Cytochalasins E and K, toxic metabolites from Aspergillus clavatus

The isolation of cytochalasin E and cytochalasin K from Aspergillus clavatus is described. The structure of cytochalasin K, a new metabolite, has been determined by spectroscopic data and chemical reactions. The relationship between cytochalasin E and cytochalasin K was confirmed by chemical conversion. Chemical reactions on cytochalasins E and K, both of which contain the unique vinyl carbonate moiety, are described.