New Dual Inhibitors of Neutral Endopeptidase and Angiotensin-Converting Enzyme: Rational Design, Bioavailability, and Pharmacological Responses in Experimental Hypertension

Abstract

In the treatment of cardiovascular diseases, it could be of therapeutic interest to associate the hypotensive effects resulting from the inhibition of angiotensin II formation, ensured by endothelial angiotensin-converting enzyme (ACE), with the diuretic and natriuretic responses due to the protection of the endogenous atrial natriuretic peptide (ANP) from inactivation by epithelial neutral endopeptidase (NEP). However, an investigation of this hypothesis requires an orally active compound able to jointly inhibit ACE and NEP. Dual inhibitors have therefore been designed by a rational approach, based on the characteristics of the active sites of both enzymes, which belong to the same family of zinc metallopeptidases, and on the structures of their most potent and selective inhibitors. As both NEP and ACE contain a large S'1-S'2 domain able to accommodate aromatic residues, the cyclic ACE inhibitor 3-(mercaptomethyl)-3,4,5,6-tetrahydro-2-oxo-1H-1-benzazocine-1-ace tic acid was selected as a template. Various aliphatic constraints were introduced on the benzyl moiety of the potent NEP inhibitor N-[2-(mercaptomethyl)-3-phenylpropanoyl]-L-tyrosine (IC50 NEP = 2 nM, IC50 ACE = 25 nM) to improve the fit between the computed most stable conformers of these molecules and the ACE template. New dual inhibitors, of general formula, N-[2(R,S)-(mercaptomethyl)-3(R,S)-phenylbutanoyl]-L-amino acid with IC50 values in the nanomolar range for both enzymes were generated by this approach. The separation of the four stereoisomers using chiral amines and the stereoselective synthesis of the 2-(mercaptomethyl)-3-phenylbutanoyl moiety showed that inhibitors with the 2S,3R configuration are the most potent on both NEP and ACE. The "in vivo" potency of various prodrugs of these inhibitors to inhibit ACE activity in lung and NEP activity in kidney was measured after oral administration in mice. From this pharmacokinetical study the most potent dual inhibitor RB 105 (N-[(2S,3R)-2-(mercaptomethyl)-3-phenylbutanoyl-L-alanine (compound 44c) (KI NEP 1.7 nM, KI ACE 4.5 nM) and its most efficient in vivo prodrug mixanpril, [N-[(2S,3R)-2-[(benzoylthio)methyl]-3-phenylbutanoyl]-L-alan ine (compound 18) (ED50 NEP approximately 1 mg/kg, ED50 ACE approximately 7 mg/kg) were selected. Competition experiments with a tritiated inhibitor of ACE or NEP bound to mouse lung and kidney membranes respectively showed that mixanpril has a long duration of action (> 8 h). As expected, after i.v. administration in the spontaneously hypertensive rat (SHR), RB 105 decreased blood pressure and increased diuresis and natriuresis.(ABSTRACT TRUNCATED AT 400 WORDS)

Dual inhibition of angiotensin-converting enzyme and neutral endopeptidase by the orally active inhibitor mixanpril: a potential therapeutic approach in hypertension.

“…Introduction ofa methyl group in the f3 position ofthis residue led to the best superimposition with both the putative biologically active conformation ofthiorphan in the active site of NEP (36) and the constrained benzolactam II structure obtained from molecular modeling studies (48 In this study, a comparison between SHRs and the other models of hypertension showed that there was no difference for the hypotensive and the natriuretic response with RB 105 at 25 mg/kg in the different models. The natriuretic effect in the three models is likely to be related to NEP inhibition, and the hypotensive effect is probably due to NEP inhibition in deoxycortisone acetate-induced hypertensive rats but related to ACE inhibition in renovascular hypertensive rats (19).…”

Comparison of Omapatrilat and Enalapril in Patients With Chronic Heart Failure

“…5,6 Single molecules that inhibit both the angiotensin-converting enzyme (ACE) and NEP (vasopeptidase inhibitors) have been developed in recent years. 7 Simultaneous inhibition of both ACE and NEP produces greater short-term and long-term benefits in experimental models of heart failure than does ACE inhibition alone. 8,9 Omapatrilat is a dual inhibitor of both ACE and NEP, which has been evaluated for the treatment of hypertension and heart failure.…”

Renal Effects of Omapatrilat and Captopril in Salt-Loaded, Nitric Oxide–Deficient Rats

“…Key Words: hypertension, renal Ⅲ kidney failure Ⅲ angiotensin-converting enzyme Ⅲ peptides Ⅲ nitric oxide Ⅲ sodium, dietary V asopeptidase inhibitors are novel molecules that inhibit both angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP). 1 The emergence of this new class of drugs followed the demonstration that ACE and NEP are 2 key enzymes that play a major role in regulating cardiovascular and renal functions. The simultaneous inhibition of these 2 enzymes can reduce the vasopressive, hypertrophic, and antinatriuretic activities of the renin-angiotensin system and potentiate the vasodilatory, natriuretic, and antiproliferative effects of bradykinin and natriuretic peptides.…”

“…1 The emergence of this new class of drugs followed the demonstration that ACE and NEP are 2 key enzymes that play a major role in regulating cardiovascular and renal functions. The simultaneous inhibition of these 2 enzymes can reduce the vasopressive, hypertrophic, and antinatriuretic activities of the renin-angiotensin system and potentiate the vasodilatory, natriuretic, and antiproliferative effects of bradykinin and natriuretic peptides.…”