1,721,147 research outputs found
A new approach to the mild extraction of madder dyes from lake and textile
No full textIn this paper, we present a new alkaline mild extraction technique of madder dyes in lake and textile, based on the use of ammonia, in association with disodium EDTA. This method was developed in order to preserve the glycoside compounds fixed on the fiber or present in the lake. This new methodology was performed on samples of dyed textile and lake, prepared following the ancient recipes. At first, the extracts, obtained from these samples, were analyzed and characterized by 1D and 2D NMR (DOSY) and ESI-MS. In the second step, we evaluated the applicability and the efficiency of extraction on real samples of 1 mg, analyzed by HPLC–DAD and HPLC–MS. These analyses allow us to recognize the signals, referable to glycoside compounds, also in 1 mg samples. The new proposed method was compared with a commonly applied mild extraction method reported in literature (DMF–Na2EDTA method). Finally, the results obtained from the different analytical techniques applied allow us to conclude that the ammonia extracts of madder dyed yarn and lake are mainly composed of glycosylated anthraquinones, according to literature
Identificazione del pattern molecolare dei coloranti antrachinonici, ottenuti dai Coccidi, nei materiali artistici, attraverso una nuova metodologia “soft” di estrazione
No full textPer preservare l'opera d'arte occorre formulare un’ipotesi sui meccanismi di degrado. Chiarire perciò l’intero pattern molecolare presente su un filato o in una lacca è una necessità a cui i diagnosti non possono più sottrarsi.
Il protocollo messo a punto dal nostro gruppo di ricerca prevede invece l’impiego di una soluzione di ammoniaca e EDTA bisodico a temperatura ambiente. Tale metodologia, sviluppata inizialmente sui coloranti antrachinonici della robbia, ha dimostrato non solo di poter riestrarre anche i coloranti glicosilati senza idrolizzare il legame O-glicosidico, ma ha fornito anche rese estrattive più elevate
Primary and secondary metabolites of an European edible mushroom and its nutraceutical value. Suillus bellinii (Inzenga) Kuntze
No full textIn this work, we report the study on the composition in primary and secondary metabolites of the polar and less-polar fractions obtained from the fruiting bodies of Suillus bellinii (Inzenga) Kuntze collected from Central Italy. Thirteen compounds were identified through a series of classical chromatographic methods and through spectroscopic techniques (nuclear magnetic resonance (NMR) and mass spectrometry (MS)), namely suillin (1), ergosterol (2), glutamic acid (3), isoleucine (4), leucine (5), threonine (6), tyrosine (7), valine (8), D-mannitol (9), sucrose (10), D-sorbitol (11), fumaric acid (12) and alanine (13). These results allowed us to make specific considerations about the possible applications of this mushroom, which vary from medicine, due to the high cytotoxic and antitumor properties of suillin (1), to nutritional values, due to the presence of essential nutrients as amino acids and pre-vitamin D2 (ergosterol), together with low-calories sweeteners, confirming the close association between the identified components and the health-promoting properties of this species
Phytochemical analysis on the leaves of Agathis microstachya J.F. Bailey & C.T. White
No full textThe first phytochemical analysis on the leaves of Agathis microstachya J.F. Bailey & C.T. White collected in Rome was reported in this work. The study evidenced the presence of four compounds i.e., 7,4’’’-dimethoxy-agathisflavone (1), 7,7’’-dimethoxy-cupressuflavone (2), dactylifric acid (3) and shikimic acid (4) which were identified by means of spectroscopic techniques. Compounds (1, 2, 4) were reported in the species for the first time as well as this is the second report on the presence of dactylifric acid (3) in the whole Araucariaceae family. The absence of diterpenoids from the studied accession is also important. All these chemotaxonomic aspects were discussed
Stereoselective synthesis and ROESY 1H NMR study of bidiaziridines
No full textThe bisaziridination reaction of symmetric (E-s-trans-E)-α-diimines using ethyl nosyloxycarbamate as aminating agent yields symmetrically functionalized bidiaziridines, under mild conditions. The reactions take place with very high stereoselectivity giving only bidiaziridines with total retention of the starting α-diimine configuration, as determined by NMR measurements. Moreover, only a single pure diastereomer, derived from attack of the aza-anion on the opposite faces of conjugate system was obtained, starting from chiral substrates. ROESY analyses clearly show that all nitrogens have a stable pyramidal conformation, and the absolute configurations of new chiral centers were assigned. © 2012 American Chemical Society
Characterization of Madder compounds present in lake and textile, throw ammonia extraction and micro-sampling with Ag-gel matrix associated with SERS analysis
No full textStereoselective synthesis of short benzyl malonyl peptides
No full textA Rh-catalyzed addition reaction on non symmetric dehydro alanine retro-peptides is the key step in the reported three-step strategy for the diastereoselective synthesis of differently functionalized benzyl malonyl peptides (74% overall yield)
Water-controlled chiral inversion of a nitrogen atom during the synthesis of diaziridines from α-branched N,N'-dialkyl α-diimines
No full textDesymmetrization of chiral α-diimines by ethyl nosyloxycarbamate using water as a co-solvent takes place with very high diastereoselectivity, the nucleophilic attack occurring only on the less hindered side of the CN double bond. Interestingly, the presence of water in the reaction medium likely stabilizes the anion intermediate slowing down the successive cyclization reaction and favoring the rotation around the C-N single bond. In fact, as confirmed by ROESY experiments, only the two diastereomeric 3-(iminomethyl) diaziridine-1-carboxylates that differ in the absolute configuration of the alkyl substituted nitrogen atoms were always obtained in equimolar ratios. Finally, all compounds were easily obtained in optically pure form through HPLC separation and can be considered as interesting chiral synthons. © 2013 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique
Natural dyes from Rubia tinctorum L., used in tapestries
No full textPlants and insects had been used for a long time in the ancient period as source for dyes for art materials. On many tapestries, there is a widespread state of decay in charge of the colour of many yarns. This phenomenon may be due to presence of alteration products or total destruction of dye molecules. If we consider madder root, for example, contains a large number of compounds characterized by anthraquinone structures, thought as the main chromophores [1]. However, it is worth to notice that the analyses of madder’s extract, obtained in the same condition of dyeing bath [2], reveal also the presence of other types of molecules (not necessarily anthraquinones), present in the matrix. Some of them can be fixed on the yarn and, probably, these are involved in the degradation processes. During this work, it has carried out extraction of dyes from R.tinctorum L. and analysed by HPTLC (Fig. 1), 1H-NMR (Fig. 2). and ESI-MS With ESI-MS/MS, in both positive and negative mode, it has been possible to draw a structural profile of the compounds. These compounds are compared to those extracted by yarns [3] [4], dyed following the ancient recipes [2], in order to evaluate which molecules are fixed on the textile
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