Novel heterocycles as selective alpha1-adrenergic receptor antagonists

A novel series of aryl piperazine substituted heterocycles has been synthesized and identified as antagonists of the alpha1a-adrenergic receptor (alpha1a-AR), which has been implicated in benign prostatic hyperplasia (BPH). These compounds selectively inhibit binding to the alpha1a-AR with K(i)s as low as 2.1 nM.

Synthesis and erythropoietin receptor binding affinities of N,N-disubstituted amino acids

N,N-Dicinnamyl, N-benzyl-N-cinnamyl, and N,N-dibenzyl amino acids were prepared and evaluated in an EPO binding assay. Several derivatives of aspartic acid, glutamic acid, and lysine exhibited moderate (10-50 microM) affinity for EBP; 'dimerization' of the most potent analogues by coupling with linear diamines led to EPO competitors having 1-2 microM binding affinities.

Design, synthesis and biological evaluation of pyridine-phenylpiperazines: a novel series of potent and selective alpha1a-adrenergic receptor antagonist

Beginning from the screening hit and literature alpha1-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective alpha1a-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective alpha1a-AR antagonists were discovered. In all cases, binding affinity and selectivity at the alpha1a-AR of S-hydroxy enantiomers were higher than the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S-hydroxy enantiomers displayed comparable potency and better selectivity at alpha1a-AR. The S-hydroxy enantiomer 17 (Ki = 0.79 nM; alpha1b/alpha1a = 800; alpha1d/alpha1a = 104) was slightly less potent but much more selective at alpha1a-AR than tamsulosin (Ki = 0.13 nM, alpha1b/alpha1a = 15, alpha1d/alpha1a = 1.4). Compound 17 displayed higher selectivity in inhibiting rat prostate contraction over rat aorta contraction and also exhibited a higher degree of uroselectivity than tamsulosin in the anesthetized dog model.

An investigation of the uroselective properties of four novel alpha(1a)-adrenergic receptor subtype-selective antagonists

The development of alpha(1a)-adrenergic receptor (AR) subtype-selective antagonists is likely to result in uroselective agents that effectively treat benign prostatic hyperplasia (BPH) symptoms without causing undesirable side effects that may be due to vascular alpha(1)-AR blockade. The properties of four aryl piperazine compounds (RWJ-38063, RWJ-68141, RWJ-68157, and RWJ-69736) are described in this report and compared with the properties of tamsulosin, an alpha(1)-AR antagonist that is used in the treatment of BPH. Radioligand binding studies show that all four RWJ compounds have significantly higher affinity for the alpha(1a)-AR subtype than for the alpha(1b) or alpha(1d) subtype and display a higher level of receptor subtype selectivity than tamsulosin. The RWJ compounds were more potent in inhibiting (+/-)-norepinephrine-induced contractions of isolated rat prostate tissue than those of isolated rat aorta tissue, whereas tamsulosin had the reversed tissue selectivity. RWJ-38063 and RWJ-69736 had the highest potency in the isolated prostate tissue assays of the four RWJ compounds, with pK(B) values of 8.24 and 9.26, respectively, and were 319- and 100-fold more potent in their effects on isolated prostate tissue than aorta tissue. The in vivo uroselectivities of RWJ-38063, RWJ-69736, and tamsulosin were examined in anesthetized dogs. Both RWJ compounds suppressed the intraurethral pressure response to phenylephrine to a greater extent than the mean arterial pressure response; however, RWJ-69736 also caused a marked transient rise in heart rate. Although less potent, RWJ-38063 and RWJ-69736 were notably more uroselective than tamsulosin in this canine model.

Design, synthesis, and structure-activity relationships of phthalimide-phenylpiperazines: a novel series of potent and selective alpha(1)(a)-adrenergic receptor antagonists

Beginning from the screening hit and literature alpha(1)-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective alpha(1a)-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective alpha(1a)-AR antagonists were discovered. In all cases, binding affinity and selectivity at the alpha(1a)-AR of S-hydroxy enantiomers were higher than those of the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S-hydroxy enantiomers had slightly lower binding affinity at alpha(1a)-AR but gained more than 2-fold selectivity for alpha(1a)-AR over alpha(1b)-AR, and 2- to 6-fold selectivity for alpha(1a)-AR over alpha(1d)-AR. They also had less cross activities against a panel of 25-35 peripheral and CNS receptors. The S-hydroxy enantiomers 23 and 24 (K(i) = 0.29 nM, 0.33 nM; alpha(1b)/alpha(1a) >5690, >6060; alpha(1d)/alpha(1a) = 186, 158, respectively) were slightly less potent but much more selective at alpha(1a)-AR than tamsulosin (K(i) = 0.13 nM, alpha(1b)/alpha(1a) = 14.8, alpha(1d)/alpha(1a) = 1.4). In the functional assay, the S-hydroxy enantiomers 20, 23, and 24 were less potent than tamsulosin in inhibiting contractions of rat prostate tissue but more selective in the inhibition of tissue contractions of rat prostate versus rat aorta. Compound 24 was selected as the development candidate for the treatment of BPH.

Novel arylpiperazines as selective alpha1-adrenergic receptor antagonists

A novel series of arylpiperazines has been synthesized and identified as antagonists of alpha1a adrenergic receptor (alpha1a-AR) implicated in benign prostatic hyperplasia. These compounds selectively bind to membrane bound alpha1a-AR with K(i)s as low as 0.66 nM. As such, these potentially represent a viable treatment for BPH without the side effects associated with known alpha1-adrenergic antagonists.

1,3-Diarylcycloalkanopyrazoles and diphenyl hydrazides as selective inhibitors of cyclooxygenase-2

Novel 1,3-diarylcycloalkanopyrazoles 1, and diphenyl hydrazides 2 were identified as selective inhibitors of cyclooxygenase-2. The 1,3-diaryl substitution pattern of the pyrazole ring in 1 differentiates these compounds from most of the known selective COX-2 inhibitors that contain two aryl rings at the adjacent positions on a heterocyclic or a phenyl ring. Similarly, the two phenyl rings in 2 are also separated by three atoms. SAR of both phenyl rings in 1 and 2, and the aliphatic ring in 1 will be discussed.

Steroids. 2. Synthesis of C-18 functionalized steroids via the Smith-Hughes route

The total synthesis of a series of racemic C-18 functionalized steroids was carried out in a search for novel estrogen-and/or progestin-receptor agonists or antagonists. The target compound 3,18-dihydroxyestra-1,3,5(10)-triene (2), 13-(2-oxopropyl)gona-4-en-3-one (3), 13-(1-hydroxy-1-prop-2-ynyl)gona-4-en-3-one (4a and 4b) and 13-(1-acetoxy-2-oxo-1-propyl)gona-4-en-3-one (5) are position isomers of the highly biologically active estradiol, progesterone, norethindrone, and 17-acetoxyprogesterone, respectively. Nevertheless the synthetic C-18 functionalized steroids 3-5 showed little activity in the Clauberg and anti-Clauberg assays. Compound 2 showed no antagonism in the postcoital assay despite the fact that it exhibited weak but measurable in vitro receptor-binding activity.