Cyclo-peptide(s) agonists to atrial natriuretic protein

Cyclopeptides and their salts are atrial natriuretic protein (ANP) agonists derived from amino acid (aa) residues of hANP Arg(27)-Phe(8)-Gly(9)-Gly(10)-Arg(11)-Met(12)-Asp(13)-Arg(14)-Ile(15), generally named Bn-Cn-Dn-En-Fn-Gn-Hn-In-Kn respectively, and structural and functional equivs., wherein an An spacer gp. is attached to the free end of Bn and joins Bn with Kn thereby changing the structure resulting in binding of the cyclopeptide to ANP receptors. Also claimed is a process for the prodn. of the cyclopeptides by cyclisation of a linear sequence made by known methods and possible salt formation, and a pharmaceutical cpd. contg. a cyclopeptide as claimed. The part of An closest to Bn pref. contains an aromatic or cycloaliphatic residue and Bn, Cn, En, Fn, Gn, Hn, In and Kn are in the L-form.