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Polyphenols in Food Products and Nutraceuticals: Bioavailability and Pharmacokinetic Issues

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  • B.K. Birla College
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Plant foods contain substantial amounts of phenolic compounds. Dietary interventions with phenolic supplementation show that phenolic compounds are transformed into phenolic acids or lactone structures by intestinal microbiota. The colon is the main site of microbial fermentation. The metabolites circulate in plasma and are excreted via urine. The entero-hepatic circulation ensures that their residence time in plasma is extended compared to that of their parent compounds. Thus these metabolites may exert systemic effects, which however have not been studied adequately. In particular the health implications of microbial metabolites of flavonoids, mostly phenolic acids, are unknown. This review aims to elucidate the microbial metabolism of most of the phenolic classes: flavonoids, isoflavonoids, lignans, phenolic acids and tannins. Some examples of biological activity studies of flavonoid and lignan metabolites are given. Biological significance of enterolactone, a mammalian plant lignan metabolite, has been studied quite extensively, but convincing evidence of the health benefits of the diverse pool of microbial metabolites is still scarce. Hopefully, novel tools in systems biology and the constant search for biomarkers will elucidate the role of the phenolic metabolome in health and in the prevention of chronic diseases. In conclusion, the colon is not only an excretion route, but also an active site of metabolism and deserves further attention from the scientific community.
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Polyphenols are naturally occurring compounds in plants and they are the most abundant antioxidants in the human diet. Due to their considerable structural diversity, this largely influences their bioavailability. Since a large proportion of polyphenols remains unabsorbed along the gastrointestinal tract, they may accumulate in the large intestine, where most of them are extensively metabolized by the intestinal microbiota. The formation of bioactive polyphenol-derived metabolites may also benefit the health status of the subjects, although the mechanisms have not been delineated. This review aims to highlight the impact of polyphenols on gut health and the modes of action could be through modulation of intestinal barrier function, innate and adaptive immune response, signaling pathways, as well as the ability to modify gut microbiota composition. The review will conclude by presenting future perspective and challenges of polyphenols application in food products to be used for preventing or treating diseases.
Chapter
Several comprehensive reviews dealing with bi- and triflavonoids have been published.1-7 This chapter focuses on compounds that have been reported since the last review by Geiger was published in 1994.7 Since that time tetra-, penta-, and hexaflavonoids have also been identified, hence necessitating a change in the title of this chapter compared to the previous review.
Book
This fascinating work provides state-of-the-art information on phenolic compounds in fruits. Written in a concise format, it covers qualitative aspects by demonstrating the diversity of phenolic features in the major fruits of economic importance. It extensively covers the role played by phenolic compounds in the quality of fruits, with regard to organoleptic characteristics and also as a parameter involved in enzymatic browning and other modifications which take place during fruit processing. This easy-to-read resource particularly emphasizes beverages made from fruits and the use of phenolic compounds in the detection of adulteration. This reference is indispensable to researchers in fundamental fields (plant physiologists, phytochemists, biochemists) as well as engineers and technologists working on practical applications in fruits.
Chapter
Regular and optimal intake of polyphenols associates with numerous health-promoting effects. Bioavailability and activity of polyphenols depend on foods' structure and interactions with other food constituents, especially proteins, lipids, and carbohydrates. Polyphenols-proteins interactions can result in various biological effects, such as sense of astringency. So far, polyphenols interactions with food lipids have not been of special importance, except in case of plant oils. Polyphenols-carbohydrates interactions can influence the organoleptic properties, while interactions with dietary fibers are particularly significant. Polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines. Also, polyphenols can slow down digestion of carbohydrates, through the inhibition of digestive enzymes or modulation of glucose uptake.Both animal and plant proteins have low impact on the bioavailability of polyphenols, but some in vitro studies reported that milk proteins could enhance intestinal absorption of polyphenols from tea. Dietary fats may alter the passage of polyphenols through gastrointestinal tract and impact absorption of more hydrophobic polyphenols in particular. While some studies reported that associations with carbohydrates could decrease bioavailability of polyphenols, the others showed the opposite effects. Macronutrients can be used for encapsulation of polyphenols, which can increase their bioavailability and ensure controlled and targeted release. Polyphenols' interactions in the body include their incorporation in cell membranes which causes changes in fatty acid profile and impacts membrane-bound transporters and enzymes. Finally, gut microbiota plays essential role in metabolism of both polyphenols and macronutrients and thus can have great impact on their interactions.
Book
The ftavonoid pigments, one of the most numerous and widespread groups of natural constituents, are ofimportance and interest to a wide variety ofphysical and biological scientists and work on their chemistry, occurrence, natural distribution and biological function continues unabated. In 1975, a mono graph covering their chemistry and biochemistry was published by Chapman and Hall under our editors hip entitled The Flavonoids. The considerable success of this publication indicated that it filled an important place in the scientific literature with its comprehensive coverage of these fascinating and versatile plant substances. The present volume is intended to update that earlier work and provide a detailed review of progress in the ftavonoid field during the years 1975 to 1980. Although cross references are made to The Flavonoids, this supplement is entirely self-contained and where necessary, tabular da ta from the earlier volume are incJuded and expanded here. The choice oftopics in Recent Advances has been dictated by the developments that have occurred in ftavonoid research since 1975, so that not all subjects covered in The Flavonoids are reviewed again here. A major advance in ftavonoid separation has been the app1ication ofhigh performance liquid chromatography (HPLC) and this is reviewed inter alia in the opening chapter on separation techniques. An equally important development in the spectral analysis of ftavonoids has been the measurement of carbon-13 NMR spectra and this subject is authoritatively discussed in Chapter 2 and is also illustrated with the spectra of 125 representative ftavonoids.
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Aronia berries, [Aronia melanocarpa (Michx.) Elliott var. Moscow (Rosaceae)], originate from North America and have been traditionally used in Native American medicine. Extracts, subfractions, isolated anthocyanins and isolated procyanidins B2, B5 and C1 from berries and bark of A. melanocarpa were investigated for their antioxidant and enzyme inhibitory activities. Four different bioassays were used, namely scavenging of the diphenylpicrylhydrazyl (DPPH) radical, inhibition of 15-lipoxygenase (15-LO), inhibition of xanthine oxidase (XO) and inhibition of α-glucosidase. Among the anthocyanins, cyanidin 3-arabinoside possessed the strongest and cyanidin 3-xyloside the weakest radical scavenging and enzyme inhibitory activity. These effects seem to be influenced by the sugar units linked to the anthocyanidin. Subfractions enriched in procyanidins were found to be potent α-glucosidase inhibitors, they possessed high radical scavenging properties, strong inhibitory activity towards 15-LO and moderate inhibitory activity towards XO. Trimeric procyanidin C1 showed higher activity in the biological assays compared to the dimeric procyanidins B2 and B5. This study suggests that different polyphenolic compounds of Aronia may have beneficial effects in reducing blood glucose levels due to inhibition of α-glucosidase and, provided sufficient bioavailability, may have a potential to alleviate oxidative stress.
Article
Bio‐based ferulic acid (FA), (E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid was converted to 1,2‐disubstituted ethylenic monomer (FA1) via methyl esterification followed by silylation with tert‐butyldimethylsilyl chloride. Radical copolymerization of FA1 with styrene (St), methyl methacrylate (MMA), and 4‐acetoxy‐3‐methoxystyrene (FA2) prepared from FA were carried out using azobisisobutyronitrile as an initiator at 80℃. It is found that FA1 was copolymerized with St and FA2, but not with MMA. The formation of copolymers was confirmed by 1H‐ and 13C‐NMR analyses. The reactivity ratios of FA1 and St estimated by the Fineman‐Ross method are rFA1=0.12 and rSt=2.46. In the case of the copolymerization of FA1 with FA2, the reactivity ratios, rFA1=0.13 and rFA2=2.66 were determined.
Article
Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases is emerging. Bioavailability differs greatly from one polyphenol to another, so that the most abundant polyphenols in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Mean values for the maximal plasma concentration, the time to reach the maximal plasma concentration, the area under the plasma concentration-time curve, the elimination half-life, and the relative urinary excretion were calculated for 18 major polyphenols. We used data from 97 studies that investigated the kinetics and extent of polyphenol absorption among adults, after ingestion of a single dose of polyphenol provided as pure compound, plant extract, or whole food/beverage. The metabolites present in blood, resulting from digestive and hepatic activity, usually differ from the native compounds. The nature of the known metabolites is described when data are available. The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L with an intake of 50 mg aglycone equivalents, and the relative urinary excretion ranged from 0.3% to 43% of the ingested dose, depending on the polyphenol. Gallic acid and isoflavones are the most well-absorbed polyphenols, followed by catechins, flavanones, and quercetin glucosides, but with different kinetics. The least well-absorbed polyphenols are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data are still too limited for assessment of hydroxycinnamic acids and other polyphenols. These data may be useful for the design and interpretation of intervention studies investigating the health effects of polyphenols.
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Coumaric acid is a hydroxy derivative of cinnamic acid and naturally occurs in three isomers (ortho-, meta- and para-); p-coumaric acid is one of the most commonly occurring isomer in nature. p-coumaric acid, classified as a phytochemical and nutraceutical, is found in various edible plants, such as carrots, tomatoes and cereals. p-coumaric acid (4-hydroxy-cinnamic acid) occurs widely in the cell walls of graminaceous plants. It decreases low-density lipoprotein (LDL) peroxidation, shows antioxidant and antimicrobial activities and plays an important role in human health. It is found in the endosperm of kernels at a limited level; however, the amount of p-coumaric acid increases significantly in peripheral tissues. In terms of cereal types, it appears that pericarp fractions in barley, wheat, oat and corn are the fractions richest in p-coumaric acid. It is both a good antioxidant and a good antimicrobial; therefore, it is natural alternative instead of synthetic additives, nowadays.
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Previous studies have shown that significant changes to green tea catechins occur as a result of changes in pH similar to those found in the gastrointestinal tract. In this study we have demonstrated that the sum of the antioxidant activities attributable to the four major catechins in brewed green and black tea samples was less than the total measured antioxidant activity, although there was a high degree of correlation between antioxidant activity and total measured polyphenol concentration. In addition, incubation of either form of tea at acid pH (as found in the stomach) had little effect of the concentration of individual catechins. However, incubation at slightly alkaline pH, similar to that found in the small intestine, resulted in a rapid decline in the concentrations of both green and black tea catechins, but with a lesser reduction in antioxidant activity and polyphenol concentration.
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Stability and release of curcumin was evaluated in silica nanoparticle stabilized Pickering emulsion during storage and simulated gastric and intestinal digestion. Stability and release kinetics of curcumin were characterized based on spectrophotometric measurements to quantify the amount of encapsulated curcumin in Pickering emulsion as a function of time. Physical stability of the emulsion during digestion was characterized using particle size, zeta potential and fluorescence imaging measurements. Biocompatibility of the emulsion and intracellular delivery of a model lipophilic fluorescent compound encapsulated in the emulsion were also determined. Stability of curcumin encapsulated in emulsion was approximately 100 fold higher than the stability of curcumin suspended in distilled water. Passive release measurements showed sustained release of over 80% of the encapsulated curcumin in 36 h. During simulated gastric digestion (2 h), over 80% of the encapsulated curcumin was retained, although limited aggregation of the emulsion droplets was observed. Incubation in simulated intestinal environment resulted in destabilization of the emulsion and approximately 60% of the encapsulated curcumin was released within 2 h of incubation. Fluorescence imaging measurements showed successful cellular uptake of emulsion droplets. Overall, this study demonstrates that Pickering emulsion has a potential for effective delivery of bioactive compounds.
Article
This study identified phenolic compounds from mustard seed meal and characterized their antibacterial activity. Phenolic compounds were extracted from defatted Oriental mustard (Brassica juncea L.) seed meal and characterized using ultra-high-performance liquid chromatography with diode array and electrospray ionization-mass spectrometric detection (UHPLC-DAD-ESI-MSn ). Sinapic acid and several sinapoyl conjugates were identified based on retention time, UV spectra, MS fragmentation pattern, and by comparison with the authentic sinapic acid reference substance. The crude extract and a purified phenolic fraction exhibited selective antibacterial effects against Gram-negative and Gram-positive spoilage bacteria including Staphylococcus aureus and Listeria monocytogenes; Lactobacillus plantarum was resistant. After alkaline hydrolysis, only sinapic acid could be detected, enabling quantification with the authentic reference substance. Alkaline hydrolysis released 2.66 ± 0.00 mg sinapic acid g−1 dry matter defatted mustard seed meal. Minimum inhibitory concentrations of the hydrolyzed extract against Bacillus subtilis, Escherichia coli, L. monocytogenes, Pseudomonas fluorescens, and S. aureus were 0.1 g L−1 or less. Growth of L. plantarum remained unaffected. Sinapic acid and sinapoyl esters are generally found in members of the Brassicaceae family. Methods for their fast identification will be useful in chemotaxonomic studies. The release of sinapic acid after alkaline hydrolysis not only allows for the quantification using the reference substances but also facilitates the standardization of the antibacterial activity of plant extracts for use as food preservative.
Article
The health-promoting effects attributable to dietary phenolic compounds strongly depend on their bioaccesibility from the food matrix and their consequent bioavailability. We carried out a pilot randomized controlled cross-over study to evaluate the effect of addition of an oil matrix during tomato sauce processing, on the bioavailability of tomato phenolics. Healthy subjects consumed a single dose of tomato sauce elaborated without oil (OO-F) and with the addition of 5% virgin olive oil (VOO-E) or refined olive oil (ROO-E). Plasma and urine samples were subjected to solid-phase extraction, followed by HPLC–MS/MS analysis. Six phenolic compounds, three aglycones (naringenin, ferulic and caffeic acids) and their corresponding glucuronide metabolites, were identified and quantified in urine after the ingestion of the tomato sauces. Two of the six phenolic urinary metabolites were also quantified in plasma samples. Only after ingestion of the oil-enriched tomato sauces, did the glucuronide metabolites of naringenin show a bi-phasic profile of absorption in plasma, suggesting that the lipid matrix added to the sauce may stimulate the occurrence of re-absorption events by enterohepatic circulation, potentially enhancing the apparent plasma half-life of the flavanone prior to excretion. The interindividual response variability observed underlies the need for further large-scale investigations.
Article
In this work hydroxycinnamic acid esters of tartaric acid (mono-p-coumaroyl tartaric acid, monocaffeoyl tartaric acid, monoferuloyl tartaric acid esters) were separated, identified and quantified in several red wines by high performance liquid chromatography coupled with tandem mass spectrometry. The method features direct analysis of wines with no preparation and analysis of grape juice with minimum sample manipulation. For the identification was used both a triple quadrupole and a quadrupole–Tof, while for the quantification a triple quadrupole.At the same time two impurities, due to interfering substances coming from methanol (stored in bottles with polypropylene tops without Teflon protection), were characterised. These impurities had the same molecular weight as the investigated compounds.
Article
Dietary factors are considered important environmental risk determinants for Western diseases. Studies have revealed beneficial or protective effects of the consumption of legumes with regard to hypercholesterolaemia and coronary heart disease, obesity, diabetes mellitus, and menopause. During the last decade attention has been focused on soy and soybean products. Several constituents have been isolated: isoflavones, phytosterols, protease inhibitors, inositol hexaphosphate, and saponins. Our interest concentrates on hormone-like bisphenolic phytoestrogens of dietary origin, the lignans and isoflavonoids. Their glycosides, converted by gut bacteria to mammalian derivatives with weak estrogenic and antioxidative activity, originate in leguminous seeds. We developed an isotope dilution gas chromatography-mass spectrometry method for quantitative determination of the isoflavones, formononetin, biochanin A, daidzein, genistein and coumestrol, and the lignans secoisolariciresinol and matairesinol, in food samples. We measured the four isoflavonoids and coumestrol, and, for the first time, the two lignans in 52 leguminous seeds and found high concentrations of isoflavonoids (0–1853.35 mg/kg; 0–7.3 mmol/kg dw) but lower amount of lignans (0–15.85 mg/kg; 0.05 mmol/kg dw). The highest plasma levels of their metabolites are found in individuals living in countries or regions with low cancer and cardiovascular disease incidence and these are probably sufficient to influence intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, and angiogenesis. Leguminous seeds, therefore, in respect to their abundant concentrations of phytoestrogens, are strong candidates for a role as natural cancer-protective food.
Article
The bio-accessibility (the release of compounds from solid food matrices) of grape polyphenols using an in vitro model simulating gastro-intestinal conditions has been investigated. In vitro studies are needed to unravel factors affecting the release of antioxidants during digestion. The amount of bio-accessible polyphenols, flavonoids and anthocyanins increases during gastric digestion. The transition in the intestinal environment causes a decrease in all the analyzed classes of polyphenols followed by a renewal in the extraction of polyphenols and flavonoids but not of anthocyanins. The stability under gastro-intestinal conditions of pure phenolic acids, flavonoids and resveratrol has been analysed. Gastric digestion had no effect on any phenolic tested. Phenolic acids and resveratrol were degraded under pancreatic conditions whereas catechin and quercetin were not. Changes in antioxidant activity during digestion were correlated to the changes in polyphenols concentration as well as to the pH. Our results suggest that the gastro-intestinal tract may act as an extractor where polyphenols are progressively released from solid matrix and made available for the absorption or to exert their biological effects in the gastro-intestinal tract.
Article
The total phenolic acid content of wheat, rice, and oat flours ranged from 71 to 87 ppm while corn flour contained 309 ppm and potato flour 410 ppm. Cis- and trans-ferulic and -p-coumaric acids and syringic acid were the principal phenolic compounds in the free acid or soluble ester fractions of the cereal flours. Alkaline hydrolysis of the insoluble residue of the cereals released the major proportion of phenolic acids, principally trans-ferulic acid. Free chlorogenic acid was the principal phenolic acid in potato flour, and a significant proportion of caffeic acid was released on hydrolysis of soluble esters. Wheat flour which had been stored for 6 months contained only 26 ppm of total phenolic acids, primarily in the bound form.
Article
The concentration and distribution of isoflavones in 29 commercial soybean foods, categorized into soy ingredients, traditional and second-generation, were evaluated by high-performance liquid chromatography and photodiode array detection. Twelve isomers were quantified, three aglycons (daidzein, genistein, glycitein) and nine glucosides (daidzin, genistin, glycitin; 6''-O-acetyldaidzin, -genistin, -glycitin; 6''-O-malonyldaidzin, -genistin, -glycitin). Compared with unprocessed soybeans, high-protein say ingredients contained similar concentrations, except alcohol-leached say concentrate. Traditional soybean foods showed differences between nonfermented and fermented foods. Nonfermented foods had greater levels of glucosides, while in contrast, greater levels of aglycons were found in fermented foods. Second-generation soy foods contained only 6-20% of the isoflavones of whole soybeans. The variety of soybean, method of processing, and addition of other components affect the retention and distribution of isoflavone isomers in soy foods.
Article
This study reports the 24 h human plasma pharmacokinetics of 3,4-dimethoxycinnamic acid (dimethoxycinnamic acid) after consumption of coffee, and the membrane transport characteristics of certain dimethoxycinnamic acid derivatives, as present in coffee. Eight healthy human volunteers consumed a low-polyphenol diet for 24 h before drinking 400 mL of commercially available coffee. Plasma samples were collected over 24 h and analyzed by HPLC-MS(2) . Investigation of the mechanism of absorption and metabolism was performed using an intestinal Caco-2 cell model. For the first time, we show that dimethoxycinnamic acid appears in plasma as the free aglycone. The time to reach the C(max) value of approximately 0.5 μM was rapid, T(max) = 30 min, and showed an additional peak at 2-4 h for several subjects. In contrast, smaller amounts of dimethoxy-dihydrocinnamic acid (C(max) ∼ 0.1 μM) peaked between 8 and 12 h after coffee intake. In the cell model, dimethoxycinnamic acid was preferentially transported in the free form by passive diffusion, and a small amount of dimethoxycinnamoylquinic acid hydrolysis was observed. These findings show that dimethoxycinnamic acid, previously identified in plasma after coffee consumption, was rapidly absorbed in the free form most likely by passive diffusion in the upper gastrointestinal tract.
Article
Quantitative data for hydroxybenzoic acids (naturally occurring and permitted additives) and their conjugates in foods and beverages are summarised. Tea, rosaceous fruits, red wines and potatoes are important sources for which more comprehensive compositional data are required. Their absorption, metabolism, toxicological evaluation and possible biological significance are discussed. There are insufficient data to properly define the dietary burdens, but it would seem that ellagic acid and gallic acid from natural sources may dominate in many cases, although the intake of added benzoic acid may be of a similar magnitude. It is pointed out that an additional, previously overlooked and possibly significant burden, particularly of benzoic acid itself, might arise as a result of the gut flora metabolism of larger-mass dietary phenols.© 2000 Society of Chemical Industry
Article
This paper summarises the occurrence in foods and beverages of the cinnamic acids, their associated conjugates and transformation products. Quantitative data are lacking for some commodities known to contain them, but it is clear that for many people coffee will be the major source. The daily dietary intake of total cinnamates may vary substantially from almost zero to perhaps close to 1 g. The data relating to their absorption and metabolism are presented along with a consideration of their possible in vivo effects. Data for true bioavailability are incomplete: in particular it is not clear whether availability differs markedly with the form of the conjugate, and whether as a consequence some dietary sources may be superior to others.
Article
The aim of this study was to investigate the influence of microencapsulation and addition of the phenolic antioxidant caffeic acid (CA) on the storage stability of olive oil. Olive oil in the absence or presence of 300 ppm CA was encapsulated in 1.5% w/w sodium alginate shells. Encapsulated oil (with/without added CA) and unencapsulated oil were stored at 20 or 37 °C for 30 days and then subjected to stability and quality evaluation based on peroxide value (PV), p-anisidine value (p-AV), Totox value, free fatty acid (FFA), total extractable phenolic content (TEPC), and fatty acid composition. The CA addition increased the stability and TPC of the final oil product. Oxidation changes were generally slower in the encapsulated oil samples. Both encapsulation and addition of CA preserved unsaturated fatty acids (UFAs) including C18:1 (omega-9 FA), C18:2 (omega-6 FA) and C18:3 (omega-3 FA). We conclude that the current oil encapsulation method using alginate microspheres could be a feasible approach to increasing olive oil stability. The addition of CA to olive oil not only provides additional protection to the oil, but also improves the nutritional values of the final oil product in terms of elevated TEPC and desired UFAs.Research highlights► Encapsulation using alginate is a feasible approach for increasing oil stability. ► Adding caffeic acid to olive oil provides additional protection to the oil. ► Encapsulated olive oil with added caffeic acid has improved nutritional values.
Article
The occurrence of ellagitannins in common foodstuffs is limited to a few fruit and nut species. Dietary intake of ellagitannins is largely explained by the consumption of strawberries, raspberries and blackberries. No reliable figures are available for the ellagitannin burden, but it will probably not exceed 5 mg day−1. Their bioavailability is not well defined. A fraction of the ellagitannins ingested is hydrolysed in the gut and the resulting ellagic acid absorbed and metabolised, but whether intact ellagitannins are absorbed is not clear. There are apparently conflicting claims for beneficial and toxic effects caused by ellagitannins, ellagic acid or ellagitannin-containing extracts in various animal species including rodents and ruminants. It seems unlikely that normal consumption can cause toxic effects in man, but any attempt to increase the intake significantly in pursuit of the suggested benefits should be resisted until the metabolism and pharmacokinetics are better understood.© 2000 Society of Chemical Industry