV nucleocapsid --- p.66 / Chapter 2.3.1. --- siRNA target site selection --- p.66 / Chapter 2.3.2. --- Cloning of target siRNA sequences into pSilencer 3.1-H1 vector --- p.71 / Chapter 2.3.3. --- Cell culture --- p.72 / Chapter 2.2.3.1. --- Sub-culture ofVeroE6 cells --- p.72 / Chapter 2.3.3.2. --- Transient co-transfection --- p.72 / Chapter 2.3.4. --- Detection of SARS-CoV nucleocapsid mRNA expression level by RT-PCR --- p.73 / Chapter 2.3.4.1. --- Total RNA isolation by TRIzol reagent --- p.73 / Chapter 2.3.4.2. --- First-strand cDNA synthesis --- p.74 / Chapter 2.3.4.3. --- RT-PCR assays --- p.74 / Chapter 2.3.5. --- Detection of SARS-CoV nucleocapsid protein expression level by Western blotting --- p.75 / Chapter 2.3.5.1. --- Total protein extraction --- p.75 / Chapter 2.3.5.2. --- Protein quantification --- p.75 / Chapter 2.3.5.3. --- Protein separation by SDS-PAGE and Western blot --- p.76 / Chapter 2.3.5.4. --- Western blot analysis --- p.78 / Chapter 2.4. --- Human fgl2 prothrombinase promoter analyses --- p.80 / Chapter 2.4.1. --- Cloning of the full-length human fgl2 prothrombinase promoter construct into a promoterless mammalian expression vector-pGL3-Basic --- p.80 / Chapter 2.4.2. --- Cloning of SARS-CoV Membrane gene into the mammalian expression vector pCMV-Tagl --- p.82 / Chapter 2.4.3. --- Cell culture --- p.84 / Chapter 2.4.3.1. --- Sub-culture of HepG2 and VeroE6 cell lines --- p.84 / Chapter 2.4.3.2. --- "Transient co-transfection of the full-length human fgl2 prothrombinase promoter construct with the pCMV-Tagl empty vector, pCMV-Tagl-SARS-CoV M expression vector, or pCMV-Tag1 -SARS-CoV N expression vector" --- p.84 / Chapter 2.4.4. --- Dual-luciferase reporter assay --- p.85 / Chapter 2.4.5. --- Detection of fgl2 mRNA expression level under the induction of SARS-CoV nucleocapsid protein by RT-PCR --- p.86 / Chapter 2.4.5.1. --- Total RNA isolation by TRIzol reagent --- p.86 / Chapter 2.4.5.2. --- First strand cDNA synthesis --- p.86 / Chapter 2.4.5.3. --- RT-PCR of fgl2 gene --- p.87 / Chapter CHAPTER THREE --- RESULTS --- p.88 / Chapter 3.1. --- Computer analysis of SARS-CoV Nucleocapsid --- p.88 / Chapter 3.2. --- Subcellular localization of SARS-CoV nucleopcasid protein in VeroE6 cells and HepG2 cells --- p.102 / Chapter 3.3. --- cDNA microarray analysis on differential gene expression pattern upon the over-expression of SARS-CoV Nucleocapsid gene --- p.114 / Chapter 3.4. --- In vitro RNA Interference of SARS nucleocapsid --- p.129 / Chapter 3.5. --- Transactivation of fgl2 prothrombinase gene promoter by SARS-CoV nucleocapsid protein in HepG2 and VE6 cells --- p.138 / Chapter CHAPTER FOUR --- DISCUSSION --- p.155 / Chapter 4.1. --- "The EGFP-tagged SARS-CoV N protein was localized in the cytoplasm only in VE6 cells, but translocated into both cytoplasm and nucleus in HepG2 cellsin the epi-fluorescence microscopy study" --- p.155 / Chapter 4.2. --- cDNA microarray demonstrated alternations of mRNA transcript level on a number of genes belonging to various functional classes upon over expression of SARS-CoV nucleocapsid gene --- p.162 / Chapter 4.3. --- RNA interference demonstrated effective gene silencing of SARS-CoV nucleocapsid gene --- p.171 / Chapter 4.4. --- SASR-CoV nucleocapsid protein induced the promoter activity of the prothrombinase fibrinogen-like protein2/ fibroleukin (fgl2) gene --- p.191 / Chapter 4.5. --- Conclusion --- p.196 / Chapter 4.6. --- Future work --- p.198 / Appendices --- p.199 / References --- p.207

Recentemente foram isolados da esponja marinha Axinella cf. corrugata dois compostos derivados da esculetina: o éster metílico do ácido 4-esculetínico e o éster etílico do ácido 4-esculetínico. Este último apresentou importante atividade contra o vírus da SARS. Este projeto teve como meta isolar e cultivar as linhagens de fungos associadas à esponja Axinella cf. corrugata, bem como analisar seus extratos por HPLC-PDA-MS, objetivando a possível detecção desses compostos (ou derivados) nesses extratos. Avaliações preliminares levaram à obtenção de 11 amostras potencialmente relacionadas a esses compostos. Dentre elas, uma apresentou espectros no UV e de massas muito similares aos obtidos para o aduto de sódio do éster metílico do ácido 4-esculetínico. No entanto análises espectroscópicas mais detalhadas por RMN - 1H, RMN - 13C, HSQC, HMBC e COSY da amostra purificada permitiram identificar o composto isolado, a 1,3,6-trihidroxi-8-metil-9H-xanten-9-ona. Simultaneamente às análises químicas, os extratos obtidos a partir das linhagens fúngicas isoladas da esponja Axinella cf. corrugata tiveram suas atividades biológicas avaliadas frente a microrganismos e células tumorais humanas, resultando em mais de 20% dos extratos com alguma atividade biológica. / Recently two compounds derived from esculetin have been isolated from the marine sponge Axinella cf. corrugata: the methyl ester of esculetin-4-carboxylic acid and the ethyl ester of esculetin-4-carboxylic acid. The latter displayed antiviral activity against the SARS virus. This project aimed the isolation and the growth of fungal strains associated to the sponge Axinella cf. corrugata, and the subsequent analysis of the fungal extracts by HPLC-PDA-MS, aiming the possible detection of the esculetin compounds (or derivatives) in those extracts. Preliminary analysis yielded 11 samples potentially related to these compounds. Among these extracts, one presented UV and MS spectra very similar to the spectra obtained for the sodium adduct of the methyl ester of esculetin-4-carboxylic acid. However, a detailed spectroscopic analysis of a pure compound isolated by RMN - 1H, RMN - 13C, HSQC, HMBC e COSY allowed the identification of the compound, which is 1,3,6-trihydroxy-8-methyl-9H-xanthen-9-one. Simultaneously to the chemical analysis of the fungal crude extracts, the biological activities of the obtained extracts were evaluated against microrganisms and human tumoral cell lines. More than 20% of the extracts displayed some biological activity.

published_or_final_version / Community Medicine / Master / Master of Public Health

Bei SARS („Schweres akutes respiratorisches Syndrom“) handelt es sich um eine Infektionskrankheit des Menschen, welche im November 2002 erstmalig auftrat. Als Erreger dieser Krankheit wurde das SARS-assoziierte Coronavirus identifiziert. Dessen viruseigene Reproduktionsmaschinerie wird vor allem durch die katalytische Aktivität einer Cysteinprotease, der SARS-Coronavirus-Hauptprotease (SARS-CoV-Mpro), und die damit verbundene Prozessierung von viralen Polyproteinen, aufrechterhalten. Diese Schlüsselfunktion der SARS-CoV-Mpro macht sie zu einem vielversprechenden Zielobjekt bei der Entwicklung von spezifischen Inhibitoren für diese Protease, welche somit eine Vermehrung des Virus verhindern. In dieser Arbeit wurde die SARS-CoV-Mpro mit optimierten Methoden exprimiert und gereinigt. Mit der Methode der ESI-MS-Analyse konnte ein kovalentes, irreversibles Bindungsverhalten verschiedener Inhibitoren gezeigt werden und erstmals auch die Bindung von Fragmenten von Inhibitormolekülen an die Protease. So zeigten die SARS-CoV-Mpro-Inhibitoren MH211A und UK-VI-1g eine kovalente Bindung des kompletten Moleküls pro Enzym-Monomer: überraschenderweise hatten bis zu vier Moleküle MH211A bzw. zwei Moleküle UK-VI-1g an ein Proteasemolekül gebunden. Die Bindung von UK-VI-1g an die Protease wurde an zwei Peptiden im Bereich von den Aminosäuren 62 bis 76 bzw. 280 bis 298 nachgewiesen, wobei beide nicht in der Nähe der active site lokalisiert sind. Im Falle des Inhibitors Lit1 bindet der 2,6-Dinitro-4-trifluoromethyl-phenyl-Rest, bei TS48 das Zimtsäure-Thioester-Fragment kovalent an jedes Monomer im dimeren Enzym. Die SARS-CoV-Mpro wurde erstmals ohne Abtrennung des C-terminalen His-tag mit spezifischen Inhibitoren co-kristallisiert. Drei mögliche Orientierungen des Inhibitors TS174 wurden in der active site der Protease identifiziert. Aufgrund der schwachen Elektronendichte des Inhibitors konnten diese nicht weiter untersucht werden. Das Iod-Isatin-Derivat IISBT wurde ebenfalls mit der SARS-CoV-Mpro zusammen co-kristallisiert und es konnte erstmalig eine kovalente Bindung eines Isatin-Derivats an die SARS-CoV-Mpro anhand einer Röntgenstruktur klar gezeigt werden. Diese Struktur zeigte dann, dass früher veröffentlichte molekulare docking-Studien, die eine nicht-kovalente Bindung von IISBT und anderen Isatin-Derivaten veranschaulichen, nochmal überdacht werden sollten. Basierend auf einer ESI-MS-Analyse und früheren Ergebnissen von MALDI- und Dialyse-Experimenten, kann man sicher annehmen, dass IISBT in einer kombinierten kovalent-reversiblen Art und Weise an die SARS-CoV-Mpro bindet. / SARS („severe acute respiratory syndrome”), a respiratory disease in humans, appeared in November 2002 for the first time. The causative agent of this disease is the SARS-associated coronavirus. Its replication machinery is maintained by the catalytic activity of a cysteine protease, named SARS coronavirus main protease (SARS-CoV-Mpro) that processes the virus derived polyproteins. Based on this key role the SARS-CoV-Mpro is an attractive target for the development of specific inhibitors against this protease thereby inhibiting the reproduction of the virus. In this work, the SARS-CoV-Mpro was expressed and purified by optimized methods. Through ESI-MS analysis an irreversible covalent interaction of various inhibitors was detected but also for the first time the binding of fragments of the inhibitors to the protease. Accordingly the SARS-CoV-Mpro inhibitors MH211A and UK-VI-1g displayed a covalent binding of the complete molecule to the enzyme monomer: surprisingly up to four molecules of MH211A and two molecules of UK-VI-1g respectively bound to one protease molecule. The interaction of UK-VI-1g with the protease was detected for two peptides ranging from amino acids 62 to 76 and 280 to 298 both of which are not located near the active site. In case of inhibitor Lit1 the 2,5-dinitro-4-trifluormethlphenyl-fragment and in TS48 the cinnamic acid-thioester-fragment binds covalently to each monomer in the dimeric enzyme. For the first time the SARS-CoV-Mpro was co-crystallized with specific inhibitors without cleaving the C-terminal His-tag. Three possible orientations of the inhibitor TS174 were identified in the active site of the protease. They could not be further resolved due to the weak electron density for the inhibitor. The iodoisatin derivative IISBT was co-crystallized with SARS-CoV-Mpro as well and a covalent binding mechanism of an isatin derivative to the SARS-CoV-Mpro was clearly shown for the first time in an X-ray structure. This structure then indicates that the previously published molecular docking studies demonstrating a noncovalent binding mode of IISBT and other isatin derivatives should be reconsidered. Based on an ESI-MS analysis and previous results of MALDI and dialysis experiments it is safe to assume that IISBT binds to the SARS-CoV-Mpro in a combined covalent reversible manner.

Einen möglichen Ansatzpunkt für eine antivirale Therapie gegen SARS-Coronaviren bildet die Hemmung der Cysteinproteasen SARS-CoV-Mpro und SARS-CoV-PLpro. Diese übernehmen die Polyprotein-Spaltung während der Virusreplikation und sind damit essentiell für das Überleben und die Verbreitung des Virus. Im Rahmen dieser Arbeit wurden potentielle Inhibitoren der SARS-CoV-Mpro synthetisiert, die Pyridin-, Piperidin-, Pyrrolidin-, Pyridylessigsäure- und Thiazol-Derivate als Grundbausteine enthalten. Durch Strukturmodifikationen wurde eine Serie neuer Verbindungen erhalten, deren inhibitorische Aktivitäten in fluorimetrischen Assays (FRET-Assays) an den Enzymen SARS-CoV-Mpro und SARS-CoV-PLpro untersucht wurden. Weiterhin wurden Testungen an Coronaviren, den Protozoen Leishmania major und Typanosoma brucei brucei und an Makrophagen durchgeführt. Die synthetisierten Verbindungen wurden in sechs Strukturklassen eingeteilt. Strukturklasse 1 enthält Pyridin-, Piperidin-, Pyrrolidin- und Pyridylessigsäure-Derivate ohne Seitenkette in α-Position. Diese bestehen aus einem peptidischen Carbonsäure-Fragment mit N-Heterozyklus. Die Strukturklasse 2 bilden Pyridylessigsäure-Derivate mit einer zusätzlichen aliphatischen Seitenkette in α-Position zur Carboxylfunktion. Die Seitenkette sollte durch Adressierung der S1‘- bzw. S2‘-Bindetasche der SARS-CoV-Mpro die Affinität zum Enzym erhöhen. In den Strukturklassen 3 bis 6 bilden Thiazolamide das bestimmende Strukturelement. In der Strukturklasse 3 kamen dabei unterschiedlich substituierte aromatische Carbonsäuren zum Einsatz, die mit einer Reihe 4,5-substituierter Thiazolamine verknüpft wurden. In den übrigen Stoffklassen, in denen ausschließlich 5-Acetyl-4-methylthiazolamin als Amin-Fragment diente, wurde der Einfluss von Säure-Bausteinen ohne Michael-System (Strukturklasse 4) bzw. mit Michael-System (Strukturklasse 5), sowie die Einführung einer Seitenkette am Benzolring oder am Michael-System (Strukturklasse 6) untersucht. Bei den durchgeführten Enzymassays an der SARS-CoV-Mpro zeigten die synthetisierten Verbindungen insgesamt nur eine geringe Hemmung der Protease (<30 %, 20 µM). Daher lassen sich aus den erhaltenen Ergebnissen keine Struktur-Wirkungsbeziehungen ableiten. Dennoch sind in den Ergebnissen Trends erkennbar. Alle aktiven Verbindungen (Hemmung >10 % bei 20 μM) der Pyridin-, Pyrrolidin-, Piperidin- und Pyridylessigsäure-Derivate enthielten als Strukturmerkmal größere Seitenketten wie n-Pentyl, Cyclopropylmethyl und Crotyl (Strukturklasse 2). Bei den Thiazolamiden der Strukturklassen 3-6 führte die Einführung eines Michael-Systems in der Strukturklasse 5 zu etwas aktiveren Verbindungen. Den größten Einfluss auf die Aktivität zeigte jedoch die Einführung einer Seitenkette in α-Postion zur Carboxylgruppe (Strukturklasse 6). In den Strukturklassen 3 und 4 erwiesen sich nur sehr wenige Verbindungen als aktiv. / Potential targets in antiviral therapy against SARS are the viral cysteine proteases SARS-CoV-Mpro and SARS-CoV-PLpro which are essential enzymes for the viability and the propagation of the virus. These are outstanding targets for the development of new protease inhibitors as antiviral drugs due to the cleavage of the polyprotein encoded by the viral RNA. The main goal of this work was the synthesis of potential inhibitors of SARS-CoV-Mpro which are comprised of pyridine-, piperidine-, pyrrolidine-, pyridyl acetic acid- and thiazole-building blocks. By structural modifications, series of new chemical entities have been synthesized and tested in fluorometric enzyme assays (FRET-assays) for inhibition of SARS-CoV-Mpro and SARS-CoV-PLpro. They were also tested against SARS-coronavirus, the protozoa Leishmania major and Typanosoma brucei brucei and macrophages. These compounds can be subdivided into six structural classes The class 1 contains pyridine-, pyrrolidine-, piperidine- and pyridyl acetic acid-derivatives without a side chain in the α-position. They consist of a carboxylic acid fragment attached to a N-heterocycle. Class 2 compounds are pyridyl acetic acid-derivatives containing an additional aliphatic side chain in α-position to the carboxylic function. Introduction of this side chain was supposed to enhance the affinity of the compound to the enzyme by addressing the S1‘-/S2‘-binding pockets of SARS-CoV-Mpro. In classes 3-6 thiazole amides are the essential structural element. Class 3 comprises thiazole amides with varying aromatic carboxylic acids linked to 4,5-substituted thiazole amines. The classes 4-6 contain 5-acetyl-4-methylthiazolamine as amine fragment with acetic acid building blocks without double bond (class 4), with double bond (class 5) as well as building blocks with an additional side chain attached to the aromatic system or the double bond (class 6). In general, all compounds showed only poor inhibition in enzyme assays with SARS-CoV-Mpro (<30 %, 20 µM). For this reason no clear structure-activity-relationship (SAR) can be deduced, nevertheless the results show some trends. All active compounds (inhibition >10 % at 20 µM) of pyridine-, pyrrolidine-, piperidine- and pyridyl acetic acid-derivatives comprise longer side chains like n-pentyl, cyclopropylmethyl and crotyl (class 2). Examining the thiazole amides of classes 3-6 the introduction of a double bond (class 5) lead to slightly more active compounds. However, the highest influence on protease activity is found with compounds containing a side chain in α-postion to the carboxylic function (class 6). Within classes 3 and 4 only few compounds are active.

Um Wirkstoffe gegen das SARS-Coronavirus zu erhalten, wurden in dieser Arbeit Proteaseinhibitoren gegen die SARS-CoV-PLpro entwickelt. Ein Ansatz um neue Wirkstoffe gegen HIV zu finden, wurde über eine versuchte Blockade von Elongin-C beschritten. Bei der computergestützten Suche nach neuen SARS-CoV-PLpro-Inihibitoren wurde zunächst die strukturell bekannte Ligand-Bindetasche analysiert, und nach Evaluation des Dockingprozesses wurden mehrere Screeningprojekte an den Röntgenkristallstrukturen 3E9S und 3MJ5 durchgeführt. Von 24 kommerziell erworbenen Screening-Verbindungen riefen 7 eine Störung des beim Enzymassay gemessenen Fluoreszenzsignals hervor (Quenching bzw. Eigenfluoreszenz). Letztlich konnte den beiden inhibitorisch aktiven Imidazolderivaten B6 und B9 je ein IC50-Wert von etwa 50 µM zugewiesen werden. Das Imidazolscaffold eröffnet damit eine neue Substanzklasse zur Inhibition der SARS-CoV-PLpro. Im präparativ-chemischen Teil des SARS-Projekts wurden weitere Substanzklassen dargestellt, von denen die Inhibitoren vom Benzamid-Typ und Isoindolin-Typ eine Hemmung im einstelligen Mikromolaren Bereich (IC50) zeigten. Die Isoindolin-Derivate sind damit eine weitere, in dieser Arbeit entwickelte Leitstruktur zur Hemmung der SARS-CoV-PLpro. Bei der Suche nach einem Wirkstoff gegen HIV-1 wurde die neue Zielstruktur Elongin-C zur Inhibition durch niedermolekulare Liganden ausgewählt. Vier virtuelle Screeningprojekte führten zur Bestellung von 27 Verbindungen. Die durchgeführten Untersuchungen lassen noch keine abschließende Beurteilung der Ergebnisse zu, und der bisherige Zellassay wird noch durch spezifischere Methoden zur Bestimmung einer Ligandbindung an Elongin-C ergänzt werden. Falls es gelingt, einer der Verbindungen Elongin-C-blockierende Aktivität nachzuweisen, sind aufgrund des Eingriffs in einen zellulären Mechanismus neben der anti-HIV-Wirkung noch weitere pharmakologische Effekte denkbar, und das therapeutische Potenzial eines solchen Stoffs könnte in zukünftigen Experimenten erforscht werden. / In this work protease inhibitors for SARS-CoV-PLpro were developed to find new active drugs against the SARS-Coronavirus. A new approach in combatting HIV was tried by blocking elongin-C. The computer-aided search for new SARS-CoV-PLpro inhibitors began with the analysis of the structurally known ligand binding pocket. After evaluation of the docking process, several virtual screening projects were performed with the X-ray structures 3E9S and 3MJ5. 24 compounds were purchased and tested for enzyme inhibition against SARS-CoV-PLpro. The fluorimetric assay was affected by 7 of the 24 compounds (quenching or fluorescence), and finally two screening hits, the imidazole derivatives B6 and B9, were found to be active with IC50 values around 50 µM. This imidazole scaffold opens up a novel class of substances displaying inhibitory activity against SARS-CoV-PLpro. In the preparative chemical part of the SARS project, further substance classes were developed. Of these, the inhibitors with the benzamide scaffold and the isoindoline scaffold displayed an inhibitory potency in the low micromolar range (IC50). Thus, the isoindoline scaffold is another lead structure developed in this work to inhibit SARS-CoV-PLpro. In the HIV project elongin-C was chosen as a new target protein and small molecules were searched to inhibit the protein-protein interaction interface of elongin-C. Four virtual screening projects led to 27 commercially available compounds. The results of the cell assays do not yet allow a concluding judgement and will be extended through further investigation. If one of the compounds displays elongin-C blocking activity, several pharmacological effects besides the anti-HIV action should be considered, as elongin-C is part of the cellular mechanism. Thus, further experiments could explore the therapeutic potential of a drug blocking cellular elongin-C.

The research desires to evaluate the preventing policies on emerging infectious diseases by system dynamics, and takes the SARS situation in Taiwan for example. According to epidemiology and everything about SARS, we build the model of SARS transmission and prevention. Therefore we can simulate the situation and policies, and find the effective policies. After the simulation and the evaluation, we find that most SARS patients at later stage are affected in hospital. For the reason, the most effective policies are the ¡uPolicy about enhancing protection abilities in hospital¡v and ¡uPolicy about reducing the interaction with people in hospital¡v. Furthermore, the effectiveness of ¡uQuarantine policies¡v is not stronger than the above policies. The most important thing is that we discover Taiwan is very lucky, because the infectivity is very low (about 3.7%). If the infectivity of SARS were as high as 10% and we still took the same policies as we took in 2003, the situation would be terrible. Anyway, when we confront this kind of emerging infectious diseases, the better way is taking policies in hospital intently.

Thesis (M. Med. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 61-67).

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences