1,720,960 research outputs found
Synthesis of novel derivatives of resveratrol and screening for potential cancer chemopreventive activities
No full textResveratrol (trans-3,4’,5-trihydroxystilbene) has attracted the attention of the biomedical researchers because of its beneficial physiological effects it produces. Positive effects of resveratrol has been observed in the field of cardiovascular diseases and neurodegenerative disorders. It has been also identified as a potent cancer chemopreventive agent in assays representing the three major stages of carcinogenesis (i.e. tumor initiation, promotion and progression). We have synthesized a variety of Resveratrol analogues by chemical modification of the parent trihydroxy stilbene skeleton. The compounds were screened for cancer chemopreventive potential using a series of bioassays relevant for the prevention of carcinogenesis in humans (inhibition of cytochrome P450 1A; determination of NAD(P)H:quinone reductase activity; scavenging of radicals; inhibition of cyclooxygenase activity; inhibition of NO synthase; antiestrogenic and estrogenic activity)
Biologically-active stilbene derivatives and compositions thereof
No full textThe present invention relates to stilbene derivatives which are structurally close to the natural compound resveratrol and which possess a large spectrum of biological activities, particularly anti-cancer, antioxidant and antiinflammatory activities.
The invention further concerns pharmaceutical and nutraceutical compositions containing such stilbene derivatives and their uses as therapeutic agents or nutritional supplements
Synthesis of resveratrol derivatives and in vitro screening for potential cancer chemopreventive activities
No full textNew resveratrol (trans-3,4’,5-trihydroxystilbene) analogs were synthesized and screened for their in vitro cancer chemopreventive potential using various bioassays relevant for the prevention of carcinogenesis in humans: Two assays to detect modulators of carcinogen metabolism (Cyp1A inhibition; determination of NAD(P)H/quinone reductase (QR) activity), three assays to identify radical scavenging and antioxidant properties (DPPH, ORAC, superoxide anion radicals in differentiated HL-60 cells), four assays to determine anti-inflammatory and anti-hormonal effects (iNOS, Cox-1 and aromatase inhibition, anti-estrogenic potential). 3,40,5-Tri-O-methyl resveratrol 1a was about seven-fold more active than resveratrol in inhibiting Cyp1A activity, it was a potent inducer of QR activity, and it showed pure anti-estrogenic activity (whereas resveratrol is a known mixed estrogen (ant)agonist with both estrogenic and anti-estrogenic properties). Dual estrogen ant-/agonist activity was restored in the mono-O-benzyl-substituted derivatives 4b (40-O-benzyl resveratrol) and 5b (3-O-benzylresveratrol). With respect to aromatase inhibition (Cyp19), which provided the highest number of actives, the benzyl-substituted series was more potent than the methyl-substituted derivatives of resveratrol, and 3-O-benzyl resveratrol 5b was about eightfold more active than resveratrol. Overall,
21 3,40,5-tri-O-pivaloyl resveratrol oxide 7c was identified as a potent inducer of phase 2 enzymes
22 concomitant with inhibition of LPS-mediated iNOS induction
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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