Five new preussomerin analogues, ymf 1029A (1), B (2), C (3), D (4), and E (5), were isolated from the liquid cultures of an unidentified freshwater fungus YMF 1.01029, along with four known compounds, preussomerin C (6), preussomerin D (7), (4RS)-4,8-dihydroxy-3,4-dihydronaphthalen-1(2H)-one (8), and 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one (9). The structures of new metabolites were determined by analysis of NMR and MS data and by analogy with the data for the known bis-spirobisnaphthalene preussomerins. In vitro immersion experiments showed that these metabolites displayed weak nematicidal activity against Bursaphelenchus xylophilus, while compound 7 was the most potent. This is the first report of these compounds, which antagonize the Bursaphelenchus xylophilus nematode.
Three new naphthoquinones, astropaquinones A-C (1-3), were isolated from cultures of the freshwater fungus Astrosphaeriella papuana YMF 1.01181, together with the known compound, 6-hydroxy-2,4-dimethoxy-7-methylanthraquinone (4). The structures of the compounds were settled mainly by interpretation of their 1D and 2D NMR spectra. Astropaquinone B (2) and C (3) were found to possess a rare pyranonaphthoquinone skeleton containing a lactol ring. Furthermore, compounds 1-4 showed moderate antagonistic activity against nine fungi and four bacterial strains.
The EtOAc extracts of cultural filtrates of 30 freshwater fungi were assayed for the in vitro antibacterial activity against Bacillus cereus YMF 3.19, Brevibacillus laterosporus YMF 3.08, Escherichia coli YMF 3.16, Staphylococcus aureus YMF 3.17 using the disc diffusion method. A total of 14 fungal strains displayed active against all of the bacteria tested and the strongest antibacterial activity was recorded in Camposporium quercicola YMF1.01300 isolate. Extraction of fermentation broth of C. quercicola YMF1.01300 and various separation and purification steps led to isolation of three pure active molecules. The chemical structures of these three compounds, a new diphenyl ether, named as quercilolin (compound 1), as well as two previously known compounds, tenellic acid A (compound 2), and 2',4'-dihydroxyacetophenone (compound 3), were established by analysis of NMR and MS data, and by comparison with reference data from the literature. These results indicate that some freshwater fungi could be a potential source of antibacterial agents.
Combined time-frequency peak filtering with wavelet modulus maxima, the millimeter wave interferometer echo signal process is presented, extracting the instantaneous frequency(IF) of the projectile in-bore. Based on that, the projectile’s velocity and acceleration curves are estimated and the length of the cannon is also calculated that’s consistent with the actual, which provides a strong basis for designing and improving weapons. And this approach ,with some commonality, can also be used to extract the IF of other signals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.