A New Antibacterial Dioxopiperazine Alkaloid Related to Gliotoxin from a Marine Isolate of the Fungus Pseudallescheria

摘要

A new antibacterial dioxopiperazine,dehydroxybisdethiobis(methylthio)gliotoxin (1),and the previously described bis dethio bis(methylthio)gliotoxin (2) and gliotoxin (3),have been isolated from the broth of a marine-derived fungus of the genus Pseudallescheria.The structure and absolute stereochemistry of the new compound was assigned on the basis of NMR and CD experiments.Compounds 1 approx 3 exhibit potent antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus with MIC values of 31.2,31.2,and 1.0 mug/ml,respectively.Compound 3 also exhibited a significant radical scavenging activity against l,l-diphenyl-2-picrylhydrazyl (DPPH) with IC_(50) value of 5.2 mu M.