Skills (4)
Publications (285) View all
-
Article: New insight into the binding mode of peptides at urotensin-II receptor by Trp-constrained analogues of P5U and urantide.
[show abstract] [hide abstract]
ABSTRACT: Urotensin II (U-II) is a disulfide bridged peptide hormone identified as the ligand of a G-protein-coupled receptor. Human U-II (H-Glu-Thr-Pro-Asp-c[Cys-Phe-Trp-Lys-Tyr-Cys]-Val-OH) has been described as the most potent vasoconstrictor compound identified to date. We have recently identified both a superagonist of human U-II termed P5U (H-Asp-c[Pen-Phe-Trp-Lys-Tyr-Cys]-Val-OH) and the compound termed urantide (H-Asp-c[Pen-Phe-d-Trp-Orn-Tyr-Cys]-Val-OH), which is the most potent UT receptor peptide antagonist described to date. In the present study, we have synthesized four analogues of P5U and urantide in which the Trp(7) residue was replaced by the highly constrained l-Tpi and d-Tpi residues. The replacement of the Trp(7) by Tpi led to active analogues. Solution NMR analysis allowed improving the knowledge on conformation-activity relationships previously reported on UT receptor ligands. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.Journal of Peptide Science 03/2013; · 1.80 Impact Factor -
Article: Characterization of ibodutant at NK(2) receptor in human colon.
[show abstract] [hide abstract]
ABSTRACT: We have characterized the pharmacological profile of the nonpeptide tachykinin NK(2) receptor antagonist ibodutant (MEN15596) through radioligand binding and contractility assays in the human colon smooth muscle. The antagonist affinity of ibodutant was evaluated through concentration-dependent inhibition curves at the [(125)I]NKA specific binding by using membranes prepared from human colon smooth muscle. In this assay the affinity of ibodutant (pK(i) 9.9) was compared to that of other two selective NK(2) receptor antagonists, nepadutant (pK(i) 8.4) and saredutant (pK(i) 9.2). The antagonist potency of ibodutant was evaluated towards the [βAla(8)]NKA(4-10)-mediated contractions of human colon smooth muscle strips. In this assay ibodutant (3, 10, 30 and 100nM) induced a concentration-dependent rightward shift of the [βAla(8)]NKA(4-10) concentration-response curves without depressing the maximal contractile effect. The analysis of the curves yielded a Schild-plot linear regression with a slope not different from unity (1.02), thus indicating a surmountable antagonist behaviour. The calculated apparent antagonist potency as pK(B) value was 9.1. No sex related differences were observed in NK(2) receptor pharmacology for [βAla(8)]NKA(4-10) or ibodutant in colonic strips obtained from male or female patients. Reversibility experiments of tachykinin NK(2) receptor blockade indicated that the inhibition of the agonist-induced contractions in preparations pre-exposed to ibodutant, and afterwards subjected to repeated washing cycles, remained almost constant showing no sign of recovery during the 3h observation period. Overall, the present study indicates ibodutant as a potent tachykinin NK(2) receptor antagonist in the human colon tissue, also endowed with a persistent duration of action.European journal of pharmacology 01/2013; · 2.59 Impact Factor -
Article: Radioligand binding characterization of the bradykinin B(2) receptor in the rabbit and pig ileal smooth muscle.
[show abstract] [hide abstract]
ABSTRACT: Several species-related differences have been reported in kinin B(2) receptor pharmacology. The present study aimed to evaluate the affinity of the bradykinin B(2) receptor antagonist MEN16132 for the rabbit and pig B(2) receptor, and radioligand binding experiments using [(3)H]bradykinin and membranes of rabbit and pig ileum smooth muscle were conducted. The [(3)H]bradykinin binding was characterized by homologous displacement curves indicating K(d) values of 0.65 and 0.33nM in rabbit and pig, respectively. The B(2) receptor specificity of [(3)H]bradykinin binding was shown by the low affinity (>microM) displayed by agonists ([desArg(9)]bradykinin and Lys[desArg(9)]bradykinin) and antagonists [Leu(8),desArg(9)]bradykinin and Lys[Leu(8),desArg(9)]bradykinin) selective for the B(1) receptor. The affinity of MEN16132 and other antagonists was determined by inhibition curves (pK(i) values in the rabbit and pig assay, respectively): MEN16132 (10.4 and 10.3) and peptide compounds such as icatibant (10.1 and 9.9) and MEN11270 (10.3 and 10.1) displayed subnanomolar potency in both assays; the nonpeptide LF16-0687 (8.4 and 8.5) and FR173657 (8.2 and 9.1) exhibited a different affinity pattern, whereas WIN64338 displayed low affinity (5.7 and <or=5). Results are discussed focusing on comparisons with previous findings obtained in rabbit and pig vascular functional assays, but also with those obtained in analog guinea pig and mouse assays and at the human B(2) receptor. An attempt to highlight differences which can undertake ligands selectivity across the species is presented. In conclusion, the present study indicates MEN16132 as the only nonpeptidic compound which displays an even subnanomolar affinity for the rabbit and pig B(2) receptor.European journal of pharmacology 03/2010; 635(1-3):34-9. · 2.59 Impact Factor -
Article: Pharmacological characterization of the bradykinin B2 receptor antagonist MEN16132 in rat in vitro bioassays.
[show abstract] [hide abstract]
ABSTRACT: The pharmacological profile of the bradykinin B(2) receptor antagonist MEN16132 at the rat B(2) receptor has been investigated and compared with that of icatibant (formerly Hoe 140). Antagonist affinity has been measured through radioligand binding experiments with membranes prepared from uterine and airway tissue. MEN16132 inhibited [(3)H]bradykinin binding with subnanomolar affinity (pK(i) values 10.4 and 10.1 in the uterus and airways, respectively), and was about 3-fold less potent than icatibant (pK(i) values 10.9 and 10.5). Antagonist potency has been estimated towards bradykinin-induced contractility of uterine and urinary bladder smooth muscle preparations. In these assays MEN16132 (pK(B): 9.7 both in uterus and bladder) was about 10-fold more potent than icatibant [pK(B): 8.8 in uterus, and pK(B) 8.0 in urinary bladder, as from Meini, S., Patacchini, R., Giuliani, S., Lazzeri, M., Turini, D., Maggi, C.A., Lecci, A., 2000a. Characterization of bradykinin B(2) receptor antagonists in human and rat urinary bladder. Eur. J. Pharmacol. 388, 177-182]. Washout experiments conducted in the uterine preparation indicated for MEN16132 (100 nM) a slower reversibility than icatibant (300 nM).Altogether present results indicate that MEN16132 displays high affinity and potency also for the rat bradykinin B(2) receptor, and thus is suitable for further investigations in pathophysiological models in this species.European journal of pharmacology 06/2009; 615(1-3):10-6. · 2.59 Impact Factor -
Article: New insight into the binding mode of peptide ligands at Urotensin-II receptor: structure-activity relationships study on P5U and urantide.
[show abstract] [hide abstract]
ABSTRACT: Urotensin II (U-II) is a disulfide bridged peptide hormone identified as the ligand of a G protein-coupled receptor. Human U-II (H-Glu-Thr-Pro-Asp-c[Cys-Phe-Trp-Lys-Tyr-Cys]-Val-OH) has been described as the most potent vasoconstrictor compound identified to date. We have recently identified both a superagonist of hU-II termed P5U (H-Asp-c[Pen-Phe-Trp-Lys-Tyr-Cys]-Val-OH) and the compound termed urantide (H-Asp-c[Pen-Phe-DTrp-Orn-Tyr-Cys]-Val-OH), which is the most potent UT receptor peptide antagonist described to date. In the present study, we have synthesized several analogues of P5U and urantide in which the Asp(4) residue in N-terminus position was replaced with coded and noncoded amino acids. The replacement of the Asp(4) residue by Tic led to an analogue, compound 14, more potent as antagonist (pK(B) = 8.94) compared to urantide. Furthermore, a different SAR was observed for the P5U compared to the urantide analogues. NMR and docking studies revealed a different binding mode for the agonist and antagonist ligands which could explain the observed SAR.Journal of Medicinal Chemistry 06/2009; 52(13):3927-40. · 4.80 Impact Factor
