RESUMO
Chronic administration of ethyl 2-methyl-2(4-chlorophenoxy)-propionate [clofibrate, CPIB], ethyl 6-cyclohexylchroman-2carboxylate, and ethyl 6-phenylchroman-2-carboxylate to normolipemic rats, in vivo, reduced serum cholesterol levels and inhibitid the activiry of hepatic 3-hydroxy-3methyl-glutaryl Coenzyme A. Only clofibrate was found to lower liver cholesterol content after pretreatment for 4 or 18 days. The cyclic analogs, ethyl 6-cholorochromone-2-carboxylate and 9-chloro-2,3-dihydro-5H-1,4-dioxepino [6,5-b] benzofuran were inaffective as cholesterol lowering agents in normolipemic rats. These findings indicate that appropriate modification of clofibrate can lead to the development of compounds which are selective and equally effective to clofibrate as potential hypocholesterolemic agents. Results obtained in these studies are also discussed in terms of the known structural requirements of biological activity for this series of cyclic analogs in the Triton WR-1339 hyperlipemic rat model and modes of action of the parent compound.
Assuntos
Anticolesterolemiantes , Colesterol/sangue , Clofibrato/análogos & derivados , Animais , Peso Corporal/efeitos dos fármacos , Clofibrato/administração & dosagem , Glucose Oxidase/antagonistas & inibidores , Masculino , Microssomos Hepáticos/metabolismo , Tamanho do Órgão/efeitos dos fármacos , Pré-Medicação , Ratos , Triglicerídeos/metabolismoRESUMO
This paper reports the synthesis of 4-(3,4,5-trimethoxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (2) and 2-(3,4-dihydroxyphenyl)-3-(3,4,5-trimethoxyphenyl)propylamine (3). The biological activity of these agents relative to that of trimetoquinol (1) in guinea pig atria and guinea pig trachea is reported. The relative activities in relaxation of guinea pig trachea is 1 greater than 2 greater than 3 while in the chronotropic response in guinea pig atria the relative order of activity is 1 greater than 3 greater than 2.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Animais , Feminino , Cobaias , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Isoquinolinas/farmacologia , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Traqueia/efeitos dos fármacosRESUMO
The synthesis of N-(3',4',5'-trimethoxyphenylethyl)-3,4-dihydroxyphenylethylamine (2) and 1-(3,4,5-trimethoxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (1) is presented. Comparative pharmacological effects of the optical isomers of 1 and compound 2 are reported in guinea pig atria, rat adipose tissue, guinea pig trachea, and guinea pig aortic strip preparations. In the beta-adrenoreceptor preparations, (-)-1 was shown to be more potent than (+)-1 or 2. Racemic 1 and 2 were shown to have equal alpha-antagonist properties in the inhibition of norepinephrine-induced contractions of guinea pig aorta.
Assuntos
Isoquinolinas/síntese química , Tretoquinol/síntese química , Tecido Adiposo/metabolismo , Antagonistas Adrenérgicos alfa/síntese química , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Epididimo/metabolismo , Feminino , Cobaias , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Metabolismo dos Lipídeos , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Ratos , Receptores Adrenérgicos , Estereoisomerismo , Relação Estrutura-Atividade , Traqueia/efeitos dos fármacos , Tretoquinol/farmacologiaRESUMO
The synthesis of the 1,1-disubstituted tetrahydroisoquinoline analogues, 1-methyl-1-(3,4,5-trimethoxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline hydrochloride (2) and 1-benzyl-1-(3,4,5-trimethoxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline hydrochloride (3), is described. The profile of beta-adrenergic activity for these analogues was determined and compared to that of trimetoquinol (1) in isolated guinea pig atrial, tracheal, and rat adipocyte preparations. Unexpected selective beta1-blocking activity in guinea pig trachea was noted with analogue 3. With the exception of 2 in guinea pig atria, 2 and 3 did not possess any beta-stimulant activity. Substitution at the 1 position of trimetoquinol (1) has revealed qualitative differences in beta-adrenergic activity.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Antagonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Tretoquinol/síntese química , Tecido Adiposo/metabolismo , Animais , Feminino , Cobaias , Frequência Cardíaca/efeitos dos fármacos , Técnicas In Vitro , Metabolismo dos Lipídeos , Masculino , Relaxamento Muscular , Músculo Liso/efeitos dos fármacos , Ratos , Tretoquinol/análogos & derivados , Tretoquinol/farmacologiaRESUMO
A positional isomer of trimetoquinol (1), 1-(2',4',5'-trimethoxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (3), was synthesized and found to possess less beta-adrenergic activity than 1 in isolated guinea pig atrial and tracheal preparations. The analogue 3 was an effective antiaggregatory agent in human and rabbit platelet-rich plasma preparations, while 1 was effective only as an inhibitor of arachidonic acid induced aggregation in human platelets. These findings indicate that both qualitative and quantitative differences in biological activity have occurred as a result of changing the position of the methoxy groups on the 1-benzyl substituent of 1.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Agregação Plaquetária/efeitos dos fármacos , Tretoquinol/síntese química , Animais , Feminino , Cobaias , Frequência Cardíaca/efeitos dos fármacos , Humanos , Técnicas In Vitro , Masculino , Relação Estrutura-Atividade , Traqueia/efeitos dos fármacos , Tretoquinol/farmacologiaRESUMO
Trimetoquinol [1-(3,4,5-trimethoxybenzyl)-6,7- dihydroxy-1,2,3,4-tetrahydroisoquinoline, TMQ] is a potent beta-adrenergic receptor agonist and inhibitor of human platelet aggregation. Selective cleavage of O-benzyl groups in the presence of an N-benzyl group using HCl and formation of a cyclic sulfite ester from the reaction of a catechol with thionyl chloride were achieved. The N-substituents included methyl, benzyl, and beta-hydroxy- and beta-chloroethyl groups. Each N-substituted TMQ caused a concentration-dependent stimulation of beta 2 (trachea) and beta 1 (atria) adrenoceptor tissues and inhibition of 15(S)-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13(E)-dienoic acid (U46619, a thromboxane A2 mimetic) mediated human platelet activation. TMQ remained the most potent in the series. Structure-activity results indicated that the larger the N-substituent, the lower the beta-adrenergic activity but the higher the inhibition of platelet aggregatory activity. Thus, the structural requirements of these TMQ analogues for the two types of biological activity are different.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Isoquinolinas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Tretoquinol/farmacologia , Animais , Bioensaio , Fenômenos Químicos , Química , Cobaias , Humanos , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/fisiologia , Receptores Adrenérgicos beta/fisiologia , Tromboxano A2/antagonistas & inibidores , Tretoquinol/análogos & derivados , Tretoquinol/síntese químicaRESUMO
A synthetic method for the preparation of aci-reductone 6-chloro-3,4-dihydroxy-2H-1-benzopyran-2-one (3) from 5-chlorosalicylate is presented. In human platelets, the benzopyranone derivative 3, clofibric acid (1), and the 2,3-dihydrobenzofuran analogue 4 inhibited aggregation and serotonin secretory responses to adenosine diphosphate (ADP) with a rank order of potency 3 greater than or equal to 4 greater than 1. Only analogues 3 and 4 consistently blocked the aggregatory responses (greater than 50%) to arachidonic acid (AA) and U46619, a thromboxane A2 agonist. Further, the rank order of inhibitory potency against U46619-induced serotonin secretion was 4 greater than 3 greater than 1. Benzopyranone 3 is of interest since it was the most potent inhibitor of thrombin-induced [3H]AA release (3 much greater than 4 = 1) and more potent than 1 or 4 for the blockade of the ADP- or AA-mediated pathway of platelet aggregation.
Assuntos
Benzofuranos/farmacologia , Clofibrato/análogos & derivados , Ácido Clofíbrico/farmacologia , Cumarínicos/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico , Ácido Araquidônico , Ácidos Araquidônicos/metabolismo , Ácidos Araquidônicos/farmacologia , Plaquetas/metabolismo , Humanos , Técnicas In Vitro , Endoperóxidos Sintéticos de Prostaglandinas/farmacologia , Serotonina/metabolismo , Relação Estrutura-AtividadeRESUMO
IBI [2-(4'-isothiocyanatobenzyl)imidazoline, 3] has been shown to cause slow-onset, long-lasting contractions of rat thoracic aorta through a non-alpha-adrenergic receptor (non-alpha-AR) mediated mechanism. A series of IBI-related anlogs 7-14 and 16 was prepared to determine the structural requirements for the interaction with non-alpha-AR in rat aortic strips. All IBI analogs produced concentration-dependent contractile responses on rat thoracic aorta. Whereas the actions of analogs 7, 14, and 16 were partly mediated by alpha-ARs, the stimulatory activities of the remaining IBI analogs were unaffected by phenoxybenzamine pretreatment, suggesting that a non-alpha-adrenergic mechanism is involved. We have shown that the contractile actions of IBI and analogs 10-13 were not blocked with the imidazoline/guanidinium receptive site (IGRS) ligands idazoxan, cirazoline, or clonidine. However, the calcium channel blockers nifedipine or verapamil shifted the concentration-response curve of IBI and its analogs 10-13 to the right and reduced the maximal contractile responses. The action of IBI on rat thoracic aorta was reduced by the omission of extracellular calcium in the medium. These results suggest that the stimulatory activities of IBI and analogs 10-13 are not related to the activation of alpha-AR or IGRS receptors and are likely coupled to the voltage-dependent Ca2+ channels.
Assuntos
Aorta Torácica/efeitos dos fármacos , Tolazolina/análogos & derivados , Animais , Aorta Torácica/fisiologia , Canais de Cálcio/efeitos dos fármacos , Dioxanos/farmacologia , Idazoxano , Imidazóis/farmacologia , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Nifedipino/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Adrenérgicos alfa/efeitos dos fármacos , Tolazolina/síntese química , Tolazolina/química , Tolazolina/farmacologia , Verapamil/farmacologiaRESUMO
The 5-fluoro and 8-fluoro analogues of trimetoquinol, TMQ, have been synthesized and evaluated for beta 2- and beta 1-adrenoceptor activity in guinea pig trachea and atria, respectively. The fluoro analogues of TMQ maintained potent beta 2-adrenoceptor agonist activity but had reduced beta 1-adrenoceptor agonist activity. The changes in beta 1-activity of these compounds were correlated to differences in phenolic pKa's. The beta 1- and beta 2-adrenoceptor actions of 2 and 3 were blocked in a competitive manner by propranolol. The enhanced beta 2/beta 1 selectivity for the analogues was found to be 8-fluoro analogue 3 greater than 5-fluoro analogue 2 greater than trimetoquinol (1).
Assuntos
Agonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Receptores Adrenérgicos beta/metabolismo , Tretoquinol/síntese química , Agonistas Adrenérgicos beta/metabolismo , Animais , Função Atrial , Cobaias , Técnicas In Vitro , Indicadores e Reagentes , Cinética , Espectroscopia de Ressonância Magnética , Masculino , Contração Muscular/efeitos dos fármacos , Contração Miocárdica/efeitos dos fármacos , Propranolol/farmacologia , Receptores Adrenérgicos beta/efeitos dos fármacos , Espectrofotometria Infravermelho , Relação Estrutura-Atividade , Traqueia/fisiologia , Tretoquinol/análogos & derivados , Tretoquinol/metabolismo , Tretoquinol/farmacologiaRESUMO
Trimetoquinol (1, TMQ) is a potent nonselective beta-adrenergic receptor (AR) agonist and a thromboxane A(2)/prostaglandin endoperoxide (TP) receptor antagonist, while 3',5'-diiodo-TMQ (2) exhibits beta(3)-AR selectivity. In search of selective beta(3)-AR agonists as potential drugs for the treatment of human obesity and type II diabetes mellitus, a series of 1-(3, 5-diiodo-4-methoxybenzyl)-1,2,3,4-tetrahydroisoquinolin-6-ols has been prepared and evaluated for their biological activities at human beta(1)-, beta(2)-, and beta(3)-ARs expressed in Chinese hamster ovary (CHO) cells. The compounds have been synthesized by the Bischler-Napieralski cyclization of corresponding amides followed by NaBH(4) reduction, and the halogens in the aromatic ring A were introduced by direct halogenation of protected compound 11. Whereas halogen substitution in ring A reduced either potency or intrinsic activity on beta(3)-AR, the non-halogen-substituted compounds 8 and 10 were potent, selective, nearly full agonists for beta(3)-AR.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Receptores Adrenérgicos beta/efeitos dos fármacos , Agonistas Adrenérgicos beta/química , Agonistas Adrenérgicos beta/farmacologia , Animais , Células CHO , Cricetinae , AMP Cíclico/metabolismo , Humanos , Isoquinolinas/química , Isoquinolinas/farmacologia , Radioimunoensaio , Receptores Adrenérgicos beta/metabolismo , Relação Estrutura-Atividade , TransfecçãoRESUMO
The synthesis and pharmacological activity of erythro and threo isomers of 1-(3',4',5'-trimethoxy-alpha-hydroxy-benzyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, 2 and 3, are reported. The structural assignments of 2 and 3 are based upon NMR spectra of the 6,7-dibenzyl precursors, 6 and 10, and of the synthetic derivatives of 13alpha- and 13beta-hydroxy-2,3-(dibenzyloxy)-9,10,11-trimethoxytetrahydroprotoberberine, 8 and 12, respectively. The erythro isomer 2 was a more potent beta-adrenoceptor stimulant than the threo isomer 3 in guinea pig atrial, guinea pig tracheal, and rat adipocyte preparations. The differential activity of these compounds on lipolysis was favorably correlated to changes in the stimulation of adenylate cyclase activity and cAMP accumulation in rat adipocytes.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Isoquinolinas/síntese química , Tretoquinol/síntese química , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Resistência das Vias Respiratórias/efeitos dos fármacos , Animais , AMP Cíclico/metabolismo , Feminino , Cobaias , Frequência Cardíaca/efeitos dos fármacos , Técnicas In Vitro , Metabolismo dos Lipídeos , Espectroscopia de Ressonância Magnética , Masculino , Ratos , Estereoisomerismo , Tretoquinol/análogos & derivados , Tretoquinol/farmacologiaRESUMO
The synthesis and antilipidemic activity of 9-chloro-2,3-dihydro-5H-1,4-dioxepino[6,5-b]benzofuran (3), a novel enol lactone which is considerably more resistant to serum esterase hydrolysis than clofibrate (1), are discussed. Whereas both 3 and 1 reduced hypercholesterolemic and hypertriglyceridemic serum levels in the Triton WR-1339 induced hyperlipidemic Sprague-Dawley rat to normal, the hydrolysis product of 3, namely 5-chloro-3(2'-hydroxyethoxy)-2-benzofurancarboxylic acid (4), was found to be inactive. Further, 3 is comparable to the hydrolysis product of 1 when both were assessed for their ability to block norepinephrine (NE) induced lipolysis in vitro. 4 is inactive at comparable concentrations (5 times 10(-4)-10(-3) M). The antilipidemic action of 3 and 1 may, in part, be due to their ability to block NE-induced lipolysis.
Assuntos
Benzofuranos/síntese química , Clofibrato , Hipolipemiantes/síntese química , Tecido Adiposo/citologia , Tecido Adiposo/metabolismo , Animais , Benzofuranos/sangue , Benzofuranos/farmacologia , Colesterol/sangue , Clofibrato/sangue , Depressão Química , Glicerol/metabolismo , Hidrólise , Hipolipemiantes/sangue , Masculino , Espectrometria de Massas , Norepinefrina/farmacologia , Oxepinas/sangue , Oxepinas/síntese química , Oxepinas/farmacologia , Ratos , Espectrofotometria Infravermelho , Triglicerídeos/sangueRESUMO
The chemistry and pharmacology of two delta-lactones, cis-6-chloro-9a-methyl-3,4,4a,9a-tetrahydro-1H-pyrano[3,4-b]benzofuran-1-one (2) and the 9a-demethyl analogue 3, are reported. Lactones were prepared from dihydrobenzofuran precursors possessing geometrical configurations confirmed both by synthesis and 1H NMR spectroscopy. All cis-dihydrobenzofurans exhibited Jvic = 9.0-10.8 Hz, whereas their trans isomers exhibited Jvic = 5.0--6.0 Hz in agreement with predictions based on the Karplus equation. The pharmacological profiles for 2 and 3 were compared to that of clofibrate (1) in normal male Sprague-Dawley rats. Using equimolar doses (0.4 mmol/kg, po, twice daily for 7 days), 1 exhibited both anticholesterolemic and antitriglyceridemic activity, lactone 2 exhibited only antitriglyceridemic activity, and 3 was inactive as an antilipidemic agent. No correlation was observed for inhibition of hepatic HMG-CoA reductase activity and serum cholesterol lowering.
Assuntos
Benzofuranos/síntese química , Clofibrato/análogos & derivados , Animais , Benzofuranos/farmacologia , Colesterol/sangue , Colesterol/metabolismo , Clofibrato/síntese química , Clofibrato/farmacologia , Etilmorfina-N-Demetilasa/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases , Lactonas/síntese química , Lactonas/farmacologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Microssomos Hepáticos/enzimologia , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Ratos , Triglicerídeos/sangue , Triglicerídeos/metabolismoRESUMO
The synthesis and biological evaluation of 7,8-dihydroxy (2) and 7,8-methylenedioxy (3) analogues of 1-[(3,4,5-trimethyoxyphenyl)methyl]-2,3,4,5-tetradhyo-1H-2-b enzazepine on beta-adrenoceptor systems and human platelets were undertaken and compared with trimetoquinol (TMQ, 1). Whereas 1 is a potent beta-adrenoceptor agonist in guinea pig atria and trachea (pD2 = 8.2), analogue 2 was marginally effective at relaxing guinea pig tracheal smooth muscle (pD2 = 4.4) and inactive as an agonist on guinea pig atria. Analogues 2 and 3 were inhibitors of phospholipase C (PLC; from Clostridium perfringens) induced and secondary wave of ADP-induced aggregation responses and inactive against low-dose thrombin-induced or stable endoperoxide (U46619) induced human platelet aggregation. Against ADP-induced serotonin secretion, 3 was 9-fold more active than analogue 2. Further, the rank order of TMQ isomers and 3 as inhibitors of PLC-induced platelet aggregation, serotonin secretion, and phosphatidylinositol degradation was identical (3 greater than (S)-(-)-1 greater than (R)-(+)-1). The results suggest that these compounds are blocking the action of PLC by interfering with phosphatidylinositol turnover in platelet membranes. The inhibition of ADP-induced responses in human platelets by analogues 2 and 3 also suggests a site of inhibition at a level of arachidonic acid release. Thus, ring expansion of 1 as in the benzazepine analogues 2 and 3 has allowed us to develop selective inhibitors of platelet function that lack significant beta-adrenoceptor activity.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Isoquinolinas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Tretoquinol/farmacologia , Difosfato de Adenosina/farmacologia , Agonistas Adrenérgicos beta/síntese química , Animais , Plaquetas/metabolismo , Feminino , Cobaias , Humanos , Técnicas In Vitro , Masculino , Fosfatidilinositóis/metabolismo , Relação Estrutura-Atividade , Fosfolipases Tipo C/antagonistas & inibidoresRESUMO
The naphthalene analog of medetomidine (1), 4-[1-(1-naphthyl)ethyl]-1H- imidazole (2), is a highly potent, selective alpha 2-adrenoceptor agonist. We have initiated a structure-activity relationship study of the replacement of the methyl group on the carbon bridge between the naphthalene and imidazole rings of 2 with a hydrogen, hydroxy, methoxy, carbonyl, or trifluoromethyl group and compared their biological activities with medetomidine 1 and the optical isomers of 2. Analogs of 2 were antagonists of alpha 2A-adrenoceptor-mediated human platelet aggregation and agonists on alpha 1- and alpha 2-adrenoceptors in guinea pig ileum. The rank order and potencies of these analogs on platelets (alpha 2A-subtype) and guinea pig ileum (alpha 1-subtype) were nearly the same, whereas racemic and S-(+)-2, desmethyl, and hydroxy analogs were potent agonists on alpha 2-adrenoceptors in guinea pig ileum. With the exception of the desmethyl analog 5, none of the other analogs were as potent as the parent drug 2 on alpha 2A- (human platelets), alpha 1- (guinea pig ileum), or alpha 2- (guinea pig ileum) adrenergic receptor systems. As with analog 2, the desmethyl- and methoxy-substituted analogs retained a greater alpha 2/alpha 1-selectivity in both functional (agonist activity) and biochemical (receptor displacement) studies. Receptor binding studies indicate that S-(+)-2 possessed greater affinity than the R-(-)-isomer on both alpha 1- and alpha 2-adrenoceptors in rat brain. In addition, R-(-)-2 did not show agonist activity in alpha 2-adrenoceptors of guinea pig ileum and was 10-fold more potent than S-(+)-2 as an antagonist of alpha 2A-adrenoceptors in human platelets. Thus, the nature of the substituent and the chirality at the carbon bridge between the naphthalene and imidazole rings play an important role in maintaining potent alpha 2-adrenoceptor activity and high alpha 2/alpha 1-selectivity within the 4-substituted imidazole class.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Compostos de Benzil/química , Imidazóis/farmacologia , Receptores Adrenérgicos alfa 1/efeitos dos fármacos , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Agonistas alfa-Adrenérgicos/química , Animais , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cobaias , Humanos , Íleo/efeitos dos fármacos , Íleo/metabolismo , Imidazóis/química , Técnicas In Vitro , Masculino , Medetomidina/análogos & derivados , Relação Estrutura-AtividadeRESUMO
It is currently believed that the platelet thromboxane A2 (TXA2/PGH2) receptor is different from the vascular TXA2/PGH2 receptor. While the majority of TXA2 receptor antagonists are structurally related to the prostaglandins, trimetoquinol (TMQ) represents a unique nonprostanoid antagonist. TMQ also possesses beta-adrenergic activity; however, an N-benzyl substituent on TMQ has been shown to impart some selectivity for platelet antiaggregatory activity versus beta-adrenergic activity. In this study, we examined the synthesis and TXA2 antagonist activity of a series of substituted N-benzyl analogues of TMQ. While these analogues showed an apparent direct correlation between platelet antiaggregatory activity and electron-donating ability of the N-benzyl substituents, no such correlation could be demonstrated for the inhibition of contractile responses. Thus, nonprostanoid TXA2 antagonists can be used to demonstrate differences between platelet and vascular TXA2/PGH2 responses.
Assuntos
Isoquinolinas/síntese química , Tromboxano A2/antagonistas & inibidores , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico , Animais , Fenômenos Químicos , Química , Humanos , Técnicas In Vitro , Isoquinolinas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Endoperóxidos Sintéticos de Prostaglandinas/antagonistas & inibidores , Ratos , Relação Estrutura-AtividadeRESUMO
A series of trimetoquinol (1, TMQ) analogs were designed and synthesized based on the lead compound 2, a diiodinated analog of trimetoquinol which exhibits improved selectivity for beta 2-versus beta 1-adrenoceptors (AR). To determine the influence of 1-benzyl substituents of trimetoquinol on beta 2-AR binding affinity and selectivity, we replaced and/or removed the 3'-, 4'-, and 5'-methoxy substituents of trimetoquinol. Replacement of the 4'-methoxy group of 2 with an amino (21c) or acetamido (15) moiety did not significantly alter beta 2-AR and thromboxane A2/prostaglandin H2 (TP) receptor affinity. Substitution with a 4'-hydroxy (18) or -iodo (21b) group did not significantly alter beta 2-AR affinity, but greatly reduced TP receptor affinity (380- and 1200-fold, respectively). Further, the beta 2-AR can accommodate larger substituents such as a benzamide at the 4'-position (26b). Other monoiodo derivatives (24, 26a) have similar or slightly lower affinity to both beta 2-AR and TP receptor compared to their diiodo analogs. Interestingly, removal of the 4'-substituent of 3',5'-diiodo analogs increased beta 2-AR affinity with little or no effect on beta 1-AR and TP binding. Thus, analog 21a displayed highly potent (pKi 9.52) and selective (beta 2/beta 1 = 600) binding affinity for beta 2-AR. On the other hand, trifluoromethyl substituents at the 3'- and 5'-positions (27) essentially abolished binding affinity at beta 2-AR and TP receptors. The differential binding effects of the aforementioned trimetoquinol modifications on the receptor systems may reflect differences in the binding pocket that interacts with the benzyl portion of trimetoquinol analogs. Thus, manipulation of the 1-benzyl moiety of trimetoquinol (1) has resulted in analogs that exhibit potent beta 2-AR binding affinity and significantly lower beta 1-AR and TP receptor affinities.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Iodo/química , Receptores Adrenérgicos beta/metabolismo , Tretoquinol/análogos & derivados , Agonistas Adrenérgicos beta/metabolismo , Animais , Ligação Competitiva , Plaquetas/química , Células CHO , Cricetinae , Humanos , Iodocianopindolol , Ligantes , Estrutura Molecular , Pindolol/análogos & derivados , Pindolol/metabolismo , Receptores Adrenérgicos beta/genética , Receptores de Prostaglandina/metabolismo , Receptores de Tromboxanos/metabolismo , Receptores de Tromboxano A2 e Prostaglandina H2 , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , Tretoquinol/síntese química , Tretoquinol/química , Tretoquinol/metabolismoRESUMO
Seven analogues of medetomidine and naphazoline were synthesized and evaluated for their alpha 1 (aorta) and alpha 2 (platelet) activities. The analogues were composed of 2- and 4-substituted imidazoles and imidazolines attached through a methylene bridge to either the 1- or 2-naphthalene ring system. In general the 1-naphthalene analogues were the most potent inhibitors of epinephrine-induced platelet aggregation. Of considerable interest was the fact that the 1-naphthalene analogues (2, 5-7) were partial agonists while the 2-naphthalene analogues (3, 8, 9) were antagonists in an alpha 1-adrenergic system (aorta). Thus, appropriately substituted naphthalene analogues of medetomidine and naphthazoline provide a spectrum of alpha 1-agonist, alpha 1-antagonist, and alpha 2-antagonist activity.
Assuntos
Agonistas alfa-Adrenérgicos/síntese química , Antagonistas Adrenérgicos alfa/síntese química , Imidazóis/síntese química , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Aorta/efeitos dos fármacos , Aorta/fisiologia , Epinefrina/farmacologia , Humanos , Imidazóis/química , Imidazóis/farmacologia , Masculino , Medetomidina , Nafazolina/análogos & derivados , Nafazolina/química , Nafazolina/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/química , Inibidores da Agregação Plaquetária/farmacologia , Ratos , Vasoconstrição/efeitos dos fármacosRESUMO
The 5,8-difluoro (4), 5-iodo (5), 8-iodo (6), and 5-trifluoromethyl (7) derivatives of trimetoquinol (TMQ, 1) have been synthesized and evaluated for their ability to stimulate beta 1 (guinea pig atria) and beta 2 (guinea pig trachea) adrenoceptors as well as for their inhibitory activity against U46619 [a thromboxane A2 (TXA2) mimetic]-mediated contraction of rat thoracic aorta and human platelet aggregation. Both 5 and 6 were considerably less active than TMQ on both beta-adrenergic systems and gave a rank order of stimulatory potency of 1 much greater than 6 greater than or equal to 5. Similarly, iodine substitution at either position also caused a reduction in TXA2 antagonist activity with a rank order potency of 1 greater than 6 much greater than 5. Compared to 1, however, 5-iodo-TMQ (5) showed a marked selectivity for blockade of U46619 responses in rat aorta over human platelets. On beta-systems, 4 had reduced potency compared to TMQ and was similarly nonselective. Introduction of a trifluoromethyl group at the 5-position of TMQ completely abolished both beta 1- and beta 2-adrenergic agonist activities while imparting weak antagonist activity on beta 1 receptors. On TXA2 systems, both 4 and 7 possessed significantly decreased inhibitory activity compared to TMQ. The synthetic approaches to the synthesis of 8-(trifluoromethyl)-TMQ (8) are also described. The enantiomers of the 8-fluoro derivative (3) of TMQ were separated on a preparative Chiralcel OD column and evaluated on beta-adrenergic systems and TXA2 systems. On beta-adrenergic systems, (S)-(+)-8-fluoro-TMQ was at least 10-fold more potent than (R)-(-)-8-fluoro-TMQ. Conversely, (R)-(-)-8-fluoro-TMQ was approximately 14-fold more potent as an antagonist of TXA2-mediated aggregation in human platelets than (S)-(+)-8-fluoro-TMQ. In contrast to platelets, (S)-(+)-8-fluoro-TMQ was an agonist in rat aorta whereas (R)-(-)-8-fluoro-TMQ was an antagonist.
Assuntos
Agonistas Adrenérgicos beta/síntese química , Tromboxano A2/antagonistas & inibidores , Tretoquinol/análogos & derivados , Agonistas Adrenérgicos beta/farmacologia , Animais , Cobaias , Humanos , Masculino , Ratos , Ratos Endogâmicos , Estereoisomerismo , Relação Estrutura-Atividade , Tretoquinol/farmacologiaRESUMO
Trimetoquinol (TMQ, 1) is a unique catecholamine with a strong stereodependence for agonism at beta-adrenergic (S > > R) and antagonism at thromboxane A2/prostaglandin H2 (TP; R > > S) receptors. Our laboratory has reported the effects of N-alkylation and modification of the trisubstituted benzyl group in these receptor systems. For iodinated derivative 5, maintaining potency in TP receptor systems (112%) was coupled with maintaining limited potency in beta-adrenergic receptor systems (34% for beta 1 and 47% for beta 2). In this study, several diverse TMQ derivatives were prepared to probe for binding interactions specific to a particular receptor system. Planar amidine 2, which was designed to explore the importance of TMQ's chiral center, showed a dramatic loss of potency (< 1%) in each receptor system. Likewise, the homologation of a previously described N-benzyl derivative (3) to the N-phenylethyl derivative 4 also showed reduced potency (< 3%) in both receptor systems. However, modification of the trimethoxybenzyl group of TMQ to a 4-hydroxy-3-nitrobenzyl group (7) provided a unique lead for TMQ derivatives with significant potency in TP receptor systems (91%) and reduced potency in beta-adrenergic receptor systems (4% for beta 1 and 19% for beta 2).