Retro analogs related to oxytocin

[D-alle3]-retro-D-deaminotocinamide (I), retro-L-deaminotocinamide (III) and their respective N-formyl derivatives (II and IV) were synthesized by the stepwise active ester method: deaminotocinamide was prepared by the solid-phase method. The retro-analogs of deaminotocinamide, tested at concentrations up to 10)-5)M, were found to be without activity as agonists or antagonists in the oxytocic assay. At 10(-4)M,[D-alle]-retro-D-deaminotocinamide is a weak competitive inhibitor of oxytocin. [D-alle3, Gly7]-retro-D-deaminooxytocin (V) was synthesized either by the active ester method or by a fragment condensation method employing the retro-D-RING, [D-alle3]-retro-D-deaminotocinamide, and D-tail, Boc-Gly-D-Leu-Gly, as the fragments...