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1.
Intake of flavanols, a subgroup of dietary polyphenols present in many fruits and vegetables, may be associated with health benefits, particularly with reducing the risk of coronary diseases. Cocoa and chocolate products are rich in flavanol monomers, oligomers, and polymers (procyanidins). This study used normal phase HPLC to detect, identify, and quantify epicatechin, catechin, total monomers, procyanidin oligomers and polymers in 14 commercially available chocolate bars. In addition, methylxanthines (theobromine and caffeine) were also quantified. Nonfat cocoa solids (NFCS) were determined both gravimetrically and by calculation from theobromine contents. The flavanol levels of 12 commonly consumed brands of dark chocolate have been quantified and correlated with % theobromine and % NFCS. Epicatechin comprised the largest fraction of total chocolate flavonoids, with the remainder being catechin and procyanidins. Calculated NFCS did not reflect epicatechin (R(2) = 0.41) or total flavanol contents (R(2) = 0.49). Epicatechin (R(2) = 0.96) was a reliable marker of total flavanols, catechin (R(2) = 0.67) to a lesser extent. All dark chocolate tested contained higher levels of total flavanols (93.5-651.1 mg of epicatechin equiv/100 g of product) than a milk or a white "chocolate" (40.6 and 0.0 mg of epicatechin equiv/100 g, respectively). The amount and integrity of procyanidins often suffer in the manufacturing of chocolate, chiefly due to oxidation and alkalinization. In this study, the labeled cocoa content of the chocolate did not always reflect analyzed levels of flavonoids. Increasingly, high % NFCS is being used commercially to reflect chocolate quality. If the flavanol content of chocolate is accepted to be a key determinant of health benefits, then continued monitoring of flavanol levels in commercially available chocolate products may be essential for consumer assurance.  相似文献   

2.
Epidemiological studies indicate an inverse relationship between flavanol intake and the risk of cardiovascular disease. Potential mechanisms include their effects on endothelial function and hypertension. A number of studies have shown that flavanol-rich cocoa reduces blood pressure and endothelial dysfunction, whereas black tea may have opposite effects. These results highlight the importance of the different effects of the multitude of phytochemical constituents in these foods and the need for studying the individual flavanols. Epicatechin seems to be a major bioactive constituent of cocoa and other flavanol-rich foods and beverages. It has been shown to improve endothelial function in animals and humans. In salt-sensitive animal models of hypertension, epicatechin lowers blood pressure and the associated end-organ damage. Nitric oxide (NO) seems to play a key role in the protection of both hypertension and endothelial dysfunction.  相似文献   

3.
Quantitative analysis of flavan-3-ols in Spanish foodstuffs and beverages   总被引：2，自引：0，他引：2  
An HPLC method, using detection after postcolumn derivatization with p-dimethylaminocynnamaldehyde (DMACA), was developed for the quantitative analysis of individual flavanols in food. This method was applied to flavanol determination in 56 different kinds of Spanish food products, including fruit, vegetables, legumes, beverages (cider, coffee, beer, tea, and wine), and chocolate. The determined compounds corresponded to the catechins and proanthocyanidin dimers and trimers usually present in food and, therefore, they were representative of the flavanols of low degree of polymerization consumed with the diet. The data generated could be used for calculation of the dietary intake of either individual or total flavanols, which would allow the further establishment of epidemiological correlations with the incidence of chronic diseases. Similar flavanol profiles were found in the different samples of a similar type of product, even though important variations could exist in the concentrations of total and individual flavanols among them. This was attributed to factors such as sample origin, stage of ripeness, post-harvesting conservation, and processing. Total flavanol contents varied from nondetectable in most of the vegetables to 184 mg/100 g found in a sample of broad bean. Substantial amounts were also found in some fruits, such as plum and apple, as well as in tea and red wine. Epicatechin was the most abundant flavanol, followed by catechin and procyanidin B2. In general, catechins were found in all the flavanol-containing products, but the presence of gallocatechins was only relevant in pomegranate, broad bean, lentil, grape, wine, beer, and tea, and most of the berries. Galloyled flavanols were only detected in strawberry, medlar, grape, and tea.  相似文献   

4.
Cocoa is a food ingredient that is important for the contribution of flavor to foods but is also associated with potential health benefits. The chemistry thought to be responsible for its cardiovascular health benefits is the flavanol (flavan-3-ol) antioxidants. Evidence from the literature indicates that natural cocoas are high in flavanols, but when the cocoa is processed with alkali, also known as Dutch processing or Dutching, the flavanols are substantially reduced. This paper provides a survey of the physical and chemical composition of representative natural cocoas and lightly, medium, and heavily alkalized cocoas. As part of the survey, both brown/black and red/brown alkali-processed cocoas were measured. Natural cocoa powders have an extractable pH of 5.3-5.8. Alkalized cocoa powders were grouped into lightly treated (pH 6.50-7.20), medium-treated (pH 7.21-7.60), and heavily treated (pH 7.61 and higher). The natural, nonalkalized powders had the highest ORAC and total polyphenols and flavanols (including procyanidins). These chemical measurements showed a linear decrease as the extractable pH of the cocoa powder increased. Likewise, the flavanol monomers, oligomers, and polymers all showed a linear decrease with increasing pH of the final cocoa powder. When brown/black cocoa powders were compared to red cocoa powders, similar decreases in flavanols were observed with increased alkalization. The average total flavanol contents were 34.6 +/- 6.8 mg/g for the natural cocoas, 13.8 +/- 7.3 mg/g for the lightly processed cocoas, 7.8 +/- 4.0 mg/g for the medium processed cocoas, and 3.9 +/- 1.8 mg/g for the heavily processed cocoa powders. The observed linear and predictable impact of alkalization on flavanol content is discussed with respect to other reports in the literature as well as what implications it may have on diet and food manufacturing.  相似文献   

5.
Proanthocyanidins, particularly those coming from wine and grape products, have became of interest to nutritionists. Particular attention is currently being paid to the exploitation of this kind of grape byproducts for obtaining bio-active phenolic compounds with potential application as food antioxidants and preventive agents against cancer and other diseases. In this work, the flavanol composition of various winery byproducts submitted to different degrees of industrial exploitation has been studied and their antioxidant activity determined using two different methods (TBARS and TEAC) to evaluate their interest as suitable sources for the preparation of flavanol-rich antioxidant extracts. All the byproducts studied were still good flavanol sources no matter their exploitation degree. An important conclusion was that dried grape seeds, obtained as an end byproduct after the color extraction and alcohol distillation of the wine pomace, still kept important flavanol concentrations and significant antioxidant activity, even if they were submitted to high temperatures. These byproducts can be considered a cheap source for the extraction of antioxidant flavanols, which can be used as dietary supplements or in the production of phytochemicals.  相似文献   

6.
Thiolysis of a wine tannin fraction yielded trihydroxylated flavanol units (as previously observed in grape skins) in addition to the well-known procyanidins (dihydroxylated units), usually described in the literature for grape condensed tannins. To determine how they occur in condensed tannins, the wine fraction was analyzed by liquid chromatography coupled to electrospray ionization mass spectrometry. Thus, various series of ion peaks containing a variable number of trihydroxylated units were detected as monocharged ions from dimers up to pentamers. From pentamers, oligomers were found as doubly charged ions. Heptamer species corresponded to the highest mass detected. These results showed that wine condensed tannins consist of, besides procyanidins, mixed tri- and dihydroxylated flavanol units and also of pure trihydroxylated flavanol units. These new data should be taken into account to interpret organoleptic properties of wines.  相似文献   

7.
The effect of procyanidin solutions on superoxide anion radicals was studied with an enzymatic method and their EC(50) values were determined. A comparative study of the results suggested that the free radical scavenger potential of these phenolic compounds closely depends on their chemical and stereochemical structures. Oligomeric procyanidins were isolated in different fractions from grapes and wines by low- and high-pressure liquid chromatography. These compounds were found to be efficient free radical scavengers even for the weak concentrations in wines. Their activity in grapes or wines was much stronger than that of other commercially available natural antioxidants (such as ascorbic acid and gallic acid). The effect of tannins isolated from grapes on different radicals was analyzed according to three distinct methods: an enzymatic method for superoxide anion radicals (O(2)(*)(-)), a chemical method for the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(*)), and an immunochemical method to study the scavenging activity of seed procyanidins on DNA lesions induced by the radical HO(*).  相似文献   

8.
In the United States, commercially available foods, including cocoa and chocolate, are being marketed with statements referring to the level of antioxidant activity and polyphenols. For cocoa-containing foods, there has been no comprehensive survey of the content of these and other chemistries. A survey of cocoa and chocolate-containing products marketed in the United States was conducted to determine antioxidant activity and polyphenol and procyanidin contents. Commercially available samples consisted of the top market share products in each of the following six categories: natural cocoa, unsweetened baking chocolate, dark chocolate, semisweet baking chips, milk chocolate, and chocolate syrup. Composite samples were characterized using four different methods: oxygen radical absorbance capacity (ORAC), vitamin C equivalence antioxidant capacity (VCEAC), total polyphenols, and procyanidins. All composite lots were further characterized for percent nonfat cocoa solids (NFCS) and percent fat. Natural cocoas had the highest levels of antioxidant activities, total polyphenols, and procyanidins followed by baking chocolates, dark chocolates and baking chips, and finally milk chocolate and syrups. The results showed a strong linear correlation between NFCS and ORAC (R (2) = 0.9849), total polyphenols (R (2) = 0.9793), and procyanidins (R (2) = 0.946), respectively. On the basis of principal component analysis, 81.4% of the sample set was associated with NFCS, antioxidant activity, total polyphenols, and procyanidins. The results indicated that, regardless of the product category, NFCS were the primary factor contributing to the level of cocoa antioxidants in the products tested. Results further suggested that differences in cocoa bean blends and processing, with the possible exception of Dutching, are minor factors in determining the level of antioxidants in commercially available cocoa-containing products in the United States.  相似文献   

9.
A peptide possessing antihypertensive activity was purified from Nile tilapia ( Oreochromis niloticus ) gelatin using alcalase, Pronase E, pepsin, and trypsin. Among them, the alcalase hydrolysate exhibited the highest angiotensin converting enzyme (ACE) inhibitory activity. Therefore, it was further analyzed, and a potent ACE inhibitory peptide of DPALATEPDPMPF (1382 Da) was separated and purified. In addition, the protective effect of the purified peptide against free radical-induced cellular and DNA damage in murine microglial cells (BV-2) was determined. These results suggest that the peptide isolated from Nile tilapia (O. niloticus) gelatin acts as a candidate against hypertension and oxidative stress and could be used in health-functional foods.  相似文献   

10.
This research was conducted to understand the effects of heat processing and storage on flavanols and sensory qualities of green tea extract. Fresh tea leaves were processed into steamed and roasted green teas by commercial methods and then extracted with hot water (80 degrees C) at 1:160 ratio (tea leaves/water by weight). Green tea extracts were heat processed at 121 degrees C for 1 min and then stored at 50 degrees C to accelerate chemical reactions. Changes in flavanol composition and sensory qualities of green tea extracts during processing and storage were measured. Eight major flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate, catechin gallate, epigallocatechin gallate, and gallocatechin gallate) were identified in the processed tea extract. Among them, epigallocatechin gallate and epigallocatechin appeared to play the key role in the changes of sensory qualities of processed green tea beverage. The steamed tea leaves produced a more desirable quality of processed green tea beverage than the roasted ones.  相似文献   

11.
An HPLC-MS method for the characterization of proanthocyanidins (PA) has been refined. Further application to red wines provided interesting conclusions about the composition of the flavanol fraction and PA extractability during winemaking. The yield in PA extraction increases with the length of the postfermentative maceration (PFM), as well as the mean degree of polymerization (mDP) of wine flavanols. In early winemaking events mostly monomers to trimers are extracted from grape solids, whereas PFM is required for the significant extraction of higher oligomers. Nevertheless, at the end of a regular process of elaboration the mDP is not very high and does not usually exceed a value of 2.3, dimers and trimers being the predominant flavanols in red wines. With regard to groups of compounds, gallocatechins and prodelphinidins (located in the skins) are extracted rapidly in the first stages of the winemaking. On the contrary, long postfermentative macerations are required for the extraction of galloyled derivatives from the seeds. PA extractability is also dependent on the grape variety used for winemaking. Thus, wines made with Graciano grapes were found to require a longer process of PFM than those made from Tempranillo grapes to obtain similar yields in the extraction of flavanols.  相似文献   

12.
Aged red wines possess significantly different polyphenolic composition compared with young ones, mainly due not only to formation of polymeric compounds but also because of oxidation, hydrolysis, and other transformations that may occur in native grape phenolics during aging. Representative Greek, single-variety, aged red wines were examined for total phenol, total flavanol, and total anthocyanin content using spectrophotometry, and attempts were made to establish correlations with the antiradical, reducing, and hydroxyl free radical scavenging activity. In addition, HPLC analyses were carried out, to ascertain whether individual polyphenols are actually responsible for the antioxidant effects of aged red wines. It was found that total flavanols are the class of polyphenols that account for hydroxyl free radical scavenging efficacy and to a lesser extent for antiradical and reducing ability, whereas there was a less significant link between the antioxidant properties and the total phenolics and only a weak relationship to total anthocyanin content. The correlation of the antioxidant properties with the principal polyphenols showed that individual compounds are weakly associated with all the antioxidant parameters, suggesting that the expression of antioxidant activity in aged red wines is rather a consequence of synergism between various phenolics, and it is not simply attributed to specific constituents.  相似文献   

13.
The physicochemical properties of acidified milk gels after the addition of cocoa flavanols were studied. As the flavanol level increased (from 0 to 2.5 mg/g), syneresis and gel elasticity (tan δ) were found to significantly increase and decrease, respectively. Flavanol addition reduced the stress at fracture, with no changes in fracture strain, suggesting that the bond type (i.e., covalent vs noncovalent) was the underlying factor explaining the ease of fracture. Gels made from recombined milks containing the casein fraction of heated milk and the serum of heated flavanol/milk mixtures showed the lowest values of G' and fracture stress. It was concluded that whey proteins/flavanol interactions were responsible for the poor mechanical properties of flavanol-added acidified milk gels. High-performance liquid chromatography analysis of milk sera showed that 60% of the total available monomeric flavanols was found in the serum phase from which 75% was non-associated to whey proteins. Concomitantly, >70% of flavanols with degree of polymerization >3 were found to be associated with the casein fraction.  相似文献   

14.
This study evaluated the inhibitory effects of plant-based extracts (grape seed, green tea, and white tea) and their constituent flavan-3-ol monomers (catechins) on α-amylase and α-glucosidase activity, two key glucosidases required for starch digestion in humans. To evaluate the relative potency of extracts and catechins, their concentrations required for 50 and 90% inhibition of enzyme activity were determined and compared to the widely used pharmacological glucosidase inhibitor, acarbose. Maximum enzyme inhibition was used to assess relative inhibitory efficacy. Results showed that grape seed extract strongly inhibited both α-amylase and α-glucosidase activity, with equal and much higher potency, respectively, than acarbose. Whereas tea extracts and catechin 3-gallates were less effective inhibitors of α-amylase, they were potent inhibitors of α-glucosidase. Nongallated catechins were ineffective. The data show that plant extracts containing catechin 3-gallates, in particular epigallocatechin gallate, are potent inhibitors of α-glucosidase activity and suggest that procyanidins in grape seed extract strongly inhibit α-amylase activity.  相似文献   

15.
Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable an epidemiological evaluation of catechins, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-catechin, (-)-epicatechin, (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg) in 8 types of black tea, 18 types of red and white wines, apple juice, grape juice, iced tea, beer, chocolate milk, and coffee. Tea infusions contained high levels of catechins (102-418 mg of total catechins/L), and tea was the only beverage that contained GC, EGC, ECg, and EGCg in addition to (+)-catechin and (-)-epicatechin. Catechin concentrations were still substantial in red wine (27-96 mg/L), but low to negligible amounts were found in white wine, commercially available fruit juices, iced tea, and chocolate milk. Catechins were absent from beer and coffee. The data reported here provide a base for the epidemiological evaluation of the effect of catechins on the risk for chronic diseases.  相似文献   

16.
Phenolic compounds are abundant vegetable secondary metabolites in the human diet. The ability of procyanidin oligomers and wine polyphenols to inhibit trypsin activity was studied using a versatile and reliable in vitro method. The hydrolysis of the chromogenic substrate N-benzoyl-d,l-arginine-p-nitroanilide (BApNA) by trypsin was followed by spectrophotometry in the presence and absence of condensed tannins and wine. A clear relationship between the degree of polymerization of procyanidins and enzymatic inhibition was observed. Trypsin activity inhibition was also detected in several types of wine. In general, the inhibition increased with the concentration of phenolic compounds in wines. These results may be relevant when considering these compounds as antinutritional factors, thereby contributing to a reduced absorption of nutrients.  相似文献   

17.
Two monohydroxamates of l-aspartic acid beta-hydroxamate (AAH) and l-glutamic acid gamma-hydroxamate (GAH) were used for testing antioxidant and angiotensin converting enzyme (ACE) inhibitory activities in comparison with those of asparagine and glutamine, respectively. The half-inhibition concentrations, IC(50), of scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 36 and 48 microM and against superoxide radicals were 18.99 and 6.33 mM, respectively, for AAH and GAH. However, no activities of asparagine and glutamine were found. AAH and GAH also exhibited activities against peroxynitrite-mediated dihydrorhodamine 123 oxidations and hydroxyl radical-mediated DNA damage. For ACE inhibitory activities, the IC(50) values were 4.92 and 6.56 mM, respectively, for AAH and GAH. The ACE hydrolyzed products on the TLC chromatogram also confirmed the inhibitory activities of the two amino acid hydroxamates on ACE. When 1.23 mM AAH was added, AAH showed competitive inhibitions against ACE, and the apparent inhibition constant (K(i)) was 2.20 mM.  相似文献   

18.
Dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20.83-62.5% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6.404 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51.32% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber.  相似文献   

19.
White and red wines spiked with catechin-rich green tea extract and grape seed extract were assessed for phenolic content, antioxidant activity, and cross-cultural consumer rejection thresholds in relation to wine as a functional food. Health functionality is an important factor in functional foods, and spiking pure compounds or plant extracts is an effective method to increase or control functionality. The total phenolic content and antioxidant activity were measured in wines spiked to different extract concentrations, namely, control and 50, 100, 200, 400, and 800 mg/L, to confirm the dose-response curves in both white and red wines. Consumer rejection thresholds (CRTs) were established for spiked wines in a Korean and in an Australian population. Our results showed that the green tea extract and grape seed extract increased the antioxidant activity dose dependently, and the CRTs varied considerably between the Korean and the Australian groups, with Koreans preferring wines spiked with green tea extract and Australians showing a preference for wines spiked with grape seed extract. These results have implications for producing wine products that are enhanced in phenolic compounds and targeted to different cultural groups.  相似文献   

20.
Several red wines were elaborated to assess the effect of the degree of grape ripening on wine color and on the levels of flavanol and anthocyanin compounds, which are chiefly responsible for the wine color attributes. Two different cultivars and three different degrees of ripening were studied in two consecutive years. The wines were aged for 1 year in American oak barrels of medium-high char followed by 6 months in the bottle. The results showed that the wines made from more mature grapes had generally higher free anthocyanin content, and during aging the decrease of the free anthocyanins and flavanols took place in conjunction with an increase in the levels of the anthocyanin derivatives or "new pigments", which are responsible for maintaining color intensity and adding violet hues in aged wines. From the results obtained, it seems to be clear that the characteristics and composition of grapes harvested later (7-8 days in this region and for these varieties) than the usual time are quite beneficial to obtaining quality aged wines. The phenolic composition of wines made from the last harvested grapes is mainly responsible for the stability of their color, which is extremely important in product acceptance with a significant increase hence of product quality.  相似文献   

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