Synthesis and Analgesic Activity of C-Terminal Fragment Peptides of Cholecystokinin

Eleven C-terminal fragment peptides of cholecystokinin (CCK) which contain a O-sulfated tyrosine residue [CCK (27-32), CCK (27-31), CCK (27-31) amide, CCK (27-30), CCK (27-30) amide, CCK (27-29), CCK (27-29) amide, CCK (26-27), CCK (26-27) amide, CCK (25-27) and CCK (25-27) amide] were prepared by the solution method. The syntheses of these peptides were carried out by stepwise condensation in combination with fragment condensation. Analgesic effects of these fragment peptides were measured by means of the writhing test. The ED50 value of CCK (27-32) was 9.1 mg/kg and that of CCK (25-27) was 7.5 mg/kg, but the other synthetic peptides produced no statistically significant response at a dose of 8 or 10 mg/kg.