Despite extensive literature describing the biological effects of polyphenols, little is known about their absorption from diet, one major unresolved point consisting of the absorption of the bound ...forms of polyphenols. In this view, in the present work we studied the absorption in humans of phenolic acids from coffee, a common beverage particularly rich in bound phenolic acids, such as caffeic acid, ferulic acid, and p-coumaric acid. Coffee brew was analyzed for free and total (free + bound) phenolic acids. Chlorogenic acid (5‘-caffeoylquinic acid), a bound form of caffeic acid, was present in coffee at high levels, while free phenolic acids were undetectable. After alkaline hydrolysis, which released bound phenolic acids, ferulic acid, p-coumaric acid, and high levels of caffeic acid were detected. Plasma samples were collected before and 1 and 2 h after coffee administration and analyzed for free and total phenolic acid content. Two different procedures were applied to release bound phenolic acids in plasma: β-glucuronidase treatment and alkaline hydrolysis. Coffee administration resulted in increased total plasma caffeic acid concentration, with an absorption peak at 1 h. Caffeic acid was the only phenolic acid found in plasma samples after coffee administration, while chlorogenic acid was undetectable. Most of caffeic acid was present in plasma in bound form, mainly in the glucuronate/sulfate forms. Due to the absence of free caffeic acid in coffee, plasma caffeic acid is likely to be derived from hydrolysis of chlorogenic acid in the gastrointestinal tract. Keywords: Chlorogenic acid; caffeic acid; coffee; polyphenols; human plasma
Aim of this study was to analyse the relationship between the plasma levels of polyphenols and the antioxidant activity of red and white wine. Twenty healthy subjects (HS) were randomly allocated to ...drink 300
ml of red (
n
=
10) or white
n
=
10 wine for 15 days. Ten HS who refrained from any alcohol beverage for 15 days were used as control. Urinary PGF-2α-III, a marker of oxidative stress and plasma levels of polyphenols were measured. Urinary PGF-2α-III significantly fell in subjects taking wine with a higher percentage decrease in subjects given red wine (−38.5
±
6%,
p
<
0.001) than in those given white wine (−23.1
±
6%). Subjects taking red wine had higher plasma polyphenols than those taking white wine (1.9
±
0.6
μM versus 1.5
±
0.33
μM,
p
<
0.001). Plasma polyphenols were inversely correlated with urinary PGF2α (
r
=
0.77,
p
<
0.001). No changes of urinary isoprostanes were observed in subjects who refrained from wine intake.
In vitro study demonstrated that only a mixture of polyphenols, all in a range corresponding to that found in human circulation, inhibited LDL oxidation and PKC-mediated NADPH oxidase activation. Such inhibitory effects were more marked using the concentrations of polyphenols detected in human circulation after red wine intake.
This study shows that red wine is more antioxidant than white wine in virtue of its higher content of polyphenols, an effect that may be dependent upon a synergism among polyphenols.
This study aims to characterize in vitro D-chiro-inositol intestinal absorption and identify factors able to improve its bioavailability. D-chiro-inositol, one of the natural occurring stereoisomer ...of myo-inositol, acts as a second messenger in insulin-regulated glucose metabolism in complementary mode with myo-inositol. Because of their insulin-mimetic activities and safety, both myo-inositol and D-chiro-inositol are often employed as supplements in insulin-resistance treatment.
Trans-epithelial passage of D-chiro-inositol was evaluated in the human intestinal Caco-2 cell line differentiated on filter, a widely established in vitro model to study intestinal absorption. D-chiro-inositol transport was assayed in a concentration range corresponding to an estimated in vivo concentration following oral supplementation. α-Lactalbumin peptides, obtained by in vitro simulated gastrointestinal digestion, were tested as possible modulators of the intestinal permeability of D-chiro-inositol.
The absorption of this stereoisomer was relatively low and presumably due to passive diffusion, while it was greatly enhanced by the presence of α-Lactalbumin digest. α-Lactalbumin peptides induced an increase in paracellular permeability that was completely reversible, indicating lack of cytotoxicity. This effect involved temporary rearrangement of F-actin apical cytoskeleton and of the tight junction protein ZO-1.
Although further studies are required to identify and characterize the most effective peptides, the ability of α-Lactalbumin digest to act as absorption enhancers may have very interesting and promising applications in the fields of nutritional supplements and pharmacology.
Epidemiological studies indicate a J-shaped relationship linking coffee consumption and cardiovascular risk, suggesting that moderate coffee consumption can be beneficial. Platelet aggregation is of ...critical importance in thrombotic events, and platelets play a major role in the aetiology of several CVD. The aim of this study was to evaluate the effect of coffee drinking on platelet aggregation ex vivo, using caffeine as control. A crossover study was performed on ten healthy subjects. In two different sessions, subjects drank 200 ml coffee, containing 180 mg caffeine, or a capsule of caffeine (180 mg) with 200 ml water. Platelets were separated from plasma at baseline and 30 and 60 min after coffee drinking. Platelet aggregation was induced with three different agonists: collagen, arachidonic acid and ADP. Coffee drinking inhibited collagen (P < 0·05 from baseline at time 30 min) and arachidonic acid (P < 0·05 from baseline at time 60 min) induced platelet aggregation. Caffeine intake did not affect platelet aggregation induced by the three agonists. Coffee consumption induced a significant increase of platelet phenolic acids (likely present as glucuronate and sulphate derivatives), caffeic acid, the principal phenolic acid in coffee, raising from 0·3 (sem 0·1) to 2·4 (sem 0·6) ng/mg (P < 0·01). Caffeine was not detectable in platelets. Coffee drinking decreases platelet aggregation, and induces a significant increase in phenolic acid platelet concentration. The antiplatelet effect of coffee is independent from caffeine and could be a result of the interaction of coffee phenolic acids with the intracellular signalling network leading to platelet aggregation.
Moderate wine consumption has been shown to lower cardiovascular risk. One of the mechanisms could involve the control of postprandial hyperlipaemia, a well-defined risk factor for atherosclerosis, ...reasonably by reducing the absorption of lipid oxidised species from the meal. The objective of the present study was to investigate whether wine consumption with the meal is able to reduce the postprandial increase in plasma lipid hydroperoxides and cholesterol oxidation products, in human subjects. In two different study sessions, twelve healthy volunteers consumed the same test meal rich in oxidised and oxidisable lipids (a double cheeseburger), with 300 ml of water (control) or with 300 ml of red wine (wine). The postprandial plasma concentration of cholesterol oxidation products was measured by GC–MS. The control meal induced a significant increase in the plasma concentration of lipid hydroperoxides and of two cholesterol oxidation products, 7-β-hydroxycholesterol and 7-ketocholesterol. The postprandial increase in lipid hydroperoxides and cholesterol oxidation products was fully prevented by wine when consumed with the meal. In conclusion, the present study provides evidence that consumption of wine with the meal could prevent the postprandial increase in plasma cholesterol oxidation products.
The experimental conditions commonly used to detect bound phenolic acids by alkaline hydrolysis result in loss of several phenolic acids, particularly dihydroxy-derivatives (caffeic acid, ...dihydrocaffeic acid, homogentisic acid). In this study we show that the addition of ascorbic acid, a strong antioxidant, and ethylenediaminetetraacetic acid, a metal chelator, totally prevent the loss of phenolic acids during alkaline hydrolysis. In these conditions, a complete recovery of caffeic acid following hydrolysis of chlorogenic acid (5′-caffeoylquinic acid, an ester of caffeic acid with quinic acid) was found. This procedure has been successfully applied to quantitatively detect bound phenolic acids in coffee brew and apple.
The measure of antioxidant capacity (AC) considers the cumulative action of all the antioxidants present in plasma and body fluids, thus providing an integrated parameter rather than the simple sum ...of measurable antioxidants. The capacity of known and unknown antioxidants and their synergistic interaction is therefore assessed, thus giving an insight into the delicate balance in vivo between oxidants and antioxidants. Measuring plasma AC may help in the evaluation of physiological, environmental, and nutritional factors of the redox status in humans. Determining plasma AC may help to identify conditions affecting oxidative status in vivo (e.g., exposure to reactive oxygen species and antioxidant supplementation). Moreover, changes in the plasma AC after supplementation with galenic antioxidants or with antioxidant-rich foods may provide information on the absorption and bioavailability of nutritional compounds. Consequently, this review discusses the rationale, interpretation, confounding factors, measurement limits, and human applications of the measure of plasma AC.
Moderate wine consumption has been shown to lower cardiovascular risk when part of a healthy life style. Red wine compounds, especially polyphenols, might play a role in preventing the development ...and progression of atherosclerosis, through different modalities of action, including inhibition of lipid peroxidation, metal chelation, free radical scavenging, inhibition of platelet aggregation, anti-inflammatory and estrogenic activity, improvement of endothelial function, lowering of blood pressure and modulation of lipoprotein metabolism. The attenuation of the postprandial oxidative stress could be another mechanism involved in protection by wine phenols, as the absorption of prooxidant/oxidized species with a meal can induce physiological events, such as the formation of mildly oxidized lipoprotein or endothelial dysfunction and inflammatory responses, all linked to the development of cardiovascular disease. As regards oxidizable/oxidized dietary fats, the typical Western diet contains substantial quantities of oxidized lipids. In view of the health implications of their absorption from food, we studied the effect of wine consumption with a meal on modulation of oxidative stress and postprandial increase of plasma oxidized lipids in humans.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Coffee and tea are widely consumed beverages, but only tea has been studied for its antioxidant capacity (AC) in vivo. The aim of this study was to compare the capacities of coffee and tea to affect ...plasma redox homeostasis in humans. The AC of plasma before and after supplementation with 200 mL of beverages (0, 1, and 2 h) was measured by the TRAP and crocin tests. The crocin test detected an increase in plasma AC only in subjects supplemented with coffee (+7% at peak time), whereas the TRAP method showed an increase in plasma AC after consumption of both coffee and tea (+6 and +4%, respectively, at peak time). Both beverages induced a significant increase in plasma uric acid (+5 and +7%, respectively). Uric acid strongly affects the results obtained by the TRAP test and does not affect those obtained by the crocin test. We can thus argue that uric acid is the main component responsible for the plasma AC increase after tea drinking, whereas molecules other than uric acid (probably phenolic compounds) are likely to be responsible for the increase in plasma AC after coffee drinking. Keywords: Coffee; tea; polyphenols; antioxidant capacity; human
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