1,721,207 research outputs found
Polyphenol composition of olive leaves with regard to cultivar, time of collection and shoot type
No full textPolyphenols in the olive have a relevant importance both in the physiology of the plant and the nutritional and biological value of its products. Olive leaves are increasingly important as a herbal remedy in western herbalism and a number of polyphenols have been shown to contribute to the healing properties of olive leaf teas. The present research is investigating the occurrence of such compounds in the leaves with regard to collection time, leaf age, shoot type and cultivar. The polyphenol composition of the leaves was determined by reversed-phase HPLC coupled with diode array and ESI-MS detection. The main extracted components were flavonol glycosides, flavone glycosides, and secoiridoids. A large variations in the total amounts of the different components was observed as function of the different cultivars and collection time (May, July, December). Leaf age and shoot type induce little or no variation in the concentration of most substances investigated. The maximal content of polyphenols and secoiridoids was found in December: in particular, the highest increase was observed for oleuropein, with a maximum value around 12 mg/g of leaves
Hyphenated chromatographic techniques for structural characterization and determination of masked mycotoxins
No full textMycotoxins are secondary metabolites produced by fungi that can contaminate a wide range of food and feed commodities and that are harmful to humans for their poisonous and toxic effects. An increasing
amount of data have been accumulated in the last years, showing that mycotoxins may also occur in modified forms originating by plant, fungi or animal metabolism or by food processing. In particular, this modified forms may be produced via conjugation with sugars or other biological components (masked mycotoxins) or may occur as non extractable forms on account of strong interaction, association or binding with macromolecules in the food matrix (bound or hidden mycotoxins). Analytical methods have been set up in order to check for the occurrence of these forms and to evaluate their amount, in order to obtain reliable data for toxicity and exposure studies. In this paper hyphenated chromatographic methods for the determination and structural characterization of masked mycotoxins are reviewed, with a particular emphasis on liquid chromatography–(tandem) mass spectrometry as the most effective approach for their determination
Fig. 5 in Exploiting the potential of micropropagated durum wheat organs as modified mycotoxin biofactories: The case of deoxynivalenol
No full textFig. 5. Scores and Loadings plots obtained for PCA analysis of roots and leaves treated with DON. (L: leaves; R: roots; high: 100 μg DON; low: 12.5 μg DON).Published as part of Righetti, Laura, Damiani, Tito, Rolli, Enrico, Galaverna, Gianni, Suman, Michele, Bruni, Renato & Dall'Asta, Chiara, 2020, Exploiting the potential of micropropagated durum wheat organs as modified mycotoxin biofactories: The case of deoxynivalenol, pp. 1-7 in Phytochemistry (112194) 170 on page 5, DOI: 10.1016/j.phytochem.2019.112194, http://zenodo.org/record/829277
Simultaneous detection of type A and type B trichothecenes in cereals by liquid chromatography-electrospray ionization mass spectrometry using NaCl as cationization agent
No full textA LC/MS method for the simultaneous determination of both type A and type B trichothecenes by using an electrospray ionization (ESI)
interface in the positive ionization mode with a single quadrupole analyzer is described. In order to enhance the ionization of both groups
of trichothecenes, the sodium ion was used as cationization agent by adding sodium chloride to the eluent. All LC/MS parameters were
optimized. The newly developed LC/ESI-MS method was applied to the analysis of a wheat reference material and cereal-based foods and
feed
Simultaneous HPLC-FLD Detection of Type A and Type B Trichothecenes as 3-cumaroyl-derivatives.
No full text
Diaminomethane dihydrochloride, a novel reagent for the synthesis of primary amides of amino acids and peptides from active esters
No full textAmide formation from acids, N-protected amino acids and peptides was achieved in an easy and convenient way by treating “active esters” such as succinimidyl or 4-nitrophenyl esters or acyl chlorides with diami–nomethane dihydrochloride in dioxane in the presence of EtsN. Diaminomethane dihydrochloride behaves as a slow ammonia-releasing agent. The method is a good alternative to the use of concentrated aqueous ammonia; it avoids solubility problems and allows better control of the stoichiometry of the reaction and of the pH. It gives good yields and does not induce racemization. The mechanism of the reaction is discussed
Hazard identification of cis/trans-zearalenone through the looking-glass
No full textAmong the food-related health issues, the presence of contaminants has a prominent role, due to the wide range of exogenous compounds that can occur in food commodities and to their large differences in structure and biological activity. A comprehensive assessment of the related risk is thus actually demanding in terms of time and facilities involved. In this context, the use of computational strategies can be an effective choice for supporting the hazard identification procedure at the early stage. In this work, we focused on the food contaminant zearalenone by comparing the trans and cis isomers, respectively the well-known mycoestrogen and its still largely understudied isomer. We estimated the possible effects exerted by human metabolism on the xenoestrogenicity of cis-ZEN by using a validated in silico strategy based on docking simulations and rescoring procedures. Similarly, the exploitation of the most promising enzymatic detoxifying routes designed for trans-ZEN - which relies on the enzyme lactono hydrolase from Clonostachys rosea - has been assessed for the cis-isomer as well. Our results showed that both isomers can act as functional analogues with respect to xenoestrogenic activity, and several cis-ZEN metabolites with high biological potential have been identified. On the contrary, in spite of the high degree of structural analogy, the cis isomer showed a pattern of interaction with the degrading enzyme in stark contrast with that observed for trans-ZEN. For these reasons, the outcomes presented herein strongly support the inclusion of cis-ZEN in further studies of occurrence, metabolism and bioactivity assessment, and suggest the need for a dedicated handling for the cis isomer in risk assessment studies
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