Diphenyl Ether Derivative Rhexocerins and Rhexocercosporins from the Endophytic Fungus Rhexocercosporidium sp. Dzf14 Active against Gram-Positive Bacteria with Multidrug-Resistance

Ten new diphenyl ether polyketides, including rhexocerins A–D ( 1 – 4 ) and rhexocercosporins A–F ( 5 – 10 ), together with three known congeners ( 11 – 13 ), were isolated from the endophytic fungus Rhexocercosporidium sp. Dzf14 obtained from Dioscorea zingiberensis . Their structures were elucidated by analysis of NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography. Compounds 1 – 4 featured an unprecedented tetracyclic carbon skeleton (6/7/5/6). Among them, compounds 1 and 5 – 9 showed antibacterial activities against methicillin-resistant S. aureus T144 and vancomycin-resistant E. faecalis 10.