The isolation, structure, and absolute configuration of the mycotoxin, rhizonin A, a novel cyclic heptapeptide containing N-methyl-3-(3-furyl)alanine, produced by Rhizopus microsporus
Rhizonin A, the main mycotoxin from Rhizopus microsporus, is a cyclic heptapeptide containing valine, allo-isoleucine, leucine, N-methylalanine, N-methyl-3-(3-furyl)alanine (2 : 1 : 1 : 1 : 2), its amino-acid sequence having been established by mass spectrometry; X-ray crystallography verified the structure of rhizonin A and afforded its conformation and relative configuration, and its absolute configuration was obtained from high performance liquid chromatographic studies of the dansyl-derivatised amino-acids.