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Editorial [Hot Topic: Catalysis/Natural Product Chemistry (Guest Editor: Massimo Curini)]
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Chemical composition, antimicrobial and antioxidant activity of the essential oil of Teucrium marum(Lamiaceae)
Full text linkThe chemical composition of the essential oil obtained from Teucrium marum subsp. Marum (Lamiaceae) was analysed by GC/MS and 30 components were identified. Isocaryophyllene (20.24%), _-bisabolene (14.73%), _-sesquiphellandrene (11.27%), _-santalene (10.97%),
dolichodial (9.38%) and, _-caryophyllene (7.18%) were the main components. The antimicrobial activity of the essential oil was assayed against four phytopathogenic fungi and Rhyzoctonia solani resulted to be the most sensitive microorganism with a MIC value of 250 ppm.
The antioxidant activity of the essential oil was evaluated using the DPPH test, 5-lipoxygenase test and luminol/xanthine/xanthine oxidase chemiluminescence assay
A new flow reactor for the treatment of polluted water with microwave and ultrasound
No full textMicrowave (MW) and high-intensity ultrasound (US) provide innovative techniques for the degradation of persistent organic pollutants (POPs). When Fenton's reagent is used to treat industrial wastes, organic pollutants are degraded by highly reactive hydroxyl radicals (HO·) that can oxidize almost any organic compound to carbon dioxide and water. These reactions, when carried out under US or MW, are faster and much more efficient. The present work assesses the combined effect of US and MW using a new flow reactor developed in our laboratory. In this 5 L pilot reactor the liquid was pumped in parallel through a modified domestic MW oven and through a cell where it was irradiated with two US generators working at 20 and 300 kHz, while MW irradiation took place in a modified domestic oven. We studied the degradation of 2,4-dibromophenol (0.1 g L−1 in water) by Fenton's reagent, assessing the contribution of each energy source to the overall effect, and found that MW and US-300 kHz played the main role. A modest amount of oxidant (6 mL 30% H2O2 per 1 L of polluted water) sufficed to achieve complete degradation within 6 h, at which time organic compounds were no longer detectable. Even if no Fenton's reagent was added, about one half of the pollutant was degraded after 3 h irradiation. Copyright © 2007 Society of Chemical Industr
Quali-quantitative evaluation of chemopreventive coumarins in citrus fruits by HPLC-UV/F/MS: comparison of original analytical methods
No full textThe Citrus genus includes fruits belonging to several species and hybrids commonly used for food and industrial purposes (lemon, sweet and bitter orange, tangerine, grapefruit, lime, bergamot orange, kumquat). In addition to being rich in vitamin C, folate and fibre, some Citrus fruits contain auraptene and umbelliferone, coumarin-based molecules that can increase the potential of these fruits as functional foods. Auraptene (7-((E)-3,7-dimethylocta-2,6-dienyloxy)-2H-chromen-2-one) seems to be promising as an adjuvant for cancer prevention: in particular against melanoma, gastro-intestinal, liver and mammary cancers. Due to its strong UV absorbance, umbelliferone (7-hydroxychromen-2-one) is employed in cosmetic and sunscreen preparations. Both auraptene and umbelliferone are also reported to have antioxidant properties. Therefore it is very useful to develop innovative analytical methods able to provide a reliable measurement of the content of these molecules in Citrus fruits. Three methods have been developed for this purpose based on HPLC with spectrophotometric (UV), spectrofluorimetric (F) and tandem-mass (MS/MS) detection. The sample pre-treatment is carried out by means of original miniaturized extraction procedures. The HPLC-UV system has the great advantage of being simple and inexpensive, thus a good choice for preliminary assays. At the same time, HPLC-F takes advantage of the native fluorescence possessed by the analytes to achieve very high sensitivity. Finally, LC-MS/MS system allows analyte identification through mass spectra and provides a very accurate and selective quantification. The comparison of the developed analytical methods gives an useful overview about the content of chemopreventive coumarins in different types of Citrus, as well as in the same fruits coming from several cultivars and at different ripening levels. Moreover, coumarin levels are being also investigated in various parts of the fruits (exocarp, mesocarp, endocarp and seeds) to gather information both from a nutraceutical point of view, and for the possibility of use as raw materials for nutritional supplements
Neuroprotective effect of prenyloxycoumarins from edible vegetables
No full textThe present Study is designed to investigate the effect of some natural prenyloxypherylpropanoids as neuroprotective agents against NMDA-induced toxicity in mixed cortical cell Cultures containing both neurons and astrocytes. Excitotoxicity was induced by exposure of cultures to NMDA (100 mu M) at room temperature in a HEPES-buffered salt Solution followed by incubation at 37 degrees C for the following 24 h in MEM-Eagle's supplemented with 15.8 mM NaHCO3 and 25 mM glucose. Tested compounds were mixed with NMDA. Neuronal injury was measured in all experiments by examination Of Cultures with phase-contrast microscopy at 20x, 18-20 h after the insult while neuronal damage was quantitatively assessed by counting dead neurons stained with trypan blue and by measuring lactate dehydrogenase (LDH) released in the medium. Results showed that only natural prenyloxypherylpropanoids containing a coumarin nucleus, namely 7-isopentenyloxycounnarin and auraptene, both found in nature from plants belonging to the genus Citrus and other of the family of Rutaceae, including edible ones, exerted a good dose-dependent manner protective effect against NMDA-induced neurotoxicity in particular at concentrations ranging from 1 to 10 mu M. (c) 2008 Elsevier Ireland Ltd. All rights reserved
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
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