Oxytocin and Its Analogs, Methyl-Substituted in Ortho-, Meta- or Para- Position of Aromatic Ring of Phenylalanine in Position 2: NMR Study and Biological Activities

Complete analyses of NMR data of oxytocin (OT) and 4 analogues, ([o-MePhe2]OT, [mMe-Phe2]OT, [m- OMePhe2]OT and [p-MePhe2]OT), are given. The same conformational behavior in solution on one hand and large differences in biological activities on the other hand indicate that the compounds adopt a “biologically active conformation” at the stage of interaction with the receptor when the character of the substituent and its position on the aromatic ring may play a role in hindering attaining the ideal complementarity of both interacting components.