[Effective synthesis of cyclic analogs of bradykinin].

Cyclo-epsilon-(L-lysine1, glycine6-bradykinin) (CLGB) and cyclo-epsilon-kallidin have been synthesised in solution. To prepare linear precursors, fragment condensation (3 + 3 or 4) + 3 was used. Peptide bond formation, including cyclization, was carried out mainly through intermediate pentafluorophenyl esters. After purification on silicagel, protected cyclopeptides were obtained with a 50 to 60% yield. The protecting groups were eliminated by treatment with hydrogen fluoride in the presence of anisole. CLGB and CK were purified by droplet countercurrent chromatography and by reversed-phase HPLC, respectively.