Amphiphilic kanamycin is one of the promising class of compounds for the treatment of fungal infections in plants and animal. Factor that lead to the restricting of compounds for commercialization includes, the higher cost of production and poor stability of the compound. However, the new lead, identified from the synthesis and biological testing, can be synthesized on a large scale with a cost comparable to commercial antifungals. The newly reported lead is stable at the acidic and basic conditions. Additionally, this compound has an excellent activity towards Candida auris, a multidrug-resistant superbug. Heart disease is the leading cause of death in the United States most of which are caused by cardiac ischemia and arrhythmias. Abnormal opening of Cx43 hemichannel can damage the heart muscles and lead to these conditions. A compound which can selectively inhibit the opening of Cx43 hemichannel may pave the way to reducing the mortality rate of heart disease. A selective inhibitor towards Cx43 hemichannel is explored from the synthesis and biological testing of kanamycin derivatives. The synthesis of the new inhibitor is scalable and cost-effective.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17830号 / 農博第2015号 / 新制||農||1016(附属図書館) / 学位論文||H25||N4787(農学部図書室) / 30645 / 京都大学大学院農学研究科農学専攻 / (主査)教授 稲村 達也, 教授 冨永 達, 教授 奥本 裕 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

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Antibiotic resistance is a worldwide threat to human health yet fewer new antibiotics are being approved. New antimicrobial drugs are urgently required. 3 Deoxy-D-manno-2-octulosonate-8-phosphate synthase (KDO8PS) is a target for antimicrobial drug design. KDO8PS catalyzes the condensation of D-arabinose-5 phosphate (A5P) with phosphoenolpyruvate (PEP) to produce KDO8P. KDO8PS catalyzes the first committed step in the lipopolysaccharides (LPS) biosynthesis pathway in Gram-negative bacteria and is critical for bacterial pathogenicity/virulence. We have characterized KDO8PS from Campylobacter jejuni (cjKDO8PS), a new metal-dependent KDO8P synthase (KDO8PS). cjKDO8PS is a tetramer in solution and optimally active at pH 7.5 and 60 °C. We have kinetically established that cjKDO8PS follows a rapid equilibrium sequential ordered ter ter kinetic mechanism, where Mn2+ binds first, followed by PEP, then A5P. Pi dissociates first, before KDO8P, then Mn2+. cjKDO8PS was inhibited by KDO8P oxime, a novel slow tight-binding inhibitor. KDO8P oxime is a competitive inhibitor with respect to PEP and A5P, but uncompetitive with respect to Mn2+, with Ki = 10 ± 1 μM and an ultimate Ki* = 0.28 ± 0.10 μM. KDO8P oxime has a residence time (tR) of 5 days on the enzyme, a parameter that is highly correlated to in vivo efficacy. Crystallization conditions for the cjKDO8PS‧Mn2+‧KDO8P oxime complex have been found and can be optimized to obtain a crystal structure that shows how KDO8P oxime interacts with the active sites. / Thesis / Doctor of Science (PhD) / The relentless increase in global antibiotic resistance is, regrettably, not matched with an increase in new effective antibiotics. New antimicrobial drug discovery strategies are desperately needed. Enzymes are key targets for drug design because they catalyze the majority of biological processes. In this project we sought to study and inhibit the activity of KDO8P synthase (KDO8PS) from Campylobacter jejuni, a common cause of food poisoning. KDO8P synthase is a critical enzyme involved in the lipopolysaccharide (LPS) biosynthesis in Gram-negative bacteria. The LPS acts as a permeability barrier and is crucial for bacterial pathogenicity/virulence. We found that C. jejuni KDO8PS is potently inhibited by KDO8P oxime, a novel inhibitor of KDO8PS. This inhibitor presents a unique opportunity to study these enzymes and a platform from which antibiotics against Gram-negative bacteria can be developed.

In dieser Arbeit wurden zwei Klassen von analog-sensitiven (AS) Kinaseinhibitoren, welche wichtige pharmakologische Instrumente für die Untersuchung von Signalwegen darstellen, durch den Einbau von lichtempfindlichen Komponenten in ihre Struktur photoschaltbar gemacht. Die Einführung eines Cyclohexa-1,3-diens anstelle des zentralen Benzolrings im Staralog-Grundgerüst ermöglicht eine reversible 6π Elektrozyklisierung analog zu Diarylethenen (DAEs). Nach der Entwicklung eines Synthesewegs führte die iterative Verbesserung des strukturellen Designs schließlich zu einer Reihe von Photoschaltern, die in reinem Wasser bestrahlt werden können. Eine detaillierte Untersuchung des photochemischen Verhaltens ergab effizientes Schalten für beide Bestrahlungsprozesse, was auf hohe Quantenausbeuten und eine ausreichende Bandenseparation zwischen beiden Isomeren zurückzuführen ist. Die vorgestellte Studie demonstriert das Potenzial von DAE-basierten Kinaseinhibitoren und stellt eine vielversprechende Möglichkeit dar, um die momentanen Einschränkungen anderer Photoschalterklassen zu überwinden. Um die katalytische Aktivität von TgCDPK1 zu kontrollieren, wurden auf Grundlage des 5-Aminopyrazol-4-carboxamid Gerüsts photoschaltbare Kinaseinhibitoren entwickelt, die auf einer lichtinduzierten E/Z Isomerisierung eines Arylazopyrazols basieren. Aus einer Bibliothek von synthetisierten Inhibitoren wurden die effektivsten Derivate identifiziert, die ein optimales Verhältnis zwischen guten photochemischen Eigenschaften und Affinität gegenüber der Kinase aufweisen. Tatsächlich konnte so eine reversible Kontrolle der katalytischen Aktivität von TgCDPK1 durch die Anwendung von Licht verschiedener Wellenlängen erreicht werden. Es wurde gezeigt, dass die Wirksamkeit dieser Inhibitoren stark mit der Größe des Gatekeeper-Rests korreliert, was die Möglichkeit einer universellen Anwendung dieses Konzepts für die selektive lichtinduzierte Kontrolle von AS Kinasen in der Zukunft eröffnet. / In this work two general classes of analog-sensitive (AS) kinase inhibitors, which constitute pharmacological key elements for studying kinase-mediated signaling pathways, were rendered photoresponsive by implementing two photoswitchable moieties into the scaffold of their corresponding parent inhibitors. Photoswitchability was introduced to the staralog inhibitor scaffold by implementing a cyclohexa-1,3-diene capable of undergoing 6πelectrocyclization analog to diarylethenes (DAEs). A robust synthetic route was established, and iterative improvement of the structural design eventually led to a set of photoswitches which can be readily operated in pure water. In depth investigation of the photochemical behavior revealed high quantum yields for both processes resulting in efficient photoswitching and sufficient band separation between both isomers. This investigation illustrates the potential of DAE-based kinase inhibitors and presents an attractive strategy to address current limitations of other photoswitch classes and currently employed DAE motifs. Furthermore, photoswitchable kinase inhibitors based on the 5-aminopyrazolo-4-carboxamide (PCA) scaffold were used to control the catalytic activity of TgCDPK1 utilizing light-induced structural changes of an arylazopyrazole. Within a library of synthesized small molecule inhibitors, the best candidates exhibiting an optimal balance between good photochemical properties and target affinity were identified. A substantial difference in IC50 values was achieved between both photostationary states and consequently, the catalytic activity of TgCDPK1 was controlled effectively in a reversible fashion by applying light of different wavelengths. The potency of these inhibitors strongly correlates with the size of the gatekeeper residue, highlighting the potential of these photoswitchable inhibitors for the selective light-induced control over AS kinases in the future.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第25190号 / 医博第5076号 / 新制||医||1072(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 伊藤 貴浩, 教授 藤田 恭之, 教授 武藤 学 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM