Antibacterial Diphenyl Ethers from Fungi Aspergillus versicolor YC-27

Microbial metabolites serve as a vital source for drug discovery, with diphenyl ether derivatives from Aspergillus sp. garnering significant attention due to their antimicrobial activities. This work focused on the antibacterial compounds from the fungi Aspergillus versicolor YC-27, which led to the isolation of one new diphenyl ether derivative, aspesicol (1), together with eight known compounds (2-9). The structure of the new compound was elucidated by spectroscopic methods, high-resolution electrospray ionization mass spectrometry, and nuclear magnetic resonance calculations with DP4+ methods. In the in vitro bioassays, compounds 4, 5, and 9 exhibited good inhibitory activity against Staphylococcus aureus with minimum inhibitory concentration (MIC) values of 8 µg/mL, and compound 6 showed potent inhibitory activity against S. aureus with MIC value of 4 µg/mL. These diphenyl ether derivatives demonstrating significant antimicrobial activity, particularly compound 6, represent highly promising lead candidates for the development of therapeutic agents against multidrug-resistant bacterial infections.