N-PHOSPHONOMETHYL DIPEPTIDES AND THEIR PHOSPHONATE PRODRUGS, A NEW-GENERATION OF NEUTRAL ENDOPEPTIDASE (NEP,EC-3.4.24.11) INHIBITORS

Inhibitors of the zinc protease neutral endopeptidase (NEP, EC 3.4.24. 11) offer significant therapeutic interest as antihypertensives due to their ability to potentiate the biological action of the circulating natriuretic hormone ANF (atrial natriuretic factor), N-Phosphonomethyl ; dipeptides bearing a central (4-phenyl)phenylalanine residue have be en designed to effort potent and selective NEP inhibition. In particul ar, l)amino]-3-(4-biphenylyl)propionyl]amino]propionic acid (10a) (CGS 24592) displayed high inhibitory potency. in vitro (IC50 = 1.9 +/- 0. 1 nM) and a long plasma half-life in rats but lacked,oral bioavailabil ity. This drawback was overcome by using esterase-sensitive (acyloxy)a lkyl phosphonates. More remarkable, several diaryl phosphonate derivat ives of 10a also performed as effective prodrugs. Specifically, the st ructurally simple diphenyl phosphonate 18 (CGS 25462) induced potent i nhibition of NEP ex vivo fdr at least 8 h after oral administration to rats (30 mg/kg). Its antihypertensive effect was demonstrated in DOCA -salt rats. At 30 mg/kg orally, 18 caused a significant reduction in m ean arterial pressure measuring -35 +/- 7 mmHg at 5-h postdosing. The a-aminomethyl phosphonate 18 represents a new generation of selective NEP inhibitors that combine high potency, long duration of action, and oral bioavailability. Therefore, it holds promise as a novel therapeu tic agent for the treatment of human hypertension and congestive heart failure.