Eric Mignolet

Inulin-type fructans with prebiotic properties counteract GPR43 overexpression and PPARγ-related adipogenesis in the white adipose tissue of high-fat diet-fed mice

Inulin-type fructans (ITF) are nondigestible/fermentable carbohydrates which are able - through the modification of the gut microbiota - to counteract high-fat (HF) diet-induced obesity, endotoxemia and related-metabolic alterations. However, their influence on adipose tissue metabolism has been poorly studied until now. The aim of this study was to assess the influence of ITF supplementation on adipose tissue metabolism, by focusing on a G protein-coupled receptor (GPR), GPR43, as a potential link between gut fermentation processes and white adipose tissue development. Male C57bl6/J mice were fed a standard diet or an HF diet without or with ITF (0.2 g/day per mouse) during 4 weeks. The HF diet induced an accumulation of large adipocytes, promoted peroxisome proliferator activated receptor gamma (PPARγ)-activated differentiation factors and led to a huge increase in GPR43 expression in the subcutaneous adipose tissue. All those effects were blunted by ITF treatment, which modulated the gut microbiota in favor of bifidobacteria at the expense of Roseburia spp. and of Clostridium cluster XIVa. The dietary modulation of GPR43 expression seems independent of endotoxemia, in view of data obtained in vivo (acute and chronic lipopolysaccharides treatment). In conclusion, ITF, which promote gut fermentation, paradoxically counteract GPR43 overexpression induced in the adipose tissue by an HF diet, a phenomenon that correlates with a beneficial effect on adiposity and with potential decrease in PPARγ-activated processes.

Patulin in domestic and imported apple-based drinks in Belgium: occurrence and exposure assessment.

Apple-based beverages are regularly consumed by adults and children in Belgium. They are locally produced or imported from other countries. The apples used as starting material for these productions are frequently contaminated by mycotoxin-producing moulds and damaged during transport and handling. The current study was undertaken to investigate whether patulin (PAT) is present in the industrial or handicraft-made apple juices and ciders consumed by the Belgian population and to assess the populations exposure to this mycotoxin through apple-based drinks. Belgian (n = 29) and imported (14) apple juices as well as ciders (7) were assayed for PAT by high-performance liquid chromatography with ultraviolet light detection. PAT was detected respectively in 79, 86 and 43% of these tested samples. However, no contaminated sample exceeded the safe level of 50 μg PAT l-1. Levels of PAT contamination were comparable in Belgian and imported juice samples. The overall mean PAT concentrations were 9.0 and 3.4 μg l-1 for contaminated apple juices and ciders, respectively. This study also indicates that there was no statistically significant difference in the mean PAT contamination between clear (7.8 μg lμ1) and cloudy (10.7 μg lμ1) apple juices, as well as between handicraft-made apple juices (14.6 μg lμ1) and industrial ones (7.0 μg lμ1). On the basis of the mean results, a consumer exposure assessment indicates that a daily intake of 0.2 litres apple juice contributes to 45% of the provisional maximum tolerable daily intake for a child of 10 kg body weight.

Glycoalkaloids in potato tubers : the effect of variety and drought stress on the α-solanine and α-chaconine contents of potatoes

Six varieties of Solanum tuberosum L potato grown in the Bolivian highlands under drought stress, with and without irrigation, were analysed for their content of glycoalkaloids (GAs). The plant material consisted of three drought-tolerant varieties from a local breeding progranune (PROINPA), Potosina, Chapaquita and Pampena, and three control cultivated varieties, Malcacho, Sani Imilla and Desiree, either susceptible or relatively tolerant to drought, alpha -Solanine and alpha -chaconine were quantified in both the peel and flesh of the tubers. A significant increase in GA concentration (alpha -solanine+alpha -chaconine) was observed under drought stress conditions in most varieties; average concentration increases of 43 and 50% were registered in the improved and control cultivars respectively. In all tested cultivars, however, the GA concentration remained lower than the recommended food safety level (200 mg kg(-1) fresh tubers). It ranged from 52.4 to 100 mg kg(-1) fresh tubers in the improved cultivars and from 55.6 to 122.3 mg kg(-1) fresh tubers in the controls. In the improved and control varieties the cu-solanine content averaged 42.6 and 35.4% of the total potato GAs respectively and was not significantly affected by drought stress, except in Desiree. In all conditions the peel contained the greatest proportion of total GAs. The hybrid variety Pampeiia (new drought-tolerant variety) contained the lowest amounts of GAs, which were lower than those of the control varieties, with and without irrigation

Sacha inchi (Plukenetia volubilis): A seed source of polyunsaturated fatty acids, tocopherols, phytosterols, phenolic compounds and antioxidant capacity

Fatty acids (FA), phytosterols, tocopherols, phenolic compounds, total carotenoids and hydrophilic and lipophilic ORAC antioxidant capacities were evaluated in 16 cultivars of Sacha inchi (SI) seeds with the aim to valorise them and offer more information on the functional properties of SI seeds. A high α linolenic (α-Ln) fatty acid content was found in all cultivars (ω3, 12.8-16.0 g/100 g seed), followed by linoleic (L) fatty acid (ω6, 12.4-14.1g/100g seed). The ratio ω6/ω3 was within the 0.83-1.09 range. γ- and δ-tocopherols were the most important tocopherols, whereas the most representative phytosterols were β-sitosterol and stigmasterol. Contents of total phenolics, total carotenoids and hydrophilic and lipophilic antioxidant capacities ranged from 64.6 to 80 mg of gallic acid equivalent/100g seed; from 0.07 to 0.09 mg of β-carotene equivalent/100g of seed; from 4.3 to 7.3 and, from 1.0 to 2.8 μmol of Trolox equivalent/g of seed, respectively, among the evaluated SI cultivars. Results showed significant differences (p<0.05) among the evaluated SI cultivars in the contents of ω3, ω6, antioxidant capacities and other evaluated phytochemicals. SI seeds should be considered as an important dietary source of health promoting phytochemicals.

Linseed oil stabilisation with pure natural phenolic compounds

Linseed has been used for a very long time in human and animal nutrition. Currently, there is an increasing interest in linseed oil because of its particularly high content in α-linolenic acid (ALA), an omega-3 fatty acid (FA). Unfortunately, ALA turns also the oil extremely sensitive to oxidation. This study aimed at assessing four pure representative phenolic compounds, myricetin (flavonol), (+)-catechin (flavanol), genistein (isoflavone), and caffeic acid (hydroxycinnamic acid) at a concentration of 555μmol/kg as antioxidants in refined linseed oil (RLO). Their protective effect was assessed by monitoring the hydroperoxide formation, the FA profile and the residual antioxidant concentration in RLO, along its storage at 60°C according to the Schaal oven test procedure. Caffeic acid, (+)-catechin and myricetin were found to be more efficient than butylated hydroxyanisole (BHA), a synthetic antioxidant. Interestingly, myricetin strongly reduced ALA oxidation. These results confirm that the chemical structure of the phenolic compounds plays a major role in their antioxidant properties.

Conversion of t11t13 CLA into c9t11 CLA in Caco-2 Cells and Inhibition by Sterculic Oil

Background Conjugated linoleic acids (CLA), and principally c9t11 CLA, are suspected to have numerous preventive properties regarding non-infectious pathologies such as inflammatory diseases, atherosclerosis and several types of cancer. C9t11 CLA is produced in the rumen during biohydrogenation of linoleic acid, but can also be synthesized in mammalian tissues from trans-vaccenic acid (C18:1 t11) through the action of delta-9 desaturase (D9D). For several years, it is also known that c9t11 CLA can be synthesized from conjugated linolenic acids (CLnA), i.e. c9t11c13 CLnA and c9t11t13 CLnA. This study aimed at investigating to which extent and by which route c9t11 CLA can be produced from another isomer of CLA, the t11t13 CLA that is structurally very similar to c9t11t13 CLnA, in Caco-2 cells. Methodology/Principal Findings Caco-2 cells were incubated for 24 h with 20 µmol/l of t11t13 CLA in the absence or presence of sterculic oil used as an inhibitor of D9D. Caco-2 cells were able to convert t11t13 CLA into c9t11 CLA, and c9t11t13 CLnA was formed as an intermediate compound. In the presence of sterculic oil, the production of this intermediate was decreased by 46% and the formation of c9t11 CLA was decreased by 26%. No other metabolite was detected. Conclusions/Significance These results not only highlight the conversion of t11t13 CLA into c9t11 CLA but demonstrate also that this conversion involves first a desaturation step catalysed by D9D to produce c9t11t13 CLnA and then the action of another enzyme reducing the double bond on the Δ13 position.

Nutritional composition and antioxidant properties of the sim fruit (Rhodomyrtus tomentosa)

In this study, detailed chemical properties of sim (Rhodomyrtus tomentosa (Ait.) Hassk.) fruit including nutritional composition, phenolic content and antioxidant capacity were determined for the first time. A 150g serving of sim fruit contained high levels of dietary fibre (69.94-87.43% of Recommended Daily Intake (RDI)), α-tocopherol (38.90-51.87% RDI), manganese (>100% RDI), and copper (44.44% RDI) but low levels of protein (2.63% RDI), lipid (1.59-3.5% RDI), and sugars (5.65% RDI). The predominant fatty acid in the sim fruit sample was linoleic acid (75.36% of total fatty acids). Interestingly, total phenolics (49.21±0.35mg gallic acid equivalent (GAE)/g dry weight (DW)) were particularly high and resulted in a high antioxidant capacity (431.17±14.56μmol Trolox equivalent (TE)/g DW). These results, together with our recent discovery of high amount of piceatannol, a stilbene with potent biological activities, highlight the potential of sim, an under-utilised plant species from South-East Asia, as a new source of health-promoting compounds including dietary fibres, essential fatty acids, and phenolic compounds.

Differential changes of fat-soluble vitamins and pollutants during lactation in northern elephant seal mother-pup pairs.

We investigated the changes of vitamins A and E as well as PCBs and DDTs during lactation in northern elephant seal (Mirounga angustirostris) mother-pup pairs. On average, milk vitamin A concentrations were 6 times higher during late lactation than during early lactation, a pattern that differs dramatically from terrestrial mammals. Vitamin A concentrations also significantly increased in the inner blubber throughout lactation, whereas they remained constant in the outer blubber. Similar dynamics were observed for PCBs and DDTs in maternal blubber and milk. Blubber appears to be an important storage site for vitamin A and organochlorines in seals and a direct transfer of those molecules to the mammary gland may occur. The dynamics of vitamin A, PCBs and DDTs differed from those of vitamin E. There was a significant drop in milk vitamin E concentrations between early and late lactation, which is the usual pattern observed in terrestrial mammals. The dynamics of vitamin E in the blubber layers also differed from those of vitamin A, suggesting different mechanisms of mobilization and transfer into the milk.

Performance comparison of UV and FT-Raman spectroscopy in the determination of conjugated linoleic acids in cow milk fat.

The determination of conjugated linoleic acids (CLA) in cow milk fat was studied by using UV (210-250 nm) and Fourier transform (FT)-Raman (900-3400 cm (-1)) spectroscopy in order to determine the best spectrophotometric technique for routine analysis of milk fat. A collection of 57 milk fat samples was randomly divided into two sets, a calibration set and a validation set, representing two-thirds and one-third of the samples, respectively. All calculations were performed on the calibration set and then applied to the validation set. The CLA content ranged from 0.56 to 4.70%. A comparison of various spectral pretreatments and different multivariate calibration techniques, such as partial least-squares (PLS) and multiple linear regression (MLR), was done. This paper shows that UV spectroscopy is as reliable as FT-Raman spectroscopy to monitor CLA in cow milk fat. The best calibration for FT-Raman was given by a PLS model of seven factors with a standard error of prediction (SEP) of 0.246. For UV spectroscopy, PLS models were also better than MLR models. The most robust PLS model was constructed with only one factor and with SEP=0.288.

Determination by fourier transform Raman spectroscopy of conjugated linoleic acid in I2-photoisomerized soybean oil.

The potential of Fourier transform (FT)-Raman spectroscopy to quantify the total conjugated linoleic acid (CLA) content was evaluated to find a technique for the routine control of CLA synthesis by chemical procedures. The calibration and validation samples were obtained by photoisomerization of linoleic acid contained in soybean oil. The catalyst was iodine (I(2)), and the light source was the green line (514.5 nm) of an argon ion laser. The criteria to select the best partial least-squares (PLS) calibration model were a low standard error of prediction (SEP), a high correlation coefficient (R), and the selection of relevant variables of the Raman spectrum to reduce spectral interferences. The total CLA content of the 22 samples ranged from 0.05 to 3.28% of total lipids. The best PLS calibration model was obtained with three optimal factors, a SEP of 0.22, and a R of 0.97. This calibration model was obtained after baseline correction of the CC stretching region (1642-1680 cm(-1)), which contained sufficient spectral information for reliable CLA quantification.