Novel 2,7-dialkyl-substituted 5(S)-Amino-4(S)-hydroxy-8-phenyl-octanecarboxamide transition state peptidomimetics are potent and orally active inhibitors of human renin

The action of renin is the rate-limiting step of the renin-angiotensin system (RAS), a key regulator of blood pressure. Effective renin inhibitors directly block the RAS entirely at source and, thus, may provide a vital weapon for hypertension therapy. Our efforts toward identifying novel small-molecule peptidomimetic renin inhibitors have resulted in the design of transition-state isosteres such as I bearing an all-carbon 8-phenyl-octanecarboxamide framework. Optimization of the extended P3 portion of I and extensive P2' modifications provided analogues with improved in vitro potencies in the presence of plasma. X-ray resolution of rhrenin/38a in the course of SAR work surprisingly unveiled the exploitation of a previously unexplored pocket (S3(SP)) important for strong binding affinities. Several inhibitors demonstrated oral efficacy in sodium-depleted marmosets. The most potent, 38a, induced dose-dependently a pronounced reduction in mean arterial blood pressure, paralleled by complete blockade of active plasma renin, up to 8 h post-dose. Oral bioavailability of 38a was 16% in marmosets.