Radiosumin B, an Unusual Dipeptide from the CyanobacteriumMicrocystisaeruginosa

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