Synthesis and biological activities of oxytocin and lysine vasopressin analogs containing glutamic acid gamma-hydrazide in position 4

Solution methods, using N-hydroxysuccinimide esters, were used to synthesize [Glu(NHNH2)4] oxytocin and [Glu(NHNH2)4, Lys8] vasopressin. In these analogs of neurohypophyseal hormones, the side-chain carboxamide function of a glutamine residue is formally replaced by a hydrazide group at position 4. The hormone analogs were assayed for uterototonic activity, milk ejection activity, antidiuretic activity, and rat pressor activity. The specific biological activities of the oxytocin and vasopressin analogs were decreased compared to the respective parent hormones in all assay systems.