Polyphenols in chocolate: is there a contribution to human health?

Recent developments on polyphenol–protein interactions: effects on tea and coffee taste, antioxidant properties and the digestive system

Tea and coffee are widely consumed beverages across the world and they are rich sources of various polyphenols. Polyphenols are responsible for the bitterness and astringency of beverages and are also well known to impart antioxidant properties which is beneficial against several oxidative stress related diseases like cancer, cardiovascular diseases, and aging. On the other hand, proteins are also known to display many important roles in several physiological activities. Polyphenols can interact with proteins through hydrophobic or hydrophilic interactions, leading to the formation of soluble or insoluble complexes. According to recent studies, this complex formation can affect the bioavailability and beneficiary properties of both the individual components, in either way. For example, polyphenol-protein complex formation can reduce or enhance the antioxidant activity of polyphenols; similarly it can also affect the digestion ability of several digestive enzymes present in our body. Surprisingly, no review article has been published recently which has focused on the progress in this area, despite numerous articles having appeared in this field. This review summarizes the recent trends and patterns (2005 onwards) in polyphenol-protein interaction studies focusing on the characterization of the complex, the effect of this complex formation on tea and coffee taste, antioxidant properties and the digestive system.

Cocoa polyphenols and their potential benefits for human health

This paper compiles the beneficial effects of cocoa polyphenols on human health, especially with regard to cardiovascular and inflammatory diseases, metabolic disorders, and cancer prevention. Their antioxidant properties may be responsible for many of their pharmacological effects, including the inhibition of lipid peroxidation and the protection of LDL-cholesterol against oxidation, and increase resistance to oxidative stress. The phenolics from cocoa also modify the glycemic response and the lipid profile, decreasing platelet function and inflammation along with diastolic and systolic arterial pressures, which, taken together, may reduce the risk of cardiovascular mortality. Cocoa polyphenols can also modulate intestinal inflammation through the reduction of neutrophil infiltration and expression of different transcription factors, which leads to decreases in the production of proinflammatory enzymes and cytokines. The phenolics from cocoa may thus protect against diseases in which oxidative stress is implicated as a causal or contributing factor, such as cancer. They also have antiproliferative, antimutagenic, and chemoprotective effects, in addition to their anticariogenic effects.

Simultaneous determination of free amino acid content in tea infusions by using high-performance liquid chromatography with fluorescence detection coupled with alternating penalty trilinear decomposition algorithm

In this paper, a novel application of alternating penalty trilinear decomposition (APTLD) for high-performance liquid chromatography with fluorescence detection (HPLC-FLD) has been developed to simultaneously determine the contents of free amino acids in tea. Although the spectra of amino acid derivatives were similar and a large number of water-soluble compounds are coextracted, APTLD could predict the accurate concentrations together with reasonable resolution of chromatographic and spectral profiles for the amino acids of interest owing to its "second-order advantage". An additional advantage of the proposed method is lower cost than traditional methods. The results indicate that it is an attractive alternative strategy for the routine resolution and quantification of amino acids in the presence of unknown interferences or when complete separation is not easily achieved.

Relationship of sensory and instrumental aroma measurements of dark chocolate as influenced by fermentation method, roasting and conching conditions

The investigation was undertaken to establish a relationship between key odorants and perceived flavor attributes of dark chocolate as influenced by cocoa fermentation method, roasting and conching conditions, using multivariate data analysis in an attempt to use one variable to predict the other. Eight of the sixteen flavor attributes used by a trained sensory panel to describe and quantify the intensity of attributes in the samples were significantly different (p < 0.05). Roasting significantly reduced astringency in heap-fermented samples but the reduction in tray-fermented samples was not significant. Unconched samples were rated higher in banana attribute than conched samples. Multivariate data analytical tools, Principal Component Analysis (PCA) and Partial Least Squares (PLS) were used to investigate quantitative descriptive analysis and GC-O data and also to relate the two sets of data. PLS 1 models based on single sensory attributes gave better models than PLS2 models based on all sixteen sensory attributes. Ethyl-3-methylbutanoate (fruity, flowery); 2,5-dimethylpyrazine (popcorn); dihydro-2(3H)-furanone, (sweet); linalool oxide (sweet, flowery); benzaldehyde (earthy, nutty) and 2/3-methylbutanal (cocoa, roasted) modeled fruit attribute. It was also possible to model the attribute astringent from the aroma compounds 5-methyl-2-phenyl-2-hexenal (sweet, roasted cocoa), ethyl-3-methylbutanoate and pentyl acetate (green, cucumber). Since fruit attribute was higher in unconched samples and astringent higher in unroasted samples, it may be possible to use the levels of these important aroma compounds as indicators of the sensory attributes fruit and astringent.

Anti-inflammatory properties of clovamide and Theobroma cacao phenolic extracts in human monocytes: evaluation of respiratory burst, cytokine release, NF-κB activation, and PPARγ modulation

There is a great interest in the potential health benefits of biologically active phenolic compounds in cocoa (Theobroma cacao) and dark chocolate. We investigated the anti-inflammatory potential of clovamide (a N-phenylpropenoyl-L-amino acid amide present in cocoa beans) and two phenolic extracts from unroasted and roasted cocoa beans, by evaluating superoxide anion (O(2)(-)) production, cytokine release, and NF-κB activation in human monocytes stimulated by phorbol 12-myristate 13-acetate (PMA). The effects of rosmarinic acid are shown for comparison. Clovamide and rosmarinic acid inhibited PMA-induced O(2)(-) production and cytokine release (with a bell-shaped curve and maximal inhibition at 10-100 nM), as well as PMA-induced NF-κB activation; the two cocoa extracts were less effective. In all tests, clovamide was the most potent compound and also enhanced peroxisome proliferator-activated receptor-γ (PPARγ) activity, which may exert anti-inflammatory effects. These findings indicate clovamide as a possible bioactive compound with anti-inflammatory activity in human cells.

Plant polyphenols: chemical properties, biological activities, and synthesis

Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Protective activity of Theobroma cacao L. phenolic extract on AML12 and MLP29 liver cells by preventing apoptosis and inducing autophagy

Theobroma cacao L. is known to have potential cardiovascular and cancer chemopreventive activities because of its high content of phenolic phytochemicals and their antioxidant capacities. In this work, we show for the first time that cocoa inhibits drug-triggered liver cytotoxicity by inducing autophagy. Phenolic-rich extracts of both unroasted and roasted cocoa prevented Celecoxib-induced cell viability inhibition in MLP29 liver cells because of the accumulation of G1 cells and cell death. Death prevented by cocoa had hallmarks of apoptosis such as the sub-G1 peak at flow cytometry and activation of Bax expression, together with down-regulation of Bcl-2, released cytochrome c in the cytosol with activation of Caspase 3, indicating that components of the apoptotic pathway such as Bax or upstream are major targets of cocoa phytochemicals. The protective effect of cocoa against liver cytotoxicity by Celecoxib was probably accounted for by inducing the autophagic process, as shown by enhanced Beclin 1 expression and accumulation of monodansylcadaverine in autolysosomes. This fact suggests that apoptosis was prevented by inducing autophagy. Finally, considering all these findings, we suggest that cocoa can be added to the list of natural chemopreventive agents whose potential in hepatopathy prevention and therapy should be evaluated.

Antihypertensive effect of a polyphenol-rich cocoa powder industrially processed to preserve the original flavonoids of the cocoa beans

A natural flavonoid-enriched cocoa powder, commercially named CocoanOX and developed via a patented industrial process, was characterized and tested for a possible antihypertensive effect. The bioavailability of this polyphenol-rich cocoa powder developed at pilot scale was previously demonstrated in humans. The present results showed that this product was very rich in total procyanidins (128.9 mg/g), especially monomers, dimers, and trimers (54.1 mg/g), and mainly (-)-epicatechin (19.36 mg/g). The effect of a single oral administration of CocoanOX in spontaneously hypertensive rats (SHR) was evaluated at different doses (50, 100, 300, and 600 mg/kg). This product produced a clear antihypertensive effect in these animals, but these doses did not modify the arterial blood pressure in the normotensive Wistar-Kyoto rats. Paradoxically, the maximum effect in the systolic blood pressure (SBP) of SHR was caused by 300 mg/kg of CocoanOX. This dose brought about a decrease in this variable very similar to that caused by 50 mg/kg Captopril. It was also surprising that the maximum effect in the diastolic blood pressure (DBP) was caused by 100 mg/kg CocoanOX. The initial values of DBP and SBP were recovered in SHR, respectively, 24 and 48 h postadministration of the different doses of CocoanOX or Captopril. These results suggest that CocoanOX could be used as a functional ingredient with antihypertensive effect, although it would be also necessary to carry out bioavailability and clinical studies to demonstrate its long-term antihypertensive efficiency in humans.

Bioactivity and structure of biophenols as mediators of chronic diseases

Biophenols and their associated activity have generated intense interest. Current topics of debate are their bioavailability and bioactivity. It is generally assumed that their plasma concentrations are insufficient to produce the health benefits previously attributed to their consumption. However, data on localized in vivo concentrations are not available and many questions remain unanswered. Potential mechanisms by which they may exert significant bioactivity are discussed together with structure activity relationships. Biophenols are highly reactive species and they can react with a range of other compounds. Products of their reaction when functioning as antioxidants are examined.

Flavor formation and character in cocoa and chocolate: a critical review

Chocolate characters not only originate in flavor precursors present in cocoa beans, but are generated during post-harvest treatments and transformed into desirable odor notes in the manufacturing processes. Complex biochemical modifications of bean constituents are further altered by thermal reactions in roasting and conching and in alkalization. However, the extent to which the inherent bean constituents from the cocoa genotype, environmental factors, post-harvest treatment, and processing technologies influence chocolate flavor formation and relationships with final flavor quality, has not been clear. With increasing speciality niche products in chocolate confectionery, greater understanding of factors contributing to the variations in flavor character would have significant commercial implications.

Polyphenols in cocoa and cocoa products: is there a link between antioxidant properties and health?

Cocoa and cocoa products have received much attention due to their significant polyphenol contents. Cocoa and cocoa products, namely cocoa liquor, cocoa powder and chocolates (milk and dark chocolates) may present varied polyphenol contents and possess different levels of antioxidant potentials. For the past ten years, at least 28 human studies have been conducted utilizing one of these cocoa products. However, questions arise on which of these products would deliver the best polyphenol contents and antioxidant effects. Moreover, the presence of methylxanthines, peptides, and minerals could synergistically enhance or reduce antioxidant properties of cocoa and cocoa products. To a greater extent, cocoa beans from different countries of origins and the methods of preparation (primary and secondary) could also partially influence the antioxidant polyphenols of cocoa products. Hence, comprehensive studies on the aforementioned factors could provide the understanding of health-promoting activities of cocoa or cocoa products components.

Analysis of phenolic acids as chloroformate derivatives using solid phase microextraction–gas chromatography

In the presented study, a simple and original procedure of phenolic acids derivatization treated by ethyl and methyl chloroformate performed in an aqueous media consisting of acetonitrile, water, methanol/ethanol and pyridine has been modified and optimized. Seven phenolic acid standards-caffeic, ferulic, gallic, p-coumaric, protocatechuic, syringic and vanillic were derivatized into corresponding methyl/ethyl esters and subsequently determined by the means of gas chromatography connected to the flame-ionisation detector (FID). Some selected validation parameters as linearity, detection and quantitation limits and peak area repeatability were valued. The total time of gas chromatography (GC) analysis was 24 min for methyl chloroformate and 30 min for ethyl chloroformate derivatization. The more suitable methyl chloroformate derivatization was used for further experiments on the possibility of multiple pre-concentration by the direct solid phase microextraction technique (SPME). For this purpose, polyacrylate (PA), polydimethylsiloxane (PDMS), carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibres were tested and the extraction conditions concerning time of extraction, temperature and time of desorption were optimized. The most polar PA fibre gave the best results under optimal extraction conditions (50 min extraction time, 25 degrees C extraction temperature and 10 min desorption time). As a result, the total time of SPME-GC analysis was 74 min and an increase in method sensitivity was reached. The limits of quantitation (LOQ) of p-coumaric, ferulic, syringic and vanillic acid esters after SPME pre-concentration were 0.02, 0.17, 0.2 and 0.2 microg mL(-1), respectively, showing approximately 10 times higher sensitivity in comparison with the original GC method.

Functional Foods: A Survey of Health Claims, Pros and Cons, and Current Legislation

Functional foods stand for a new category of remarkably promising foods bearing properties (i.e., low cholesterol, antioxidant, anti-aging, anticancer, etc.) that have already rendered them quite appealing. There are many classes offunctionalfoods (pro- and pre-biotics, dietary fiber, low fat, etc.), and their definition is occasionally confused with that of nutraceuticals and novel foods. Consumers' main skepticism regarding functional foods resides in the veracity of health claims and in the low and often inadequate control of their claimed properties. Legislation concerning this matter is progressing at an extremely low pace and currently only Japan, the U.K., U.S.A., and Scandinavian countries have managed to make notable progress. Moreover, the labeling of functional foods is far from informative, providing scanty information about nutritional value, storage, and cooking recipes. It is anticipated that technological advances in the food industry, in conjunction with extensive clinical trials and governmental control, will eventually guarantee the credibility of health claims and ensure consumers' confidence in functional foods.

Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates

The potential of microcristaline cellulose as sorbent in the separation of eight compounds: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), procyanidin B1 and procyanidin B2 was studied. Cellulose HPTLC plates prewashed in water (not necessary, when water was used as developing solvent) and dried with a hair dryer, bandwise application and development in horizontal developing chamber (sandwich configuration) gave the best results. Detection was performed using vanillin-H3PO4 reagent. Four new developing solvent systems were proposed: water, 1-propanol-water (20:80, v/v), 1-propanol-water-acetic acid (4:2:1, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v), and at least two of them were needed for the differentiation between all eight compounds. Surprisingly, water enabled the separation of epimers C from EC and GC from EGC, as well as the dimers procianidin B1 and B2. Additionally, C, EGC, B1 and B2 were separated from all the other compounds. The best choice for developing solvent is given for each of the studied compounds. The best separation of the five main catechins (EC, GC, EGC, ECg, EGCg) present in green tea extract was achieved using 1-propanol-water-acetic acid (20:80:1, v/v). The chromatograms of oak bark extract developed in solvents with higher water content (1-propanol-water (1:4, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v)) showed less bands than chromatograms developed in solvents with higher organic modifier content (e.g. 1-propanol-water-acetic acid (4:2:1, v/v)). It was proved that such behavior was due to the presence of procyanidins beside the main component catechin.

Effect of cacao liquor extract on tumor marker enzymes during chemical hepatocarcinogenesis in rats

This study investigated the effect of cacao liquor extract (CLE) on tumor marker enzymes--alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), glutathione-S-transferase (GST), and glutathione reductase (GR) activities--in plasma and/or liver of hepatocarcinogenic rats, which were induced with diethylnitrosamine and 2-acetylaminofluorene. Twenty-nine male Sprague-Dawley rats (weighing 150-330 g) were divided into four groups (n = 6-8): normal control group (N), normal group + CLE (NE), cancer group (C), and cancer group + CLE (CE). Analysis of variance showed significant differences (P<.05) in the specific activities of ALP, GGT, and GST between the C and N groups. However, GR activity for the C group was not significantly different compared with the N group. In the CE group, the specific activities of ALP, GGT, GST, and GR were significantly lower (P<.05) compared with the C group. The findings showed that CLE could lower the activity of tumor marker enzymes of rats during hepatocarcinogenesis. Based on the results obtained, polyphenol compounds present in the cacao liquor, extracted by using ethanol, have the potential in decreasing the severity of hepatocarcinogenesis.

Dietary flavonoids fail to suppress F2-isoprostane formation in vivo

Dietary antioxidants, including alpha-tocopherol (alpha-TOH) and polyphenolic flavonoid compounds, have been the subject of much research interest, but few studies have investigated interactions between these two antioxidants in vivo. We have conducted a feeding study to determine if supplementation with dietary flavonoids or polyphenol-containing compounds will provide antioxidant protection in tocopherol-deficient animals or exceed the antioxidant protection provided by alpha-TOH alone, using the sensitive and specific measure of lipid peroxidation, F2-isoprostanes. Seventy-two male Sprague Dawley rats were divided into 12 treatment groups to receive either alpha-TOH-sufficient or -deficient AIN93-G diet supplemented with one of five compounds: 0.5% quercetin, catechin, or epicatechin; or 1% cocoa powder or lignin. The fat source was polyunsaturated oil, increased from 7 to 11.05% (w/w with diet) to maximize lipid peroxidation while staying within a physiological range. After 7 weeks of treatment, animals were sacrificed with plasma and hearts analyzed to determine differences in F2-isoprostane levels. None of the treatment compounds significantly decreased plasma or heart F2-isoprostanes compared to the control beyond the significant protection displayed by alpha-tocopherol. We conclude that under these experimental conditions, quercetin, catechin, and epicatechin do not suppress lipid peroxidation in vivo.

Cocoa and chocolate flavonoids: implications for cardiovascular health

This paper offers a review of current scientific research regarding the potential cardiovascular health benefits of flavonoids found in cocoa and chocolate. Recent reports indicate that the main flavonoids found in cocoa, flavan-3-ols and their oligomeric derivatives, procyanidins, have a variety of beneficial actions, including antioxidant protection and modulation of vascular homeostasis. These findings are supported by similar research on other flavonoid-rich foods. Other constituents in cocoa and chocolate that may also influence cardiovascular health are briefly reviewed. The lipid content of chocolate is relatively high; however, one third of the lipid in cocoa butter is composed of the fat stearic acid, which exerts a neutral cholesterolemic response in humans. Cocoa and chocolate contribute to trace mineral intake, which is necessary for optimum functioning of all biologic systems and for vascular tone. Thus, multiple components in chocolate, particularly flavonoids, can contribute to the complex interplay of nutrition and health. Applications of this knowledge include recommendations by health professionals to encourage individuals to consume a wide range of phytochemical-rich foods, which can include dark chocolate in moderate amounts.

Analysis of procyanidins in chocolate by reversed-phase high-performance liquid chromatography with electrospray ionisation mass spectrometric and tandem mass spectrometric detection

The analysis of procyanidins in crude chocolate extracts by reversed-phase high-performance liquid chromatography (HPLC) with electrospray ionisation mass spectrometry (MS) is described in this report. Catechin monomers and procyanidin oligomers (dimers to hexamers) were identified according to the mass of the single charged pseudomolecular ion ([M-H]-). Identification was further confirmed by collision-induced dissociation MS-MS analysis, which in addition, permitted the identification of double charged pentameric, hexameric, and heptameric ions. This study demonstrates the capability of the combination of HPLC and modern ion trap mass analysers to significantly reduce sample preparation and analysis time in combination with high specificity and structural information for compound identification.

Molecular aspects of procyanidin biological activity: disease preventative and therapeutic potentials

There is a growing interest in the utilization of procyanidins for their dietary and pharmacological properties. A wide spectrum of beneficial activity for human health has been advocated for procyanidins due, in part, to their strong antioxidant activity. More recently the ability of procyanidins to affect gene expression and cell response in vitro has been reported, providing a novel mechanistic perspective on the biological activity of these phytochemicals. This article reviews recent cellular and molecular aspects of the biological activity of procyandins and discusses their disease preventative and therapeutic potentials.