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The design, synthesis and structure-activity relationship studies of a novel series of CRF-1 receptor antagonists, the 2-arylpyrimidines, are described. The effects of substitution on the aromatic ring and the pyrimidine core on CRF-1 receptor binding were investigated. A number of compounds with K(i) values below 10 nM and lipophilicity in a minimally acceptable range for a CNS drug (cLogP5) were discovered.

Bioisosteric replacement of piperazine with an aryl ring in lead VR1 antagonist 1 led to the biarylamide series. The development of B-ring SAR led to the conformationally constrained analog 70. The resulting aminoquinazoline 70 represents a novel VR1 antagonist with improved in vitro potency and oral bioavailability vs the analogous compounds from the lead series.

Optimization of the lead compound 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2,3-dihydro-indol-1-yl)-ethanone 1 by systematic structure-activity relation (SAR) studies lead to two potent compounds 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2-methy-2,3-dihydro-indol-1-yl)-ethanone 2n and 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2-methy-2,3-dihydro-indol-1-yl)-ethanone 7b. Their related synthesis was also reported.

Benzodiazepines are allosteric modulators of the GABA(A) receptor. The traditionally prescribed benzodiazepines are nonselective and suffer from numerous side effects. Upon the identification of receptor subtypes, we set out to discover selective agents with the anticipation that these agents would have superior therapeutic potential. Herein, we describe the synthesis and biological evaluation of substituted 7,8,9,10-tetrahydroimidazo[1,2-c]pyrido[3,4-e]pyrimidin-5(6H)-ones and disclose that these compounds exhibit functional selectivity at the benzodiazepine receptor of GABA(A) receptor subtypes. The alpha(2)/alpha(3)-selective partial agonist 42 exhibited potent in vivo activity.

A series of 2-phenyl-4-(aminomethyl)imidazoles were designed as conformationally restricted analogs of the dopamine D2 selective benzamide antipsychotics. The title compounds were synthesized and tested for blockade of [3H]YM-09151 binding in cloned African green monkey dopamine D2 receptor preparations. The binding affinity data thus obtained were compared against that of the benzamides and a previously described series of 2-phenyl-5-(aminomethyl)-pyrroles.

A series of chromene derivatives was synthesized and evaluated for their in vitro and ex vivo 5-lipoxygenase (5-LO) inhibitory activity. These compounds were prepared by condensation of appropriate salicyl aldehydes with alpha, beta-unsaturated carbonyl compounds, followed by transformation to the corresponding hydroxamic acids or N-hydroxyureas. Placement of phenoxy or p-fluorophenoxy substituents at the 6 position of the chromene ring led to a dramatic increase in the in vitro potency as demonstrated by the guinea pig PMN 5-LO assay. Chromene hydroxamic acids, in general, behaved poorly in the ex vivo dog model. On the other hand, replacement of the hydroxamic acid function with N-hydroxyurea yielded potent and long-lasting 5-LO inhibitors in the dog model. In most cases, the oral efficacy of the chromene N-hydroxyureas correlated very well with their in vitro activity. Compounds 43 (CGS 23885) and 55 (CGS 24891) are among the most potent inhibitors prepared, showing IC50 values of 48 and 51 nM, respectively. The values for the duration of action (DA) for compounds 43 and 55 are 21 and 20 h, respectively, following intravenous (i.v.) administration of 1.0 mg/kg. In the oral (po) experiments, 43 and 55 have DA's of 14 and 15 h, respectively, at a 1.0 mg/kg dose. In both iv and po experiments, 43 and 55 showed sustained maximal inhibition (> 95%) at earlier time points. The oral ED50 values of 43 and 55 in the ex vivo dog model are 0.23 and 0.23 mg/kg, respectively, at 6.0 h, and 2.37 and 1.63 mg/kg, respectively, at 24 h. Compound 43, which inhibits sheep seminal vesicle cyclooxygenase (CO) with an IC50 value of 36 microM, was shown to be a selective 5-lipoxygenase inhibitor in the ex vivo study. These compounds compare favorably with zileuton (A-64077) in all the parameters examined.

A high-affinity iodinated agonist radioligand for the A2 adenosine receptor has been synthesized to facilitate studies of the A2 adenosine receptor binding subunit. The radioligand 125I-labeled PAPA-APEC (125I-labeled 2-[4-(2-[2-[(4- aminophenyl)methylcarbonylamino]ethylaminocarbonyl]- ethyl)phenyl]ethylamino-5'-N-ethylcarboxamidoadenosine) was synthesized and found to bind to the A2 adenosine receptor in bovine striatal membranes with high affinity (Kd = 1.5 nM) and A2 receptor selectivity. Competitive binding studies reveal the appropriate A2 receptor pharmacologic potency order with 5'-N-ethylcarboxamidoadenosine (NECA) greater than (-)-N6-[(R)-1-methyl- 2-phenylethyl]adenosine (R-PIA) greater than (+)-N6-[(S)-1-methyl-2- phenylethyl]adenosine (S-PIA). Adenylate cyclase assays, in human platelet membranes, demonstrate a dose-dependent stimulation of cAMP production. PAPA-APEC (1 microM) produces a 43% increase in cAMP production, which is essentially the same degree of increase produced by 5'-N- ethylcarboxamidoadenosine (the prototypic A2 receptor agonist). These findings combined with the observed guanine nucleotide-mediated decrease in binding suggest that PAPA-APEC is a full A2 agonist. The A2 receptor binding subunit was identified by photoaffinity-crosslinking studies using 125I-labeled PAPA-APEC and the heterobifunctional crosslinking agent N-succinimidyl 6-(4'-azido-2'-nitrophenylamino)hexanoate (SANPAH). After covalent incorporation, a single specifically radiolabeled protein with an apparent molecular mass of 45 kDa was observed on NaDodSO4/PAGE/autoradiography. Incorporation of 125I-labeled PAPA-APEC into this polypeptide is blocked by agonists and antagonists with the expected potency for A2 receptors (see above) and is decreased in the presence of 10(-4) M guanosine 5'-[beta, gamma-imido]triphosphate. Photoaffinity crosslinking of the A1 adenosine receptor binding subunit with 125I-labeled 8-[4-[2-(4- aminophenylacetylamino)ethyl]carbonylmethyloxyphenyl]-1,3-di propylxanthine (PAPAXAC) (an A1 selective photoaffinity probe) in the same tissue reveals a 38-kDa peptide that exhibits the appropriate A1 receptor pharmacology. 125I-labeled PAPA-APEC, therefore, has identified the A2 receptor binding subunit as a 45-kDa protein that is unique and distinct from the A1 binding subunit.

The adenosine agonist 2-(4-(2-carboxyethyl)phenylethylamino)-5′-N-ethylcarboxamidoadenosine ({"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680) was recently reported to be selective for the A2A adenosine receptor subtype, which mediates its hypotensive action. To investigate structurelactivity relationships at a distal site, {"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680 was derivatized using a functionalized congener approach. The carboxylic group of {"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680 has been esterified to form a methyl ester, which was then treated with ethylenediamine to produce an amine congener. The amine congener was an intermediate for acylation reactions, in which the reactive acyl species contained a reported group, or the precursor for such. For radioiodination, derivatives of p-hydroxyphenylpropionic, 2-thiophenylacetic, and p-aminophenylacetic acids were prepared. The latter derivative (PAPA-APEC) was iodinated electrophilically using [125I]iodide resulting in a radioligand which was used for studies of competition of binding to striatal A, adenosine receptors in bovine brain. A biotin conjugate and an aryl sulfonate were at least 350-fold selective for A, receptors. For spectroscopic detection, a derivative of the stable free radical tetramethyl-1-piperidinyloxy (TEMPO) was prepared. For irreversible inhibition of receptors, meta- and para-phenylenediisothiocyanate groups were incorporated in the analogs. We have demonstrated that binding at A2A receptors is relatively insensitive to distal structural changes at the 2-position, and we report high affinity molecular probes for receptor characterization by radioactive, spectroscopic and affinity labelling methodology.

1. CGS 19755 (cis-4-phosphonomethyl-2-piperidine carboxylic acid), a rigid analogue of 2-amino-5-phosphonopentanoic acid (AP5), is one of the most potent competitive N-methyl-D-aspartate (NMDA) antagonists described. Using Triton-treated crude synaptic membranes from rat brain, binding studies indicated that [3H]-CGS 19755 bound with high affinity and selectivity to the NMDA-type excitatory amino acid receptor. 2. [3H]-CGS 19755 binding was saturable, reversible, heat-labile, pH-dependent and linear with protein concentration. Specific binding represented 80-85% of the total amount bound. 3. Using a centrifugation assay, saturation experiments revealed two distinct binding components with Kd values of 9 and 200 nM, and corresponding Bmax values of 0.55 and 1.00 pmol mg-1 protein. In contrast, a single binding component with a Kd value of 24 nM and an apparent Bmax value of 0.74 pmol mg-1 protein was observed with a filtration assay. 4. Competition experiments in which both assay techniques were used, showed that [3H]-CGS 19755 selectively labels the NMDA receptor. The most active inhibitors of [3H]-CGS 19755 binding were L-glutamate and CGS 19755 (IC50 values = 100 nM). 5. In the centrifugation assay, a number of excitatory amino acids were found to generate shallow inhibition curves, and computer analysis indicated the presence of two binding components. The quisqualate receptor ligand AMPA (D,L-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate), kainic acid and the non-competitive NMDA antagonists, such as phencyclidine, tiletamine and MK-801, were without activity. 6. The high affinity binding obtained with [3H]-CGS 19755 by use of filtration techniques thus permits the more rapid evaluation of compounds as potential NMDA antagonists and agonists. Therefore, this rigid analogue of AP5 is a more suitable radioligand for NMDA receptors than [3H]-CPP (34-+/-)2-carboxypiperazin-4-yl)propyl-1-phosphonic acid), the corresponding analogue of 2-amino-7-phosphonoheptanoic acid (AP7).

Two general synthetic approaches to a novel series of 2H-[1]benzopyrano[3,4-b]pyridines are described together with their receptor binding profile at a variety of monoamine receptors in mammalian brain tissue. The biologically active members of this series fall into into one of two broad classes: 3,4,4a,5-tetrahydro-2H-[1]benzopyrano[3,4-b]pyridines or trans-1,3,4,4a,5,10b-hexahydro-2H-[1]benzopyrano[3,4-b]pyridines. By appropriate pharmacophoric modification potent selective ligands for D2, alpha-2, 5HT1A, and 5HT2 receptors may be obtained. The previously published in vivo data on certain key representatives of these series are also summarized.

Two general synthetic approaches to a novel series of 2H-[1]benzopyrano[3,4-b]pyridines are described together with their receptor binding profile at a variety of monoamine receptors in mammalian brain tissue. The biologically active members of this series fall into into one of two broad classes: 3,4,4a,5-tetrahydro-2H-[1]benzopyrano[3,4-b]pyridines or trans-1,3,4,4a,5,10b-hexahydro-2H-[1]benzopyrano[3,4-b]pyridines. By appropriate pharmacophoric modification potent selective ligands for D2, alpha-2, 5HT1A, and 5HT2 receptors may be obtained. The previously published in vivo data on certain key representatives of these series are also summarized.

A general synthetic approach to a novel series of cis-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols is described together with their receptor-binding profile on opioid-receptor subtypes (mu, kappa, delta). In addition, their in vivo antinociceptive activity was assessed. A number of the analogues synthesized showed potent affinity for opioid receptors and have potent antinociceptive activity in a mouse phenylquinone abdominal stretching model. In addition, the SAR for nitrogen substitution in the above series is explored with respect to the overall opioid receptor subtype binding profile. In general it was found that substituents which enhanced mu and kappa binding affinity in the benzomorphan series had a similar effect in the benzofuropyridine series described in this manuscript. An overlap hypothesis topologically connecting the benzomorphan nucleus to the cis-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridine nucleus is also presented.

A new Stereoselective three-step total synthesis of (±)-aristeromycin starting from readily available 1-hydroxymethyl-3-cyclopentene is described.