RESUMEN
The pharmacological properties of the ephedrine derivative pseudoephedrine were investigated at the nuclear level. Following intraperitoneal injection of Sprague Dawley rats with pseudoephedrine, Fos induction was measured in various brain areas by Western blots and immunocytochemistry. Pseudoephedrine induced Fos-like immunoreactivity in the nucleus accumbens and striatum in a time and concentration-dependent manner with maximal effect at 60 mg/kg 2 h after injection. Immunocytochemical studies confirmed that the majority of the signal was detectable in the nucleus accumbens and striatum. Pre-injection with the D1 dopamine receptor antagonist SCH23390 partially and completely blocked pseudoephedrine-induced Fos-like immunoreactivity in the striatum and nucleus accumbens, respectively, suggesting that the action of pseudoephedrine is mediated via dopamine release and results in the activation of D1 dopamine receptors. With the exception of the higher doses required, the actions of pseudoephedrine were similar to those previously described for the psychostimulant amphetamine.
Asunto(s)
Cuerpo Estriado/efectos de los fármacos , Efedrina/farmacología , Núcleo Accumbens/efectos de los fármacos , Proteínas Proto-Oncogénicas c-fos/metabolismo , Simpatomiméticos/farmacología , Anfetamina/farmacología , Animales , Benzazepinas/farmacología , Cuerpo Estriado/metabolismo , Antagonistas de Dopamina/farmacología , Relación Dosis-Respuesta a Droga , Masculino , Núcleo Accumbens/metabolismo , Proteínas Proto-Oncogénicas c-fos/inmunología , Ratas , Ratas Sprague-Dawley , Factores de TiempoRESUMEN
We previously suggested that the degree of polyamine stimulation of oligopeptide-binding protein (OppA) synthesis is dependent on the secondary structure and position of the Shine-Dalgarno (SD) sequence of OppA mRNA. To study the structural change of OppA mRNA induced by polyamines and polyamine stimulation of initiation complex formation, four different 130-mer OppA mRNAs containing the initiation region were synthesized in vitro. The structural change of these mRNAs induced by polyamines was examined by measuring their sensitivity to RNase T(1), specific for single-stranded RNA, and RNase V(1), which recognizes double-stranded or stacked RNA. In parallel, the effect of spermidine on mRNA-dependent fMet-tRNA binding to ribosomes was examined. Our results indicate that the secondary structure of the SD sequence and initiation codon AUG is important for the efficiency of initiation complex formation and that spermidine relaxes the structure of the SD sequence and the initiation codon AUG. The existence of a GC-rich double-stranded region close to the SD sequence is important for spermidine stimulation of fMet-tRNA binding to ribosomes. Spermidine apparently binds to this GC-rich stem and causes a structural change of the SD sequence and the initiation codon, facilitating an interaction with 30 S ribosomal subunits.
Asunto(s)
Regiones no Traducidas 5'/efectos de los fármacos , Proteínas Portadoras/biosíntesis , Codón Iniciador/efectos de los fármacos , Lipoproteínas/biosíntesis , Iniciación de la Cadena Peptídica Traduccional/efectos de los fármacos , Poliaminas/farmacología , Proteínas Bacterianas , Secuencia de Bases , Proteínas Portadoras/genética , Regulación Bacteriana de la Expresión Génica , Lipoproteínas/genética , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , ARN de Transferencia de Metionina/metabolismo , Ribosomas/metabolismo , Espermidina/farmacologíaRESUMEN
The conformation of ATP in the presence of Mg2+ and/or spermine was studied by 31P and 1H NMR, to clarify how polyamines interact with ATP. Spermine predominantly interacted with the beta- and gamma-phosphates of ATP in the presence of Mg2+. A conformational change of the beta- and gamma-phosphate of ATP with spermine could not be observed in the absence of Mg2+ by 31P NMR. It was found by 1H NMR that the conformation of adenosine moiety of ATP was not influenced significantly by spermine. The binding of Mg2+ to ATP was slightly inhibited by spermine and vice versa. The results indicate that the binding sites of Mg2+ and spermine on ATP only partially overlap. The PotA protein, an ATP-dependent enzyme, was used as a model system to study the biological role of the ATP-Mg2+-spermine complex. The ATPase activity of PotA was greatly enhanced by spermine. Double reciprocal plots at several concentrations of spermine as an activator indicate that spermine interacts with ATP, but not with PotA. The activity of protein kinase A was also stimulated about 2-fold by spermine. The results suggest that a ternary complex of ATP-Mg2+-spermine may play an important role in some ATP-dependent reactions in vivo and in the physiological effects of endogenous polyamines.
Asunto(s)
Transportadoras de Casetes de Unión a ATP , Adenosina Trifosfato/química , Proteínas de Escherichia coli , Magnesio/química , Espermina/química , Adenosina Trifosfato/metabolismo , Sitios de Unión , Proteínas Portadoras/efectos de los fármacos , Cationes Bivalentes , Proteínas Quinasas Dependientes de AMP Cíclico/efectos de los fármacos , Magnesio/metabolismo , Proteínas de la Membrana/efectos de los fármacos , Conformación Molecular , Resonancia Magnética Nuclear Biomolecular , Isótopos de Fósforo , Espermina/metabolismo , Espermina/farmacologíaRESUMEN
Rats were trained to discriminate amphetamine, 1 mg/kg given intraperitoneally, from saline injection in a two-lever operant drug discrimination task. Pseudoephedrine (a sympathomimetic drug with central and peripheral actions) at doses of 10 mg/kg failed to substitute for amphetamine, at 20 mg/kg partial substitution occurred, while at a 40 mg/kg full substitution was seen. The specificity of the amphetamine cue at the training dose used (1 mg/kg) was shown by the finding that a peripherally acting sympathomimetic drug phenylephrine at doses from 0.2 to 0.8 mg/kg failed to substitute for amphetamine. The potential for abuse of pseudoephedrine administered at high doses is discussed.
Asunto(s)
Agonistas alfa-Adrenérgicos/farmacología , Anfetamina/farmacología , Estimulantes del Sistema Nervioso Central/farmacología , Discriminación en Psicología/efectos de los fármacos , Efedrina/farmacología , Animales , Señales (Psicología) , Aprendizaje Discriminativo/efectos de los fármacos , Generalización del Estimulo/efectos de los fármacos , Masculino , Ratas , Ratas Sprague-Dawley , RecompensaRESUMEN
From the leaves and stems of Larrea tridentata six new furanoid lignans, compounds 1-6, have been isolated and their structures determined through interpretation of physical and spectroscopic properties. The use of 1D and 2D nOe experiments was of particular importance in assigning the stereochemistry.
Asunto(s)
Furanos/aislamiento & purificación , Lignina/aislamiento & purificación , Plantas Medicinales/química , Animales , Implantación del Embrión/efectos de los fármacos , Femenino , Furanos/farmacología , Larrea , Lignanos , Lignina/farmacología , Espectroscopía de Resonancia Magnética , Estructura Molecular , Embarazo , Ratas , Ratas EndogámicasRESUMEN
The first four members of a new class of natural products, the retrodihydrochalcones, have been isolated from the leaves of Dracaena loureiri. The structures of the loureirins 1-4 were elucidated through interpretation of their spectroscopic data, with particular use being made of the selective INEPT nmr technique.
Asunto(s)
Chalcona/análisis , Plantas/análisis , Propiofenonas/análisis , Chalcona/análogos & derivados , Espectroscopía de Resonancia Magnética , Estructura MolecularRESUMEN
Complete and unambiguous assignments of the 1H- and 13C-nmr spectra of the potent antitumor antibiotic staurosporine have been accomplished using a combination of one- and two-dimensional nmr techniques, including one-bond and long-range heteronuclear multiple-quantum coherence spectroscopy (HMQC). Staurosporine was found to be highly cytotoxic in the KB and P-388 assays but was inactive in the microtubulin assembly assay.
Asunto(s)
Alcaloides/biosíntesis , Alcaloides/farmacología , Espectroscopía de Resonancia Magnética , Microtúbulos/efectos de los fármacos , Estaurosporina , Streptomyces/metabolismoRESUMEN
Following studies to define the time course, media, and nutrient parameters for the production of the potent cytotoxic antibiotic staurosporine in Streptomyces staurosporeus, biosynthetic studies of staurosporine with singly- and doubly-labeled radioactive precursors established that either one or two units of tryptophan was incorporated efficiently. From the 13C-nmr spectrum of staurosporine subsequent to stable isotope incorporation experiments, it was established that the aglycone moiety was derived from two units of tryptophan with the carbon skeleton incorporated intact.
Asunto(s)
Alcaloides/biosíntesis , Triptófano/metabolismo , Alcaloides/aislamiento & purificación , Alcaloides/metabolismo , Cromatografía Líquida de Alta Presión , Medios de Cultivo/metabolismo , Radioisótopos , Estaurosporina , Streptomyces/metabolismo , Factores de TiempoRESUMEN
Unambiguous 1H- and 13C-nmr assignments of colchicine, beta-lumicolchicine, and gamma-lumicolchicine have been obtained using a combination of 1D- and 2D-nmr spectroscopic techniques. The data indicate that gamma-lumicolchicine is a stereoisomer of beta-lumicolchicine and provide definitive evidence for their stereochemical assignments.
Asunto(s)
Colchicina/análogos & derivados , Colchicina/análisis , Lumicolchicinas/análisis , Colchicina/efectos de la radiación , Espectroscopía de Resonancia Magnética , Fotoquímica , Rayos UltravioletaRESUMEN
Examination of Dracaena loureiri, a Thai medicinal plant possessing anti-bacterial activity, has led to the isolation of two new representatives, 1 and 2, of a rare skeleton of homoisoflavans. Proton assignments of the two isolates were aided by extensive 2D-homonuclear chemical shift correlation and nOe difference spectroscopy. Carbon assignments were completed through the utilization of simple and sensitive one-dimensional techniques such as selective population transfer via one-bond (CSCM 1D) and selective polarization transfer via long range coupling (selective INEPT) experiments. Conformational assignments were proposed through nOe difference spectroscopy and have been established by X-ray crystallography. The absolute configuration is proposed based on the octant rule and a biogenetic pathway for this type of homoisoflavan is briefly discussed.