RESUMEN
RP 73870, the racemic potassium salt of (([N-(methoxy-3-phenyl)-N-(N-methyl-N-phenyl-carbamoylmethyl)- carbamoylmethyl]-3-ureido)-3-phenyl)-2-ethylsulfonate-(RS) is a potent, reversible antagonist of both gastrin and cholecystokinin-B receptors in guinea pig and rat tissues. This compound is a potent inhibitor of pentagastrin-stimulated gastric acid secretion in the perfused rat stomach. RP 73870 also inhibits basal gastric acid secretion in the rat, although at doses higher than that required for inhibition of pentagastrin-stimulated gastric acid secretion. RP 73870 is a potent inhibitor of aspirin-induced gastric damage in the rat. In the prevention of aspirin-induced gastric damage, RP 73870, given p.o., was 10-fold less potent than when given i.v. RP 73870 was as potent as a H2 receptor antagonist or proton pump inhibitor in the prevention of cysteamine-induced duodenal ulcers in the rat. Relative to other gastrin/cholecystokinin-B antagonists, RP 73870 demonstrates greater affinity to gastrin binding sites, and possesses a unique spectrum of in vivo biological activities appropriate for an anti-ulcer indication.
Asunto(s)
Antiulcerosos/farmacología , Compuestos de Fenilurea/farmacología , Receptores de Colecistoquinina/antagonistas & inhibidores , Animales , Antiulcerosos/metabolismo , Corteza Cerebral/metabolismo , Úlcera Duodenal/prevención & control , Mucosa Gástrica/metabolismo , Cobayas , Compuestos de Fenilurea/metabolismo , Ratas , Receptor de Colecistoquinina B , Receptores de Colecistoquinina/metabolismo , Úlcera Gástrica/prevención & controlRESUMEN
We present here the pharmacological properties of 3 ureido-acetamide members of a novel family of non-peptide cholecystokinin-B (CCKB) receptor antagonists. RP 69758 (3-(3-[N-(N-methyl N-phenyl-carbamoylmethyl) N-phenyl-carbamoylmethyl] ureido)phenylacetic acid), RP 71483 ((E)-2-[3-(3-hydroxyiminomethyl phenyl) ureido] N-(8-quinolyl) N-[(1,2,3,4-tetrahydro 1-quinolyl)carbonylmethyl]acetamide) and RP 72540 ((RS)-2-[3-(3-[N-(3-methoxy phenyl) N-(N-methyl N-phenyl-carbamoylmethyl) carbamoylmethyl] ureido) phenyl] propionic acid) displayed nanomolar affinity for guinea-pig, rat and mouse CCKB receptors labelled with [3H]pCCK-8 or with the selective CCKB receptor ligand [3H]pBC264. RP 69758 and RP 72540 showed selectivity factors in express of 200 for CCKB versus CCKA receptors. All three compounds had also high affinity for gastrin binding sites in the stomach. The ureido-acetamides behaved as potent antagonists of CCK-8-induced neuronal firing in rat hippocampal slices in vitro, a functional model of brain CCKB receptor mediated responses. RP 69758 is also a potent gastrin receptor antagonist in vivo that dose dependently inhibits gastric acid secretion induced by i.v. injection of pentagastrin in the rat. None of the three ureido-acetamides, at concentrations up to 1 microM, significantly blocked CCK-8-evoked contractions of the guinea-pig ileum in vitro, a CCKA receptor bioassay. In ex vivo binding studies, i.p. administration of RP 69758 and RP 72540 resulted in a dose-dependent inhibition of [3H]pCCK-8 binding in mouse brain homogenate. However, the relative penetration of these ureido-acetamides into the forebrain after peripheral administration was below 0.01%. RP 71483 did not appear to cross the blood-brain barrier in quantities sufficient to prevent [3H]pCCK-8 binding at low doses, a property that makes it suitable for the exploration of the peripheral versus central origin of the behavioural effects observed following systemic administration of CCK. RP 69758, RP 71483 and RP 72540 are highly potent and selective non-peptide CCKB receptor antagonists which are useful tools to explore the physiological functions of CCKB receptors.
Asunto(s)
Acetamidas/farmacología , Compuestos de Fenilurea/farmacología , Receptores de Colecistoquinina/antagonistas & inhibidores , Acetamidas/administración & dosificación , Animales , Unión Competitiva , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/metabolismo , Simulación por Computador , Relación Dosis-Respuesta a Droga , Electrofisiología , Ácido Gástrico/metabolismo , Mucosa Gástrica/metabolismo , Cobayas , Hipocampo/efectos de los fármacos , Hipocampo/fisiología , Íleon/efectos de los fármacos , Íleon/fisiología , Técnicas In Vitro , Inyecciones Intraperitoneales , Inyecciones Intravenosas , Masculino , Ratones , Modelos Biológicos , Neuronas/efectos de los fármacos , Páncreas/efectos de los fármacos , Páncreas/metabolismo , Pentagastrina/farmacología , Compuestos de Fenilurea/administración & dosificación , Ratas , Estómago/efectos de los fármacosRESUMEN
L-365,260, a nonpeptide antagonist of gastrin/CCK-B receptors, was evaluated in receptor binding, antisecretory and gastrointestinal damage assays. L-365,260 binds potently and stereo-selectively to gastrin and CCK-B sites in guinea pig tissue. In contrast, L-365,260 binds to the isolated canine parietal cell gastrin receptor weakly, and without stereoselectivity. In the pylorus-ligated rat, low doses of L-365,260, given i.v., attenuated pentagastrin-stimulated acid secretion, whereas higher doses were required to inhibit both histamine-stimulated and basal acid secretion. In an aspirin-induced gastric damage model, L-365,260 was 2.4-fold less potent than the standard histamine H2 antagonist cimetidine in preventing gastric damage when given i.v., and was 8.3-fold less potent than cimetidine when given p.o. Moreover, the ED50 value for L-365,260, given i.v., in prevention of aspirin-induced gastric damage (11.5 mg/kg) agreed well with its ED50 value for inhibition of basal acid secretion (12.6 mg/kg). At doses as great as 100 mg/kg p.o., neither L-365,260 nor cimetidine had an effect on ethanol-induced gastric damage. L-365,260, although p.o. less bioavailable relative to cimetidine in the aspirin gastric damage model, was as potent as cimetidine in the prevention of cysteamine-induced duodenal ulcers in the rat. We conclude that the gastrin/CCK-B receptor antagonist L-365,260, at doses supramaximal for the inhibition of pentagastrin-stimulated secretory responses in vivo, inhibits gastrointestinal damage in models of peptic ulcer disease by an antisecretory mechanism of action.
Asunto(s)
Aspirina/antagonistas & inhibidores , Benzodiazepinonas/farmacología , Cisteamina/antagonistas & inhibidores , Sistema Digestivo/efectos de los fármacos , Etanol/antagonistas & inhibidores , Ácido Gástrico/metabolismo , Compuestos de Fenilurea , Receptores de Colecistoquinina/antagonistas & inhibidores , Animales , Aspirina/efectos adversos , Cisteamina/efectos adversos , Relación Dosis-Respuesta a Droga , Etanol/efectos adversos , Cobayas , Técnicas In Vitro , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
This report describes the development of novel benzamides which are orally active, highly potent, specific antagonists of 5-HT3 receptors. Described in this first report are the structure-activity relationships that led to novel structures with improved potency and selectivity. From this series of compounds, (S)-28 was identified and selected for further evaluation as a 5-HT3 receptor antagonist. Compared with 5-HT3 antagonists such as GR 38032F, BRL 43694, and metoclopramide, (S)-28 was most active in (a) inhibiting binding to 5-HT3 receptor binding sites in rat entorhinal cortex with an Ki value of 0.19 nM and (b) blocking cisplatin-induced emesis in the ferret with an ED50 value determined to be 9 micrograms/kg po.
Asunto(s)
Antieméticos/síntesis química , Benzamidas/síntesis química , Benzofuranos/síntesis química , Compuestos Bicíclicos Heterocíclicos con Puentes , Compuestos Bicíclicos con Puentes/síntesis química , Antagonistas de la Serotonina , Animales , Antieméticos/farmacología , Antieméticos/uso terapéutico , Benzamidas/farmacología , Benzamidas/uso terapéutico , Benzofuranos/farmacología , Benzofuranos/uso terapéutico , Unión Competitiva , Compuestos Bicíclicos con Puentes/farmacología , Compuestos Bicíclicos con Puentes/uso terapéutico , Corteza Cerebral/metabolismo , Cisplatino/toxicidad , Hurones , Granisetrón , Imidazoles/metabolismo , Imidazoles/farmacología , Imidazoles/uso terapéutico , Indazoles/farmacología , Indazoles/uso terapéutico , Indoles/metabolismo , Masculino , Metoclopramida/farmacología , Metoclopramida/uso terapéutico , Estructura Molecular , Ondansetrón , Ratas , Receptores de Serotonina/metabolismo , Relación Estructura-Actividad , Vómitos/inducido químicamente , Vómitos/prevención & controlRESUMEN
RG 12915 [4-[N-(1-azabicyclo[2.2.2.]octan-3-(S)-yl)]2-chloro-cis 5a-(S)-9a-(S)-5a,6,7,8,9,9a-hexahydrobenzofurancarboxamide hydrochloride] is a potent and effective agent against cisplatin-induced emesis in the ferret after i.v. or p.o. administration. This agent (p.o.) is also highly protective against cisplatin-induced emesis in the dog, as well as cyclophosphamide/doxorubicin-induced emesis in the ferret. When administered either p.o. or i.v., RG 12915 has a lower ED50 value (0.004 mg/kg) than GR 38032F, BRL 43694 and metoclopramide for attenuating cisplatin-induced emetic episodes in the ferret. It also has a long duration of action against cisplatin-induced emesis in the ferret. In contrast to metoclopramide, RG 12915 lacks significant antidopaminergic activity both in vitro [( 3H]spiroperidol displacement), as well as in vivo (apomorphine-induced emesis). In radioligand binding assays, RG 12915 is a potent and selective displacer of binding of 5-hydroxytryptamine (5-HT)3 binding sites (IC50 value = 0.16 nM), whereas failing to displace binding of ligands for the alpha-1, alpha-2 and beta adrenergic, 5-HT1 or 5-HT2 or cholinergic-muscarinic sites with IC50 values less than 1 microM. At a p.o. dose (1 mg/kg) in which RG 12915 is highly protective against cisplatin-induced emesis in the dog, RG 12915 has no significant gastroprokinetic activity in the same species. In summary, RG 12915 is a potent and p.o. effective agent against cytotoxic drug-induced emesis in animal models. The antiemetic potency of RG 12915 against cisplatin is unrelated to antidopaminergic or gastroprokinetic activity, but may be related to its affinity for 5-HT3 binding sites.
Asunto(s)
Antieméticos/uso terapéutico , Benzofuranos/uso terapéutico , Compuestos Bicíclicos Heterocíclicos con Puentes , Compuestos Bicíclicos con Puentes/uso terapéutico , Hidrocarburos Aromáticos con Puentes/uso terapéutico , Cisplatino/efectos adversos , Receptores de Serotonina/efectos de los fármacos , Antagonistas de la Serotonina/uso terapéutico , Vómitos/prevención & control , Administración Oral , Animales , Antineoplásicos/efectos adversos , Benzofuranos/administración & dosificación , Benzofuranos/metabolismo , Compuestos Bicíclicos con Puentes/administración & dosificación , Compuestos Bicíclicos con Puentes/metabolismo , Perros , Dopamina/metabolismo , Hurones , Vaciamiento Gástrico/efectos de los fármacos , Granisetrón , Imidazoles/metabolismo , Imidazoles/uso terapéutico , Indazoles/metabolismo , Indazoles/uso terapéutico , Ondansetrón , Receptores de Serotonina/metabolismo , Antagonistas de la Serotonina/administración & dosificación , Vómitos/inducido químicamenteRESUMEN
Recent results from our laboratory and others have suggested a possible physiological functional role(s) for leukotrienes in gastric mucosa. In the present study 3H-LTC4 binds to washed rabbit gastric mucosal membranes at 4 degrees C with a Kd of 5 nM and a Bmax of 31.3 pmol/mg protein. Leukotrienes D4, E4, B4, oxidized glutathione (GSSG), cysteine, and mercaptoethanol were unable to displace 3H-LTC4 at 1 microM concentrations, while GSH inhibited binding with a Ki of 47 nM. Differential centrifugation of the membrane preparation to remove mitochondria resulted in Ki values for LTC4 and GSH of 14 and 23 nM, respectively. The similar binding affinities and competitive receptor binding kinetics for GSH and LTC4, the low affinity for other leukotrienes, and a Ki of 7 microM for hematin, a substrate for glutathione S-transferase, suggest that 3H-LTC4 binds to a GSH site which does not discriminate between LTC4 and GSH. Membranes fractionated to remove mitochondria were assayed for glutathione peroxidase, gamma-glutamyltranspeptidase, and glutathione S-transferase as possible binding sites for LTC4. We were unable to detect enzyme activity for any of the three enzymes. The binding of LTC4 in gastric mucosa differs from other tissues with respect to the high affinity for GSH, and thus becomes an appropriate tissue in which to investigate the relationships between LTC4 and GSH.
Asunto(s)
Mucosa Gástrica/metabolismo , Glutatión/metabolismo , Receptores Inmunológicos/metabolismo , SRS-A/metabolismo , Animales , Sitios de Unión , Unión Competitiva , Femenino , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Hemina/metabolismo , Cinética , Masculino , Proteínas de la Membrana/metabolismo , Conejos , Receptores de Leucotrienos , Temperatura , gamma-Glutamiltransferasa/metabolismoRESUMEN
High-performance liquid chromatographic methods for the separation and quantitation of phospholipids were developed and shown to give sensitive, reliable measurements of tissue phospholipids, including difficult-to-resolve pairs such as choline plasmalogen (plasmenylcholine) and phosphatidylcholine, choline glycerophospholipids and sphingomyelin, phosphatidylinositol and phosphatidylserine, and phosphatidylserine and lysophosphatidylethanolamine. Separations of most phospholipids including those mentioned above are more complete than in existing procedures, and require only 40 min per injection. Utilization of the hexane-2-propanol-water system has an advantage over separation techniques that employ acidic solvents in that the plasmalogens are not hydrolyzed and a less degradative environment for labile lipids is provided. Further, a rapid high-performance liquid chromatographic procedure for the separation of intact ethanolamine plasmalogen (plasmenylethanolamine) from phosphatidylethanolamine was developed. Previous procedures have required derivatized samples or acid hydrolysis of the plasmalogen vinyl ether linkage. A slight modification of the primary method (method I) increases the resolution of lysophosphatidylethanolamine from other classes (method II). A third modification (method III) can replace the standard silicic acid column separation of lipids into neutral, glycolipid, and phospholipid fractions.
Asunto(s)
Etanolaminas/aislamiento & purificación , Lisofosfolípidos , Fosfatidiletanolaminas/aislamiento & purificación , Fosfolípidos/aislamiento & purificación , Plasmalógenos/aislamiento & purificación , Animales , Química Encefálica , Bovinos , Membrana Celular/análisis , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Lípidos de la Membrana/análisisRESUMEN
Spectrophotometric techniques for determining the activities of lipases, lysophospholipases, and phospholipases are reviewed. These methods involve the use of thioester substrate analogs as well as omega-nitrophenyl derivatives of the corresponding lipids. The most promising results are obtained with the thioester substrate analogs. Mono- and diacylglycerol lipases are assayed by using rac-1-S-decanoyl-1-mercapto-2,3-propanediol and rac-1,2-S,O-didecanoyl-1-mercapto-2,3-propanediol, respectively. Phospholipases A1 and A2 are determined by using rac-1,2-S,O-didecanoyl-3-phosphocholine-1-mercapto-2,3-propanediol and 2-hexadecanoylthio-1-ethyl-phosphocholine, respectively. Lysophospholipases are measured by using 2-hexadecanoylthio-1-ethyl-phosphocholine. Phospholipase C is assayed with rac-1-S-phosphocholine-2,3-O-didecanoyl-1-mercapto-2,3-propanediol. Thioester substrate analog assay procedures are more rapid, sensitive, convenient, continuous, and less expensive than the classical radiochemical techniques.