RESUMEN
A series of fluorochlorozirconate (FCZ) glasses, each doped with a different rare-earth, was prepared and examined to determine thermal stability and activation energy, Ea , of the dopant dependent BaCl2 crystallization. Non-isothermal differential scanning calorimetry (DSC) measurements were done to investigate the endothermic and exothermic reactions upon heat treatment of the glass samples. In comparison to the rare-earth free FCZ glass, significant changes in the Hruby constant, Hr , and Ea were found due to the addition of a rare-earth and also between the individual dopants.
RESUMEN
A series of transparent erbium-doped fluorozirconate glasses has been investigated using differential scanning calorimetry, optical absorption, and upconverted fluorescence spectroscopy. The upconverted fluorescence intensity versus excitation power dependence shows that the ratio of the two-photon upconverted emission in the near infrared at 980 nm to the three-photon upconverted emissions in the visible at 530, 550, and 660 nm decreases with increasing excitation power. The integrated upconverted fluorescence intensity to excitation power ratio shows 'saturation' with increasing excitation power, while the point of saturation shifts to lower excitation power with increasing erbium concentration. The experimental lifetime of the upconverted fluorescence decreases with increasing erbium concentration.
RESUMEN
The properties of Eu-doped fluorochlorozirconate (FCZ) glass ceramics upon thermal processing and the influence of Eu-doping on the formation of BaCl(2) nanocrystals therein have been investigated. Differential scanning calorimetry indicates that higher Eu-doping shifts the crystallization peak of the nanocrystals in the glass to lower temperatures, while the glass transition temperature remains constant. The activation energy and the thermal stability parameters for the BaCl(2) crystallization are determined.
RESUMEN
Thermal processing of as-made fluorozirconate glasses, which were additionally doped with rare-earth and chlorine ions, results in the formation of fluorescent nanocrystals therein. For medical applications, the glasses were doped with divalent europium ions as the fluorescent rare-earth ion, while trivalent neodymium was used to develop up-conversion systems. The samples were annealed up to 290 °C to initiate the growth of hexagonal or orthorhombic phase BaCl2 nanocrystals therein. Upon annealing some of the rare-earth ions were incorporated into the BaCl2 nanocrystals leading to enhanced fluorescence properties. The particle diameters were in the range of a few nanometers to several tens of nanometers.
RESUMEN
The influence of InF(3) doping and remelting on Eu-doped fluorozirconate-based glass ceramics was investigated using near-edge x-ray absorption and optical spectroscopy. It was found that the addition of InF(3) to the melt decreases the Eu(2+)Eu(3+) mole ratio, while remelting leads to a significant change in the Eu(2+)Eu(3+) ratio in favor of Eu(2+). Photoluminescence spectroscopy shows that additional annealing steps lead to the formation of BaCl(2) nanoparticles in the glass. In as-made glass ceramics containing InF(3), a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. This phase transition is not observed in the remelted glasses studied here.
RESUMEN
The Peroxisome Proliferator-Activated Receptors-PPAR alpha, PPAR gamma, and PPAR delta--are members of the nuclear receptor gene family that have emerged as therapeutic targets for the development of drugs to treat human metabolic diseases. The discovery of high affinity, subtype-selective agonists for each of the three PPAR subtypes has allowed elucidation of the pharmacology of these receptors and development of first-generation therapeutic agents for the treatment of diabetes and dyslipidemia. However, despite proven therapeutic benefits of selective PPAR agonists, safety concerns and dose-limiting side effects have been observed, and a number of late-stage development failures have been reported. Scientists have continued to explore ligand-based activation of PPARs in hopes of developing safer and more effective drugs. This review highlights recent efforts on two newer approaches, the simultaneous activation of all three PPAR receptors with a single ligand (PPAR pan agonists) and the selective modulation of a single PPAR receptor in a cell or tissue specific manner (selective PPAR modulator or SPPARM) in order to induce a subset of target genes and affect a restricted number of metabolic pathways.
Asunto(s)
Enfermedades Metabólicas/tratamiento farmacológico , Receptores Activados del Proliferador del Peroxisoma/efectos de los fármacos , Sistemas de Liberación de Medicamentos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Humanos , Receptores Activados del Proliferador del Peroxisoma/agonistas , Receptores Activados del Proliferador del Peroxisoma/química , Unión ProteicaRESUMEN
A series of PPARgamma agonists were synthesized from L-tyrosine that incorporated low molecular weight N-substituents. The most potent analogue, pyrrole (4e), demonstrated a K(i) of 6.9nM and an EC(50) of 4.7nM in PPARgamma binding and functional assays, respectively. Pyrrole (4e), which is readily synthesized from L-tyrosine methyl ester in four steps, also demonstrated in vivo activity in a rodent model of Type 2 diabetes.
Asunto(s)
Hipoglucemiantes/síntesis química , Hipoglucemiantes/farmacología , Receptores Citoplasmáticos y Nucleares/agonistas , Factores de Transcripción/agonistas , Tirosina/síntesis química , Animales , Diabetes Mellitus Experimental/tratamiento farmacológico , Hipoglucemiantes/química , Hipoglucemiantes/uso terapéutico , Masculino , Peso Molecular , Ratas , Ratas ZuckerRESUMEN
A series of oxadiazole-substituted alpha-isopropoxy phenylpropanoic acids with dual agonist activity on PPARalpha and PPARgamma is described. Several of these compounds also showed partial agonist activity on PPARdelta. Resolution of one analogue showed that PPARalpha and PPARgamma activity resided in mainly one enantiomer, whereas PPARdelta activity was retained in both enantiomers.
Asunto(s)
Receptores Citoplasmáticos y Nucleares/agonistas , Factores de Transcripción/agonistas , Cromatografía Líquida de Alta Presión , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Humanos , Isomerismo , Oxadiazoles/química , Relación Estructura-ActividadRESUMEN
We have prepared a novel series of 2-amino-4,6-diarylpyridines that function as ligands of estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta). These compounds bind to both ERalpha and ERbeta with a modest selectivity for the alpha subtype. The most potent of these analogues, compound 19, has a K(i)=20nM at ERalpha. These molecules represent a novel template for designing potentially useful ligands for the estrogen receptor.
Asunto(s)
Receptores de Estrógenos/metabolismo , Moduladores Selectivos de los Receptores de Estrógeno/síntesis química , Moduladores Selectivos de los Receptores de Estrógeno/farmacología , Bacterias/genética , Bacterias/metabolismo , Sitios de Unión/fisiología , Cristalografía por Rayos X , Receptor alfa de Estrógeno , Receptor beta de Estrógeno , Humanos , Ligandos , Unión Proteica/fisiología , Piridinas/síntesis química , Piridinas/metabolismo , Clorhidrato de Raloxifeno/metabolismo , Sensibilidad y EspecificidadAsunto(s)
Diseño de Fármacos , Proteínas Nucleares/fisiología , Receptores Citoplasmáticos y Nucleares/efectos de los fármacos , Receptores Citoplasmáticos y Nucleares/fisiología , Factores de Transcripción/efectos de los fármacos , Factores de Transcripción/fisiología , Animales , Diabetes Mellitus/tratamiento farmacológico , Diabetes Mellitus/metabolismo , Humanos , Hiperlipidemias/tratamiento farmacológico , Hiperlipidemias/metabolismo , Hipertensión/tratamiento farmacológico , Hipertensión/metabolismo , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Ligandos , Modelos Moleculares , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Obesidad/tratamiento farmacológico , Obesidad/metabolismo , Receptores Citoplasmáticos y Nucleares/química , Receptores Citoplasmáticos y Nucleares/metabolismo , Factores de Transcripción/química , Factores de Transcripción/metabolismoRESUMEN
The synthesis and structure-activity relationships of a novel series of indole 5-carboxylic acids that bind and activate peroxisome proliferator-activated receptor gamma (PPARgamma) are reported. These new analogs are selective for PPARgamma vs the other PPAR subtypes, and the most potent compounds in this series are comparable to in vitro potencies at PPARgamma reported for the thiazolidinedione-based antidiabetic drugs currently in clinical use.
Asunto(s)
Indoles/síntesis química , Indoles/farmacología , Receptores Citoplasmáticos y Nucleares/agonistas , Factores de Transcripción/agonistas , Animales , Disponibilidad Biológica , Humanos , Indoles/farmacocinética , Ratas , Relación Estructura-ActividadRESUMEN
The discovery that peroxisome proliferator-activated receptor (PPAR)-gamma was the molecular target of the thiazolidinedione class of antidiabetic agents suggested a key role for PPAR-gamma in the regulation of carbohydrate and lipid metabolism. Through the use of high-throughput biochemical assays, GW1929, a novel N-aryl tyrosine activator of human PPAR-gamma, was identified. Chronic oral administration of GW1929 or troglitazone to Zucker diabetic fatty (ZDF) rats resulted in dose-dependent decreases in daily glucose, free fatty acid, and triglyceride exposure compared with pretreatment values, as well as significant decreases in glycosylated hemoglobin. Whole body insulin sensitivity, as determined by the euglycemic-hyperinsulinemic clamp technique, was significantly increased in treated animals. Comparison of the magnitude of glucose lowering as a function of serum drug concentrations showed that GW1929 was 2 orders of magnitude more potent than troglitazone in vivo. These data were consistent with the relative in vitro potencies of GW1929 and troglitazone. Isolated perfused pancreas studies performed at the end of the study confirmed that pancreata from vehicle-treated rats showed no increase in insulin secretion in response to a step change in glucose from 3 to 10 mmol/l. In contrast, pancreata from animals treated with GW1929 showed a first- and second-phase insulin secretion pattern. Consistent with the functional data from the perfusion experiments, animals treated with the PPAR-gamma agonist had more normal islet architecture with preserved insulin staining compared with vehicle-treated ZDF rats. This is the first demonstration of in vivo efficacy of a novel nonthiazolidinedione identified as a high-affinity ligand for human PPAR-gamma. The increased potency of GW1929 compared with troglitazone both in vitro and in vivo may translate into improved clinical efficacy when used as monotherapy in type 2 diabetic patients. In addition, the significant improvement in daily meal tolerance may impact cardiovascular risk factor management in these patients.
Asunto(s)
Benzofenonas/farmacología , Diabetes Mellitus Experimental/fisiopatología , Obesidad/fisiopatología , Receptores Citoplasmáticos y Nucleares/metabolismo , Tiazolidinedionas , Factores de Transcripción/metabolismo , Tirosina/análogos & derivados , Animales , Cromanos/uso terapéutico , Células Clonales , Diabetes Mellitus Experimental/genética , Técnica de Clampeo de la Glucosa , Humanos , Hipoglucemiantes/uso terapéutico , Inmunohistoquímica , Modelos Logísticos , Obesidad/genética , Fenotipo , Ratas , Ratas Zucker , Receptores Citoplasmáticos y Nucleares/agonistas , Tiazoles/uso terapéutico , Factores de Transcripción/agonistas , Troglitazona , Tirosina/farmacologíaRESUMEN
Glibenclamide is a potent inhibitor of the ATP-dependent potassium channel. Opening of the ATP-dependent potassium channel is regarded as a mechanism of ischemic preconditioning. This in vitro study examines the influence of glibenclamide and glimepiride, a new sulfonylurea, on the negative inotropic action of the potassium channel opener rilmakalim in isolated ventricular myocytes. Cardiac myocytes were isolated from adult guinea pig hearts by collagenase perfusion and incubated with rilmakalim (concentration range 0.1-12.0 microM), glibenclamide (concentration range 0.03-3.0 microM) plus rilmakalim (3.0 or 7.5 microM), and glimepiride (0.03-9.0 microM) plus rilmakalim (3.0 or 7.5 microM) and paced by electrical field stimulation. Contractility of the myocytes was evaluated by digital image analysis, intracellular free calcium was determined by means of fura-2 fluorescence measurements, and cell viability was assessed morphologically as well as by measurement of lactate dehydrogenase activity. Rilmakalim reduced the systolic intracellular free calcium and contractility of ventricular myocytes in a concentration dependent manner. This effect was antagonized by glibenclamide at lower concentrations (0.3 microM) than glimepiride (3.0 microM). The smaller antagonistic action of glimepiride on the negative inotropic effect of rilmakalim as compared with glibenclamide most likely reflects a less potent inhibition of ATP-dependent potassium channels by glimepiride.
Asunto(s)
Antiarrítmicos/farmacología , Cromanos/farmacología , Gliburida/farmacología , Hipoglucemiantes/farmacología , Contracción Miocárdica/efectos de los fármacos , Pirrolidinas/farmacología , Compuestos de Sulfonilurea/farmacología , Adenosina Trifosfato/metabolismo , Animales , Antiarrítmicos/antagonistas & inhibidores , Calcio/metabolismo , Cromanos/antagonistas & inhibidores , Cobayas , Técnicas In Vitro , Potasio/metabolismo , Canales de Potasio/efectos de los fármacos , Pirrolidinas/antagonistas & inhibidoresRESUMEN
We have identified a novel series of antidiabetic N-(2-benzoylphenyl)-L-tyrosine derivatives which are potent, selective PPARgamma agonists. Through the use of in vitro PPARgamma binding and functional assays (2S)-3-(4-(benzyloxy)phenyl)-2-((1-methyl-3-oxo-3-phenylpropenyl)+ ++amin o)propionic acid (2) was identified as a structurally novel PPARgamma agonist. Structure-activity relationships identified the 2-aminobenzophenone moiety as a suitable isostere for the chemically labile enaminone moiety in compound 2, affording 2-((2-benzoylphenyl)amino)-3-(4-(benzyloxy)phenyl)propionic acid (9). Replacement of the benzyl group in 9 with substituents known to confer in vivo potency in the thiazolidinedione (TZD) class of antidiabetic agents provided a dramatic increase in the in vitro functional potency and affinity at PPARgamma, affording a series of potent and selective PPARgamma agonists exemplified by (2S)-((2-benzoylphenyl)amino)-3-¿4-[2-(methylpyridin-2-ylamino+ ++)ethoxy ]phenyl¿propionic acid (18), 3-¿4-[2-(benzoxazol-2-ylmethylamino)ethoxy]phenyl¿-(2S)-((2- benzoylph enyl)amino)propanoic acid (19), and (2S)-((2-benzoylphenyl)amino)-3-¿4-[2-(5-methyl-2-phenyloxazol-4-y l)e thoxy]phenyl¿propanoic acid (20). Compounds 18 and 20 show potent antihyperglycemic and antihyperlipidemic activity when given orally in two rodent models of type 2 diabetes. In addition, these analogues are readily prepared in chiral nonracemic fashion from L-tyrosine and do not show a propensity to undergo racemization in vitro. The increased potency of these PPARgamma agonists relative to troglitazone may translate into superior clinical efficacy for the treatment of type 2 diabetes.
Asunto(s)
Aminopiridinas/síntesis química , Proteínas de Unión al ADN/agonistas , Hipoglucemiantes/síntesis química , Hipolipemiantes/síntesis química , Oxazoles/síntesis química , Propionatos/síntesis química , Receptores Citoplasmáticos y Nucleares/agonistas , Factores de Transcripción/agonistas , Tirosina/análogos & derivados , Tirosina/síntesis química , Administración Oral , Aminopiridinas/química , Aminopiridinas/farmacología , Animales , Glucemia/metabolismo , Línea Celular , Diabetes Mellitus Experimental/sangre , Humanos , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Hipolipemiantes/química , Hipolipemiantes/farmacología , Ligandos , Lípidos/biosíntesis , Masculino , Ratones , Oxazoles/química , Oxazoles/farmacología , Propionatos/química , Propionatos/farmacología , Ensayo de Unión Radioligante , Ratas , Receptores Citoplasmáticos y Nucleares/metabolismo , Proteínas Recombinantes de Fusión/agonistas , Proteínas Recombinantes de Fusión/metabolismo , Estereoisomerismo , Relación Estructura-Actividad , Factores de Transcripción/metabolismo , Transfección , Tirosina/química , Tirosina/farmacologíaRESUMEN
We previously reported the identification of (2S)-((2-benzoylphenyl)amino)-3-¿4-[2-(5-methyl-2-phenyloxazol-4-y l)e thoxy]phenyl¿propanoic acid (2) (PPARgamma pKi = 8.94, PPARgamma pEC50 = 9.47) as a potent and selective PPARgamma agonist. We now report the expanded structure-activity relationship around the phenyl alkyl ether moiety by pursuing both a classical medicinal chemistry approach and a solid-phase chemistry approach for analogue synthesis. The solution-phase strategy focused on evaluating the effects of oxazole and phenyl ring replacements of the 2-(5-methyl-2-phenyloxazol-4-yl)ethyl side chain of 2 with several replacements providing potent and selective PPARgamma agonists with improved aqueous solubility. Specifically, replacement of the phenyl ring of the phenyloxazole moiety with a 4-pyridyl group to give 2(S)-((2-benzoylphenyl)amino)-3-¿4-[2-(5-methyl-2-pyridin-4-yloxazol+ ++- 4-yl)ethoxy]phenyl¿propionic acid (16) (PPARgamma pKi = 8.85, PPARgamma pEC50 = 8.74) or a 4-methylpiperazine to give 2(S)-((2-benzoylphenyl)amino)-3-(4-¿2-[5-methyl-2-(4-methylpiperazin+ ++- 1-yl)thiazol-4-yl]ethoxy¿phenyl)propionic acid (24) (PPARgamma pKi = 8.66, PPARgamma pEC50 = 8.89) provided two potent and selective PPARgamma agonists with increased solubility in pH 7.4 phosphate buffer and simulated gastric fluid as compared to 2. The second strategy took advantage of the speed and ease of parallel solid-phase analogue synthesis to generate a more diverse set of phenyl alkyl ethers which led to the identification of a number of novel, high-affinity PPARgamma ligands (PPARgamma pKi's 6.98-8.03). The combined structure-activity data derived from the two strategies provide valuable insight on the requirements for PPARgamma binding, functional activity, selectivity, and aqueous solubility.
Asunto(s)
Proteínas de Unión al ADN/agonistas , Hipoglucemiantes/síntesis química , Hipolipemiantes/síntesis química , Oxazoles/síntesis química , Propionatos/síntesis química , Receptores Citoplasmáticos y Nucleares/agonistas , Tiazoles/síntesis química , Factores de Transcripción/agonistas , Tirosina/análogos & derivados , Tirosina/síntesis química , Adipocitos/citología , Adipocitos/efectos de los fármacos , Animales , Diferenciación Celular/efectos de los fármacos , Línea Celular , Humanos , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Hipolipemiantes/química , Hipolipemiantes/farmacología , Ligandos , Lípidos/biosíntesis , Ratones , Oxazoles/química , Oxazoles/farmacología , Propionatos/química , Propionatos/farmacología , Ensayo de Unión Radioligante , Receptores Citoplasmáticos y Nucleares/metabolismo , Proteínas Recombinantes de Fusión/agonistas , Proteínas Recombinantes de Fusión/metabolismo , Solubilidad , Relación Estructura-Actividad , Tiazoles/química , Tiazoles/farmacología , Factores de Transcripción/metabolismo , Transfección , Tirosina/química , Tirosina/farmacologíaRESUMEN
3-¿4-[2-(Benzoxazol-2-ylmethylamino)ethoxy]phenyl¿-(2S)-((2- benzoylph enyl)amino)propionic acid (1) and (2S)-((2-benzoylphenyl)amino)-3-¿4-[2-(5-methyl-2-phenyloxazol-4-y l)e thoxy]phenyl¿propionic acid (2) are peroxisome proliferator-activated receptor gamma (PPARgamma) agonists and have antidiabetic activity in rodent models of type 2 diabetes. As part of an effort to develop the SAR of the N-2-benzoylphenyl moiety of 1 and 2, a series of novel carboxylic acid analogues, 23-66, modified only in the N-2-benzoylphenyl moiety were synthesized from L-tyrosine and evaluated as PPARgamma agonists. In general, only modest changes in the N-2-benzoylphenyl moiety of 1 and 2 are tolerated. More specifically, the best changes involve bioisosteric replacement of one of the two phenyl rings of this moiety. Addition of substituents to this moiety generally produced compounds that are less active in the cell-based functional assays of PPARgamma activity although binding affinity to PPARgamma may be maintained. A particularly promising set of analogues is the anthranilic acid esters 63-66 in which the phenyl ring in the 2-benzoyl group of 1 and 2 has been replaced by an alkoxy group. In particular, (S)-2-(1-carboxy-2-¿4-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]phen yl¿ ethylamino)benzoic acid methyl ester (63) has a pKi of 8.43 in the binding assay using human PPARgamma ligand binding domain and a pEC50 of 9.21 in the in vitro murine lipogenesis functional assay of PPARgamma activity. Finally, 63 was found to normalize glycemia when dosed at 3 mg/kg bid po in the Zucker diabetic fatty rat model of type 2 diabetes.
Asunto(s)
Benzoatos/síntesis química , Proteínas de Unión al ADN/agonistas , Hipoglucemiantes/síntesis química , Hipolipemiantes/síntesis química , Oxazoles/síntesis química , Receptores Citoplasmáticos y Nucleares/agonistas , Factores de Transcripción/agonistas , Tirosina/análogos & derivados , Tirosina/síntesis química , Administración Oral , Animales , Benzoatos/química , Benzoatos/farmacología , Glucemia/metabolismo , Línea Celular , Diabetes Mellitus Experimental/sangre , Humanos , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Hipolipemiantes/química , Hipolipemiantes/farmacología , Ligandos , Lípidos/biosíntesis , Masculino , Ratones , Oxazoles/química , Oxazoles/farmacología , Ensayo de Unión Radioligante , Ratas , Receptores Citoplasmáticos y Nucleares/metabolismo , Solubilidad , Relación Estructura-Actividad , Factores de Transcripción/metabolismo , Tirosina/química , Tirosina/farmacología , ortoaminobenzoatosRESUMEN
We report on a familial three way translocation involving chromosomes 3, 6, and 15 identified by prometaphase banding and fluorescence in situ hybridisation (FISH). Two mentally retarded sibs with different phenotypic abnormalities, their phenotypically normal sister and mother, and two fetuses of the phenotypically normal sister were analysed. The terminal regions of chromosomes 3q, 6q, and 15q were involved in a reciprocal translocation, in addition to a paracentric inversion of the derivative chromosome 15. Conventional cytogenetic studies with high resolution GTG banding did not resolve this rearrangement. FISH using whole chromosome paints (WCPs) identified the chromosomal regions involved, except the aberrant region of 3q, which was undetectable with these probes. Investigation of this region with the subtelomeric FISH probe D3S1445/D3S1446 showed a balanced karyotype, 46,XX,t(3;15;6) (q29;q26.1;q26), inv der(15) (q15.1q26.1) in two adult females and one fetus. It was unbalanced in two sibs, showing two different types of unbalanced translocation resulting in partial trisomy 3q in combination with partial monosomy 6q in one patient and partial trisomy 15q with partial monosomy 6q in the other patient and one fetus. These represent apparently new chromosomal phenotypes.
Asunto(s)
Cromosomas Humanos Par 15/genética , Cromosomas Humanos Par 3/genética , Cromosomas Humanos Par 6/genética , Translocación Genética , Adulto , Bandeo Cromosómico , Deleción Cromosómica , Femenino , Asesoramiento Genético , Humanos , Hibridación Fluorescente in Situ , Discapacidad Intelectual/genética , Cariotipificación , Masculino , Linaje , Fenotipo , EmbarazoRESUMEN
In Saccharomyces cerevisiae the metabolic degradation of saturated fatty acids is exclusively confined to peroxisomes. In addition to a functional beta-oxidation system, the degradation of unsaturated fatty acids requires auxiliary enzymes, including a Delta2, Delta3-enoyl-CoA isomerase and an NADPH-dependent 2,4-dienoyl-CoA reductase. We found both enzymes to be present in yeast peroxisomes. The impermeability of the peroxisomal membrane for pyrimidine nucleotides led to the question of how the NADPH needed by the reductase is regenerated in the peroxisomal lumen. We report the identification and functional analysis of the IDP3 gene product, which is a yeast peroxisomal NADP-dependent isocitrate dehydrogenase. The newly identified peroxisomal protein is homologous to the mitochondrial Idp1p and cytosolic Idp2p, which both are yeast NADP-dependent isocitrate dehydrogenases. Yeast cells lacking Idp3p grow normally on saturated fatty acids, but growth is impaired on unsaturated fatty acids, indicating that the peroxisomal Idp3p is involved in their metabolic utilization. The data presented are consistent with the assumption that peroxisomes of S. cerevisiae contain the enzyme equipment needed for the degradation of unsaturated fatty acids, including an NADP-dependent isocitrate dehydrogenase, a putative constituent of a peroxisomal NADPH-regenerating redox system.
Asunto(s)
Ácidos Grasos Insaturados/metabolismo , Isocitrato Deshidrogenasa/metabolismo , Microcuerpos/enzimología , NADP/metabolismo , Saccharomyces cerevisiae/enzimología , Secuencia de Aminoácidos , Secuencia de Bases , Isocitrato Deshidrogenasa/genética , Datos de Secuencia Molecular , Oxidación-Reducción , Saccharomyces cerevisiae/metabolismo , Homología de Secuencia de AminoácidoRESUMEN
The estrogen receptor (ER) mixed agonists tamoxifen and raloxifene have been shown to protect against bone loss in ovariectomized rats. However, the mechanism by which these compounds manifest their activity in bone is unknown. We have used a series of in vitro screens to select for compounds that are mechanistically distinct from tamoxifen and raloxifene in an effort to define the properties of an ER modulator required for bone protection. Using this approach, we identified a novel high affinity ER antagonist, GW5638, which when assayed in vitro functions as an ER antagonist, inhibiting the agonist activity of estrogen, tamoxifen, and raloxifene and reversing the "inverse agonist" activity of the pure antiestrogen ICI182,780. Thus, GW5638 appears to function as an antagonist in these in vitro systems, although in a manner distinct from other known ER modulators. Predictably, therefore, GW5638 alone displays minimal uterotropic activity in ovariectomized rats, but will inhibit the agonist activity of estradiol in this environment. Unexpectedly, however, this compound functions as a full ER agonist in bone and the cardiovascular system. These data suggest that the mechanism by which ER operates in different cells is not identical, and that classical agonist activity is not required for the bone protective activity of ER modulators.
Asunto(s)
Huesos/fisiología , Cinamatos/farmacología , Antagonistas de Estrógenos/farmacología , Receptores de Estrógenos/antagonistas & inhibidores , Receptores de Estrógenos/fisiología , Estilbenos/farmacología , Animales , Densidad Ósea , Huesos/efectos de los fármacos , Estradiol/farmacología , Estrógenos/agonistas , Femenino , Humanos , Osteoporosis/etiología , Osteoporosis/prevención & control , Ovariectomía , Piperidinas/farmacología , Clorhidrato de Raloxifeno , Ratas , Ratas Sprague-Dawley , Receptores de Estrógenos/genética , Tamoxifeno/farmacología , Células Tumorales Cultivadas , Útero/efectos de los fármacosRESUMEN
We previously described a series of 3-(1H-indazol-3-ylmethyl)-1,5-benzodiazepine CCK-A agonists exemplified by compound 1 (GW 5823), which is the first reported binding selective CCK-A full agonist demonstrating oral efficacy in a rat feeding model. In this report we describe analogs of compound 1 designed to explore changes to the C3 and N1 pharmacophores and their effect on agonist activity and receptor selectivity. Agonist efficacy in this series was affected by stereoelectronic factors within the C3 moiety. Binding affinity for the CCK-A vs CCK-B receptor showed little dependence on the structure of the C3 moiety but was affected by the nature of the second substituent at C3. Structure-activity relationships at the N1-anilidoacetamide "trigger" moiety within the C3 indazole series were also investigated. Both agonist efficacy and binding affinity within this series were modulated by variation of substituents on the N1-anilidoacetamide moiety. Evaluation of several analogs in an vivo mouse gallbladder emptying assay revealed compound 1 to be the most potent and efficacious of all the analogs tested. The pharmacokinetic and pharmacodynamic profile of 1 in rats is also discussed.