1,720,978 research outputs found
Diaryl urea:A privileged structure in anticancer agents
No full textThe diaryl urea is an important fragment/pharmacophore in constructing anticancer molecules due to its near-perfect binding with certain acceptors. The urea NH moiety is a favorable hydrogen bond donor, while the urea oxygen atom is regarded as an excellent acceptor. Many novel compounds have been synthesized and evaluated for their antitumor activity with the successful development of sorafenib. Moreover, this structure is used to link alkylating pharmacophores with high affinity DNA binders. In addition, the diaryl urea is present in several kinase inhibitors, such as RAF, KDR and Aurora kinases. Above all, this moiety is used in the type II inhibitors: it usually forms one or two hydrogen bonds with a conserved glutamic acid and one with the backbone amide of the aspartic acid in the DFG motif. In addition, some diaryl urea derivatives act as Hedgehog (Hh) ligands, binding and inhibiting proteins involved in the homonymous Hh signaling pathway. In this review we provide some of the methodologies adopted for the synthesis of diaryl ureas and a description of the most representative antitumor agents bearing the diaryl urea moiety, focusing on their mechanisms bound to the receptors and structure-activity relationships (SAR). An increased knowledge of these derivatives could prompt the search to find new and more potent compounds.</p
Multi-kinase inhibitors
No full textThe limitations of many mono-kinase inhibitors can be overcome by agents with multi-target action. An important advantage of targeting more than one kinase, is an increase in potency, due to the synergistic effect. Moreover, this approach can reduce the possibility of developing drug resistance. Several multitarget agents have been designed as single kinase inhibitors and found to be multi-target inhibitors because of the structural homology among the ATP-binding site of kinases. In other cases, these inhibitors have been obtained by optimization of potent individual inhibitors or by combination of selective ligands. Also some irreversible inhibitors act on different kinases and covalently modify the cysteine residues located near the ATP-binding pocket. In this review the most recent examples of multi-kinase inhibitors are reported, focusing on chemical structures, structure-activity relationship (SAR) and biological activity. These inhibitors, suitably substituted, could be used in designing other multitarget agents. Virtual molecular docking would suggest potential targets of molecules, moreover combining pharmacophore combination and screening methods could probably help in the discovery of more potent multikinase inhibitors.</p
Diaryl Urea: A Privileged Structure in Anticancer Agents
No full textAbstract: The diaryl urea is an important fragment/pharmacophore in constructing anticancer
molecules due to its near-perfect binding with certain acceptors. The urea NH moiety is a
favorable hydrogen bond donor, while the urea oxygen atom is regarded as an excellent acceptor.
Many novel compounds have been synthesized and evaluated for their antitumor activity
with the successful development of sorafenib. Moreover, this structure is used to link
alkylating pharmacophores with high affinity DNA binders. In addition, the diaryl urea is present in several
kinase inhibitors, such as RAF, KDR and Aurora kinases. Above all, this moiety is used in the type II inhibitors:
it usually forms one or two hydrogen bonds with a conserved glutamic acid and one with the backbone
amide of the aspartic acid in the DFG motif. In addition, some diaryl urea derivatives act as Hedgehog (Hh)
ligands, binding and inhibiting proteins involved in the homonymous Hh signaling pathway. In this review we
provide some of the methodologies adopted for the synthesis of diaryl ureas and a description of the most representative
antitumor agents bearing the diaryl urea moiety, focusing on their mechanisms bound to the receptors
and structure-activity relationships (SAR). An increased knowledge of these derivatives could prompt the
search to find new and more potent compounds
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
Design and synthesis of 3-(benzimidazol-2-yl)propionic acids as thromboxane A2 receptor antagonists
No full textA series of 3-(benzimidazol-2-yl)propionic acids substituted at the N1 nitrogen with Me and benzyl groups and at the C5 and C6 positions with chloro, methoxy, amino, hydroxyl groups were synthesized and tested as TXA2 receptor antagonists. None of the compds. showed any antiaggregating activity
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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