Synthèses de la Phé2-arginine-vasopressine et de la Phé2-arginine-vasotocine et nouvelles synthèses de l'argininevasopressine et de l'arginine-vasotocine

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

New, potent, selective, and short-acting peptidic V1a receptor agonists

[Arg(8)]vasopressin (AVP) produces vasoconstriction via V(1a) receptor (V(1a)R)-mediated vascular smooth muscle cell contraction and is being used to increase blood pressure in septic shock, a form of vasodilatory hypotension. However, AVP also induces V(2) receptor (V(2)R)-mediated antidiuresis, vasodilation, and coagulation factor release, all deleterious in septic shock. The V(1a)R agonist terlipressin (H-Gly(3)[Lys(8)]VP) also lacks selectivity vs the V(2)R and has sizably longer duration of action than AVP, preventing rapid titration of its vasopressor effect in the clinic. We designed and synthesized new short acting V(1a)R selective analogues of general structure [Xaa(2),Ile(3),Yaa(4),Zaa(8)]VP. The most potent and selective compounds in in vitro functional assays (e.g., [Phe(2),Ile(3),Asn(Me(2))(4),Orn(8)]VP (31), [Phe(2),Ile(3),Asn((CH(2))(3)OH)(4),Orn(8)]VP (34), [Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]VP (45), [Phe(2),Ile(3),Asn(Et)(4),Dab(8)]VP (49), [Thi(2),Ile(3),Orn(iPr)(8)]VP (59), [Cha(2),Ile(3),Asn(4),Orn(iPr)(8)]VP (68)) were tested by intravenous bolus in rats for duration of vasopressive action. Analogues 31, 34, 45, and 49 were as short-acting as AVP. Compound 45, FE 202158, is currently undergoing clinical trials in septic shock.

Bidirectional synthesis of [5-aspartic acid] arginine vasopressin on poly-N-acrylylpyrrolidine resin

In the proposed biologically active conformation of vasopressin at its antidiuretic receptor, the side-chain carboxamide moiety of the 5-position asparaginyl residue has been suggested to be an active element for the initiation of the antidiuretic response. [5-Aspartic acid] arginine vasopressin, the analog in which the -NH2 portion of the primary amide has been replaced by an -OH group, has been synthesized and tested for some of the pharmacological activities of vasopressin. The partially protected nonapeptide intermediate was assembled bidirectionally on a poly-N-acrylylpyrrolidine resin. The 6-position cysteinyl residue was attached to the resin via its side-chain through an S-carbamoyl linkage. First the COOH-terminus was extended by coupling with Pro-Arg(Tos)-Gly-NH2, then the NH2-terminus was extended in a stepwise manner. [5-Aspartic acid] arginine vasopressin was found to possess 86.5 +/- 4.8 units/mg of antidiuretic potency, 17% of the parent hormone. In addition, the analog possesses rat pressor and rat uterotonic potencies of 6.93 +/- 0.15 and 0.38 +/- 0.03 units/mg, respectively. This result suggests that a carboxylic acid moiety on the 5-position aspartyl residue retains sufficient steric features and hydrophilicity in common with the carboxamide moiety present in the hormone to substitute for it as an active element at the antidiuretic receptor.

Phenypressin (Phe2-Arg8-vasopressin), a new neurohypophysial peptide found in marsupials

Recent investigations on marsupial neurohypophysial hormones have revealed that species belonging to the Australian family Macropodidae and the American family Didelphidae have, apart from an oxytocin-like hormone, two vasopressin-like peptides which can be separated either by ion-exchange chromatography or chromatoelectrophoresis. The major pressor hormone of two Australian species, the red kangaroo (Macropus rufus) and the tammar (Macropus eugenii), has been identified as lysine vasopressin by its amino acid sequence anda its pharmacological properties. We report here that the minor pressor hormone, which chromatographs on Amberlite CG-50 like arginine vasopressin, differs from it in sequence only at position 2 where phenylalanine replaces the tyrosine of arginine vasopressin.

Synthesis and biological activities of arginine-vasopressin analogues with reactive groups

The synthesis and biological activities of arginine-vasopressin analogues are described, where p-azido-L-phenylalanine [Phe(pN3)] or p-(bromoacetylamino)-L-phenylalanine [Phe-(pNHCOCH2Br)] replace Tyr2 or Phe3. The hormone analogues are prepared via precursors containing p-aminophenylalanine [Phe(pNH2)] in position 2 or 3. During peptide synthesis the p-amino group of [Phe(pNH2)] is protected by the tert-butyloxycarbonyl or the benzyloxycarbonyl group, the side chains of cysteine and arginine by the acetamidomethyl residue and the tosyl group, respectively. The amino and guanidino protecting groups are removed from the nonapeptides by trifluoromethanesulfonic acid yielding the S-protected derivatives which are cyclized by means of iodine. The ring closure by disulfide formation is confirmed by Edman degradation, CD and 1H-NMR spectroscopy. Modification at the p- and alpha-amino groups result in [Phe(pN3)2]-vasopressin, [Phe(pNHCOCH2Br)2]vasopressin, Nalpha-dansyl-[Phe(pN3)2]vasopressin, [Phe2,Phe-(pN3)3]vasopressin and [Phe2,Phe(pNHCOCH2-Br)3]vasopressin. The analogues modified only in position 2, [Phe(pN3)2]vasopressin stimulate the adenylate cyclase derived from bovine kidney inner medulla to similar maximal velocities as arginine vasopressin and show high apparent affinities for enzyme activation. The Nalpha-dansyl derivative and the analogues with reactive groups in position 3 have reduced maximal velocities and apparent affinities for vasopressin-sensitive adenylate cyclase. These results suggest that especially the derivatives with reactive groups in position 2 are useful for the labelling of vasopressin receptors in plasma membranes and for studies of covalent hormone-receptor complexes.