Studies on N-terminal glycation of peptides in hypoallergenic infant formulas: quantification of alpha-N-(2-furoylmethyl) amino acids

To obtain information about the extent of the early Maillard reaction between the N-termini of peptides and lactose, alpha-N-(2-furoylmethyl) amino acids (FMAAs) were quantified together with epsilon-N-(2-furoylmethyl)lysine (furosine) in acid hydrolyzates of hypoallergenic infant formulas, conventional infant formulas, and human milk samples using RP-HPLC with UV-detection. FMAAs are formed during acid hydrolysis of peptide-bound N-terminal Amadori products (APs), and furosine is formed from the Amadori products of peptide-bound lysine. Unambiguous identification was achieved by means of LC/MS and UV-spectroscopy using independently prepared reference material. The extent of acid-induced conversion of APs to FMAAs was studied by RP-HPLC with chemiluminescent nitrogen detection (CLND). Depending on the corresponding alpha-N-lactulosyl amino acid, between 6.0% and 18.1% of FMAAs were formed during hydrolysis for 23 h at 110 degrees C in 8 N HCl. From epsilon-N-lactulosyllysine, 50% furosine is formed under these conditions. Whereas furosine was detectable in all assayed samples, five different FMAAs, alpha-FM-Lys, alpha-FM-Ala, alpha-FM-Val, alpha-FM-Ile, and alpha-FM-Leu, were exclusively detected in acid hydrolyzates of hypoallergenic infant formulas in amounts ranging from 35 to 396 mumol/100 g protein. Taking the conversion factors into account, modification of N-terminal amino acids in peptides by reducing carbohydrates was between 0.3% and 8.4%. This has to be considered within the discussion concerning the nutritional quality of peptide-containing foods.     

Effects of Titanium Dioxide Nanoparticles in Different Metabolic Pathways in the Freshwater Microalga <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis> (Trebouxiophyceae)

The products that employ nanoparticles (NPs) in their composition have increased since the beginning of NP production; hence, their availability in the environment, especially in aquatic ecosystems, tends to increase. In these ecosystems, the phytoplankton is immersed in a complex matrix of nutrients, excreted materials, and other chemical compounds, which can influence the metabolic strategy of microalgae. One of the metabolic ways is mixotrophy, a situation whereby microalgae perform photosynthesis and use dissolved organic carbon at the same time. Most toxicity evaluations do not consider such a metabolic route, but this can represent a preferential metabolism in natural environments. The present study aimed at evaluating the effects of NP-TiO₂ at a log concentration range of ??3.10 to 0.89, on photosynthesis, growth, viability, and biochemical composition of the microalgae Chlorella sorokiniana during photoautotrophic and mixotrophic growth (glucose as the organic carbon source). The results showed lower chlorophyll a and photosynthetic activity in mixotrophy than in photoautotrophy, which can be due to a decreased need for photosynthesis in mixotrophy. Photoautotrophy cultures were sensitive to NPs, reaching 39% of viability at log 0.89, while in mixotrophy, cell viability was not affected by NPs. The biochemical composition and cell density changed as a function of NP concentrations, with increase in the protein/carbohydrate ratio in both treatments. The results showed that C. sorokiniana is more resistant to NPs during mixotrophic growth, but with changes in biochemical composition, whereas the photoautotrophic cultures were more sensitive to the increase in NP concentrations.     

Different sorption behaviors for wine polyphenols in contact with oak wood

The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contribution of sorption to oak wood in the disappearance phenomena, sorption kinetics were determined for trans-resveratrol and malvidin-3-glucoside through the extraction and the quantification of the fraction sorbed to wood. These curves showed that the wood intake of trans-resveratrol and malvidin-3-glucoside followed a two-step behavior, with a higher rate during the first 2 days, likely due to a surface sorption mechanism, and then a slower rate to reach the equilibrium, which could be related to a diffusion mechanism. The comparison of disappeared and sorbed amounts at equilibrium showed that a minor part of the disappeared monomeric anthocyanins were sorbed by wood. In contrast, half of the concentration decrease of trans-resveratrol in wine finds its origin in a sorption mechanism by oak wood. Results in real wine show similar sorption kinetics.     

Interactions of three s-triazines with humic acids of different structure

The adsorption of three s-triazines (atrazine, terbutylazine, and simazine) on three different humic acids (HAs), before and after acidic hydrolysis, was studied at four diverse pH values from 3 to 4.5. The Freundlich sorption affinity (K(f)) and intensity (1/n) of s-triazines were related to the chemical and structural composition of HA and used in a multivariate statistical analysis. At low pH, the sorption values for s-triazines were not directly justified by the content of carboxyl groups in original HA, while only an increase of phenolic carbons in hydrolyzed HA supported the increased s-triazine adsorption. The structural composition of both s-triazines and humic samples explained 86% of the significance in multivariate analyses, whereas the role of pH remained hidden in only 14% of the statistical significance. Adsorption of s-triazines was mainly related to carbon content, hydrophobicity, and aromaticity of HA, thereby implying a predominant binding role of weak dispersive forces. Steric properties explained the larger adsorption affinity of atrazine and terbutylazine with respect to simazine. The occurrence of charge-transfer interactions between atrazine and mainly hydrolyzed HA was further suggested by the increased number of free radicals detected in atrazine-HA complexes at different pH values. Charge-transfer interactions were postulated to occur when HA conformations became progressively controlled by aromatic components. This work indicates that humic matter rich in hydrophobic and aromatic constituents is more likely to adsorb s-triazines and reduce their environmental mobility.     

Chemical speciation of copper and manganese in solution of a copper-contaminated soil and young grapevine growth with amendment application

Copper(Cu)-based fungicide application to control foliar diseases in grapevine(Vitis vinifera L.) can increase soil Cu availability. Brazilian soils have high natural Cu and manganese(Mn) concentrations, increasing the potential for toxicity to grapevine plants. Application of amendment substances can reduce the concentrations of toxic chemical species of Cu and Mn in soil solution, especially for the soils grown with young plants. We evaluated the chemical speciation of Cu and Mn in soil soluti...     

Identification and characterization of complex bioactive oligosaccharides in white and red wine by a combination of mass spectrometry and gas chromatography

Over forty-five complex free oligosaccharides (of which several are novel) have been isolated and chemically characterized by gas chromatography and high resolution and high mass accuracy matrix-assisted laser desorption/ionization mass spectrometry (MALDI-FTICR MS) in red and white wines, Grignolino and Chardonnay, respectively. Oligosaccharides with a degree of polymerization between 3 and 14 were separated from simple monosaccharides and disaccharides by solid-phase extraction. The concentrations of free oligosaccharides were over 100 mg/L in both red and white wines. The free oligosaccharides-characterized for the first time in the present study-include hexose-oligosaccharides, xyloglucans, and arabinogalactans and may be the natural byproduct of the degradation of cell wall polysaccharides. The coupled gas chromatography and accurate mass spectrometry approach revealed an effective method to characterize and quantify complex functional oligosaccharides in both red and white wine.     

Rapid tests to assess the antioxidant activity of Phaseolus vulgaris L. dry beans

The antiradical activity of dry beans was evaluated in order to assess the validity of this test and to correlate the results with those achieved with the Folin-Ciocalteu method and with a rapid spectrophotometric method for the analysis of total flavonoids. Four landraces (12 samples) of common beans (Phaseolus vulgaris L.), collected in two regions of Italy (Tuscany and Basilicata) in three different years, were analyzed. The EC50 values ranged from 39 to 2810 mg sample/mg 1,1-diphenyl-2-picrylhydrazil radical. The phenolic content of each sample was expressed as gallic acid equivalents; it changed from 1.17 to 4.40 mg/g. The flavonoid content, expressed as mg of (+)-catechin per g of dry seeds, ranged from 0.24 to 1.43 mg/g. The qualiquantitative composition of polyphenols has been also elucidated by means of high-performance liquid chromatography (HPLC)-diode array detection and HPLC/MS. These investigations showed that rapid tests can contribute to assessing the quality of functional food.