1,721,019 research outputs found
Volatile constituents of different organs of Psoralea bituminosa L
No full textThe essential oil and SPME samples of the leaves, flowers and seeds of Psoralea bituminosa L. were analysed by GC and GC–MS. We have investigated also the presence of monoterpene or aliphatic alcohol glucosides. The essential oils showed both qualitative and quantitative differences. The main constituents of the leaf and the flower essential oils were caryophyllene (23% and 18%, respectively), β-farnesene (15% and 6%, respectively), and germacrene D (24% and 18%, respectively). Significant amounts (7%) of the same compounds were also directed in the seed essential oil, but tricyclene (11%) and α-pinene (50%) were the most important constituents of this oil. The volatile fractions of remaining leaf aqueous extracts after treatment with β-glucosidase revealed qualitative differences in comparison with the composition of the corresponding essential oils, and high levels of 3-hexen-1-ol (37%) and 1-octen-3-ol (27%) were observed. The SPME analysis of the fresh leaves, flowers and seeds of P. bituminosa confirmed the qualitative composition of the volatile oils, even if we detected significative differences in the percentage ratio between monoterpenes and sesquiterpenes in comparison with the oils, where sesquiterpenes were the main components. In fact the variation of the monoterpenes, tricyclene, α-pinene and camphene between the leaf oil and the corresponding headspace sample was remarkable: tricyclene increased from 0.1% to 8%, α-pinene from 0.1% to 16% and camphene from 0.3% to 10% in the SPME samples
Comparative free radical scavenging potential and cytotoxicity of different extracts from Iris pseudopumila Tineo flowers and rhizomes
No full textDifferent Iris species are known as medicinal plants. The aim of this study was to evaluate the in vitro antioxidant and cytotoxic activities of different extracts from Iris pseudopumila Tineo flowers and rhizomes. The radical scavenging activity was assessed by means of DPPH assay. The antioxidant activity was assessed by means of two tests: bleaching of β-carotene and lipid peroxidation of liposomes. Methanolic and chloroform extracts from the flowers of I. pseudopumila showed a significant antiradical effect with IC50 of 101 and 83 μg mL-1, respectively. As regards to lipid peroxidation, the best activity was showed by methanolic extract of flowers (IC50 of 18 μg mL-1) and chloroformic extract of rhizomes (IC50 33 μg mL-1). The cytotoxic activity was carried out using the SRB assay. The chloroform extract from rhizomes demonstrated a good cytotoxic activity against amelanotic melanoma cancer cell line (C32) with an IC50 of 57 μg mL-1. The results obtained support the ethnomedical claims for the plant
Antiproliferative activity on human cancer cell lines after treatment with polyphenolic compounds isolated from Iris pseudopumila flowers and rhizomes
No full textThe present study describes the antiproliferative properties of Iris pseudopumila flowers and rhizomes extracts and fourteen constituents isolated from them. The in vitro cytotoxic activity assay against two human cancer cell lines, large lung carcinoma (CORL-23) and amelanotic melanoma (C32), showed that the most antiproliferative extract was the MeOH extract from flowers with a percentage of inhibition of 50.9 at 100 μg/ml against amelanotic melanoma cells. The most antiproliferative compounds against amelanotic melanoma cells were kaempferol-3-O-β-D-glucopyranoside and irisolidone with a percentage of inhibition of 100 and 96.6, respectively, and against large lung carcinoma cells with a percentage of inhibition of 82.1 and 84.6, respectively. Significant activity on the amelanotic melanoma cell line was also showed by irigenin-7-O-β-D-glucopyranoside, with a percentage of inhibition of 89.3. The compounds isovitexin and isoorientin-6-O''-β-D-glucopyranoside showed a selective activity against amelanotic melanoma cells with a percentage of inhibition of 83.2 and 79.8, respectively
Attività antiproliferativa di differenti estratti di Iris pseudopumila Tineo su linee cellulari tumorali umane
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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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