Application of the TTC concept to unknown substances found in analysis of foods

Unknown substances, not previously observed, are frequently detected in foods by quality control laboratories. In many cases, the assessment of these 'new' substances requires additional chemical analysis for their identification prior to assessing risk. This identification procedure can be time-consuming, expensive and in some instances difficult. Furthermore, in many cases, no toxicological information will be available for the substance. Therefore, there is a need to develop pragmatic tools for the assessment of the potential toxicity of substances with unknown identity to avoid delays in their risk assessment. Hence, the 'ILSI Europe expert group on the application of the threshold of toxicological concern (TTC) to unexpected peaks found in food' was established to explore whether the TTC concept may enable a more pragmatic risk assessment of unknown substances that were not previously detected in food. A step-wise approach is introduced that uses expert judgement on the source of the food, information on the analytical techniques, the dietary consumption of food sources containing the unknown substance and quantitative information of the unknown substance to assess the safety to the consumer using the TTC. By following this step-wise approach, it may be possible to apply a TTC threshold of 90. µg/day for an unknown substance in food. © 2011 Elsevier Ltd

Generation of Large-Scale Vorticity in a Homogeneous Turbulence with a Mean Velocity Shear

An effect of a mean velocity shear on a turbulence and on the effective force which is determined by the gradient of Reynolds stresses is studied. Generation of a mean vorticity in a homogeneous incompressible turbulent flow with an imposed mean velocity shear due to an excitation of a large-scale instability is found. The instability is caused by a combined effect of the large-scale shear motions (''skew-induced" deflection of equilibrium mean vorticity) and ''Reynolds stress-induced" generation of perturbations of mean vorticity. Spatial characteristics, such as the minimum size of the growing perturbations and the size of perturbations with the maximum growth rate, are determined. This instability and the dynamics of the mean vorticity are associated with the Prandtl's turbulent secondary flows. This instability is similar to the mean-field magnetic dynamo instability. Astrophysical applications of the obtained results are discussed.Comment: 8 pages, 3 figures, REVTEX4, submitted to Phys. Rev.

Characterization of brewer's spent grain extracts by tandem mass spectrometry and HPLC-DAD: Ferulic acid dehydrodimers, phenolamides, and oxylipins

Brewer's spent grain (BSG) is a major by-product of the brewing industry which is generated in high amounts. In recent years, sustainable food production has become more and more important. BSG mainly used as cattle feed has gained high interest due to not only its valuable ingredients such as fiber and proteins but also secondary metabolites remaining in BSG after the brewing process and known for many biological effects. In the present study, various methods were applied, such as acetone extraction (A), alkaline hydrolysis followed by ethyl acetate extraction (HE), and acetone extraction of alkaline hydrolysis residue (HA). Compounds present in the respective bioactive extracts were characterized by mass spectrometry to identify the active compounds. Various hydroxycinnamic acid derivatives as well as oxylipins and some dicarboxylic acids, such as azelaic acid, were present in HE and HA extracts. In contrast, some catechins and phenolamides, such as numerous hordatines, as well as oxylipins and phospholipids were detected in A extracts. Quantification using HPLC-DAD revealed hordatine contents up to 172.2 ± 2.1 μg p-coumaric acid equivalents/mg extract. Hydroxycinnamic acid derivatives content accounted for up to 48% of the total extract (HE extracts) but only around 3% of the total HA extracts. In summary, all extracts contained secondary plant metabolites belonging to different classes, ranging from hydroxycinnamic acids to phenolamides, such as not only hordatines but also oxylipins, which were identified for the first time in BSG

Effects of Vine Shoot Extract on Riboflavin-Induced DNA Damage in HepG2 Cells

Winery by-products, including pomace, stem, vine leaves and shoots, arise in high amounts during the wine-making process. Due to high contents of secondary plant metabolites, such as polyphenols, their usage in the food, cosmetics and pharmaceutical industry is possible. In this study, we investigated effects of an extract prepared from vine shoots (Vitis vinifera L. cv. Riesling) on riboflavin-induced DNA damage in human hepatocellular carcinoma cells HepG2 by comet assay. Significant decreases of DNA damages were detected after 2 h and 24 h extract incubation at concentration ranges of 1 to 30 µg/mL (2 h) and 1 to 10 µg/mL (24 h), respectively. These effects may be attributable to polyphenolic compounds, which has to be further investigated

DNA Protection by an Aronia Juice-Based Food Supplement

Background: This study investigated the effects of an aronia juice-based food supplement on background and total DNA strand breaks in whole blood, and on H2O2-induced DNA strand breaks in isolated peripheral blood lymphocytes. Methods: Ninety-one healthy volunteers were randomly selected to consume either the food supplement (2 × 25 mL drinking ampules, n = 45) or no supplement (n = 46) daily for eight weeks. Results: Background DNA strand breaks decreased significantly after four and eight weeks of supplement consumption, compared to baseline (p < 0.05), but the overall effect was low, and neither group showed a decrease in total DNA strand breaks. Conversely, supplement consumption clearly reduced H2O2-induced DNA strand breaks ex vivo (p < 0.001), with statistically significant reductions after four and eight weeks, compared to the control group (p < 0.05). Conclusions: Thus, although consuming antioxidant supplements might produce only marginal immediate benefits under healthy conditions, potential preventive effects warrant further investigation

Fast, Sensitive and Robust Determination of Nicotinic Acid (Vitamin B₃) Contents in Coffee Beverages Depending on the Degree of Roasting and Brewing Technique

The vitamin B3 (niacin) is present in various foods. During roasting of green coffee beans, niacin is formed from the alkaloid trigonelline. Therefore, we established a novel fast and sensitive HPLC-MS/MS method to determine niacin in coffee brews from five commercially available coffee samples. Additionally, we investigated the influence of the brewing method, brewing temperature, and degree of roasting on niacin contents. In the respective coffee brews, we were able to show that the content of niacin in coffee beverages is not only affected by the degree of roasting, but also by the extraction performance of different brewing methods to a lesser extent

Activity-Guided Fractionation of Red Fruit Extracts for the Identification of Compounds Influencing Glucose Metabolism

An activity-guided search for compounds influencing glucose metabolism in extracts from aronia (Aronia melanocarpa, A.), pomegranate (Punica granatum L., P.), and red grape (Vitis vinifera, RG) was carried out. The three extracts were fractionated by means of membrane chromatography to separate the anthocyanins from other noncolored phenolic compounds (copigments). In addition, precipitation with hexane was performed to isolate the polymers (PF). The anthocyanin and copigment fractions (AF, CF) of aronia, pomegranate, and red grape were furthermore fractionated with high-performance countercurrent chromatography (HPCCC) and the subfractions were characterized by HPLC-PDA-MS/MS analyses. Each of the (sub-)fractions was examined by in vitro-tests, i.e., the inhibition of the activity of α-amylase and α-glucosidase. On the basis of this screening, several potent inhibitors of the two enzymes could be identified, which included flavonols (e.g., quercetin), ellagitannins (e.g., pedunculagin), and anthocyanins (e.g., delphinidin-3-glucoside and petunidin-3-glucoside). In the α-glucosidase assay all of the examined fractions and subfractions of the fruit extracts were more active than the positive control acarbose

Absorption of Anthocyanin Rutinosides after Consumption of a Blackcurrant ( Ribes nigrum L.) Extract.

The dominant anthocyanins in blackcurrant are delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside. Data on their absorption and distribution in the human body are limited. Therefore, we performed a human pilot study on five healthy male volunteers consuming a blackcurrant (Ribes nigrum L.) extract. The rutinosides and their degradation products gallic acid and protocatechuic acid were determined in plasma and urine. The rutinosides’ concentrations peaked in both plasma and urine samples within 2 h of extract ingestion. The recoveries of delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside from urine samples were 0.040 ± 0.011% and 0.048 ± 0.016%, respectively, over a 48 h period. Protocatechuic acid concentration increased significantly after ingestion of the blackcurrant extract. Our results show that after ingestion of a blackcurrant extract containing delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside, significant quantities of biologically active compounds circulated in the plasma and were excreted via urine. Furthermore, these results contribute to the understanding of anthocyanin metabolism in humans

Isolation and Characterisation of Hordatine-Rich Fractions from Brewer’s Spent Grain and Their Biological Activity on α-Glucosidase and Glycogen Phosphorylase α

Hordatines are a characteristic class of secondary metabolites found in barley which have been reported to be present in barley malt, beer and, recently, brewer´s spent grain (BSG). However, little is known about their biological activities such as antioxidative effects in beer or antifungal activity as their main task within the plants. We conducted an in vitro investigation of the activity of hordatines isolated from BSG towards enzymes of glucose metabolism. Hordatine-rich fractions from BSG were prepared by solid-liquid extraction (SLE) with 60% acetone followed by purification and fractionation. The fractions were characterised and investigated for their in vitro inhibitory potential on α-glucosidase and glycogen phosphorylase α (GPα). Both enzymes are relevant within the human glucose metabolism regarding the digestion of carbohydrates as well as the liberation of glucose from the liver. In total, 10 hordatine-rich fractions varying in the composition of different hordatines were separated and analysed by mass spectrometry. Hordatine A, B and C, as well as hydroxylated aglycons and many glycosides, were detected in the fractions. The total hordatine content was analysed by HPLC-DAD using a semi-quantitative approach and ranged from 60.7 ± 3.1 to 259.6 ± 6.1 µg p-coumaric acid equivalents/mg fraction. Regarding the biological activity of fractions, no inhibitory effect on GPα was observed, whereas an inhibitory effect on α-glucosidase was detected (IC50 values: 77.5 ± 6.5–194.1 ± 2.6 µg/mL). Overall, the results confirmed that hordatines are present in BSG in relatively high amounts and provided evidence that they are potent inhibitors of α-glucosidase. Further research is needed to confirm these results and identify the active hordatine structure