A cytotoxic pyrrolidinoindoline diketopiperazine dimer from the algal fungus Eurotium herbariorum HT-2

Abstract A new cytotoxic pyrrolidinoindoline diketopiperazine dimer, cristatumin E ( 1 ), was isolated from the fermentation broth of the algal fungus Eurotium herbariorum HT-2 associated with the marine algae, Enteromorpha prolifera . The structure was determined by spectroscopic analyses and Marfey's amino acid analysis. Cristatumin E ( 1 ) showed cytotoxicity against K562 tumor cell line and antibacterial activity against Enterobacter aerogenes and Escherichia coli with IC 50 and MIC values of 8.3, 44.0 and 44.0 μmol/L, respectively.