A mixture of 234.5 mg (1.06 mmoles) of 7-guanidino-2-heptenamide hydrochloride, 372.3 mg (1.27 mmoles) of N-[4-(3-aminopropyl)aminobutyl]-2,2-dihydroxyethanamide dihydrochloride, 140.4 mg (1.06 mmoles) of glutaric acid and 0.2 ml of water was heated at 60° C. for 24 hours. After completion of the reaction, the reaction mixture was purified in a manner similar to that in Example 1 using CM-Sephadex® C-25 (Na-type) and Sephadex® LH-20 to obtain 244.6 mg (46.5% yield) of a white powder of N-[4-(3-aminopropyl)aminobutyl]-2-(7-guanidino-2-heptenamido)-2-hydroxyethanamide trihydrochloride.
