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

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 mu g/mL, while compounds 1-3, and 5-7 displayed inhibitory activities against the other bacteria with MIC range of 25 similar to 100 mu g/mL. Meanwhile, compound 6 showed potent hydroxyl radical-scavenging activity with EC50 value of 15.1 mu g/mL, while compounds 5-7 showed certain ferric reducing ability.

Automated summary

Several compounds isolated from the endophytic fungus Xylomelasma sp. Samif07 showed significant antibacterial, antitubercular, and antioxidant activities, indicating their potential as natural products for drug development.