Chetocochliodins A-I, Epipoly(thiodioxopiperazines) from .

Nine new epipoly(thiodioxopiperazine) (ETP) analogues, chetocochliodins AI (-), along with two known ones, chetoseminudins E and C ( and ), were purified from the fungus . The planar structures and absolute configurations of these new compounds were determined by extensive NMR spectroscopic analysis, CD spectra, and chemical reactions. Shielding effects from the indole on the 3-SCH/3-OCH/3-OCH- groups facilitated the determination of relative configuration of the analogues. Compound was cytotoxic, suggesting the importance of the sulfide bridge for the diketopiperazine bioactivities.