1,721,035 research outputs found
Determination of biogenic amine profiles in conventional and organic cocoa-based products
No full textCocoa contains a lot of compounds knowing to influence consumers health, as biogenic amines (BAs). Spermine, spermidine, putrescine, histamine, tyramine, -phenylethylamine, cadaverine and serotonine have been determined in several cocoa-based products by LC-UV after derivatization with dansyl-chloride. Once optimized in terms of linearity, recovery percentages, LOD, LOQ and repeatability, the method has been applied to real samples. Total BAs concentration ranged from 5.7 μg g-1 to 79.0 μg g-1 with wide variations depending on the sample. BAs present in all samples were, in decreasing order, HIS (1.9-38.1 μg g-1) and TYR (1.7-31.7 μg g-1), while PUT (0.9-32.7 μg g-1), SPD (1.0-9.7 μg g-1) and SPM (0.6-9.3 μg g-1) were present in most of the samples. CAD, SER and PHE are in few samples at much lower concentrations. Organic samples always contained much lower BAs levels than their conventional counterparts and, generally speaking, the highest BAs amounts has been found in the most processed products
Application of LC with Evaporative Light Scattering Detector for Biogenic Amines Determination in Fair Trade Cocoa-Based Products
No full textIn this study the separation of eight biogenic amines (cadaverine, serotonin, histamine, spermidine, spermine, tyramine, putrescine and -phenylethylamine) by an LC method with evaporative light scattering detection (ELSD) was performed. The LC-ELSD method was validated by comparison of the results with those obtained through LC-UV determination, based on a pre-column dansyl chloride derivatisation step and the recorded data showed as both analytical methods can be interchangeably used for biogenic amines determination. LC–ELSD methodology showed good precision and permitted to achieve, for standard solutions, limits of detection (LOD) ranging from 0.01 to 0.02 g mL−1 and limits of quantitation (LOQ) ranging from 0.03 to 0.05 g mL−1. The whole methodology, comprehensive of the homogenization-extraction process and LC–ELSD analysis, has been applied in the analysis of several samples of fair trade cocoa-derivatives. The most abundant amine found was histamine for a total amount of biogenic amines in the range 5.81-38.82 g g−1. The highest amounts of BAs were found in the most processed products but never representing a possible risk for consumer health, according to the toxicity levels reported in literature and regarded as acceptable
Extraction Efficiency of Different Solvents and LC-UV Determination of Biogenic Amines in Tea Leaves and Infusions
No full textBiogenic amines (BAs), that is, spermine, spermidine, putrescine, histamine, tyramine, β-phenylethylamine, cadaverine, and serotonin, have been determined in several samples of tea leaves, tea infusions, and tea drinks by LC-UV method after derivatization with dansyl chloride. Different extraction solvents have been tested and TCA 5% showed better analytical performances in terms of linearity, recovery percentages, LOD, LOQ, and repeatability than HCl 0.1 M and HClO4 0.1 M and was finally exploited for the quantitative determination of BAs in all samples. In tea leaves total BAs concentration ranged from 2.23 μg g−1 to 11.24 μg g−1 and PUT (1.05–2.25 μg g−1) and SPD (1.01–1.95 μg g−1) were always present, while SER (nd–1.56 μg g−1), HIS (nd–2.44 μg g−1), and SPM (nd–1.64 μg g−1) were detected more rarely. CAD and PHE were determined in few samples at much lower concentrations while none of the samples contained TYR. Tea infusions showed the same trend with total BAs concentrations never exceeding 80.7 μg L−1. Black teas showed higher amounts of BAs than green teas and organic and decaffeinated samples always contained much lower BAs levels than their conventional counterparts
BIOMACROMOLECULES IN RADICAL PROCESSES: INNOVATIVE STRATEGIES FOR THE SYNTHESIS OF BIOMATERIALS
No full textNatural polymers, such as polysaccharides and proteins, are materials extensively investigated due to their biocompatibility, biodegradability and non-toxic and non-immunogenic characteristics. Enclosing the biomacromolecules, in a complex structure, these features can be transferred to a biomaterial in order to extend the performance of the device. Basically, the synthesis of bioconjugates, by insertion of natural polymers in a macromolecular network by radical polymerization processes, can be achieved employing two different synthetic approaches. The first method involves the chemical modification of the biomacromolecules to introduce functionality able to undergo radical polymerization reactions. In addition, polysaccharides and proteins, without any functional changes, can take part in graft radical polymerization reactions that involve the heteroatoms of the substrates. Both synthetic approaches allows to prepare biocompatible bioconjugates showing improved physico-chemical and mechanical properties respect to the starting natural species. Furthermore, radical polymerization of biomacromolecules with monomeric species bearing specific functionality, carry out to the synthesis of polymeric network that undergo a phase transition process in response to external stimuli changes (temperature, pH, magnetic and electric field). These findings showed that the radical polymerization techniques, improving the performance of natural polymer, represent an innovative tools for the preparation of macromolecular devices potentially useful in pharmaceutical and biomedical field
UV protecting activity of ferulic acid polymeric derivative
No full textIn this work, polymeric derivative of ferulic acid was synthesized by employing ascorbic acid-H(2)O(2) as redox initiator system at room temperature The insertion of ferulic acid into the polymeric chain was confirmed by FT-IR analyses, and the total antioxidant capacity of the macromolecular system determined by the molybdate method, and correspond to a ferulic acid equivalent concentration of 0 59 mM UV spectra are characterized by broad absorption bands in the UVA and UVB region, showing the efficiency of the polymeric system in preventing the UV-induced damage
Incorporation of carbon nanotubes into a gelatin-catechin conjugate: Innovative approach for the preparation of anticancer materials
No full textA new hybrid material made of gelatin, catechin and carbon nanotubes was prepared by the non-covalent incorporation of carbon nanotubes (CNTs) into a gelatin–catechin covalent conjugate. The composite materials was tested by means of determination of the dispersion stability in water and the functionalization degree was assessed by the Folin–Ciocalteu method, finding a 0.9 mg of CT/g of protein conjugate. Subsequently, the complete retention of the antioxidant properties of the flavonoid after incorporation into the composite was proved by DPPH and ABTS assays and IC50 values of 5.74 mg mL−1 and 0.39 mg mL−1 were recorded. The presence of CNT into the materials did not interfere with the scavenging activities of the catechin. Finally, the anticancer activity on HeLa cancer cells was evaluated and a considerable increase in the therapeutic activity of the flavonoid was recorded moving from the free to the conjugated form in the presence of CNT, while in absence of CNT a reduction of the efficiency was observed
Technological aspects and analytical determination of biogenic amines in cheese
No full textBiogenic amines (BAs) are detrimental to health and the con-sumption of food containing high concentrations of these com-pounds may cause toxic reactions. In particular, cases oftyramine intoxication have occurred subsequent to the con-sumption of cheese and the term “cheese reaction” has beencoined to refer to it. The main pre-requisites for the presenceof BAs in foods include: availability of free amino acids, thepresence of microorganisms producing BA enzymes (mainlyfrom raw materials and/or added starter cultures), conditionsallowing their growth (particularly temperature, pH), as wellas conditions affecting the enzyme production and activity(particularly low pH). The main technological aspects affectingaminogenesis in cheese are the presence of micro-organisms,their proteolytic and decarboxylase activities, ripening time,ripening temperature, pH and NaCl concentration. Moreover secondary parameters such as post-ripening processes andpackaging can affect the accumulation of BAs as well. High temperature, high pH, low salt content, prolonged ageing and air packaging seem to accelerate the amino acid accumulation while the effect of grating seem to be mostly related with microbiological contamination, both aspects supporting the BAs increase
Selective recognition of methotrexate by molecularly imprinted polymers
No full textThe aim of this study is the preparation of molecularly imprinted polymers with high selectivity for metotrexate (MTX), a useful antineoplastic drug widely employed in clinical trials. Methacrylic acid, 2-(dimethylamino) ethyl methacrylate and a mixture of them were tested as functional monomers in order to optimize the performance of imprinted materials. The specificity and the selectivity of imprinted polymers was tested by performing rebinding experiments in water at pH 7.4. The best results were obtained by employing both functional monomers in the polymeric feed. In this way, each monomer interacts with complementary functionalities on template molecule, stabilizing the prepolymerization complex and minimizing the repulsive effects (due to the ionization of functional groups) in the rebinding media
Evaluation of fatty acids and biogenic amines profiles in mullet and tuna roe during six months of storage at 4 °C
No full textThe aim of this study was to monitor the fatty acids and biogenic amines (BAs) profiles in mullet (MugilCephalus) and tuna (Thunnus thynnus) roe (bottarga) during storage (0–180 days) at 4 8C. Fatty acids wereanalyzed by gas chromatography (GC) as methyl ester derivatives while BAs were investigated usingreverse-phase liquid chromatography (RP-LC) as dansyl derivatives. The content of total fatty acidsdecreased with time in mullet bottarga (BM) while in tuna bottarga (BT) the PUFA value showed a slightdecrease up to 30 days followed by an intense reduction after 90 and 180 days. An increasing content ofBAs was observed with time in all investigated samples without reaching hazardous concentrations. Ingeneral, the BAs concentrations were in decreasing order: tyramine, putrescine, cadaverine andhistamine. In BM, phenylethylamine was always present, representing a possible discriminatingcompound as it was absent in tuna bottarga at any time of storage. A Pearson correlation matrix showedthat lipid and protein degradation products were strongly and significantly correlated over theconsidered storage time implying that lipid oxidation processes are in some way linked to the chemicalproduction of BAs
Temperature-sensitive hydrogels by graft polymerization of chitosan and N-isopropylacrylamide for drug release
No full textThermo-responsive polysaccharidic hydrogels were designed and synthesized by a free radical induced grafting procedure. Chitosan was chosen as biopolymer to impart biocompatibility and biodegradability to the macromolecular systems, while N-isopropylacrylamide (NIPAAm) was selected as co-monomer responsive for the thermo-sensitive properties. Ammonium persulfate was the initiator system and different polymeric networks have been synthesized by modulating the amount of NIPAAm in the polymerization feed. The resulting hydrogels were proposed as drug delivery devices and their performance was evaluated by using Diclofenac sodium salt as a model drug. Hydrogels were carefully characterized by FT-IR spectrophotometry, calorimetric analyses and swelling behavior in a temperature range of 15-45 degrees C. Finally, to verify the suitability of these hydrogels as thermo-responsive devices, the drug release profiles were studied performing in vitro experiments around the swelling-shrinking transition temperatures of the macromolecular systems
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