@article{SchlosserCibulkaGrossetal.2020, author = {Schlosser, Julika and Cibulka, Radek and Groß, Philipp and Ihmels, Heiko and Mohrschladt, Christian J.}, title = {Visible-Light-Induced Di-\(\pi\)-Methane Rearrangement of Dibenzobarrelene Derivatives}, series = {ChemPhotoChem}, volume = {4}, journal = {ChemPhotoChem}, number = {2}, doi = {10.1002/cptc.201900221}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212633}, pages = {132 -- 137}, year = {2020}, abstract = {It is demonstrated that the di-\(\pi\)-methane (DPM) rearrangement of carbonyl-substituted dibenzobarrelene (9,10-dihydro-9,10-ethenoanthracene) derivatives is induced by visible-light-induced triplet photosensitization with Ir(ppy)\(_{3}\), Ir(dFppy)\(_{3}\) or 1-butyl-7,8-dimethoxy-3-methylalloxazine as catalysts, whereas derivatives that lack carbonyl substituents are photoinert under these conditions. Notably, the products are formed almost quantitatively.}, language = {en} } @phdthesis{KimbadiLombe2021, author = {Kimbadi Lombe, Blaise}, title = {Novel-Type Dimeric Naphthylisoquinoline Alkaloids from Congolese Ancistrocladus Lianas: Isolation, Structural Elucidation, and Antiprotozoal and Anti-Tumoral Activities}, doi = {10.25972/OPUS-19178}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191789}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Herein described is the discovery of three novel types of dimeric naphthylisoquinoline alkaloids, named mbandakamines, cyclombandakamines, and spirombandakamines. They were found in the leaves of a botanically as yet unidentified, potentially new Ancistrocladus species, collected in the rainforest of the Democratic Republic of the Congo (DRC). Mbandakamines showed an exceptional 6′,1′′-coupling, in the peri-position neighboring one of the outer axes, leading to an extremely high steric hindrance at the central axis, and to U-turn-like molecular shape, which - different from all other dimeric NIQs, whose basic structures are all quite linear - brings three of the four bicyclic ring systems in close proximity to each other. This created an unprecedented follow-up chemistry, involving ring closure reactions, leading to two further, structurally even more intriguing subclasses, the cyclo- and the spirombandakamines, displaying eight stereogenic elements (the highest total number ever found in naphthylisoquinoline alkaloids). The metabolites exhibited pronounced antiplasmodial and antitrypanosomal activities. Likewise reported in this doctoral thesis are the isolation and structural elucidation of naphthylisoquinoline alkaloids from two further potentially new Ancistrocladus species from DRC. Some of these metabolites have shown pronounced antiausterity activities against human pancreatic cancer PANC-1 cells.}, subject = {Naphthylisochinolinalkaloide}, language = {en} } @article{WawraFeselWidmeretal.2016, author = {Wawra, Stephan and Fesel, Philipp and Widmer, Heidi and Timm, Malte and Seibel, J{\"u}rgen and Leson, Lisa and Kesseler, Leona and Nostadt, Robin and Hilbert, Magdalena and Langen, Gregor and Zuccaro, Alga}, title = {The fungal-specific beta-glucan-binding lectin FGB1 alters cell-wall composition and suppresses glucan-triggered immunity in plants}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms13188}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165945}, pages = {13188}, year = {2016}, abstract = {β-glucans are well-known modulators of the immune system in mammals but little is known about β-glucan triggered immunity in planta. Here we show by isothermal titration calorimetry, circular dichroism spectroscopy and nuclear magnetic resonance spectroscopy that the FGB1 gene from the root endophyte Piriformospora indica encodes for a secreted fungal-specific β-glucan-binding lectin with dual function. This lectin has the potential to both alter fungal cell wall composition and properties, and to efficiently suppress β-glucan-triggered immunity in different plant hosts, such as Arabidopsis, barley and Nicotiana benthamiana. Our results hint at the existence of fungal effectors that deregulate innate sensing of β-glucan in plants.}, language = {en} } @article{BaeumerKarthaAllampallyetal.2019, author = {B{\"a}umer, Nils and Kartha, Kalathil K. and Allampally, Naveen Kumar and Yagai, Shiki and Albuquerque, Rodrigo Q. and Fern{\´a}ndez, Gustavo}, title = {Kontrolle {\"u}ber Selbstassemblierung durch Ausnutzung von Koordinationsisomerie}, series = {Angewandte Chemie}, volume = {131}, journal = {Angewandte Chemie}, number = {44}, doi = {10.1002/ange.201908002}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212176}, pages = {15772 -- 15776}, year = {2019}, abstract = {Hierin wird die inh{\"a}rente geometrische Isomerie eines PtII Komplexes als neues Werkzeug zur Kontrolle von supramolekularen Assemblierungsprozessen ausgenutzt. Bestrahlung mit UV-Licht sowie die sorgf{\"a}ltige Auswahl des verwendeten L{\"o}sungsmittels, der Temperatur und Konzentration f{\"u}hren zu einer regelbaren Koordinationsisomerie. Dies erm{\"o}glicht ein vollst{\"a}ndig reversibles Schalten zwischen zwei definierten aggregierten Spezies (1D Fasern ↔ 2D Lamellen) mit unterschiedlichem photoresponsivem Verhalten. Unsere Erkenntnisse erweitern nicht nur die Reichweite von Koordinationsisomerie, sondern er{\"o}ffnen auch aufregende M{\"o}glichkeiten zur Entwicklung neuartiger stimuliresponsiver Materialien.}, language = {de} } @phdthesis{Rausch2021, author = {Rausch, Rodger}, title = {Chemistry of Chromophore Bridged Biradicals - Synthesis and Properties}, doi = {10.25972/OPUS-22650}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226501}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Within this PhD thesis, chromophore-bridged biradicals were synthesised and their properties characterised. Therefore, it was necessary to develop novel synthetic procedures and implement several experimental characterisation methods. In summary, within this thesis the scope of pigment chromophore phenoxyl radical decoration was further explored and expanded to IIn as well as DPP colourants. HOMA analysis highlighted the importance of aromaticity in order to understand the spin crossover from heteroaromatic quinoidal to aromatic open shell DPPs. Finally, PBI, IIn and DPP biradicals were advanced towards stable materials by introduction of nitronyl nitroxide radical centres.}, subject = {Biradikal}, language = {en} } @article{ZahranAlbohyKhaliletal.2020, author = {Zahran, Eman Maher and Albohy, Amgad and Khalil, Amira and Ibrahim, Alyaa Hatem and Ahmed, Heba Ali and El-Hossary, Ebaa M. and Bringmann, Gerhard and Abdelmohsen, Usama Ramadan}, title = {Bioactivity Potential of Marine Natural Products from Scleractinia-Associated Microbes and In Silico Anti-SARS-COV-2 Evaluation}, series = {Marine Drugs}, volume = {18}, journal = {Marine Drugs}, number = {12}, issn = {1660-3397}, doi = {10.3390/md18120645}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-220041}, year = {2020}, abstract = {Marine organisms and their associated microbes are rich in diverse chemical leads. With the development of marine biotechnology, a considerable number of research activities are focused on marine bacteria and fungi-derived bioactive compounds. Marine bacteria and fungi are ranked on the top of the hierarchy of all organisms, as they are responsible for producing a wide range of bioactive secondary metabolites with possible pharmaceutical applications. Thus, they have the potential to provide future drugs against challenging diseases, such as cancer, a range of viral diseases, malaria, and inflammation. This review aims at describing the literature on secondary metabolites that have been obtained from Scleractinian-associated organisms including bacteria, fungi, and zooxanthellae, with full coverage of the period from 1982 to 2020, as well as illustrating their biological activities and structure activity relationship (SAR). Moreover, all these compounds were filtered based on ADME analysis to determine their physicochemical properties, and 15 compounds were selected. The selected compounds were virtually investigated for potential inhibition for SARS-CoV-2 targets using molecular docking studies. Promising potential results against SARS-CoV-2 RNA dependent RNA polymerase (RdRp) and methyltransferase (nsp16) are presented.}, language = {en} } @article{WuerthnerNoll2021, author = {W{\"u}rthner, Frank and Noll, Niklas}, title = {A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation}, series = {Chemistry - A European Journal}, volume = {27}, journal = {Chemistry - A European Journal}, number = {1}, doi = {10.1002/chem.202004486}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230030}, pages = {444-450}, year = {2021}, abstract = {A cyclic dinuclear ruthenium(bda) (bda: 2,2'-bipyridine-6,6'-dicarboxylate) complex equipped with oligo(ethylene glycol)-functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)\(_2\)]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)\(_3\)]Cl\(_2\) as a standard photosensitizer revealed a turnover frequency of 15.5 s\(^{-1}\) and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water-soluble WOC for artificial photosynthesis.}, language = {en} } @article{WuerthnerMezaChinchaSchindleretal.2021, author = {W{\"u}rthner, Frank and Meza-Chincha, Ana-Lucia and Schindler, Dorothee and Natali, Mirco}, title = {Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles}, series = {ChemPhotoChem}, volume = {5}, journal = {ChemPhotoChem}, number = {2}, doi = {10.1002/cptc.202000133}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230116}, pages = {173-183}, year = {2021}, abstract = {Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light-driven water oxidation with a trinuclear Ru(bda) (bda: 2,2'-bipyridine-6,6'-dicarboxylate) macrocycle MC3 and its highly water soluble derivative m-CH\(_2\)NMe\(_2\)-MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady-state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS\(^+\) and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co-solvent.}, language = {en} } @article{SchindlerGil‐SepulcreLindneretal.2020, author = {Schindler, Dorothee and Gil-Sepulcre, Marcos and Lindner, Joachim O. and Stepanenko, Vladimir and Moonshiram, Dooshaye and Llobet, Antoni and W{\"u}rthner, Frank}, title = {Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi-Walled Carbon Nanotube Electrodes}, series = {Advanced Energy Materials}, volume = {10}, journal = {Advanced Energy Materials}, number = {43}, doi = {10.1002/aenm.202002329}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218381}, year = {2020}, abstract = {Catalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) catalyst, anchored on multi-walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm\(^{-2}\) at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X-ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s\(^{-1}\).}, language = {en} } @article{SolgerKunzFinketal.2020, author = {Solger, Franziska and Kunz, Tobias C. and Fink, Julian and Paprotka, Kerstin and Pfister, Pauline and Hagen, Franziska and Schumacher, Fabian and Kleuser, Burkhard and Seibel, J{\"u}rgen and Rudel, Thomas}, title = {A Role of Sphingosine in the Intracellular Survival of Neisseria gonorrhoeae}, series = {Frontiers in Cellular and Infection Microbiology}, volume = {10}, journal = {Frontiers in Cellular and Infection Microbiology}, issn = {2235-2988}, doi = {10.3389/fcimb.2020.00215}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204111}, year = {2020}, abstract = {Obligate human pathogenic Neisseria gonorrhoeae are the second most frequent bacterial cause of sexually transmitted diseases. These bacteria invade different mucosal tissues and occasionally disseminate into the bloodstream. Invasion into epithelial cells requires the activation of host cell receptors by the formation of ceramide-rich platforms. Here, we investigated the role of sphingosine in the invasion and intracellular survival of gonococci. Sphingosine exhibited an anti-gonococcal activity in vitro. We used specific sphingosine analogs and click chemistry to visualize sphingosine in infected cells. Sphingosine localized to the membrane of intracellular gonococci. Inhibitor studies and the application of a sphingosine derivative indicated that increased sphingosine levels reduced the intracellular survival of gonococci. We demonstrate here, that sphingosine can target intracellular bacteria and may therefore exert a direct bactericidal effect inside cells.}, language = {en} }