RESUMEN
The selective N-acylation of 1,2-amino alcohols has been proposed to occur through the proton shuttle mechanism. However, the O-acetylation of propranolol catalyzed by Candida antarctica lipase B is an exception. We investigated the relation between the chemoselectivity of this reaction and the acyl group length. For this purpose, we compared the acyl groups: ethanoyl, butanoyl, octanoyl, and hexadecanoyl. We studied the Michaelis complexes between serine-acylated Candida antarctica lipase B and propranolol, employing a computational approach that involved sampling Michaelis complex conformations through ensemble docking plus consensus scoring and molecular dynamics simulations. The conformations were then classified as near attack conformations for acylation of the amino or hydroxy group. The relative populations of these two classes of conformations were found to be consistent with the experimentally observed chemoselective O-acetylation. We predict that increasing the length of the hydrocarbon chain of the acyl group will cause O-acylation to be unfavorable with respect to N-acylation. The nucleophilic attack of propranolol to the acylated lipase was found to be more favorable through the classical mechanism when compared with the proton shuttle mechanism.
Asunto(s)
Proteínas Fúngicas/metabolismo , Lipasa/metabolismo , Modelos Moleculares , Propranolol/metabolismo , Acilación , Basidiomycota/enzimología , Biología Computacional , Cinética , Simulación de Dinámica Molecular , Conformación Proteica , Especificidad por SustratoRESUMEN
Enzyme preparations of Candida antarctica B lipase (CAL-B) - immobilized on Eupergit C and partially modified Eupergit C supports - were tested for kinetic resolution of (R/S)-propranolol, using vinyl acetate as acyl donor, and toluene as organic solvent. The effects of (R/S)-propranolol concentration, vinyl acetate concentration and biocatalyst loading on the esterification and resolution of propranolol were studied. Additionally, different types of immobilized lipase derivatives were also evaluated in terms of its selectivity on kinetic resolution of (R,S)-propranolol. These derivatives showed different enantiomeric ratios (E), with high enantiomeric ratios (E=57) with CAL-B immobilized on Eupergit C supports.
Asunto(s)
Enzimas Inmovilizadas/metabolismo , Lipasa/metabolismo , Propranolol/análogos & derivados , Propranolol/metabolismo , Catálisis , Esterificación , Proteínas Fúngicas , Estructura Molecular , Polímeros/química , Solventes/química , Solventes/metabolismo , Estereoisomerismo , Tolueno/química , Tolueno/metabolismo , Compuestos de Vinilo/química , Compuestos de Vinilo/metabolismoRESUMEN
Central leptin action requires PI3K activity to modulate glucose homeostasis and peripheral metabolism. However, the mechanism behind this phenomenon is not clearly understood. We hypothesize that hypothalamic PI3K activity is important for the modulation of the AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) pathway, PGC1 alpha, and AKT in skeletal muscle (SM). To address this issue, we injected leptin into the lateral ventricle of rats. Hypothalamic JAK2 and AKT were activated by intracerebroventricular (ICV) injection of leptin in a time-dependent manner. Central leptin improved tolerance to glucose (GTT), increased PGC1 alpha expression, and AKT, AMPK, ACC and JAK2 phosphorylation in the soleus muscle. Previous ICV administration of either LY294002 or propranolol (IP) blocked these effects. We concluded that the activation of the hypothalamic PI3K pathway is important for leptin-induced AKT phosphorylation, as well as for active catabolic pathway through AMPK and PGC1 alpha in SM. Thus, a defective leptin signalling PI3K pathway in the hypothalamus may contribute to peripheral resistance to insulin associated to diet-induced obesity.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Hipotálamo , Leptina/metabolismo , Músculo Esquelético/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas de Unión al ARN/metabolismo , Factores de Transcripción/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Antagonistas Adrenérgicos beta/metabolismo , Animales , Cromonas/metabolismo , Metabolismo Energético , Glucosa/metabolismo , Homeostasis , Hipotálamo/efectos de los fármacos , Hipotálamo/metabolismo , Insulina/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Leptina/farmacología , Masculino , Morfolinas/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Fosfatidilinositol 3-Quinasas/genética , Inhibidores de las Quinasa Fosfoinosítidos-3 , Propranolol/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas de Unión al ARN/genética , Ratas , Ratas Wistar , Transducción de Señal/fisiología , Factores de Transcripción/genéticaRESUMEN
A CE method is described for the enantioselective analysis of propranolol (Prop) and 4-hydroxypropranolol (4-OH-Prop) in liquid Czapek medium with application in the study of the enantioselective biotransformation of Prop by endophytic fungi. The electrophoretic conditions previously optimized were as follows: an uncoated fused-silica capillary, 4% w/v carboxymethyl-beta-CD in 25 mmol/L triethylamine/phosphoric acid (H(3)PO(4)) buffer at pH 9 as running electrolyte and 17 kV of voltage. UV detection was carried out at 208 nm. Liquid-liquid extraction using diethyl ether: ethyl acetate (1:1 v/v) as extractor solvent was employed for sample preparation. The calibration curves were linear over the concentration range of 0.25-10.0 microg/mL for each 4-OH-Prop enantiomer and 0.10-10.0 microg/mL for each Prop enantiomer (r>or=0.995). Within-day and between-day relative standard deviations and relative errors for precision and accuracy were lower than 15% for all the enantiomers. Finally, the validated method was used to evaluate Prop biotransformation in its mammalian metabolite 4-OH-Prop by some selected endophytic fungi. The screening of five strains of endophytic fungi was performed and all of them could biotransform Prop to some extent. Specifically, Glomerella cingulata (VA1) biotransformed 47.8% of (-)-(S)-Prop to (-)-(S)-4-OH-Prop with no formation of (+)-(R)-4-OH-Prop in 72 h of incubation.
Asunto(s)
Electroforesis Capilar/métodos , Propranolol/análogos & derivados , Propranolol/análisis , Aspergillus fumigatus/metabolismo , Asteraceae/microbiología , Biotransformación , Chaetomium/metabolismo , Límite de Detección , Penicillium/metabolismo , Phyllachorales/metabolismo , Propranolol/metabolismo , EstereoisomerismoRESUMEN
Rapid eye movement (REM) sleep deprivation induces a cortical down-regulation of beta-adrenergic receptors. Down-regulation of cortical beta-adrenergic receptors is consistently observed after a number of different chronic antidepressant treatments (drugs and electroconvulsive shock). REM sleep deprivation has an antidepressant effect in humans, and in rats, it decreases immobility in the behavioral despair test, an effect also produced by antidepressant treatments. To verify whether REM sleep deprivation also affects hippocampal beta-adrenergic receptors, we carried out the binding of [3H]-dihydroalprenolol ([3H]-DHA) to hippocampal membranes from rats deprived of REM sleep for 96 h. We also determined the binding of [3H]-DHA to brainstem membranes, a brain region where noradrenergic nuclei are located. Rats were deprived of REM sleep using a water tank with multiple small platforms. [3H-DHA] saturation conditions (concentrations ranging from 0.15 to 6 nM) were obtained in a crude hippocampus and brainstem membrane preparation. Nonspecific binding was determined using DL-propranolol in hippocampus homogenates. In the brainstem homogenates, nonspecific binding was determined in the presence of DL-propranolol or L-isoproterenol. The results obtained showed statistically significant down-regulation of beta-adrenergic receptors in both the hippocampus and the brainstem after REM sleep deprivation. In the hippocampus, there was also a significant decrease in the dissociation constant (KD). In the brainstem, a significant decrease in KD was observed when DL-propranolol was used to determine nonspecific binding. The down-regulation of beta-adrenergic receptors in the hippocampus and brainstem suggests the involvement of these brain areas in the antidepressant effect of REM sleep deprivation.
Asunto(s)
Tronco Encefálico/fisiología , Hipocampo/fisiología , Receptores Adrenérgicos beta/fisiología , Privación de Sueño/fisiopatología , Sueño REM/fisiología , Antagonistas Adrenérgicos beta/metabolismo , Animales , Dihidroalprenolol/metabolismo , Regulación hacia Abajo/fisiología , Técnicas In Vitro , Indicadores y Reactivos , Masculino , Dinámicas no Lineales , Propranolol/metabolismo , Ratas , Ratas WistarRESUMEN
We have shown that the stimulation of beta-adrenoceptors is an important step in venom production in the Bothrops jararaca venom gland. In the present study, the pharmacological profile of the beta-adrenoceptor present in Bothrops jararaca venom gland was characterized by radioligand binding assay and by the ability of isoprenaline to promote accumulation of cyclic AMP in dispersed secretory cells. In both cases, the venom glands were obtained from non-extracted snakes (quiescent stage) or from snakes which venom was extracted 4 days before sacrifice (venom production stimulated stage). [125I]-iodocyanopindolol ([125I]-ICYP) bound to extracted gland membranes in a concentration-dependent and saturable manner, but with low affinity. Propranolol, beta1- or beta2-selective adrenoceptors ligands displaced the [125I]-ICYP binding with low affinity, while selective beta3-adrenoceptor ligands did not displace the [125I]-ICYP binding. The displacement of [125I]-ICYP by propranolol was similar in non-extracted and extracted glands, showing the presence of beta-adrenoceptors in both stages. In dispersed secretory cells of non-extracted glands, isoprenaline (1 microM) increased the cyclic AMP production and propranolol (10 microM) was able to block this effect. On the other hand, in extracted glands, isoprenaline had no effect. The results suggest that the beta-adrenoceptors present in the Bothrops jararaca venom glands are different from those (beta1, beta2 or beta3) described in mammals, but are coupled to the Gs protein, like the known beta-adrenoceptor subtypes. Moreover, previous in vivo stimulation of venom production desensitizes the beta-adrenoceptors system and, although the receptors could be detected by binding studies, they are not coupled to the Gs protein, indicating that beta-adrenoceptors stimulation contributes to the initial steps of venom synthesis.
Asunto(s)
Bothrops/metabolismo , Venenos de Crotálidos/biosíntesis , Receptores Adrenérgicos beta/clasificación , Receptores Adrenérgicos beta/metabolismo , Agonistas de Receptores Adrenérgicos beta 1 , Antagonistas de Receptores Adrenérgicos beta 1 , Agonistas de Receptores Adrenérgicos beta 2 , Antagonistas de Receptores Adrenérgicos beta 2 , Agonistas Adrenérgicos beta/metabolismo , Agonistas Adrenérgicos beta/farmacología , Antagonistas Adrenérgicos beta/metabolismo , Antagonistas Adrenérgicos beta/farmacología , Animales , Unión Competitiva , AMP Cíclico/biosíntesis , Dioxoles/metabolismo , Dioxoles/farmacología , Etanolaminas/metabolismo , Etanolaminas/farmacología , Glándulas Exocrinas/citología , Glándulas Exocrinas/metabolismo , Femenino , Radioisótopos de Yodo , Yodocianopindolol/metabolismo , Yodocianopindolol/farmacología , Isoproterenol/farmacología , Cinética , Masculino , Membranas/metabolismo , Metoprolol/metabolismo , Metoprolol/farmacología , Propanolaminas/metabolismo , Propanolaminas/farmacología , Propranolol/metabolismo , Propranolol/farmacocinética , Ensayo de Unión Radioligante , Receptores Adrenérgicos beta 1/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Receptores Adrenérgicos beta 3Asunto(s)
Melanocitos/metabolismo , Receptores Adrenérgicos/análisis , Antagonistas Adrenérgicos alfa/farmacología , Unión Competitiva , Células Cultivadas , Relación Dosis-Respuesta a Droga , Humanos , Idazoxan/farmacología , Melanocitos/efectos de los fármacos , Metoprolol/farmacología , Oxatiinas/farmacología , Propanolaminas/farmacología , Propranolol/metabolismo , Células Tumorales Cultivadas , Yohimbina/metabolismo , Yohimbina/farmacologíaRESUMEN
O propranolol é uma droga beta-bloqueadora que tem sua maior utilidade no tratamento de doença cardiovasculares, especialmente a hipertensäo arterial sistêmica e angina pectoris. A droga é bem absorvida pela via oral e tem importante metabolismo hepático de primeira passagem com grande variaçäo interindividual, o que pode levar a consideráveis variaçöes de doses dentro de uma mesma entidade clínica. É um fármaco geralmente bem tolerado, mas que pode ter entre seus efeitos adversos a descompensaçäo de insuficiência cardíaca e de asma; merece especial atençäo em pacientes diabéticos usando insulina e/ou hipoglicemiantes orais e cuidados especiais na descontinuaçäo do tratamento
Asunto(s)
Humanos , Enfermedades Cardiovasculares/tratamiento farmacológico , Propranolol/uso terapéutico , Propranolol/efectos adversos , Propranolol/metabolismoAsunto(s)
Antagonistas Adrenérgicos beta/uso terapéutico , Hipertensión/tratamiento farmacológico , Propranolol/uso terapéutico , Antagonistas Adrenérgicos beta/farmacología , Angina de Pecho/tratamiento farmacológico , Arritmias Cardíacas/tratamiento farmacológico , Insuficiencia Cardíaca/tratamiento farmacológico , Humanos , Propranolol/administración & dosificación , Propranolol/metabolismoRESUMEN
The administration of 160 mg of propranolol during pregnancy, labor, and delivery was associated with profound hypoglycemia and respiratory depression in a newborn infant. The neonate's plasma propranolol level rose from 40 ng/ml at the time of birth to 90 ng/ml four hours later. This increase in plasma propranolol concentration might be due to redistribution of the drug in the neonate as well as to different elimination mechanisms than in adults. The elevated propranolol level four hours after delivery was not associated with any signs or symptoms of drug toxicity, but drug effect was apparent on the electrocardiogram. The administration of propranolol during pregnancy in doses capable of producing therapeutic maternal blood levels may be dangerous to the neonate.