Richard Goschke

Structure-based design of aliskiren, a novel orally effective renin inhibitor

Hypertension is a major risk factor for cardiovascular diseases such as stroke, myocardial infarction, and heart failure, the leading causes of death in the Western world. Inhibitors of the renin-angiotensin system (RAS) have proven to be successful treatments for hypertension. As renin specifically catalyses the rate-limiting step of the RAS, it represents the optimal target for RAS inhibition. Several peptide-like renin inhibitors have been synthesized previously, but poor pharmacokinetic properties meant that these compounds were not clinically useful. We employed a combination of molecular modelling and crystallographic structure analysis to design renin inhibitors lacking the extended peptide-like backbone of earlier inhibitors, for improved pharmacokinetic properties. This led to the discovery of aliskiren, a highly potent and selective inhibitor of human renin in vitro, and in vivo; once-daily oral doses of aliskiren inhibit renin and lower blood pressure in sodium-depleted marmosets and hypertensive human patients. Aliskiren represents the first in a novel class of renin inhibitors with the potential for treatment of hypertension and related cardiovascular diseases.

Structure-based drug design: the discovery of novel nonpeptide orally active inhibitors of human renin

BACKGROUND The aspartic proteinase renin plays an important physiological role in the regulation of blood pressure. It catalyses the first step in the conversion of angiotensinogen to the hormone angiotensin II. In the past, potent peptide inhibitors of renin have been developed, but none of these compounds has made it to the end of clinical trials. Our primary aim was to develop novel nonpeptide inhibitors. Based on the available structural information concerning renin-substrate interactions, we synthesized inhibitors in which the peptide portion was replaced by lipophilic moieties that interact with the large hydrophobic S1/S3-binding pocket in renin. RESULTS Crystal structure analysis of renin-inhibitor complexes combined with computational methods were employed in the medicinal-chemistry optimisation process. Structure analysis revealed that the newly designed inhibitors bind as predicted to the S1/S3 pocket. In addition, however, these compounds interact with a hitherto unrecognised large, distinct, sub-pocket of the enzyme that extends from the S3-binding site towards the hydrophobic core of the enzyme. Binding to this S3(sp) sub-pocket was essential for high binding affinity. This unprecedented binding mode guided the drug-design process in which the mostly hydrophobic interactions within subsite S3(sp) were optimised. CONCLUSIONS Our design approach led to compounds with high in vitro affinity and specificity for renin, favourable bioavailability and excellent oral efficacy in lowering blood pressure in primates. These renin inhibitors are therefore potential therapeutic agents for the treatment of hypertension and related cardiovascular diseases.

A convergent synthesis approach towards CGP60536B, a non-peptide orally potent renin inhibitor, via an enantiomerically pure ketolactone intermediate

We report a convergent synthesis of the potent orally active non-peptide renin inhibitor CGP60536B. The key reaction employs the coupling of the enantiopure Grignard species derived from chloride 13 with the diastereomerically pure γ-lactone 9b. The stereoselective reduction of the resulting ketone 14b has been thoroughly investigated.

Design and synthesis of novel 2,7-dialkyl substituted 5(S)-amino-4(S)-hydroxy-8-phenyl-octanecarboxamides as in vitro potent peptidomimetic inhibitors of human renin

Abstract Novel low-molecular weight transition-state peptidomimetic renin inhibitors characterized by an all-carbon 8-phenyl substituted octanecarboxamide skeleton have been discovered based on a topographical design approach. The in vitro most potent inhibitors 21, 25 and 26 incorporating a strong H-bond acceptor group linked to the benzyl spacer of the (P3-P1)-unit had IC50s in the low nanomolar range against human renin.

BIOACTIVE HYDROXYETHYLENE DIPEPTIDE ISOSTERES WITH HYDROPHOBIC (P3-P1)-MOIETIES. A NOVEL STRATEGY TOWARDS SMALL NON-PEPTIDE RENIN INHIBITORS

Abstract The design and synthesis of new truncated δ-amino hydroxyethylene dipeptide isosteres lacking the P 4 -P 2 peptide backbone is described. The most active compounds 15c and 30c inhibited human renin in the submicromolar range. This promising concept may offer the possibility to discover completely non-peptide, lowmolecular weight renin inhibitors with improved pharmacokinetic properties.