1,721,046 research outputs found
Sesquiterpene lactones from Centaurea zuccariniana and their antimicrobial activity
No full textTwenty-nine compounds were isolated from the aerial parts of the Greek plant C. zuccariniana DC. The structures of the isolated compounds were established by means of NMR- (1H,1H-COSY, 1H,13C-HSQC, HMBC, NOESY, and ROESY) and mass-spectral analyses. These compounds comprise 13 sesquiterpene lactones, 14 flavonoids, two lignans, and one simple lactone. Among the isolated sesquiterpene lactones, three are new, namely one heliangolide, (1E,4Z)-15-hydroxy-8α-O-(4′- acetoxy-3′-hydroxy-2′-methylidenebutanoyl)-6βH, 7αH-germacra-1,4,11(13)-trien-6,12-olide; and two eudesmanolides, 8α-(4′,5′-diacetoxyangeloyl)sonchucarpolide and one unusual eudesmanolide with an oxygenated bridge linking C(1) and C(4), named zuccarinin. The main sesquiterpene lactones were malacitenolide, cnicin, and 4′-O-acetylcnicin. These results are in agreement with those obtained from the previously studied Greek Centaurea sp. belonging to the section Acrolophus (Cass.) DC.; this finding could be of chemotaxonomic significance for the genus Centaurea. The in vitro antimicrobial activities of the isolated new sesquiterpene lactones were against eight bacteria and eight fungal species. A 96-well microbioassay procedure for fast and easy evaluation of antibacterial and antifungal activities was applied to compare these compounds with commercial antibiotic and fungicide standards, and with previously isolated analogous sesquiterpene lactones tested by the same bioassay. All of the compounds tested showed moderate antibacterial, but significant antifungal activities; the present results corroborate with previous data, indicating that these types of compounds exhibit low or moderate antibacterial, but potent antifungal activities. The unusual eudesmanolide zuccarinin proved to be the most potent among the present tested sesquiterpene lactones, as well as among all previously tested eudesmanolides isolated from Greek Centaurea sp. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich
Antimicrobial activity of secondary metabolites isolated from Centaurea spruneri boiss. & heldr
No full textTwo coumarins, scopoletin (1) and isoscopoletin (2), two simple phenolic acids, protocatechuic acid (3) and isovanillic acid (4) and one flavonoid, eriodictyol (5) were isolated from the aerial parts of Centaurea spruneri. The structure of the compounds was established by spectroscopic methods. The in vitro antimicrobial activity of the isolated compounds was tested against eight bacteria and eight fungal species, using a microdilution method. All compounds tested showed moderate antibacterial and antifungal activities. Their minimum inhibitory concentrations were in the range 0.655-2.38 μmol ml-1 and their minimal bactericidal concentrations ranged from 0.694 to 4.15 μmol ml-1 against the tested bacterial species. All compounds showed fungistatic activity at 0.259-2.38 μmol ml-1 and fungicidal at 0.69-2.6 μmol ml-1 against all fungi tested. © 2011 Copyright (CC) SCS
Isolation and structural elucidation of two secondary metabolites from the filamentous fungus Penicillium ochrochloron with antimicrobial activity
No full textIn this investigation, the extracts of filamentous fungi exhibited inhibitory effect on the growth of Gram positive and Gram negative bacteria, as well as against the yeast Candida albicans. Penicillium ochrochloron has been proven as the most active fungus against all tested microorganisms. Further bio-guided chemical analysis of P. ochrochloron afforded two components with antimicrobial activity identified as (-) 2, 3, 4-trihydroxybutanamide and (-) erythritol. © 2005 Elsevier B.V. All rights reserved
A novel sesquiterpene lactone from Centaurea pullata: Structure elucidation, antimicrobial activity, and prediction of pharmacokinetic properties
No full textA novel elemanolide with an α-methyl-γ-lactone moiety, 8α-O-(4-hydroxy-2-methylenebutanoyloxy)melitensine, in addition to four known sesquiterpene lactones also bearing the same lactone ring, melitensin, 11β,13 dihydrosalonitenolide, 8α-hydroxy-11β,13-dihydro-4-epi-sonchucarpolide, and 8α-hydroxy-11β,13-dihydro-onopordaldehyde have been isolated from the aerial parts of Centaurea pullata. The in vitro antibacterial and antifungal activities of the isolated sesquiterpene lactones were tested against six bacteria and eight fungal species, using a microdilution method. All compounds tested showed greater antibacterial and antifungal activities than the positive controls used. Moreover, the pharmacokinetic profile of these compounds was investigated using computational methods. © 2008 Elsevier 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
Antimicrobial properties of Quercus ilex L. Proanthocyanidin dimers and simple phenolics: Evaluation of their synergistic activity with conventional antimicrobials and prediction of their pharmacokinetic profile
No full textThe antibacterial and antifungal activities of an ample number of phenolic compounds isolated from Quercus ilex leaves, belonging to the classes of flavonoids, proanthocyanidins, and phenolic acids, are discussed. The isolation of A type proanthocyanidin, (+)-epigallocatechin-(2β→O→7, 4β→8)-(+)-catechin (1) is reported for the first time. Its structure was established by means of highfield NMR (correlation spectroscopy, heteronuclear single quantum correlation, heteronuclear multiple bond correlation, and rotating frame Overhauser effect spectroscopy) and MS spectral analyses, while its absolute configuration was determined by circular dichroism measurements. The isolated compounds were tested for their antimicrobial effects against eight human bacterial species and 14 fungal species. In a second step, the most potent compounds were tested in combination with the conventional fungicides, bifonazole and ketoconazole, to evaluate possible synergistic effects. Results showed that proanthocyanidins 3 and 4 when combined with bifonazole and ketoconazole increase the activity of both of these conventional fungicides. Moreover, the pharmacokinetic profile of the isolated compounds was investigated using computational methods. © 2011 American Chemical Society
Minor sesquiterpene lactones from Centaurea pullata and their antimicrobial activity
No full textThe aerial parts of Centaurea pullata afforded, in addition to the previously isolated sesquiterpene lactones, 11β,13-dihydrocnicin and 11β,13-dihydro-19-desoxycnicin, three minor sesquiterpene lactones, namely, a new germacranolide, 8α-0-(4-acetoxy-5-hydroxyangeloyl)-11β,13- dihydrocnicin, and two new eudesmanolides, 8α-0-(4-hydroxy-2- methylenebutanoyloxy)-11β,13-dihydrosonchucarpolide and 8α-0-(4-hydroxy-2-methylenebutanoyloxy)-11β,13-dihydro-4-epi- sonchucarpolide. The in vitro antimicrobial activity of all isolated sesquiterpene lactones was tested against six bacteria and eight fungal species, using a microdilution method. All compounds tested showed greater antibacterial and antifungal activities than the positive controls used. © 2007 American Chemical Society and American Society of Pharmacognosy
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
The Triazole Ring as a Privileged Scaffold for Putative Antifungals: Synthesis and Evaluation of a Series of New Analogues
No full textThe significant antifungal activity of a series of novel 1,2,4-triazole derivatives against different strains of Candida albicans, Candida krusei and Aspergillus fumigatus, compared to the commercial fungicides ketoconazole and itraconazole, is reported. Systemic mycosis and invasive fungal infections, whether from immunodeficiency or hospital-acquired infection, have been on an upward trend for several years. The 1,2,4-triazole ring substituted with other aromatic and heteroaromatic systems plays an important role in the field of antifungal drug discovery and development. Thus, an extensive series of 29 triazoles, substituted in different positions with a variety of aromatic rings, has been designed, synthesized, and evaluated for their fungicidal activity. Almost all the agents tested in vitro showed high activity against all examined fungal strains. It is noteworthy that, in the case of A. fumigatus, all the examined compounds achieved equal or higher antifungal activity than ketoconazole, but less activity than itraconazole. Among all the derivatives studied, the dichlorourea analogue and bromo-substituted triazole stand out as the most promising compounds. Quantitative structure-activity relationship (QSAR) models were built for a systematic structure-activity relationship (SAR) profile to explain and potentially explore the potency characteristics of 1,2,4-triazole analogues
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