Four Cyclic Disulfide Pentapeptides Possessing the Ring of Isotocin and Glumitocin

Clark W. Smith, Victor Hruby, Martha F. Ferger

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[4-Serine]tocinoic acid and [4-serine]tocinamide (the 20-membered disulfide pentapeptide and pentapeptide amide ring of isotocin and glumitocin), as well as the two deamino analogs [4-serine]deaminotocinoic acid and [4-serine] deaminotocinamide, were synthesized from four protected polypeptide precursors which had been prepared by the stepwise active ester method. All four precursors were prepared from the same intermediate Boc-Tyr(Bzl)-Ile-Ser(Bzl)-Asn-Cys(Bzl)-OBzl (1). For the preparation of the two-ring compounds containing C-terminal amides, 1 was treated with MeOH saturated with NH3 prior to condensation with either Boc-Cys(Bzl)-ONSu or β-Mpa(Bzl)-ONp. For the preparation of [4-serine]tocinoic acid and [4-serine]deaminotocinoic acid, 1 was condensed with either Z-Cys(Bzl)-ONSu or β-Mpa(Bzl)-ONp. The resulting four protected precursors were then converted to the corresponding ring compounds by deprotection with Na in NH3, followed by oxidative cyclization. None of the ring compounds showed any significant oxytocic, avian vasodepressor, or rat pressor activity. All showed a slight degree of antioxytocic and antiavian vasodepressor activity but no antipressor activity. Both [4-serine]tocinoic acid and [4-serine]tocinamide showed some milk-ejecting activity.

Original languageEnglish (US)
Pages (from-to)873-876
Number of pages4
JournalJournal of Medicinal Chemistry
Issue number8
StatePublished - Aug 1 1974

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery


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