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

Abstract

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.