Collect. Czech. Chem. Commun. 1981, 46, 1689-1692

The effect of magnesium ions on the uterotonic activity of carba analogues of oxytocin modified in position 4

Jiřina Slaninová, Michal Lebl, Tomislav Barth and Karel Jošt

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Five analogues of deamino-1-carba-oxytocin, in which the γ-carboxyl group of glutamine in position 4 had been modified (free acid, monomethylamide, dimethylamide, hydrazide, p-tolylamide), were investigated regarding their uterotonic activity in vitro. The slope of the dose-response curve and the magnitude of the maximum response were compared with those of oxytocin in magnesium-free and 0.5 mM Mg-containing media. In the case of [4-glutamic acid] deamino-1-carba-oxytocin, the RMg2+ value equalled 22. The other compounds had RMg2+ values of 2-3. All the analogues evoked the same maximum response as oxytocin in both the media tested.