Radiosumin B, an unusual dipeptide from the cyanobacterium Microcystis aeruginosa

Radiosumin B (1), an N-methyl dipeptide containing two unusual amino acid r esidues, was isolated from the cyanobacterium Microcystis aeruginosa Kutzin g. The structure and stereochemical details were elucidated on the basis of 1D and 2D NMR data, MS data, and chemical degradation.