5-Valine-oxytocin and 1-Deamino-5-valine-oxytocin

SYNTHESES AND SOME PHARMACOLOGICAL PROPERTIES

From the ¹ From The Physiology Department, Mount Sinai Medical and Graduate Schools, New York, New York 10029, and The Medical Research Center, Brookhaven National Laboratory, Upton, New York 11973

The paper reports the syntheses of 5-valine-oxytocin and 1-deamino-5-valine-oxytocin, analogues of oxytocin and 1-deamino-oxytocin which contain a valine residue in place of the asparagine residue in position 5. On assay for biological activity, 5-valine-oxytocin was found to possess approximately 0.3 unit per mg of oxytocic activity and 0.1 unit per mg of avian vasodepressor activity. The 1-deamino-5-valine-oxytocin possesses approximately 0.7 unit per mg of oxytocic activity and 0.3 unit per mg of avian vasodepressor activity. Both of these analogues exhibit approximately 0.01 unit per mg of rat pressor and less than 0.001 unit per mg of rat antidiuretic activity. The detrimental effect on hormonal activities of structural alterations in position 5 of oxytocin is shown by the strikingly low potencies of 5-valine-oxytocin and 1-deamino-5-valine-oxytocin as compared with the high potencies of 4-valine-oxytocin and 1-deamino-4-valine-oxytocin.

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