Aeruginoguanidines 98-A–98-C: cytotoxic unusual peptides from the cyanobacterium Microcystis aeruginosa

Aeruginoguanidines 98-A–98-C () were isolated from the cyanobacterium Microcystis aeruginosa (NIES-98). The structures of aeruginoguanidines 98-A–98-C () were determined by two-dimensional 1H–1H and 1H–13C NMR correlation experiments and confirmed by mass spectral analysis. The absolute stereochemistry of , consisting of Hphpa trisulfate (1-(4-hydroxy-3-hydroxymethyl)phenyl-1-hydroxy-2-propylamine 4′,3′,1-tri-O-sulfate), MpArg (Nα-methyl-Nω-prenylarginine) and MgArg ((Z)-Nα-methyl-Nω-geranylarginine), was determined by the NMR analyses of phenylglycine methyl ester (PGME) or Boc phenylglycine (BPG) derivatives of acid hydrolysates. These compounds showed moderate cytotoxicity against the P388 murine leukemia cells.