One new rearranged pyranone derivative with antibacterial activity from Xylaria curta YSJ-5

The further chemical investigation of the liquid fermentation of endophytic fungus Xylaria curta , which was isolated from the medicinal plant Alpinia zerumbet B. L. Burtt & R. M. Sm., had led to the isolation of one novel compound with the trivial name of xylacurtin A ( 1 ). The chemical structure was fully characterized by means of detailed spectroscopic analysis, which thus successfully revealed it to share an unprecedented 7-butyl-4-methoxyoxepin-2(5 H )-one skeleton. It represents the first member of rearranged pyranone derivative with a novel seven-membered ring system in nature. Moreover, the biological activity of xylacurtin A ( 1 ) were also evaluated to show that 1 was a promising antibacterial lead compound towards the Staphylococcus aureus and Methicillin-resistant S. aureus with the MIC value of 6.3 μg/mL without any notable cytotoxicity. • One new rearranged pyranone derivative was isolated from Xylaria curta YSJ-5. • Xylacurtin A was represented as the first member of methoxyoxepin-2(5 H)-one derivative. • Xylacurtin A inhibit S. aureus and MRSA (MIC=6.3 μg/ML).