Dokument: Secondary Metabolites from the Endophytic Fungus Aplosporella javeedii
| Titel: | Secondary Metabolites from the Endophytic Fungus Aplosporella javeedii | |||||||
| Weiterer Titel: | Sekundärmetaboliten aus dem endophytischen Pilz Aplosporella javeedii | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=55562 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20210301-113012-8 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Dr. Gao, Ying [Autor] | |||||||
| Dateien: |
| |||||||
| Beitragende: | Prof. Dr. Proksch, Peter [Gutachter] Prof. Dr. Kalscheuer, Rainer [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibungen: | Im Verlauf der langfristigen Koexistenz und Evolution zwischen endophytischen Pilzen und Wirtspflanzen, insbesondere Heilpflanzen, haben sich endophytische Pilze entwickelt, die eine große Anzahl verschiedener Arten von Sekundärmetaboliten mit neuartigen Strukturen und z. T. herausragenden biologischen Aktivitäten produzieren. Unter diesen bieten insbesondere ungewöhnliche und selten erforschte endophytische Pilze die Möglichkeit, neue Naturstoffe zu entdecken, die bei der Entdeckung von pharmazeutisch relevanten Leitstrukturen hilfreich sein können. Während unserer Forschung zu Sekundärmetaboliten aus endophytischen Pilzen wurde der bisher selten untersuchte Endophyt Aplosporella javeedii aus der traditionellen chinesischen Heilpflanze Orychophragmus violaceus (L.) O. E. Schul (Brassicaceae) isoliert. Die an dieser Dissertation beteiligten Projekte befassten sich schwerpunktmäßig mit der Isolierung und Identifizierung bioaktiver Sekundärmetaboliten aus der axenischen Kultur von A. javeedii sowie aus OSMAC Pilzkulturen mit dem Ziel, die chemische Vielfalt der sekundären Pilzmetaboliten zuerweitern. Die Strukturen der isolierten Sekundärmetaboliten wurden durch 1D, 2D NMR Spektroskopie und Massenspektrometrie sowie durch DFT-NMR, TDDFT-ECD und SOR Berechnungen aufgeklärt. Die isolierten Verbindungen wurden auf ihre Zytotoxizität gegen die L5178Y Tumorzelllinie sowie gegen humane Jurkat J16 und Ramos Tumorzellen untersucht. Darüber hinaus wurden ihre antimikrobiellen Aktivitäten gegen Candida albicans, Mycobacterium tuberculosis H37Rv, Staphylococcus aureus, Acinetobacter baumannii und andere Stämme getestet.
Zusammenfassend wurden 13 Naturstoffe, darunter 9 neue Verbindungen, aus der axenischen Fermentation von A. javeedii isoliert, während 12 Naturstoffe, darunter 11 neue Verbindungen aus der OSMAC Fermentation von A. javeedii auf festem Reismedium in Gegenwart von NaNO3 oder Mononatrium Glutamat isoliert wurden. Diese Dissertation spiegelt die Ergebnisse von drei Manuskripten wider: Antifungal polyketide derivatives from the endophytic fungus Aplosporella javeedii (Ying Gao, Lin Wang, Rainer Kalscheuer, Zhen Liu, and Peter Proksch. Bioorganic & Medicinal Chemistry, 2020, 28, 115456.) Six new polyketides aplojaveediins A–F (1–6) were isolated from the endophytic fungus Aplosporella javeedii associated with the host plant Orychophragmus violaceus (Brassicaceae). The structures of the new metabolites were elucidated by analysis of their NMR and MS data. Compound 1 exhibited antifungal activity against the hyphae form of Candida albicans strain ATCC 24433 in the agar plate diffusion assay and the microbroth dilution assay. The kinetic of killing of C. albicans cells for compound 1 was considerably faster than that of the positive control hygromycin B. Compounds 1 and 6 also exhibited moderate antibacterial activities against sensitive (ATCC 29213) and drug-resistant (ATCC 700699) strains of Staphylococcus aureus. Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii (Ying Gao, Fabian Stuhldreier, Laura Schmitt, Sebastian Wesselborg, Lin Wang, Werner E. G. Müller, Rainer Kalscheuer, Zhiyong Guo, Kun Zou, Zhen Liu, Peter Proksch. Fitoterapia, 2020, 146, 104652.) Five sesterterpenes (1–5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 μM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong cytotoxicity against the L5178Y cell line, as well as against human Jurkat J16 and Ramos cells with IC50 values of 0.4, 5.8, and 4.4 μM, respectively. Mechanistic studies indicated that 7 induces apoptotic cell death. In addition, compounds 3, 4 and 7 showed low antibacterial activities against Mycobacterium tuberculosis H37Rv and compound 6 against Staphylococcus aureus, respectively, with MICs of 100 μM. Preliminary structure-activity relationships are discussed. Induction of new lactam derivatives from the endophytic fungus Aplosporella javeedii through an OSMAC approach (Ying Gao, Fabian Stuhldreier, Laura Schmitt, Sebastian Wesselborg, Zhiyong Guo, Kun Zou, Attila Mándi, Tibor Kurtán, Zhen Liu, and Peter Proksch. Frontiers in Microbiology, 2020, 11, 600983.) Fermentation of the endophytic fungus Aplosporella javeedii on solid rice medium in presence of either 3.5% NaNO3 or 3.5% monosodium glutamate caused a significant change of the fungal metabolite pattern compared to fungal controls grown only on rice. Chemical investigation of the former fungal extracts yielded 11 new lactam derivatives, aplosporellins A–K (2–12), in addition to the known compound, pramanicin A (1). All of these compounds were not detected when the fungus was grown on rice medium without these activators thereby indicating the power of this OSMAC approach. The structures of the new compounds were elucidated by one- and two- dimensional NMR spectroscopy, DFT-NMR calculations and by mass spectrometry as well as by comparison with the literature whereas the absolute configuration of the lactam core was determined by TDDFT-ECD and OR calculations. Pramanicin A (1) showed strong cytotoxicity against human lymphoma (Ramos) and leukemia (Jurkat J16) cells with IC50 values of 4.7 and 4.4 μM, respectively. Mechanistic studies indicated that 1 activates caspase-3 and induces apoptotic cell death.In the process of long-term coexistence and evolution between endophytic fungi and host plants, especially medicinal plants, endophytic fungi have evolved to produce a large number of various types of secondary metabolites with novel structures and prominent biological activities. Among them, unusual and rarely studied endophytic fungi can provide opportunities to discover new natural products that can be helpful in the discovery of lead structures. During our research on secondary metabolites from endophytic fungi, the endophyte Aplosporella javeedii, which had hardly been studied so far, was isolated from the traditional Chinese medicinal plant Orychophragmus violaceus (L.) O. E. Schul (Brassicaceae).The projects involved in this dissertation mainly focus on the isolation and identification of bioactive secondary metabolites from the axenic culture of A. javeedii, as well as from OSMAC fungal cultures aiming at enhancing the chemical diversity of fungal secondary metabolites. The structures of the isolated secondary metabolites were elucidated by 1D, 2D NMR spectroscopy and by mass spectrometry, as well as by DFT-NMR, TDDFT-ECD and SOR calculations. The pure compounds were investigated for their cytotoxicity against the L5178Y tumor cell line, as well as against human Jurkat J16 and Ramos tumor cells. Moreover, their antimicrobial activities were tested against Candida albicans, Mycobacterium tuberculosis H37Rv, Staphylococcus aureus, Acinetobacter baumannii and other strains. In summary, 13 natural products including 9 new compounds were isolated from the axenic fermentation of A. javeedii, whereas 12 natural products including 11 new compounds were isolated from the OSMAC fermentation of A. javeedii on solid rice medium in the presence of NaNO3 or monosodium glutamate. This dissertation reflects the results from three manuscripts. The following abstracts are excerpts from the respective manuscripts: Antifungal polyketide derivatives from the endophytic fungus Aplosporella javeedii (Ying Gao, Lin Wang, Rainer Kalscheuer, Zhen Liu, and Peter Proksch. Bioorganic & Medicinal Chemistry, 2020, 28, 115456.) Six new polyketides aplojaveediins A–F (1–6) were isolated from the endophytic fungus Aplosporella javeedii associated with the host plant Orychophragmus violaceus (Brassicaceae). The structures of the new metabolites were elucidated by analysis of their NMR and MS data. Compound 1 exhibited antifungal activity against the hyphae form of Candida albicans strain ATCC 24433 in the agar plate diffusion assay and the microbroth dilution assay. The kinetic of killing of C. albicans cells for compound 1 was considerably faster than that of the positive control hygromycin B. Compounds 1 and 6 also exhibited moderate antibacterial activities against sensitive (ATCC 29213) and drug-resistant (ATCC 700699) strains of Staphylococcus aureus. Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii (Ying Gao, Fabian Stuhldreier, Laura Schmitt, Sebastian Wesselborg, Lin Wang, Werner E. G. Müller, Rainer Kalscheuer, Zhiyong Guo, Kun Zou, Zhen Liu, Peter Proksch. Fitoterapia, 2020, 146, 104652.) Five sesterterpenes (1–5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 μM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong cytotoxicity against the L5178Y cell line, as well as against human Jurkat J16 and Ramos cells with IC50 values of 0.4, 5.8, and 4.4 μM, respectively. Mechanistic studies indicated that 7 induces apoptotic cell death. In addition, compounds 3, 4 and 7 showed low antibacterial activities against Mycobacterium tuberculosis H37Rv and compound 6 against Staphylococcus aureus, respectively, with MICs of 100 μM. Preliminary structure-activity relationships are discussed. Induction of new lactam derivatives from the endophytic fungus Aplosporella javeedii through an OSMAC approach (Ying Gao, Fabian Stuhldreier, Laura Schmitt, Sebastian Wesselborg, Zhiyong Guo, Kun Zou, Attila Mándi, Tibor Kurtán, Zhen Liu, and Peter Proksch. Frontiers in Microbiology, 2020, 11, 600983.) Fermentation of the endophytic fungus Aplosporella javeedii on solid rice medium in presence of either 3.5% NaNO3 or 3.5% monosodium glutamate caused a significant change of the fungal metabolite pattern compared to fungal controls grown only on rice. Chemical investigation of the former fungal extracts yielded 11 new lactam derivatives, aplosporellins A–K (2–12), in addition to the known compound, pramanicin A (1). All of these compounds were not detected when the fungus was grown on rice medium without these activators thereby indicating the power of this OSMAC approach. The structures of the new compounds were elucidated by one- and two- dimensional NMR spectroscopy, DFT-NMR calculations and by mass spectrometry as well as by comparison with the literature whereas the absolute configuration of the lactam core was determined by TDDFT-ECD and OR calculations. Pramanicin A (1) showed strong cytotoxicity against human lymphoma (Ramos) and leukemia (Jurkat J16) cells with IC50 values of 4.7 and 4.4 μM, respectively. Mechanistic studies indicated that 1 activates caspase-3 and induces apoptotic cell death. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät | |||||||
| Dokument erstellt am: | 01.03.2021 | |||||||
| Dateien geändert am: | 01.03.2021 | |||||||
| Promotionsantrag am: | 05.12.2020 | |||||||
| Datum der Promotion: | 28.01.2021 |
