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Chromone and isocoumarin derivatives from the endophytic fungus Xylomelasma sp. Samif07, and their antibacterial and antioxidant activities

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journal contribution
posted on 29.11.2019 by Daowan Lai, Jing Li, Siji Zhao, Gan Gu, Xiao Gong, Peter Proksch, Ligang Zhou

Five chromone derivatives, including 2,6-dimethyl-5-methoxyl-7-hydroxylchromone (1), 6-hydroxymethyleugenin (2), 6-methoxymethyleugenin (3), chaetoquadrin D (4), and isoeugenitol (5), and three isocoumarin congeners, namely diaporthin (6), 8-hydroxy-6-methoxy-3-methylisocoumarin (7), and 6-methoxymellein (8), were isolated from the culture of the endophytic fungus Xylomelasma sp. Samif07 derived from the medicinal plant Salvia miltiorrhiza Bunge. Among them, compound 1 was a new natural product. Their structures were determined by spectroscopic methods and comparison with the literature. The isolated compounds were evaluated for their antibacterial and antioxidant activities. Compound 5 showed notable antitubercular activity against Mycobacterium tuberculosis with MIC value of 10.31 µg/mL, while compounds 13, and 57 displayed inhibitory activities against the other bacteria with MIC range of 25 ∼ 100 µg/mL. Meanwhile, compound 6 showed potent hydroxyl radical-scavenging activity with EC50 value of 15.1 µg/mL, while compounds 57 showed certain ferric reducing ability.


This work was partially supported by the National Key R&D Program of China (grant number 2017YFD0201105).