Polyphenols, widely spread in our diet by the consumption of plant food products, are commonly determined using Folin−Ciocalteu reagent that interacts with other different reducing nonphenolic ...substances and leads to an overestimation of polyphenol content. In this paper we report an optimized Folin−Ciocalteu method to specifically determine the contents of total polyphenols and vitamin C. After the optimal conditions for the colorimetric assay were set, solid-phase extraction (Oasis HLB (hydrophilic−lipophilic balance)) was carried out to eliminate the water-soluble reducing interferences including vitamin C. Colorimetric correction was thus performed by subtracting interfering substances contained in the water washing extract from the raw extract. Moreover, vitamin C present in the water washing extract can be destroyed by heating and thus colorimetrically deduced. This procedure was set up with synthetic solutions and validated on different extracts from fruit products. Keywords: Polyphenols; vitamin C; Folin−Ciocalteu; colorimetry; solid-phase purification; fruit; puree; juice
Obesity is associated with a low-grade inflammation which is correlated with an increased secretion of pro-inflammatory cytokines and chemokines by adipose tissue, suspected to contribute to the ...development of insulin resistance. Because lycopene is mostly stored in adipose tissue and possesses anti-inflammatory properties, we hypothesize that lycopene could reduce the production of proinflammatory markers in adipose tissue. In agreement with this hypothesis, we observed a decrease of inflammatory markers such as IL-6, MCP-1 and IL-1β at both the mRNA and protein level when explants of epididymal adipose tissue from mice fed with a high-fat diet were incubated with lycopene
ex vivo. The same effect was reproduced with explants of adipose tissue preincubated in lycopene and then subjected to TNFα stimulation. The contribution of adipocytes and preadipocytes was evaluated. In both preadipocytes and differentiated 3T3-L1 adipocytes, lycopene preincubation for 24 h decreased the TNFα-mediated induction of IL-6 and MCP-1. Finally, the same results were reproduced with human adipocyte primary cultures. The molecular mechanism was also studied. In transient transfections, a decrease of the luciferase gene reporter under control of NF-κB responsive element was observed for cells incubated in the presence of lycopene and TNFα compared to TNFα alone. The involvement of the NF-κB pathway was confirmed by the modulation of IKKα/β phosphorylation by lycopene.
Altogether, these results showed for the first time a limiting effect of lycopene on adipose tissue proinflammatory cytokine and chemokine production. Such an effect could prevent or limit the prevalence of obesity-associated pathologies, such as insulin resistance.
The intestinal microbiota is the largest source of microbial stimulation that exerts both harmful and beneficial effects on human health. The interaction between probiotic and enterocytes is the ...initiating event in immunomodulation and merits particular attention. The effects of probiotic is strain dependent and for each new probiotic strain, profiles of cytokines secreted by lymphocytes, enterocytes or dendritic cells that come in contact with the strain should be systematically established. To evaluate the effects of probiotics on the immune system, models that mimic the mucosa, and thus the physiological reality, should be preferred whenever it is possible. Then, the in vitro observed effects should be backed up by properly conducted randomized double bind clinical studies. More detailed studies are needed to determine the precise action mode of probiotics on both mucosal and systemic immunity.
Anthocyanin extracts are increasingly used as food ingredients. A current challenge is to maintain their color properties. The stability of some colorants has been studied in sugar and non-sugar ...drink models at three pH values (3, 4, and 5) under thermal and light conditions simulating rapid food aging. At a given pH, color stability mainly depends on the structures of anthocyanins and of colorless phenolic compounds. Colorants rich in acylated anthocyanins (purple carrot, red radish, and red cabbage) display great stability due to intramolecular copigmentation. The protection of red chromophore is higher for diacylated anthocyanins in red radish and red cabbage. For colorants without acylated anthocyanins (grape-marc, elderberry, black currant, and chokeberry), intermolecular copigmentation plays a key role in color protection. Colorants rich in flavonols and with the highest copigment/pigment ratio show a remarkable stability. By contrast, catechins appear to have a negative effect on red colorants, quickly turning yellowish in drink models. This effect is more pronounced when the pH is increased. Finally, color does not seem to be greatly influenced by the addition of sugar. Keywords: Colorants; anthocyanins; flavonols; flavanols; phenolic acid; CIELAB; spectrophotometry; HPLC; diode array detection; color stability; copigment effect
Phenolics have been identified and quantified in nine varieties of barley and their corresponding malts as flavan-3-ols, flavonols, phenolic acids and apolar esters. Flavan-3-ols are monomers, ...(+)-catechin and (-)-epicatechin, and polymers constituted mainly by units of (+)-catechin and (+)-gallocatechin. The most abundant compounds were the dimers procyanidin B3 and prodelphinidin B3. The main trimeric procyanidin was procyanidin C2. After malting, the phenolic content decreased for all varieties. Catechin monomers were the most affected. Beside polyphenols, barley and malt extracts contained other antioxidants: carotenoids (1utein and zeaxanthin) and tocopherols (alpha, delta and gamma). The antioxidant activity was measured using three methods: capacity to react with DPPH (ARP), inhibition of lipoxygenase activity (LoxI) and inhibition of cooxidation of beta-carotene in a linoleate model system (AOP). The inhibition of cooxidation of beta-carotene in a linoleate model system did not allow varieties to be discriminated. They all have high antioxidative properties. Using this assay, tocopherols were the best antioxidants. The ARP (antiradical power) was correlated positively with the amount of total flavan-3-ols (r = 0.89) and increased with the degree of polymerisation. The LoxI assay allowed discrimination of the nine varieties of barley and their corresponding malts but was not correlated with any compound, although flavan-3-ols were good inhibitors of lipoxygenase activity.
Objective: (R,R,R)-α-tocopherol is a fat-soluble antioxidant vitamin generally ingested with other dietary antioxidants. The objective of this study was to assess whether the main dietary antioxidant ...classes, that is carotenoids, polyphenols, vitamin C and γ-tocopherol, affect the intestinal absorption of α-tocopherol. Methods, design and subjects: We evaluated first the effect of different combinations of antioxidants on (R,R,R)-α-tocopherol absorption by a human intestinal cell line (Caco-2 clone TC7). Then we compared the effect of two doses of a dietary antioxidant (lutein) on the postprandial chylomicron α-tocopherol responses to an α-tocopherol-rich meal. Eight healthy men ate two similar meals in a random order at a 1 month interval. The meals contained 24 mg α-tocopherol in sunflower oil plus either 18 or 36 mg lutein. Blood samples were collected during the postprandial periods to compare chylomicron α-tocopherol responses. Results: A mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene, β-carotene and lutein) significantly impaired α-tocopherol absorption in Caco-2 cells (P<0.001 and P<0.0001, respectively). The inhibitory effect of γ-tocopherol was close to significance (P=0.055). In contrast, vitamin C had no significant effect (P=0.158). Naringenin was the only polyphenol that significantly impaired α-tocopherol absorption. Postprandial α-tocopherol response was weakest at the highest dose of lutein (616+/-280 nmol/l h vs 1001+/-287 nmol/l h). The observed extent of reduction (-38%, P=0.069) supported the inhibitory effect of carotenoids observed in the Caco-2 experiments. Conclusion: Naringenin, carotenoids and probably γ-tocopherol can impair α-tocopherol absorption whereas vitamin C and phenolic acids have no effect.
The Question-Answer (Q/R) service of Lyon's teaching hospital, offers reliable and updated information for healthcare professionals (HP). The impact of Q/R activity on patient outcome was measured by ...using a survey to assess user's satisfaction and impact on HP knowledge and/or patients cares. The compatibility of this tool with daily use had been assessed too.
The survey was sent prospectively, for 9 months in 2018, to all HP whose enquiry was linked to a particular patient's care. The survey was posted 24-48h after the answer had been provided.
41 survey over 55 sent were returned (74.5%). The level of satisfaction measured is mostly good or excellent on all evaluated items. The HP surveyed consider that the responses provided have a potential positive impact on their professional knowledge and practices (97.6%), on the patient's care (n=36/37) and patient outcome (n=22/23).
High level of satisfaction with the Q/R service and positive impact of this specialized Q/R service on improvement of HP knowledge and patient's care. This tool can be used in daily practice.
Antimicrobial effect of Rosemary extracts DEL CAMPO, José; AMIOT, Marie-Josèphe; NGUYEN-THE, Christophe
Journal of food protection,
10/2000, Letnik:
63, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A rosemary extract commercially exploited (Oxy'less) as an antioxidant of lipids in foods was dissolved in ethanol (100 mg/ml), and the solution was tested against foodborne microorganisms. For ...gram-positive bacteria, the MIC of the ethanolic solution was 1% for Leuconostoc mesenteroides, 0.5% for Listeria monocytogenes, 0.5% for Staphylococcus aureus, 0.13% for Streptococcus mutans, and 0.06% for Bacillus cereus. It slowed the growth of Penicillium roquefortii and Botrytis cinerea. Up to 1% of the ethanolic solution had no activity on the gram-negative bacteria Escherichia coli, Salmonella Enteritidis, and Erwinia carotovora and on the yeasts Rhodotorula glutinis and Cryptococcus laurentii. Antibacterial activity of the rosemary extract was strongly influenced by the composition of the media. The MIC was reduced by low pH, high NaCl contents, and low temperatures. Low pH and high NaCl concentration had a synergistic effect on the MIC of the rosemary extract for S. aureus. Lipids, surface-active agents, and some proteins decreased its antibacterial activity, whereas pectin had no effect. The inhibitory effect was little modified by heat treatment (100 degrees C). The natural microflora of pasteurized zucchini broth was inhibited by 0.5% of the rosemary extract. The antibacterial activity was linked to the compounds extracted with hexane, which are presumably phenolic diterpenoids.
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•Simultaneous electroseparation of anionic and cationic peptides was studied by EDUF.•Migration rate increased with increasing peptide feed solution concentration.•Relative energy ...consumption decreased with increasing peptide concentration.•Peptide concentration affects the selectivity of free amino acids and/or peptides.
The present work aimed to determine the effect of initial peptide concentration (0.5%, 1%, 2% and 4% (w/v) in feed solution during electrodialysis with ultrafiltration membranes (EDUF) on migration rate and selectivity of both anionic and cationic peptides as well as on electrodialytic parameters. The results showed that increasing the peptide concentration in the feed solution from 0.5% to 4% increased, in a linear way, the total separation rate and affected the selectivity of free amino acids in both recovery compartments RCA− (Asp, Glu and His) and RCC+ (Arg mainly) and/or peptides containing these amino acids. The highest migration rates observed at 4% were 16.2g/m2h and 7.8g/m2h for the cationic and anionic compartments respectively. Furthermore, the relative energy consumption decreased with increasing feed solution concentration from 17.4Wh/g at 0.5% concentration to 3.53Wh/g at 4% concentration. In addition, membrane integrity and physicochemical properties were not affected in the range of peptide concentration tested. To the best of our knowledge, it was the first time that the impact of feed peptide concentration on migration, selectivity and relative energy consumption is demonstrated in EDUF.
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