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Secondary metabolites of the lichen-associated fungus Apiospora montagnei

Wang, Hao, Umeokoli, Blessing O., Eze, Peter, Heering, Christian, Janiak, Christoph, Müller, Werner E.G., Orfali, Raha S., Hartmann, Rudolf, Dai, Haofu, Lin, Wenhan, Liu, Zhen, Proksch, Peter
Tetrahedron letters 2017 v.58 pp. 1702-1705
Apiospora montagnei, Cladonia, X-ray diffraction, ammonium chloride, chemical reactions, chemical structure, cytotoxicity, diterpenoids, fungi, inhibitory concentration 50, lichens, mice, neoplasm cells, nuclear magnetic resonance spectroscopy, rice, secondary metabolites, sodium chloride, xanthone
The endolichenic fungus Apiospora montagnei isolated from the lichen Cladonia sp. was cultured on solid rice medium, yielding the new diterpenoid libertellenone L (1), the new pyridine alkaloid, 23-O-acetyl-N-hydroxyapiosporamide (2) and the new xanthone derivative 8-hydroxy-3-hydroxymethyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ether (3) together with 19 known compounds (4–22). The structures of the new compounds were elucidated by 1D and 2D NMR spectra as well as by HRESIMS data. The absolute configuration of the new 6,7-seco-libertellenone derivative 1 was determined by single-crystal X-ray diffraction. Four additional known compounds 23–26 were isolated when NaCl or NH4Cl were added to solid rice medium. Compounds 7–9, 18 and 26 exhibited significant cytotoxicity against the L5178 murine lymphoma cell line with IC50 values of 2.6, 0.2, 2.1, 2.7 and 1.7μM, respectively.