As a continue investigation of the bioactive secondary metabolites from marine derived fungi, two new anthraquinone dimers (1, 2), along with three known anthraquinones (3-5) and two known xanthones (6, 7) were isolated from the marine-derived fungus Aspergillus versicolor. Their structures, including the absolute configurations, were elucidated by NMR, HRMS, and comparison with reported ones. Among them, compounds 1 and 2 were identified as anthraquinone dimers which dimerized by a rare C-O-C ether linkage, and both of them showed selective antibacterial activity against Gram-positive Staphylococcus aureus; whilst compound 6 exhibited moderate cytotoxicity against human cancer cell lines.
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http://dx.doi.org/10.1016/j.fitote.2018.11.015 | DOI Listing |
Biomolecules
October 2024
Institute of Medical Physics, University of Szeged, 6720 Szeged, Hungary.
The pH dependence of the free energy level of the flash-induced primary charge pair PI was determined by a combination of the results from the indirect charge recombination of PQ and from the delayed fluorescence of the excited dimer (P*) in the reaction center of the photosynthetic bacterium , where the native ubiquinone at the primary quinone binding site Q was replaced by low-potential anthraquinone (AQ) derivatives. The following observations were made: (1) The free energy state of PI was pH independent below pH 10 (-370 ± 10 meV relative to that of the excited dimer P*) and showed a remarkable decrease (about 20 meV/pH unit) above pH 10. A part of the dielectric relaxation of the PI charge pair that is not insignificant (about 120 meV) should come from protonation-related changes.
View Article and Find Full Text PDFChem Biol Drug Des
September 2024
School of Pharmaceutical Sciences, Changchun University of Chinese Medicine, Changchun, Jilin, China.
ACS Appl Mater Interfaces
October 2024
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
We study the capacity fade rate of a flow battery utilizing 2,6-dihydroxyanthraquinone (DHAQ) and its dependence on hydroxide concentration, state of charge, cutoff voltages for the discharge step and for the electrochemical regeneration (oxidation of decomposition compounds back to active species) step, and the period of performing the electrochemical regeneration events. Our observations confirm that the first decomposition product, 2,6-dihydroxyanthrone (DHA), is stable, but after electro-oxidative dimerization, the anthrone dimer decomposes. We identify conditions for which there is little time after dimerization until the dimer is rapidly reoxidized electrochemically to form DHAQ.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Institute of Pharmaceutical Sciences, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, 79104, Freiburg, Germany.
Bioactive dimeric (pre-)anthraquinones are ubiquitous in nature and are found in bacteria, fungi, insects, and plants. Their biosynthesis via oxidative phenol coupling (OPC) is catalyzed by cytochrome P450 enzymes, peroxidases, or laccases. While the biocatalysis of OPC in molds (Ascomycota) is well-known, the respective enzymes in mushroom-forming fungi (Basidiomycota) are unknown.
View Article and Find Full Text PDFMar Drugs
June 2024
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
A new dimeric C-glycoside polyketide chrysomycin F (), along with four new monomeric compounds, chrysomycins G (), H (), I (), J (), as well as three known analogues, chrysomycins A (), B (), and C (), were isolated and characterised from a strain of sp. obtained from a sediment sample collected from the South China Sea. Their structures were determined by detailed spectroscopic analysis.
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