Mixed inhibitors of angiotensin-converting enzyme (EC 3.4.15.1) and enkephalinase (EC 3.4.24.11): rational design, properties, and potential cardiovascular applications of glycopril and alatriopril.

Abstract

Two major hormonal peptide systems appear to play opposite roles in the regulation of electrolyte balance and blood pressure, so that their imbalance might be responsible for cardiovascular and salt-retention disorders affecting a large fraction of the population (1). The first one is the reninangiotensin-aldosterone system, whose critical role in sodium retention and vasoconstriction was largely evidenced through the use of inhibitors of the membra~ne metallopeptidase angiotensin-converting enzyme (ACE; EC 3.4.15.1) (2, 3). These drugs, which prevent the formation of angiotensin II, a vasoactive, antidiuretic, and antinatriuretic peptide, and decrease blood pressure and aldosterone secretion, have gained wide application in the treatment of essential hypertension and congestive heart failure. The second hormonal system is constituted by the atrial natriuretic factor (ANF), a peptide secreted by the heart into the circulation to decrease blood pressure, raise the urinary excretion of water and sodium, and lower plasma renin and aldosterone levels (4). Recently, the role of another metallopeptidase, enkephalinase (EC 3.4.24.11, membrane metalloendopeptidase), in the inactivation of endogenous ANF was shown by the effects of inhibitors (reviewed in ref. 5). These drugs enhance the circulating level of the hormone in healthy volunteers as well as in patients with congestive heart failure or cirrhosis; induce diuresis, natriuresis, and urinary excretion of cGMP (6-10); and may exert antihypertensive activity (11).Hence it appears that two cell surface, zinc-containing peptidases play a key role in the activation or inactivation pathways of the two hormonal systems. Although many compounds are highly selective inhibitors of either ACE or enkephalinase, some mercaptoalkyl inhibitors display limited but significant crossreactivity toward the two peptidases (12,13). This partial overlap suggested that a careful analysis of structure-activity relationships would enable the design of a single molecular structure able to potently inhibit both enzymes in vivo and, thereby, lead to a class of potentially useful cardiovascular agents blocking both the generation of angiotensin II and the inactivation of ANF.We have now designed such mixed inhibitors which interact with the two peptidases at nanomolar concentrations in vitro and at low dosage per os. These drugs elicit the characteristic actions ofthe two classes ofenzyme inhibitors: prevention of angiotensin I-induced hypertension, protection of ANF, enhancement of diuresis and natriuresis, and increase in urinary cGMP excretion.

Fasidotril: The First Dual Inhibitor of Neprilysin and ACE

“…(12). Fasidotrilat inhibited both enzymes at nanomolar concentrations (K i = 9.8 nM against ACE and 5.1 nM against NEP) (13). Similar inhibitory potencies were found against mouse enzymes (K i = 4.4 nM against ACE and 7.7 nM against NEP), but fasidotrilat displayed a weaker potency (K i = 30 nM) against rat ACE, thereby revealing a differential pharmacological specificity of ACE.…”

“…injection of fasidotrilat 10 min before injection of angiotensin I (150 ng/kg, i.v.) resulted in a dose-dependent inhibition of the pressor response with an ID 50 of 0.9 ± 0.2 mg/kg (13). In conscious rats, the pressor response to angiotensin I (300 ng/kg, i.v.)…”

“…2C). This binding presumably occurs at the ANP "clearance receptors" because it was prevented by low doses of not only ANP but also by an ANP analogue recognized by these receptors but inactive at biological receptors linked to guanylate cyclase (13).…”

“…These data as well as the fact that ACE and NEP are both zinc metallopeptidase have led to the rational design of dual ACE/NEP inhibitors that have potent and similar inhibitory activities against both enzymes within a single molecule (10,11,13,40). Fasidotril (BP 1.137, previously named alatriopril or aladotril) was the first compound to be described with both ACE-and NEP-inhibitory activities at nanomolar concentration (13).…”

“…Fasidotril (BP 1.137, previously named alatriopril or aladotril) was the first compound to be described with both ACE-and NEP-inhibitory activities at nanomolar concentration (13).…”