Structure of Malformin A, a Phytotoxic Metabolite Produced by Aspergillus niger.

Malformins-produced by Aspergillus niger were separated by HPLC and subjected to structural determination. Amino acid analyses and mass spectra suggested that all of them structurally resembled cyclic pentapeptide malformin A1. Two-dimensional NMR experiments and MS/MS experiments led us to deduce cyclo-D-cysteinyl-D-cysteinyl-L-amino acid-D-amino acid-L-amino acid as being the essential structure of malformins.