Radiosumin B, an unusual dipeptide from the cyanobacterium Microcystis aeruginosa.

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