Gliocladins A-C and glioperazine;: Cytotoxic dioxo- or trioxopiperazine metabolites from a Gliocladium sp separated from a sea hare

New dioxo- or trioxopiperazine metabolites named gliocladins A-C (1 - 3) and glioperazine (4) have been isolated from a strain of Gliocladium sp., originally separated from the see. hare. Their structures have been elucidated by spectroscopic analyses using various NMR spectroscopic techniques. Structurally unique trioxopiperazine (3) exhibited significant cytotoxicity against cultured P388 cells.