Absorption and twenty‐four‐hour metabolism time‐course of quercetin‐3‐O‐glucoside in rats,in vivo

Rats were meal‐fed a semi‐synthetic diet, with or without quercetin 3‐O‐glucoside (Q3G; 100 mg per meal) and groups of three were killed either fasting, or at 2, 5 and 24 post‐feeding. Flavonoids and their metabolites in the diet, stomach contents, small intestinal lumen and mucosa, caecal contents and plasma were determined by LC/MS. Q3G was not hydrolysed in the stomach, but deglycosylation and further metabolism occurred in the small intestinal mucosa. At least 17 flavonoid glucuronides were identified in the lumen and mucosa, with evidence of time‐dependent changes such as de‐ and re‐glucuronidation. Quercetin mono‐sulphate was also detected in the small intestinal contents. Metabolites were still present in tissue and plasma 24 h after feeding. There was also evidence of complex microbial processing of Q3G in the caecal lumen with the appearance of at least one methylquercetin‐mono‐glucuronide, mono‐sulphate unique to this site in the gut, together with phenolic acid derivatives. Intestinal flavonoid metabolism is thus a very complex process in mammals, involving both enterocytes and bacteria. Copyright © 2004 Society of Chemical Industry     

2,6‐Di‐Tert‐Butyl‐Hydroxytoluene and Its Metabolites in Foods

2,6‐Di‐tert‐butyl‐hydroxytoluene (BHT, E‐321) is a synthetic phenolic antioxidant which has been widely used as an additive in the food, cosmetic, and plastic industries for the last 70 y. Although it is considered safe for human health at authorized levels, its ubiquitous presence and the controversial toxicological data reported are of great concern for consumers. In recent years, special attention has been paid to these 14 metabolites or degradation products: BHT‐CH₂OH, BHT‐CHO, BHT‐COOH, BHT‐Q, BHT‐QM, DBP, BHT‐OH, BHT‐OOH, TBP, BHQ, BHT‐OH(t), BHT‐OH(t)QM, 2‐BHT, and 2‐BHT‐QM. These derived compounds could pose a human health risk from a food safety point of view, but they have been little studied. In this context, this review deals with the occurrence, origin, and fate of BHT in foodstuffs, its biotransformation into metabolites, their toxicological implications, their antioxidant and prooxidant properties, the analytical determination of metabolites in foods, and human dietary exposure. Moreover, noncontrolled additional sources of exposure to BHT and its metabolites are highlighted. These include their carryover from feed to fish, poultry and eggs, their presence in smoke flavorings, their migration from plastic pipelines and packaging to water and food, and their presence in natural environments, from which they can reach the food chain.     

Moisture‐Absorption and Water Dynamics in the Powder of Egg Albumen Peptide,Met‐Pro‐Asp‐Ala‐His‐Leu

Moisture absorbed into the powder of Met‐Pro‐Asp‐Ala‐His‐Leu (MPDAHL)—a novel egg albumen antioxidant peptide—profoundly affects its properties. In this study, we elucidated water dynamics in MPDAHL using DVS, DSC, and low‐field ¹H NMR. Based on the DVS data, we found that MPDAHL sorption kinetics obey a parallel exponential model. DSC results indicated that both water and heating could change the microstructure of MPDAHL. The T₂ parameters of NMR reflected the different phases of moisture absorption revealed that there were 4 categories of water with different states or mobility in the MPDAHL during the moisture absorption process. The fastest fraction T_2b mainly dominated the hygroscopicity of MPDAHL and the absorbed water significantly changed the proton distribution and structure of MPDAHL. Thus, this study shows that DVS, DSC, and low‐field ¹H NMR are effective methods for monitoring water mobility and distribution in synthetic peptides. It can be used to improve the quality assurance of functional peptides.     

Degradation of N‐(1‐Deoxy‐d‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐xylulos‐1‐yl)proline using thermal treatment

The formation and degradation of N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)proline, derived from the secondary amine Maillard reaction in xylose‐amino acid model solutions, were detailed in this study. The identification and quantitative analysis of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline were carried out using high‐performance anion‐exchange chromatography and high‐performance liquid chromatography. The formation of intermediate and advanced products derived from N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline was also tested using an UV‐Vis spectrophotometer to gain a better comparing of the degradation process of the two important Maillard reaction products using thermal treatment. Results showed that the degradation of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine was more significant than N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline. Moreover, xylose was tested in the degradation products of both N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline, which indicated that the degradation of N‐substituted 1‐amino‐1‐deoxyketoses was a reversible reaction to form reducing sugar.     

Production and Properties of Spin‐Coated Cassava‐Starch‐Glycerol‐Beeswax Films

Cassava‐starch based polymer films containing glycerol as a plasticizer (1.0‐2.5‐5.0%, w/w) and different lipids as additives (paraffin, stearyl alcohol, and beeswax – 0.25‐0.5‐1.0%, w/w) were produced. Control films were produced by heating a mixture of glycerol, starch, and water, while treated films were produced by the addition of lipids/ ethanol solutions. The solutions were kept at around 70ºC during amalgamation, and once congealed, were placed in a vacuum oven for 1 h at 90ºC. The solutions were then spun on 7‐inch diameter non‐stick disks, allowed to dry, and conditioned at 23ºC and 50% RH before testing. Cassava starch‐glycerol‐beeswax films were successfully produced with a stable film structure at glycerol concentration equal or below 5% (w/w). Addition of glycerol and beeswax did not visually change the color of the films. Increasing glycerol content improved elongation while decreasing tensile strength. Increasing the glycerol concentration from 1.0 to 5.0% increased the water vapor permeability by 150% and addition of beeswax further increased these values by 250%.     

Dielectric determination of bio‐ and free‐calcium in commercial alkaline‐cooked ground corn

Using dielectric measurements, it was possible to determine the concentration of bio‐ and free‐calcium in a corn dough prepared mixing commercial powder of alkaline‐cooked ground‐corn kernel (maize), Zea mays, with different concentrations of Ca(OH)₂ and the same amount of water. This allows determining the conditions to obtain dough with high bio‐calcium content and consequently high nutritional value. The samples were placed in the interior of a small parallel‐plate capacitor. The capacitance and the cell current profiles were obtained with the corresponding relaxation times as a function of the Ca concentration. With this information, it was possible to determine the threshold concentration at which the Ca ions are not longer linked chemically to the cornstarch molecules and move freely in the interior of the dough. A model based on the ionic conductivity was developed to explain the dependence of the relaxation times with the Ca concentration.     

Non‐Arrhenius and non‐WLF kinetics in food systems

The classic Arrhenius and WLF equations are commonly used to describe rate–temperature relations in food and biological systems. However, they are not unique models and, because of their mathematical structure, give equal weight to rate deviations at the low‐ and high‐temperature regions. This makes them particularly useful for systems where what happens at low temperatures is of interest, as in spoilage of foods during storage, or where the effect is indeed exponential over a large temperature range, as in the case of viscosity. There are systems, however, whose activity is only noticeable above a certain temperature level. A notable example is microbial inactivation, for which these two classical models must be inadequate simply because cells and spores are not destroyed at ambient temperature. For such systems a model that identifies the temperature level at which the rate becomes significant is required. Such an alternative model is Y = ln{1 + exp[c(T ? T _c)]} ^m, where Y is the rate parameter in question (eg a reaction rate constant), T_c is the marker of the temperature range where the changes accelerate, and c and m are constants. (When m = 1, Y at T ? T_c is linear. When m ≠ 1, m is a measure of the curvature of Y at T ? T_c.) This model has at least a comparable fit to published rate–temperature relationships of browning and microbial inactivation as well as viscosity–temperature data previously described by the Arrhenius or WLF equation. This alternative log logistic model is not based on the assumption that there is a universal analogy between totally unrelated systems and simple chemical reactions, which is explicitly assumed when the Arrhenius equation is used, and it has no special reference temperature, as in the WLF equation, whose physical significance is not always clear. It is solely based on the actual behaviour of the examined system and not on any preconceived kinetics. © 2002 Society of Chemical Industry     

Sesamin attenuates intercellular cell adhesion molecule‐1 expression in vitro in TNF‐α‐treated human aortic endothelial cells and in vivo in apolipoprotein‐E‐deficient mice

Sesame lignans have antioxidative and anti‐inflammatory properties. We focused on the effects of the lignans sesamin and sesamol on the expression of endothelial‐leukocyte adhesion molecules in tumor necrosis factor‐α (TNF‐α)‐treated human aortic endothelial cells (HAECs). When HAECs were pretreated with sesamin (10 or 100 μM), the TNF‐α‐induced expression of intercellular cell adhesion molecule‐1 (ICAM‐1) was significantly reduced (35 or 70% decrease, respectively) by Western blotting. Sesamol was less effective at inhibiting ICAM‐1 expression (30% decrease at 100 μM). Sesamin and sesamol reduced the marked TNF‐α‐induced increase in human antigen R (HuR) translocation and the interaction between HuR and the 3'UTR of ICAM‐1 mRNA. Both significantly reduced the binding of monocytes to TNF‐α‐stimulated HAECs. Sesamin significantly attenuated TNF‐α‐induced ICAM‐1 expression and cell adhesion by downregulation of extracellular signal‐regulated kinase 1/2 and p38. Furthermore, in vivo, sesamin attenuated intimal thickening and ICAM‐1 expression seen in aortas of apolipoprotein‐E‐deficient mice. Taken together, these data suggest that sesamin inhibits TNF‐α‐induced extracellular signal‐regulated kinase/p38 phosphorylation, nuclear translocation of NF‐κB p65, cytoplasmic translocalization of HuR and thereby suppresses ICAM‐1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that sesamin may prevent the development of atherosclerosis and inflammatory responses.