SAR studies of capsazepinoid bronchodilators 3: The thiourea part (coupling region) and the 2-(4-chlorophenyl)ethyl moiety (C-region)

Certain derivatives and analogues of capsazepine are potent in vitro inhibitors of bronchoconstriction in human small airways. During an investigation of the dependency of the potency on the structural features of the capsazepinoids in the thiourea moiety (coupling region) and the 2-(4-chlorophenyl)ethyl moiety (C-region), it was revealed that capsazepinoids with a thiourea or an amide link between the B-ring and the C-region in general have a good bronchorelaxing activity, while urea is a less attractive choice. Further, it was shown that 1,2,3,4-tetrahydroisoquinolines with a 2-(phenyl)ethyl derivative as the C-region are considerably more potent than those with an octyl group, while 2,3,4,5-tetrahydro-1H-2-benzazepines were found to be more insensitive to the nature of the C-region.     

Synthesis and structure-activity relationships of a series of benzazepine derivatives as 5-HT2C receptor agonists

To identify potent and selective 5-HT(2C) receptor agonists, a series of novel benzazepine derivatives were synthesized, and their structure-activity relationships examined. The compounds were evaluated for their 5-HT(2C), 5-HT(2A), and 5-HT(2B) receptor binding affinity and intrinsic activity for the 5-HT(2C) and 5-HT(2A) receptors. Among these compounds, 6,7-dichloro-2,3,4,5-tetrahydro-1H-3-benzazepine (6) was effective in a rat penile erection model when administered po, which is a symptom of the serotonin syndrome reflecting 5-HT(2C) receptor activation. Moreover, compound 6 was characterized as a partial agonist of 5-HT(2A) receptors; therefore, it had little effect on the cardiovascular system.     

Gas—liquid chromatographic method for the measurement of plasma levels of d-7,8-dimethoxy-3-methyl-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine acid maleate (SCH-12679) and its major metabolites in aggressive mental retardates

A sensitive gas—liquid chromatographic technique for the quantitative analysis of SCH-12679 (d-7,8-dimethoxy-3-methyl-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine acid maleate) and its major metabolites in plasma of aggressive mental retardates receiving therapeutic doses of the medicament has been developed. The lower limits of detection are 20 ng/ml for SCH-12679, 0.5 ng/ml for 3-desmethyl SCH-12679 and 0.4 ng/ml for 7-desmethyl plus 8-desmethyl SCH-12679. SCH-12679 is estimated with a flame ionization detector. Its metabolites are quantitated using an electron-capture detector after conversion of the compounds to their heptafluorobutyryl derivatives by reaction with the appropriate anhydride. Data on plasma levels of unchanged SCH-12679, 3-desmethyl SCH-12679 and a combination of 7-desmethyl and 8-desmethyl SCH-12679 in fifteen patients treated with the medicament are presented.     

A dopamine- and octopamine-sensitive adenylate cyclase in the nervous system of Octopus vulgaris

• 1.1. Adenylate cyclase activity was assayed in the optic lobe of Octopus vulgaris.
• 2.2. Both octopamine and dopamine stimulate the octopus adenylate cyclase, apparently by competing with the same receptor site.
• 3.3. (±)-2-Amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene-HBr (6,7-ADTN) and a number of phenylethanolamine derivatives stimulate the octopus adenylate cyclase activity.
• 4.4. The dopamine D-1 antagonists R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-HCl (SCH-23390) and (±)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-HCl (SKF-83566) are unable to antagonize the effects of dopamine and octopamine, and similarly ineffective is the agonist (±)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol-HCl (SKF-38393).
• 5.5. No detectable binding of labelled SCH-23390 occurs on membrane preparations from octopus optic lobe.

     

Reversal of mu-opioid-mediated respiratory depression by alpha 2-adrenoceptor antagonism.

The present study was performed in order to evaluate the effects of the selective alpha 2-adrenoceptor antagonist 6-chloro-2,3,4,5-tetrahydro-3-methyl-1H-3-benzazepine (SK&F 86466) on dermorphin-induced analgesia, respiratory depression and inhibition of locomotor activity in the conscious rat. Intracerebroventricular (icv) administration of dermorphin (3 nmol/rat) decreased respiration rate and relative ventilatory minute volume maximally by 38% and 50% of baseline respectively. SK&F 86466 dose-dependently reversed the dermorphin-induced depression of ventilatory parameters, while SK&F 86466 exerted no effect on dermorphin-induced analgesia or depression of locomotor activity due to catalepsia. It appears, therefore, that alpha 2-adrenoceptors selectively interact with mu 2-opioid-receptor mediated effects, such as respiratory depression, but are not involved in the modulation of mu 1-opioid-related effects, such as supraspinal analgesia and depression of locomotor activity.     

Characterization of Radioiodinated TISCH: A High-Affinity and Selective Ligand for Mapping CNS D1 Dopamine Receptor

In developing CNS D1 dopamine receptor-imaging agents with improved specificity and longer brain retention, an iodinated D1 ligand was synthesized. In vitro and in vivo radiolabeling studies of a new iodinated benzazepine, TISCH [7-chloro-8-hydroxy-1-(3'-iodophenyl)-3-methyl-2,3,4,5-tetrahydro-1H-3- benzazepine], an analog of SCH 23390 (7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepin e), were investigated. After an intravenous injection, the R(+) isomer of TISCH showed high brain uptake in rats (2.20 and 0.57% dose per whole brain at 2 and 60 min, respectively). The striatum/cerebellum ratio increased progressively with time (12 at 60 min). Ex vivo autoradiography of rat brain sections, after intravenous injection of R(+)-[125I]TISCH, displayed the highest uptake in striatum and substantia nigra, regions known to have a high concentration of D1 receptors, whereas the S(-) isomer displayed no specific uptake. Furthermore, the specific uptake can be blocked by pretreatment with SCH 23390. In vitro binding studies using the rat striatum tissue preparation showed high specific and low nonspecific bindings (KD = 0.21 +/- 0.03 nM). The rank order of potency exhibiting high specificity to the D1 receptor was SCH 23390 greater than (+/-)-TISCH greater than (+)-butaclamol = (+/-)-FISCH [7-chloro-8-hydroxy-1-(4'-iodophenyl)-3-methyl-2,3,4,5-tetrahydro-1 H-3-benzazepine] much greater than WB4101 = spiperone greater than dopamine, serotonin, (+/-)-propranolol, and naloxone. Imaging studies in a monkey with the resolved isomer, R(+)-[123I]TISCH, demonstrated a high uptake in the basal ganglia and prolonged retention. The preliminary data suggest that R(+)-TISCH is selective for the CNS D1 receptor and is potentially useful for in vivo and in vitro pharmacological studies. When labeled with iodine-123, it may be suitable for noninvasive imaging in humans.     

Synthesis and biological activity of novel 4,4-difluorobenzazepine derivatives as non-peptide antagonists of the arginine vasopressin V1A receptor

To find potent and selective antagonists of the arginine vasopressin (AVP) V1A receptor, optimization studies of compounds structurally related to (Z)-N-{4'-[(4,4-difluoro-5-carbamoylmethylidene-2,3,4,5-tetrahydro-1H-1-benzazepin-1-yl)carbonyl]phenyl}carboxamide were performed. The synthesis and pharmacological properties of these compounds are described. We first investigated the effect of the carboxamide moiety, and found that a 2-methylfuran-3-carbonyl group at this position increased V1A binding affinity and selectivity for the V1A receptor versus the V2 receptor. The amino group of the 5-carbamoylmethylidene moiety was also examined, and a 4-piperidinopiperidino group was found to be optimal at this position. The hemifumarate of compound 12l (YM218) was shown to exhibit potent binding affinity, V1A receptor selectivity, and in vivo antagonist activity.     

Photoaffinity labeling of human platelet and rabbit kidney alpha 2-adrenoceptors with [3H]SKF 102229

A newly developed alpha 2-adrenergic photoaffinity ligand, 3-methyl-6-chloro-9-azido-1H-2,3,4,5-tetrahydro-3-benzazepine (SKF 102229), has been radiolabeled with tritium to a specific activity of approximately 80 Ci/mmol. Using membranes prepared from human platelets and from rabbit kidney, alpha 2-adrenoceptors have been covalently labeled following photolysis in the presence of [3H]SKF 102229. As determined by SDS-PAGE, the apparent molecular weight of alpha 2-adrenoceptors from both of these tissues was 64,000. The yield of covalent insertion of [3H]SKF 102229 into the alpha 2-adrenoceptor was very good. Thus, following photolysis up to 90% of the alpha 2-adrenoceptors could be irreversibly labeled with [3H]SKF 102229.     

2,3,4,5-tetrahydro- and 2,3,4,5,11,11a-hexahydro-1H-[1,4]diazepino[1,7-a]indoles: new templates for 5-HT(2C) agonists

The design and synthesis of the novel 2,3,4,5-tetrahydro-1H-[1,4]diazepino[1,7-a]indole 5 is described. This azepinoindole has excellent affinity for 5-HT(2C) (K(i) 4.8 nM) and modest selectivity over 5-HT(2A) ( approximately 4-fold). Several N- and C(11)-substituted analogues of 5 were prepared, as were a number of biaryl indoline derivatives. The anxiolytic potential for the azepinoindole template 5 is demonstrated by activity in a mouse shock-aggression assay.     

Conformationally constrained NR2B selective NMDA receptor antagonists derived from ifenprodil: Synthesis and biological evaluation of tetrahydro-3-benzazepine-1,7-diols

NR2B selective NMDA receptor antagonists with tetrahydro-3-benzazepine-1,7-diol scaffold have been designed by formal cleavage and reconstitution of the piperidine ring of the lead compound ifenprodil (1). The secondary amine 10 represents the central building block for the synthesis of more than 25 tetrahydro-3-benzazepin-1-ols. Generally 7-hydroxy derivatives display higher NR2B receptor affinities than the corresponding 7-benzyloxy compounds. A distance of four atoms (five bond lengths) between the basic amino group and the terminal aryl moiety led to highest NR2B affinity. 3-(4-Phenylbutyl)-2,3,4,5-tetrahydro-1H-3-benzazepine-1,7-diol (WMS-1410, 25) represents the most promising NR2B antagonist of this series showing a K(i)-value of 14nM. Compound 25 reveals excellent selectivity over more than 100 further relevant target proteins, antagonizes glutamate induced excitotoxicity (IC(50)=18.4nM) and is metabolically more stable than ifenprodil. Up to a dose of 100mg/kg 25 is well tolerated by mice and it shows dose dependent analgesic activity in the late neuropathic pain phase of the formalin assay.     

1,3-Disubstituted benzazepines as neuropeptide Y Y1 receptor antagonists.

A novel class of potent and selective non-peptide neuropeptide Y (NPY) Y1 receptor antagonists, having benzazepine nuclei, have been designed, synthesized, and evaluated for activity. Through a blind screening we found the compound 1-N-(3-(N'-(tert-butoxycarbonyl)amino)benzyl)-7-methoxy-(3-(3)-methyl ureido)-2,3,4,5-tetrahydro-1H-1-benzazepin-2-one (9: IC50 = 1.6 microM). Chemical modifications of 9 gave a potent NPY Y1 antagonist 3-(N-(4-hydroxyphenyl)-N'-methylguanidino)-1-N-(3-(N'-(tert-butoxy carbonyl)amino)benzyl)-2,3,4,5-tetrahydro-1H-1-benzazepin-2-one (14c: IC5(0=43 nM), which had no affinity for NPY Y2 and Y5 receptors.     

Binding of [3H]SKF 38393 to Dopamine D-l Receptors in Rat Striatum In Vitro; Estimation of Receptor Molecular Size by Radiation Inactivation

[3H]SKF 38393 (2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine) binds with high affinity to 3,4-dihydroxyphenylethylamine (dopamine) D-1 receptors in rat striatum in vitro (KD = 7 and 14 nM in nonfrozen and frozen striatum, respectively). The number of binding sites (Bmax) was approximately 80.0 pmol/g of original tissue, a value similar to the Bmax for the dopamine D-1 antagonist SCH 23390. Nondisplaceable [3H]SKF 38393 binding was approximately 45% of total binding. Irradiation (0-4 Mrad) of frozen whole striata decreased the number of [3H]SKF 38393 binding sites monoexponentially without changing the binding affinity. The functional molecular mass for the agonist dopamine D-1 binding site was 132,800 daltons, which is higher than the functional molecular mass of the antagonist dopamine D-1 binding site (approximately 80,000 daltons).     

Dopamine induces inhibitory effects on the circular muscle contractility of mouse distal colon via D1- and D2-like receptors

Dopamine (DA) acts as gut motility modulator, via D1- and D2-like receptors, but its effective role is far from being clear. Since alterations of the dopaminergic system could lead to gastrointestinal dysfunctions, a characterization of the enteric dopaminergic system is mandatory. In this study, we investigated the role of DA and D1- and D2-like receptors in the contractility of the circular muscle of mouse distal colon by organ-bath technique. DA caused relaxation in carbachol-precontracted circular muscle strips, sensitive to domperidone, D2-like receptor antagonist, and mimicked by bromocriptine, D2-like receptor agonist. 7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH-23390), D1-like receptor antagonist, neural toxins, L-NAME (nitric oxide (NO) synthase inhibitor), 2′-deoxy-N₆-methyl adenosine 3′,5′-diphosphate diammonium salt (MRS 2179), purinergic P2Y1 antagonist, or adrenergic antagonists were ineffective. DA also reduced the amplitude of neurally evoked cholinergic contractions. The effect was mimicked by (±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide (SKF-38393), D1-like receptor agonist and antagonized by SCH-23390, MRS 2179, or L-NAME. Western blotting analysis determined the expression of DA receptor proteins in mouse distal colon. Notably, SCH-23390 per se induced an increase in amplitude of spontaneous and neurally evoked cholinergic contractions, unaffected by neural blockers, L-NAME, MRS 2179, muscarinic, adrenergic, or D2-like receptor antagonists. Indeed, SCH-23390-induced effects were antagonized by an adenylyl cyclase blocker. In conclusion, DA inhibits colonic motility in mice via D2- and D1-like receptors, the latter reducing acetylcholine release from enteric neurons, involving nitrergic and purinergic systems. Whether constitutively active D1-like receptors, linked to adenylyl cyclase pathway, are involved in a tonic inhibitory control of colonic contractility is questioned.     

Novel 2,3,4,5-tetrahydro-1H-3-benzazepines with high affinity and selectivity for the dopamine D3 receptor

Starting from the dopamine D3 receptor antagonist SB-277011 1, a series of 2,3,4,5-tetrahydro-1H-3-benzazepines has been identified with high affinity for the dopamine D3 receptor and selectivity over the D2 receptor. The 3-acetamido-2-fluorocinnamide derivative 20 gave high D3 receptor affinity (pKi 8.4) with 130-fold selectivity over the 2, receptor.     

Involvement of D1 dopamine receptors in the cognitive effects of angiotensin IV and des-Phe6 angiotensin IV

An important role for angiotensin IV (Ang IV) in the processes of learning and memory has now been well established. We have previously found that intracerebroventricular (ICV) administration of Ang IV as well as des-Phe6-Ang IV enhances learning of conditioned avoidance responses (CARs), facilitates recall of a passive avoidance (PA) task, and improves object recognition (OR) in rats. Since the dopaminergic system is crucial for the cognitive processes, in this study our aim was to determine the dopaminergic D1 mediation of these effects using SCH 23390 as a selective D1 receptor antagonist. Male Wistar rats (180-200 g), pretreated with SCH 23390 (R-[+]-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) 0.05 mg/kg intraperitoneally (IP), were given Ang IV or des-Phe6-Ang IV (1 nmol ICV) 1 h later and then tested in the above cognitive paradigms, as well as in the open field and an elevated 'plus' maze to control for the unspecific, respectively, motor and emotional, effects of our treatments. Both, Ang IV and des-Phe6-Ang IV effectively enhanced learning of CARs (P < 0.05), recall of PA (P < 0.001), and improved OR (P < 0.001). Pretreatment with SCH 23390 abolished the cognitive effects of both peptides. SCH 23390, Ang IV, and des-Phe6-Ang IV, given at the same doses and routes as in the cognitive tests, did not significantly influence crossings, rearings and bar approaches in the open field, nor the parameters measured in the elevated 'plus' maze, thus making a major contribution of the unspecific effects of our treatments to the results of the memory tests improbable. In conclusion, these results indicate that the functional dopaminergic D1 receptors are necessary for the Ang IV and des-Phe6-Ang IV cognitive effects to occur.     

Evidence for an Antiapoptotic Role of Dopamine in Developing Retinal Tissue

Inhibition of protein synthesis leads to apoptosis in the undifferentiated neuroblastic layer of the retina of newborn rats. We have shown previously that an increase in the intracellular concentration of cyclic AMP prevented apoptosis induced in the retinal neuroblastic layer by inhibition of protein synthesis. In this study, we tested the effects of dopamine on retinal apoptosis and related these effects to the intracellular concentration of cyclic AMP. Both dopamine (100 microM) and the D1-like agonists SKF-38393, 6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (6-Cl-PB), and (+/-)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (100 microM) blocked apoptosis induced in the neuroblastic layer by the protein synthesis inhibitor anisomycin. The antiapoptotic effects of the D1-like agonists were not reversed by the D1-like antagonist SCH-23390 (5-100 microM). Both dopamine and D1-like agonists induced a five- to sevenfold increase in the intracellular concentration of cyclic AMP in the retina of newborn rats. The concentration of cyclic AMP induced by the D1-like agonists in the presence of 100 microM SCH-23390 was still at least two- to threefold as high as control values, showing that the activation of adenylyl cyclase by D1-like agonists was reversed only partially by the specific antagonist. The isoquinolinesulfonamide H-89 (20 microM), an inhibitor of cyclic AMP-dependent protein kinase, partially prevented the antiapoptotic effect of 6-Cl-PB. The data show that an early effect of dopamine in the developing retina is the control of programmed cell death. The antiapoptotic effect of dopamine is mediated, at least in part, through an atypical D1-like receptor coupled to stimulation of adenylyl cyclase, followed by activation of cyclic AMP-dependent protein kinase.     

Enhanced levels of endogenous cannabinoids in the globus pallidus are associated with a reduction in movement in an animal model of Parkinson's disease.

In recent years, cannabinoid receptors and their endogenous ligands (endocannabinoids) have been identified within the brain. The high density of CB1 cannabinoid receptors within the basal ganglia suggests a potential role for endocannabinoids in the control of voluntary movement and in basal ganglia-related movement disorders such as Parkinson's disease. However, whether endocannabinoids play a role in regulating motor behavior in health and disease is unknown. Here we report the presence in two regions of the basal ganglia, the globus pallidus and substantia nigra, of the endocannabinoids 2-arachidonoylglycerol (2AG) and anandamide. The levels of the latter compound are approximately threefold higher than those previously reported in any other brain region. In the reserpine-treated rat, an animal model of Parkinson's disease, suppression of locomotion is accompanied by a sevenfold increase in the levels of the 2AG in the globus pallidus, but not in the other five brain regions analyzed. Stimulation of locomotion in the reserpine-treated rat by either of the two selective agonists of D2 and D1 dopamine receptors, quinpirole and R-(+/-)-3-allyl-6-chloro-7, 8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (Cl-APB), respectively, results in the reduction of both anandamide and 2AG levels in the globus pallidus. Finally, full restoration of locomotion in the reserpine-treated rat is obtained by coadministration of quinpirole and the selective antagonist of the cannabinoid CB1 receptor subtype, SR141716A. These findings indicate a link between endocannabinoid signaling in the globus pallidus and symptoms of Parkinson's disease in the reserpine-treated rat, and suggest that modulation of the endocannabinoid signaling system might prove useful in treating this or other basal ganglia-related movement disorders.     

Synthesis of 8-C-glucosylflavones

The syntheses of orientin, parkinsonin A, isoswertiajaponin, and parkinsonin B, which are 8-C-beta-D-glucopyranosyl-3',4',5,7-tetrahydroxyflavone, 5-methyl orientin, 7-methyl orientin, and 5,7-dimethyl orientin, respectively, are reported herein. The C-glucosyl phloroacetophenone derivatives were obtained via a regio- and stereoselective O-->C glycosyl rearrangement. Aldol condensation of the C-glucosyl phloroacetophenone derivatives with 3,4-bisbenzyloxybenzaldehyde afforded the corresponding C-glucosylchalcones. Construction of the flavone system by reaction with I(2)-Me(2)SO, followed by the elimination of the 5-benzyl protecting group in the flavone structure, yielded an orientin derivative and a isoswertiajaponin derivative. Methylation of the orientin derivatives with dimethyl sulfate afforded the parkinsonin A derivative, the isoswertiajaponin derivative, and the parkinsonin B derivative. Finally, hydrogenolysis of these C-glucosylflavone derivatives led to the four 8-C-glucosylflavones. The NMR spectra of these C-glucosylflavones showed a duplication of signals corresponding to a major rotamer, along with a minor one. Based on NOESY experiments in Me(2)SO at ambient temperature, they adopted conformations in which the H-2"and H-4" protons in the glucose moiety were oriented toward the B-ring in the flavone structure.     

The relaxing effect of SCH 23390 in the molluscan smooth muscle

1. SCH 23390 (SCH, R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) produced the relaxation of ACh-induced contraction in the anterior byssus retractor muscle of Mytilus edulis (ABRM) in a dose-dependent manner between 10⁻⁹-10⁻⁶M.2. The dose-response curve of SCH was shifted in parallel to the right by ketanserin (KET) with pA₂ value of 5.14 ± 0.08 and by 1-(1-naphthyl)piperazine (NAP) with that of 5.06 ± 0.01, but not by cyproheptadine (CYP), mianserin (MIA), butaclamol (BUTA), ICS 205–930 (ICS) and MDL 72222 (MDL) at 3 × 10⁻⁵ M.3. α-Methyl-serotonin (α-Me-5-HT), a selective 5-HT₂ receptor agonist dose-dependently relaxed the ACh-induced contraction of ABRM. The dose-response curve of α-Me-5-HT was shifted in parallel to the right by KET with pA₂ value of 5.01 ± 0.02, but not by BUTA, CYP, MIA, ICS and MDL at 3 × 10⁻⁵ M.4. These findings suggest that 5-HT₂-like receptors exist in the ABRM, and that the relaxation induced by SCH is mediated through these receptors.     

Indole RSK inhibitors. Part 2: optimization of cell potency and kinase selectivity

A series of inhibitors for the 90 kDa ribosomal S6 kinase (RSK) based on an 1-oxo-2,3,4,5-tetrahydro-1H-[1,4]diazepino[1,2-a]indole-8-carboxamide scaffold were optimized for cellular potency and kinase selectivity. This led to the identification of compound 24, BIX 02565, an attractive candidate for use in vitro and in vivo to explore the role of RSK as a target for the treatment heart failure.