Antibacterial Cyclic Tripeptides from Antarctica-Sponge-Derived Fungus HDN151418.

Three new aspochracin-type cyclic tripeptides, sclerotiotides M-O (-), together with three known analogues, sclerotiotide L (), sclerotiotide F (), and sclerotiotide B (), were obtained from the ethyl acetate extract of the fungus HDN151418, which was isolated from an unidentified Antarctica sponge. Spectroscopic and chemical approaches were used to elucidate their structures. The absolute configuration of the side chain in compound was elucidated for the first time. Compounds and showed broad antimicrobial activity against a panel of pathogenic strains, including , , , , , , MRCNS, and MRSA, with MIC values ranging from 1.56 to 25.0 µM.