1,720,969 research outputs found
Synthesis and in vitro pharmacological activity of oxypropanol analogs of labetalol
No full textAt present α- and β-adrenoceptors are classified into α1/α2 and β1/β2 (and also β3) [1] and [2] subtypes on the basis of structural and pharmacological studies. Both α- and β-adrenoceptor antagonists were proved to be effective and useful in the treatment of hypertension. β-Blockers, especially those selectively blocking heart β-adrenoceptors (β1) with little or no activity on bronchial or vascular adrenoceptors (β2), have been widely used and tested on a numbers of patients in all major multicentre intervention trials performed during past years [3], [4] and [5]. α-Adrenoceptor blocking agents have been less widely applied, although selective α1-adrenoceptor antagonists, like prazosin, have been introduced as useful antihypertensive agents. Therapeutically, the combination of α1 and β1-adrenoceptor antagonists is a logical one [6]. These observations led to the synthesis of several compounds combining both α- and β-adrenergic antagonist activities, and labetalol [1] is the first example of combined α- and β-adrenoceptor antagonistic drug [7]
Identification and Quantification of Trans-Resveratrol in Dietary Supplements by a Rapid and Straightforward RP-HPLC Method
No full textThis paper reports the results of a study performed to develop a rapid and straightforward chromatographic method for the identification and quantification of trans-resveratrol in commercial trans-resveratrol-containing dietary supplements. The method employs an Alltech Platinum EPS 100 A C-18 column operated under isocratic elution mode with a 70:30 (v/v) water-acetonitrile mixture as the mobile phase at flow rate of 1.0 mL min-1. Peak detection is performed at 306 nm with limit of detection (LOD) of 0.27 μg mL-1 and limit of quantification (LOQ) of 0.95 μg mL-1 and linear calibration graph within the concentration range of 2.63 to 10.53 μg mL-1. Other data related to the successful method validation include representative linear regression equation and correlation coefficient of the calibration graph for quantification of trans-resveratrol, as well as the results of replicate analysis of real samples and of a recovery study, carried out to evaluate precision and accuracy, respectively. The method is successfully applied to study the stability of trans-resveratrol in methanol solution under various storage conditions and to analyse commercial preparations of trans-resveratrol-containing dietary supplements
Conformational Analysis of the N-Arachinylethanolamide (Anandamide) using Nuclear Magnetic Resonance and Theoretical Calculations
No full textThe conformational properties of cis-5,8,11,14-eicosatetraenoylethanolamide (anandamide) were analysed
by the combined use of NMRexperimental results plus molecular simulations. The structure of anandamide
was found to be a predominantly linear with a seven-atom ring of the ethanolamine group having
a hydrogen bond which stabilizes the molecule. The vinylic group present has a cis conformation in
solution. The terminal chain has a linear conformation and undergoes isotropic fast motion typical of this
structur
Nuclear magnetic resonance for studying recognition processes between anandamide and cannabinoid receptors
No full textThe understanding of the molecular basis of cannabinoid activity has greatly improved since the discovery of CB1 and CB2 receptors. In this paper, the ligand binding processes between the endogenous cannabimimetic ligand, anandamide (AEA), and the cannabinoid receptors from different parts of rat brain were studied by nuclear magnetic resonance spectroscopy. The NMR approach is based on the comparison of selective (R1(SE)) and non-selective (R1(NS)) proton spin-lattice relaxation rates of the ligand in the presence and absence of macromolecular receptors, as well as R1(NS) and R1(SE) temperature dependency analysis. From these studies, the ligand-receptor binding strength was evaluated on the basis of the calculation of the "affinity index". The derivation of the "affinity index" from chemical equilibrium kinetics for all systems allowed the comparison of the ability of anandamide to interact with cannabinoid receptors present in different brain sectors
Design, Synthesis, and Binding Studies of New Potent Ligands of Cannabinoids Receptors
No full textDespite their different chemical structures D9-tetrahydrocannabinol (THC) and anandamide (AEA) have common pharmacological properties. This study was aimed at finding new cannabinoid receptor ligands that overcome the instability of AEA and its analogues. To this end we planned the synthesis of a series of compounds which retained both a rigid structure, like that of plant cannabinoids, and a flexible portion similar to that of anandamide
The Derivation of Carbon-proton Internuclear Distances In Organic Natural-products From C-13 Relaxation Rates and Nuclear Overhauser Effects
No full textThe precise definition of the hydrogen bonding patterns of natural product organic molecules and biopolymers in solution has hitherto been very difficult. It is demonstrated here that proton-carbon n.O.e. difference spectroscopy and carbon relaxation rates readily yield carbon assignments, the donor and acceptor groups of hydrogen bonds, and the cis- and trans- stereochemistry around C-O and C-N single bonds. N.O.e. ratio methods and cross-relaxation rates gave proton-carbon distances that are in good agreement with the corresponding crystallographically derived distances
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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