1,720,961 research outputs found
Interaction of chlorogenic acids and quinides from coffee with human serum albumin
No full textChlorogenic acids and their derivatives are abundant in coffee and their composition changes between
coffee species. Human serum albumin (HSA) interacts with this family of compounds with high
affinity. We have studied by fluorescence spectroscopy the specific binding of HSA with eight compounds
that belong to the coffee polyphenols family, four acids (caffeic acid, ferulic acid, 5-O-caffeoyl quinic
acid, and 3,4-dimethoxycinnamic acid) and four lactones (3,4-O-dicaffeoyl-1,5-c-quinide, 3-O-[3,4-
(dimethoxy)cinnamoyl]-1,5-c-quinide, 3,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide, and 1,3,
4-O-tris[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide), finding dissociation constants of the albumin–chlorogenic
acids and albumin–quinides complexes in the micromolar range, between 2 and 30 lM. Such values
are comparable with those of the most powerful binders of albumin, and more favourable than the
values obtained for the majority of drugs. Interestingly in the case of 3,4-O-dicaffeoyl-1,5-c-quinide,
we have observed the entrance of two ligand molecules in the same binding site, leading up to a first dissociation
constant even in the hundred nanomolar range, which is to our knowledge the highest affinity
ever observed for HSA and its ligands. The displacement of warfarin, a reference drug binding to HSA, by
the quinide has also been demonstrated
ARTIFICIAL RECEPTORS TOWARDS BIOACTIVE COFFEE COMPOUNDS
No full textThe worldwide importance of coffee industry makes the molecules present in a coffee brew potential intriguing targets for artificial receptors: a set of selective receptors may represent a convenient tool to detect and quantify different families of compounds related with both safety and taste of coffee
Synthesis of Mono-, Di-, and Tri-3,4-dimethoxycinnamoyl-1,5-gamma-quinides
No full textTri-3,4-dimethoxycinnamoyl-1,5-γ-quinide was synthesized and fully characterized by a direct synthesis from quinic acid and a large excess of 3,4-dimethoxycinnamoyl chloride. Mono-and di-3,4-dimethoxycinnamoyl-1,5-γ- quinides were also obtained from the direct coupling of 1,5-γ-quinide and 3,4-dimethoxycinnamoyl chloride in different molar ratios. Moreover, a hypothetical mechanism of the direct lactonization is proposed. Mono-, di-, and tri-3,4-dimethoxycinnamoyl-1,5-γ-quinides have been synthesized from 1,5-γ-quinide and 3,4-dimethoxycinnamoyl chloride in different molar ratios. The only triester quinide was also easily obtained by a direct synthesis from D-(-)-quinic acid in the presence of an excess of the acyl chloride
MATERIALE IBRIDO ORGANICO-INORGANICO COMPRENDENTE METALLO E LIGNINA, PROCESSI PER LA SUA PREPARAZIONE E SUOI USI
Full text linkThe present invention concerns an organic-inorganic hybrid material comprising a metal
compound and a lignin fraction, as well as processes for preparing the same and uses as
an antimicrobial agent in agriculture, and in human and animal food industr
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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