Antibacterial diketopiperazines from an endophytic fungus Bionectria sp. Y1085

Two new diketopiperazines ( 1 , 2 ), one new polyprenol ( 3 ), together with 19 known compounds ( 4 – 22 ) were obtained from the EtOAc extract of Bionectria sp. Y1085, an endophytic fungus isolated from the plant Huperzia serrata . Their structures were elucidated by extensive NMR and MS analysis. Bionectin D ( 1 ) is a rare diketopiperazine with a single methylthio substitution at the α -carbon of cyclized amino acid residue. The antibacterial activity of compounds was assayed against Escherichia coli , Staphylococcus aureus , and Salmonella typhimurium ATCC 6539, and some metabolites ( 1 , 2 , 10 , 11 , and 14 ) exhibited evident antibacterial activity.