1,721,031 research outputs found
Complete Characterization of Extracts of Onopordum illyricum L.(Asteraceae) by HPLC/PDA/ESIMS and NMR
No full textThe aerial parts of Onopordum illyricum L. (Asteraceae) are eaten raw in salad in the Mediterranean area, representing a food of good nutritional value. Extracts of different parts of this plant have been analyzed by HPLC/DAD/ESIMS and the major compounds identified by NMR spectroscopy. Fatty acids, sesquiterpene lactones, triterpenes and polyphenols (flavones and caffeoyl quinic acids) fully describe the plant metabolism during the vegetation year. All the metabolites are non toxic nutrients, and are reported in the literature to possess biological activities positive for health, confirming the beneficial use in the diet of this thistl
Novel antioxidant bioinspired phenolic polymers and their applications in packaging
No full textPolymers of natural polyphenols have so far received little attention as bioavailable, biocompatible antioxidants for different applications e.g. in packaging and related technologies. Expected advantages with respect to the monomers would include lower volatility (with reduced adverse effects), greater chemical stability under processing conditions and lower tendency to be released from the polymer into the contact medium (food, water, etc.).
Herein we report data on the synthesis, structural characterization and antioxidant properties of two novel bioinspired phenolic polymers prepared by horseradish/H2O2 oxidation of tyrosol (polyTYR) and caffeic acid methyl ester (polyCAME). The materials, obtained in 80-85% yields, were subjected to structural characterization by solid state CPMAS NMR, mass spectrometry and gel permeation chromatography (GPC). ESI(-)/MS and NMR analysis indicated that polyTYR was a mixture of regular oligomers up to the undecamer with heptamer as the most abundant, all featuring units linked through C-C bonds. GPC showed an average molecular weight of 1862 Da with a polydispersity index of 1.64. ESI(-)/MS of polyCAME showed oligomers up to at least the decamer stage, peaking at the tetramer. Analysis of the clusters of the pseudomolecular ion peaks and the presence of CH carbons due to O-substituted benzylic positions in NMR spectra suggested a structure including dihydrobenzofuran units. Both PolyTYR and polyCAME exhibited antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays and proved to be efficient hydroxyl radical scavengers in a Fenton reaction assay. The potential of PolyCAME as stabilizer toward polyethylene (PE) thermal and photo-oxidative degradation was also evaluated. PolyCAME exhibited high stability toward decarboxylation and oxidative degradation during the thermal processes associated with PE film preparation. Characterization of PE films by thermal methods, photo-oxidative treatments combined with chemiluminescence and FTIR spectroscopy and mechanical tests indicated a significant effect of polyCAME on PE durability as shown for example by the increase of the Oxidative Induction Time (OIT).1The synthesized phenolic biopolymers are thus proposed as novel easily accessible, eco-friendly and biocompatible materials for a sustainable approach in packaging and other applications.
1) Ambrogi, V.; Panzella, L.; Persico, P.; Cerruti, P.; Lonz, C. A.; Carfagna, C.; Verotta, L.; Caneva, E.; Napolitano, A.; d'Ischia, M. Biomacromolecules 2014, 15, 302-310
In vitro antimalarial activity of hyperforin, a prenylated acylphloroglucinol. A structure-activity study
No full text
NMR Elucidation of the Structure and Conformation of a Permethylated Alditol Acetate Oligosaccharide via 1H-1H Correlation and 1H-13C Correlation with Proton Detection
No full textThe structure of the methylated derivative (1) of the tetrasaccharide-alditol-O-beta-L-rhamnopyranosyl-(1----3)-O-beta-D- xylopyranosyl-(1----4)-O-beta-L-rhamnopyranosyl-(1----2)-1,5-di-O-acetyl -L- arabinitol has been determined solely on the basis of n.m.r. data
Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks.
No full textBiomimetic oxidn. of the pheomelanin precursor 5-S-cysteinyldopa in the presence of Zn2+ ions led to the isolation of two isomeric products, one of which could be identified as the benzothiazolylthiazinodihydroisoquinoline 5, while the other proved too unstable for a complete characterization. Both these products were converted into more stable oxidized forms, which after ethylchloroformate derivatization were characterized as the Et ester/ethoxycarbonyl isoquinolines 8 and 9. Compd. 5 exhibited absorption characteristics similar to those of red hair pheomelanin, including a main band around 400 nm in acids. Similarly to red hair pheomelanin and synthetic pigments, 5 afforded on chem. degrdn. a thiazolylpyridinecarboxylic acid fragment. Model chem. studies allowed the proposal of a formation mechanism for the benzothiazole and dihydroisoquinoline systems in compd. 5
Novel antioxidant bioinspired phenolic polymers and their applications in packaging
No full textPolymers of natural polyphenols have so far received little attention as bioavailable, biocompatible antioxidants for different applications e.g. in packaging and related technologies. Expected advantages with respect to the monomers would include lower volatility (with reduced adverse effects), greater chemical stability under processing conditions and lower tendency to be released from the polymer into the contact medium (food, water, etc.).
Herein we report data on the synthesis, structural characterization and antioxidant properties of two novel bioinspired phenolic polymers prepared by horseradish/H2O2 oxidation of tyrosol (polyTYR) and caffeic acid methyl ester (polyCAME). The materials, obtained in 80-85% yields, were subjected to structural characterization by solid state CPMAS NMR, mass spectrometry and gel permeation chromatography (GPC). ESI(-)/MS and NMR analysis indicated that polyTYR was a mixture of regular oligomers up to the undecamer with heptamer as the most abundant, all featuring units linked through C-C bonds. GPC showed an average molecular weight of 1862 Da with a polydispersity index of 1.64. ESI(-)/MS of polyCAME showed oligomers up to at least the decamer stage, peaking at the tetramer. Analysis of the clusters of the pseudomolecular ion peaks and the presence of CH carbons due to O-substituted benzylic positions in NMR spectra suggested a structure including dihydrobenzofuran units. Both PolyTYR and polyCAME exhibited antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays and proved to be efficient hydroxyl radical scavengers in a Fenton reaction assay. The potential of PolyCAME as stabilizer toward polyethylene (PE) thermal and photo-oxidative degradation was also evaluated. PolyCAME exhibited high stability toward decarboxylation and oxidative degradation during the thermal processes associated with PE film preparation. Characterization of PE films by thermal methods, photo-oxidative treatments combined with chemiluminescence and FTIR spectroscopy and mechanical tests indicated a significant effect of polyCAME on PE durability as shown for example by the increase of the Oxidative Induction Time (OIT).1The synthesized phenolic biopolymers are thus proposed as novel easily accessible, eco-friendly and biocompatible materials for a sustainable approach in packaging and other applications.
1) Ambrogi, V.; Panzella, L.; Persico, P.; Cerruti, P.; Lonz, C. A.; Carfagna, C.; Verotta, L.; Caneva, E.; Napolitano, A.; d'Ischia, M. Biomacromolecules 2014, 15, 302-310
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
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