Benzazepinone calcium channel blockers. 5. Effects on antihypertensive activity associated with N1 and aromatic substituents.

We have shown that the pyrrolidinylmethyl substituent on the lactam nitrogen (N1) of benzazepinone and benzothiazepinone calcium channel blocking agents is resistant to metabolic deamination and generally increases the duration and potency of antihypertensive activity in spontaneously hypertensive rats (SHR) relative to (N,N-dimethylamino)ethyl analogs. Additionally, compounds possessing a substituent on the fused aromatic ring are more resistant to metabolic deacylation of the C3 hydroxy function, which may explain why aromatic substituents also frequently increase the potency and/or duration of antihypertensive activity. Our data also indicate the increased antihypertensive activity associated with these structural modifications is independent of any effects of potency in vitro.

Benzazepinone calcium channel blockers. 2. Structure-activity and drug metabolism studies leading to potent antihypertensive agents. Comparison with benzothiazepinones.

As part of a program to discover potent antihypertensive analogues of diltiazem (3a), we prepared 1-benzazepin-2-ones (4). Benzazepinones competitively displace radiolabeled diltiazem, and show the same absolute stereochemical preferences at the calcium channel receptor protein. Derivatives of 4 containing a trifluoromethyl substituent in the fused aromatic ring show potent and long-acting antihypertensive activity.

Benzazepinone calcium channel blockers. 4. Structure-activity overview and intracellular binding site.

We have synthesized a series of benzazepinones (2) in order to determine the structure-activity relationships (SAR) for calcium channel blockers related to diltiazem. A prerequisite for calcium channel blocking activity in vitro and in vivo is the presence of two pharmacophores: a 4'-aryl methyl ether and a basic substituent appended to N1 with a pKa in the physiological range. When these constraints are satisfied, a wide variety of substitution is tolerated at C6, C7, and C3.

Anti-ischemic activity of the novel benzazepine calcium antagonist SQ 31,486.

We tested the benzazepine, SQ 31,486 for its ability to selectively block the voltage-dependent calcium channel and to protect the ischemic myocardium. SQ 31,486 was found to be a selective calcium antagonist in vascular tissue with an IC50 value of 1.5 microM in KCl-contracted rabbit aorta.

Preclinical pharmacology of zofenopril, an inhibitor of angiotensin I converting enzyme.

Zofenopril calcium (one-half calcium salt) is a prodrug ester analog of captopril whose biological effects are manifested by its active component, SQ 26,333. Because of the relative insolubilities of both zofenopril calcium and SQ 26,333, zofenopril potassium salt and SQ 26,703, the arginine salt of the active ACE (angiotensin I converting enzyme) inhibitory moiety of zofenopril, were employed in many of the following studies. The in vitro and in vivo pharmacological effects of zofenopril have been evaluated and comparisons have been made to captopril.

Angiotensin-converting enzyme inhibitors. Mercaptan, carboxyalkyl dipeptide, and phosphinic acid inhibitors incorporating 4-substituted prolines.

Analogues of captopril, enalaprilat, and the phosphinic acid [hydroxy(4-phenylbutyl)phosphinyl]acetyl]-L-proline incorporating 4-substituted proline derivatives have been synthesized and evaluated as inhibitors of angiotensin-converting enzyme (ACE) in vitro and in vivo. The 4-substituted prolines, incorporating alkyl, aryl, alkoxy, aryloxy, alkylthio, and arylthio substituents were prepared from derivatives of 4-hydroxy- and 4-ketoproline. In general, analogues of all three classes of inhibitors with hydrophobic substituents on proline were more potent in vitro than the corresponding unsubstituted proline compounds.

Rational design and biochemical utility of specific inhibitors of angiotensin-converting enzyme.

Angiotensin-converting enzyme (ACE), the receptor for an important new class of antihypertensive drugs, is now one of the better studied zinc metallopeptidases. The development of several classes of tightly binding competitive inhibitors of ACE has led to increased understanding of the structure and function of this enzyme while also yielding important new drugs for the diagnosis and treatment of hypertensive disease. Peptides from snake venom provided the first proof of the therapeutic utility of ACE inhibitors, and a tripeptide sequence, Phe-Ala-Pro, was used as a model for sidechain interactions with ACE in the rational design of simpler nonpeptidic inhibitors such as captopril and enalapril.

Bicyclic pyrazolines, potential central nervous system depressants and antiinflammatory agents.

The synthesis and CNS activity of a series of 34 substituted bicyclic pyrazolines are described. Ten of these compounds were also screened for antiinflammatory activity. One of the compounds (15) exhibited significant antiinflammatory activity in the carrageenan-induced edema test.