Stereoisomer of [cyclo(glycylglycylglycyl-N5-acetyl-N5-hydroxy-L-ornithyl-N5-acetyl-N5-hydroxy-L-ornithyl-N5-acetyl-N5-hydroxy-L-ornithyl)ato(3-)][55Fe]iron [55Fe] FC [55Fe] Ferrichrome [55Fe]-FC [55Fe]-Ferrichrome [55Fe]Iron, [N,N',N''-[(3,6,9,12,15,18-hexaoxo-1,4,7,10,13,16-hexaazacyclooctadecane-2,5,8-triyl)tris(trimethylene)]triacetohydroxamato]- (8CI) 1,4,7,10,13,16-Hexaazacyclooctadecane, cyclic peptide d eriv.