A new depsidone derivative botryorhodine J (1), along with six known compounds (2-7) were obtained from solid rice cultures of Alternaria alternata Pas11 that was isolated from leaves of Phragmites australis. The structure of the new compound was elucidated on the basis of combination of NMR spectroscopic data and high resolution mass spectrometry (HRMS). All the isolated compounds were evaluated for their antibacterial activities against a panel of Gram-positive bacterial strains (methicillin-resistant Staphylococcus aureus [MRSA], Bacillus subtilis and S. aureus). Compounds 1 and 6 displayed antibacterial activity against the three bacterial strains with the minimum inhibitory concentration values (MICs) of 14 - 32 μg/mL, while compound 5 showed good antibacterial activity against above bacterial strains with MIC values of 5 - 8 μg/mL.
Keywords: Alternaria alternata; Phragmites australis; antibacterial activity; botryorhodine J; endophytic fungus.