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

Xifeng Li, Se-Kwon Kim, Ki Wan Nam, Jung Sook Kang, Hong Dae Choi, Byeng Wha Son

Received: February 2, 2006 / Accepted: April 7, 2006
© Japan Antibiotics Research Association

Abstract A new antibacterial dioxopiperazine, dehydroxybisdethiobis(methylthio)gliotoxin (1), and the previously described bisdethiobis(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 1~3 exhibit potent antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus with MIC values of 31.2, 31.2, and 1.0 μg/ml, respectively. Compound 3 also exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 value of 5.2 μM.

Keywords marine-derived fungus Pseudallescheria, dehydroxybisdethiobis(methylthio)gliotoxin, bisdethiobis(methylthio)gliotoxin, gliotoxin, antibacterial activity, radical scavenging activity

B. W. Son (Corresponding author), X. Li, S.-K. Kim: Department of Chemistry, Pukyong National University, Busan 608-737, Korea, E-mail:
K. W. Nam: Department of Marine Biology, Pukyong National University, Busan 608-737, Korea
J. S. Kang: College of Dentistry, Pusan National University, Busan 602-739, Korea
H. D. Choi: Department of Chemistry, Dongeui University, Busan 614-714, Korea
Present address: Analysis Measurement Center, Yanbian University, Jilin 133002, P.R. China