Effect of the number of flavanol units on the antioxidant activity of procyanidin fractions isolated from chocolate

Of three different solvents (acetone, ethanol, and methanol) mixed with water and acetic acid, the acetone/water/acetic acid mixture (70:28:2, v/v) proved to be best for extracting dark-chocolate procyanidins. High-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-MS-ESI) was further used to identify oligomers found in the extract. After HPLC fraction collection, the reduction power of flavanoid fractions was measured in the AAPH [2,2'-azobis(2-amidinopropane)dihydrochloride] assay, where oxidation of linoleic acid is induced in an aqueous dispersion. Even expressed in relative monomeric efficiency units, the oxidation-inhibiting power of polymerized oligomers is much stronger than that of monomers. A comparison with 10 usual antioxidants indicated that oligomers with three or more (epi)catechin units are by far the most efficient.     

Procyanidin and catechin contents and antioxidant capacity of cocoa and chocolate products

Cocoa and chocolate products from major brands were analyzed blind for total antioxidant capacity (AOC) (lipophilic and hydrophilic ORAC(FL)), catechins, and procyanidins (monomer through polymers). Accuracy of analyses was ascertained by comparing analyses on a NIST standard reference chocolate with NIST certified values. Procyanidin (PC) content was related to the nonfat cocoa solid (NFCS) content. The natural cocoa powders (average 87% of NFCS) contained the highest levels of AOC (826 +/- 103 micromol of TE/g) and PCs (40.8 +/- 8.3 mg/g). Alkalized cocoa (Dutched powders, average 80% NFCS) contained lower AOC (402 +/- 6 micromol of TE /g) and PCs (8.9 +/- 2.7 mg/g). Unsweetened chocolates or chocolate liquor (50% NFCS) contained 496 +/- 40 micromol of TE /g of AOC and 22.3 +/- 2.9 mg/g of PCs. Milk chocolates, which contain the least amount of NFCS (7.1%), had the lowest concentrations of AOC (80 +/- 10 micromol of TE /g) and PCs (2.7 +/- 0.5 mg/g). One serving of cocoa (5 g) or chocolate (15 or 40 g, depending upon the type of chocolate) provides 2000-9100 micromol of TE of AOC and 45-517 mg of PCs, amounts that exceed the amount in a serving of the majority of foods consumed in America. The monomers through trimers, which are thought to be directly bioavailable, contributed 30% of the total PCs in chocolates. Hydrophilic antioxidant capacity contributed >90% of AOC in all products. The correlation coefficient between AOC and PCs in chocolates was 0.92, suggesting that PCs are the dominant antioxidants in cocoa and chocolates. These results indicate that NFCS is correlated with AOC and PC in cocoa and chocolate products. Alkalizing dramatically decreased both the procyanidin content and antioxidant capacity, although not to the same extent.     

A comparison of carotenoid content and total antioxidant activity in catsup from several commercial sources in the United States

Samples of catsup from 13 commercial sources, representing at least 10 U.S. manufacturers, were analyzed for carotenoid content, antioxidant activity, and percentage solids. The solids content of these catsup brand samples varied from 26.31 to 38.06% solids. The lycopene content ranged from 59.42 to 183.36 microg, and total carotenoids were as high as 216.6 microg/g fresh weight, respectively. In addition, both hydrophilic and lipophilic antioxidant activities were measured using the Trolox equivalent antioxidant capacity (TEAC) assay. These measurements of samples of the various catsup brands ranged from 176.5 to 356.8 total TEAC units.     

Inositol penta- and hexaphosphate content of some cocoa soils in Ghana

The inositol penta- and hexaphosphate content of some typical cocoa soils in Ghana was measured by anion exchange chromatography with HCOONH₄ as eluant. The values which ranged from 6 to 35 ppm P (average 18 ± 8 ppm P) and accounted for 6% to 40% (average 14%) of the organic phosphorus are within those ranges reported for Canadian, Nigerian, but much lower than those for Scottish soils. The penta- and hexaphosphate content of the soil significantly correlated with total P, organic P, organic C, total N, Fe and P retention capacity. Incubation of soil for 11 weeks did not alter the inositol penta- and hexaphosphate content of the soil. Inorganic P adsorption could be decreased by adding inositol hexaphosphate. These data support the suggestion that a role of the esters in nutrition of crops is probably through the indirect effect of blocking of retention sites and agents which would otherwise be free to bind inorganic phosphorus.     

Predictive relationship between polyphenol and nonfat cocoa solids content of chocolate

Chocolate is often labeled with percent cocoa solids content. It is assumed that higher cocoa solids contents are indicative of higher polyphenol concentrations, which have potential health benefits. However, cocoa solids include polyphenol-free cocoa butter and polyphenol-rich nonfat cocoa solids (NFCS). In this study the strength of the relationship between NFCS content (estimated by theobromine as a proxy) and polyphenol content was tested in chocolate samples with labeled cocoa solids contents in the range of 20-100%, grouped as dark (n = 46), milk (n = 8), and those chocolates containing inclusions such as wafers or nuts (n = 15). The relationship was calculated with regard to both total polyphenol content and individual polyphenols. In dark chocolates, NFCS is linearly related to total polyphenols (r2 = 0.73). Total polyphenol content appears to be systematically slightly higher for milk chocolates than estimated by the dark chocolate model, whereas for chocolates containing other ingredients, the estimates fall close to or slightly below the model results. This shows that extra components such as milk, wafers, or nuts might influence the measurements of both theobromine and polyphenol contents. For each of the six main polyphenols (as well as their sum), the relationship with the estimated NFCS was much lower than for total polyphenols (r2 < 0.40), but these relationships were independent of the nature of the chocolate type, indicating that they might still have some predictive capabilities.     

Processing effects on lycopene content and antioxidant activity of tomatoes

Consumption of tomato products has been associated with decreased risk of some cancer types, and the tomato antioxidant, lycopene, is thought to play an important role in the observed health effects. In this study, four carotenoids, trans-lycopene, phytofluene, phytoene, and zeta-carotene, were quantified in tomato products. Samples of raw tomatoes, tomato juice after hot break scalder, and final paste were obtained from two different processing plants over two years. Comparison of carotenoid levels throughout processing indicated that lycopene losses during processing of tomatoes into final paste (25-30 degrees Brix) ranged from 9 to 28%. The initial Brix level of the raw tomatoes appeared to influence the amount of lycopene loss that occurred, possibly due to the differences in processing time required to achieve the final desired Brix level of the paste. In general, no consistent changes in the other carotenoids were observed as a function of processing. The antioxidant activity of fresh tomatoes, tomato paste, and three fractions obtained from these products (i.e., aqueous, methanol, and hexane fractions) was also determined. In both a free radical quenching assay and a singlet oxygen quenching assay, significant antioxidant activity was found in both the hexane fraction (containing lycopene) and the methanol fraction, which contained the phenolic antioxidants caffeic and chlorogenic acid. The results suggest that in addition to lycopene, polyphenols in tomatoes may also be important in conferring protective antioxidative effects.     

Effects of processing steps on the phenolic content and antioxidant activity of beer

A new analytical method (liquid chromatography-antioxidant, LC-AOx) was used that is intended to separate beer polyphenols and to determine the potential antioxidant activity of these constituents after they were allowed to react online with a buffered solution of the radical cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(?+)). Using the LC-AOx method, it was possible to demonstrate that the extent of the antioxidant activity was very much dependent on the phenolic compound considered. The method was also applied to the analysis of beer extracts and allowed the evaluation of their antioxidant activity at different steps of beer processing: brewing, boiling, and fermentation. This study showed that the total antioxidant activity remained unchanged throughout beer processing, as opposed to the polyphenolic content, which showed a 3-fold increase. Hopping and fermentation steps were the main causes of this increase. However, the increase measured after fermentation was attributed to a better extraction of polyphenols due to the presence of ethanol, rather than to a real increase in their content. Moreover, this method allowed the detection of three unknown antioxidant compounds, which accounted for 64 ± 4% of the total antioxidant activity of beer and were individually more efficient than caffeic acid and epicatechin.     

基于盐（碱）生植被盖度的土壤碱化分级

以土壤大面积碱化的新疆奇台绿洲为研究区,探讨了盐(碱)生植被盖度与土壤碱化指标pH、碱化度(ESP)、钠吸附比(SAR)、残余碳酸钠(RSC)、总碱度(TA)的关系。研究表明:研究区土壤存在大量的可代换性钠,碱化强烈。植被盖度与各土壤碱化指标均呈极显著的负相关关系,其与pH的相关系数最高,达0.810,其次为ESP,植被盖度主要受土壤碱化程度的影响。以盐(碱)生植被盖度为主要依据并结合多种土壤碱化指标对研究区碱化土壤进行分级:植被盖度50%左右,pH<8.0,ESP<3%,SAR<3,为非碱化土;植被盖度10%～40%,pH 8.0～9.5,ESP 3%～35%,SAR 3～40,为碱化土;植被盖度<10%,pH>9.5,ESP>35%,SAR>40,为碱土。以植被盖度对碱化土壤的响应为依据建立的土壤碱化分级标准既拓宽了碱化土壤分级的研究视角,也符合研究区的实际情况。     

Phenolic content and antioxidant capacity of muscadine grapes

Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in southern Georgia were separated into skin, seed, and pulp. Each fruit part and the leaves from the corresponding varieties were extracted for HPLC analysis of major phenolics. Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent. Total anthocyanins were determined according to a pH-differential method, using a UV-visible spectrophotometer. Antioxidant capacity was determined by the Trolox equivalent antioxidant capacity (TEAC) assay. Gallic acid, (+)-catechin, and epicatechin were the major phenolics in seeds, with average values of 6.9, 558.4, and 1299.4 mg/100 g of fresh weight (FW), respectively. In the skins, ellagic acid, myricetin, quercetin, kaempferol, and trans-resveratrol were the major phenolics, with respective average values of 16.5, 8.4, 1.8, 0.6, and 0.1 mg/100 g of FW. Contrary to previous results, ellagic acid and not resveratrol was the major phenolic in muscadine grapes. The HPLC solvent system used coupled with fluorescence detection allowed separation of ellagic acid from resveratrol and detection of resveratrol. Reported here for the first time are the phenolic content and antioxidant capacity of muscadine leaves. Major phenolics in muscadine leaves were myricetin, ellagic acid, kaempferol, quercetin, and gallic acid, with average concentrations of 157.6, 66.7, 8.9, 9.8, and 8.6, respectively. Average total phenolics were 2178.8, 374.6, 23.8, and 351.6 mg/g gallic acid equivalent in seed, skin, pulp, and leaves, respectively. Total anthocyanin contents were 2.1 and 132.1 mg/100 g of FW in the skins of bronze and purple grapes, respectively, and 4.3 and 4.6 mg/100 g of FW in seeds and pulps, in that order. Antioxidant capacity values were, on average, 2.4, 12.8, 281.3, and 236.1 microM TEAC/g of FW for pulps, skins, seeds, and leaves, respectively.     

trans-resveratrol content in commercial peanuts and peanut products

A modified high-performance liquid chromatographic (HPLC) method for determination of trans-resveratrol (resveratrol) in peanuts and peanut products has been developed. Resveratrol was extracted with acetonitrile-water (90/10, v/v) by blending with diatomaceous earth at high speed followed by purification of an aliquot of the extract on a minicolumn packed with Al(2)O(3)-ODS (C(18)) mixture. The column was eluted with acetonitrile-water (90/10, v/v), eluate was evaporated under nitrogen, and residue was dissolved in HPLC mobile phase. Resveratrol in an aliquot of purified extract was quantitated by HPLC on silica gel with n-hexane-2-propanol-water-acetonitrile-acetic acid (1050/270/17/5/1, v/v) as a mobile phase. The recovery of resveratrol added to diatomaceous earth at 0.05 microg/g was 98.95 +/- 17.79%; the recovery of the standard added to fresh peanuts (with 0.070 microg/g natural level of resveratrol) at 0.50, 5.00, and 10.00 microg/g was 117.23 +/- 8.87, 100.10 +/- 2.49, and 100.45 +/- 1.51%, respectively. The quantitation limit of resveratrol in fresh peanuts was about 0. 01 microg/g. Roasted peanuts had the lowest content of resveratrol of 0.055 +/- 0.023 microg/g (n = 21), while in peanut butter its concentration was significantly higher, 0.324 +/- 0.129 microg/g (n = 46), and boiled peanuts had the highest level of 5.138 +/- 2.849 microg/g (n = 12). Resveratrol content in commercial peanut products was similar to the resveratrol content of the raw peanut fractions routinely used for making them.     

HPLC method for the quantification of procyanidins in cocoa and chocolate samples and correlation to total antioxidant capacity.

Monomeric and oligomeric procyanidins present in cocoa liquors and chocolates were separated and quantified in four different laboratories using a normal-phase high-performance liquid chromatography (HPLC) method with fluorescence detection. Procyanidin standards through decamers were obtained by extraction from cocoa beans, enrichment by Sephadex LH-20 gel permeation chromatography, and final purification by preparative normal-phase HPLC. The purity of each oligomeric fraction was assessed using HPLC coupled to mass spectrometry. A composite standard was then prepared, and calibration curves were generated for each oligomeric class using a quadratic fit of area sum versus concentration. Results obtained by each of the laboratories were in close agreement, which suggests this method is reliable and reproducible for quantification of procyanidins. Furthermore, the procyanidin content of the samples was correlated to the antioxidant capacity measured using the ORAC assay as an indicator for potential biological activity.     

Effects of cocoa extract on glucometabolism, oxidative stress, and antioxidant enzymes in obese-diabetic (Ob-db) rats

In this present study, we investigated the effects of cocoa extract containing polyphenols and methylxanthines prepared from cocoa powder on the biochemical parameters of obese-diabetic (Ob-db) rats. Obese-diabetic (Ob-db) rats were developed using a high-fat diet (49% fat, 32% carbohydrate, and 19% protein from total energy, kcal) for 3 months, followed by a low dose (35 mg/kg body weight) streptozotocin (STZ) injection. Cocoa extract (600 mg/kg body weight/day) was given to the rats for 4 weeks. The results indicated that there were no significant differences in fasting plasma glucose and insulin level after 4 weeks of cocoa extract administration. Oral glucose tolerance test revealed that cocoa supplementation in Ob-db rats significantly (p < 0.05) reduced plasma glucose at 60 and 90 min compared to unsupplemented Ob-db rats. Plasma free fatty acid and oxidative stress biomarker (8-isoprostane) were significantly (p < 0.05) reduced after cocoa supplementation. Superoxide dismutase activity was enhanced in Ob-db compared to that in nonsupplemented rats. However, no change was observed in catalase activity. The results showed that cocoa supplementation had an effect on postprandial glucose control but not for long term (4 weeks). Moreover, cocoa supplementation could reduce circulating plasma free fatty acid and 8-isoprostane and may enhance the antioxidant defense system.     

Soil quality effects on Chenopodium album flavonoid content and antioxidant potential

Antioxidant capacity, total phenolic content and flavonoid glycosides profile were compared in C.album samples grown in intensively cultivated (IC) and nondisturbed (ND) soils to evaluate differences in their nutraceutical potential. Petroleum ether, methanol, and aqueous extracts were sequentially obtained from C. album dried samples. Methanol crude extract exhibited the highest antioxidant potential and phenolic content, which were significantly enhanced by soil deterioration. This feature was enhanced in its ethyl acetate/n-buthanol subextract that also yielded higher amounts of the fraction containing flavonoid glycosides in samples grown in IC soils. Compounds were isolated by activity guided fractionation, and chemical structure-antioxidant activity relationships were established. Chemical structures were elucidated by chemical and spectroscopic methods. Six known flavonoid glycosides were isolated, and their antioxidant activity was determined by DPPH assay. 1, quercetin-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 2, kaempferol-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 3, quercetin-3-O-beta-D-glucopyranosyl-(1'-->6")-beta-D-glucopyranoside; 4, rutin; 5, quercetin-3-O-beta-D-glucopyranoside; and 6, kaempferol-3-O-beta-D-glucopyranoside. Triosides 1 and 2 were identified for the first time in C. album. Our results suggest that this edible weed, ubiquitously present in cultivated fields, should be considered as a nutraceutical food and an alternative source for nutrients and free radical scavenging compounds, particularly when collected from cultivated fields that seem to increase some of its advantages.     

Flavanol content and antioxidant activity in winery byproducts

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.     

Effect of Aspergillus oryzae-challenged germination on soybean isoflavone content and antioxidant activity

Application of microbial stress to soybean during germination induces the accumulation of phytoalexins, which have many health benefits. In this study, the effects of stress induced by Aspergillus oryzae on the phytochemical composition of germinating soybeans were investigated, and their radical scavenging activity was compared with those of ungerminated (US) and germinated (GS) soybeans. Additionally, the antioxidant activity of coumestrol, a soybean phytoalexin, against hydrogen peroxide-induced reactive oxygen species (ROS) was investigated in HepG2 cells. A. oryzae exposure significantly decreased the total isoflavone content and induced coumestrol and glyceollin I. A. oryzae-challenged germinated soybeans exhibited the highest radical scavenging activity (IC(50) = 0.55 mg/mL) as compared to US and GS. Coumestrol exhibited significantly higher radical scavenging activity than daidzein and genistein. Furthermore, coumestrol significantly prevented hydrogen peroxide-induced ROS production and lipid peroxidation and inhibited decreases in cell viability, intracellular glutathione (GSH) levels, and superoxide dismutase (SOD) activity. These results indicate that using food-grade A. oryzae to elicit the biosynthesis of phytoalexins alters the secondary metabolite profiles of the soybeans and offers enhanced bioactivity of soybean as a functional food ingredient.     

Impact of isolation method on the antioxidant activity of rapeseed meal phenolics

Rapeseed meal is the byproduct of the rapeseed deoiling process. Among oilseed plants, rapeseed contains the greatest amount of phenolic compounds. In this study, the rapeseed phenolics were isolated with aqueous methanol, aqueous ethanol, hot water, and enzymatically with ferulic acid esterase. These isolates were tested for radical scavenging and for liposome and low-density lipoprotein (LDL) model systems. The radical scavenging activities of all isolates were >60% at a concentration of 1.5 mg/mL. In the liposome model system the formation of hexanal was inhibited by all rapeseed meal isolates by >90% and the formation of conjugated diene hydroperoxides by >80% (8.4 microg/mL concentration). All rapeseed meal isolates also inhibited oxidation of LDL particles by >90% inhibition (4.2 microg/mL concentration). Isolation of rapeseed meal phenolics with either water or enzyme is a very suitable method devoid of organic solvents. Thus, rapeseed meal phenolics constitute an interesting source for food and cosmetic applications with antioxidant effect.     

Composition of phenolic compounds and antioxidant activity of commercial aqueous smoke flavorings

The antioxidant activity of 12 aqueous commercial smoke flavorings used in the food industry was determined by two methods: bleaching of the carotenoid crocin and scavenging of the DPPH radical. The reaction with the DPPH radical was evaluated by calculating the effective concentration (EC50) and the antiradical efficiency (AE). A gas chromatography-mass spectrometry method was, moreover, used for the determination of 2-methoxyphenols, 2,6-dimethoxyphenols, and dihydroxybenzenes. The methoxyphenols were extracted from the aqueous smoke by dichloromethane, and also the residue aqueous phase was analyzed to determine the more water-soluble dihydroxybenzenes. The recovery and the repeatability of the method are reported. The total phenolic concentrations of the smoke flavorings showed a wide range, from about 1000 to 25000 mg/kg. Considering the three classes of compounds, the concentrations were about 300-3000 mg/kg for the 2-methoxyphenols, 200-11000 mg/kg for the 2,6-dimethoxyphenols, and 140-10000 mg/kg for the dihydroxybenzenes. The range of the antioxidant activities of the smoke flavorings was wide, reflecting the wide range of the phenolic concentrations. Good correlations were obtained between the total phenolic concentration and the antioxidant activities determined by both the DPPH and crocin assays.     

Effect of a commercial plant growth regulator on the elemental content of tea plants

Abstract

Response of field grown mature tea to the foliar application of Biozyme Crop Plus, a commercial plant growth regulator, applied at different concentrations ranging from 250 to 1000 ppm was evaluated. Tea shoots were analysed to determine their N, P, K, Ca, and Mg contents. The treated tea plant shoots contained significantly higher contents of N and K followed by Ca and Mg than the untreated control plant shoots. The total chlorophyll content of Biozyme treated tea shoots was also increased significantly. Yield response to Biozyme applied to tea bushes were also determined.     

Determination of the chromium content in commercial breakfast cereals in Spain

Chromium (Cr) is an essential element, but the content of this element in many foodstuffs, including breakfast cereals, is still unknown. For this reason, the Cr content in different types of commercially available breakfast cereals in Spain (n = 36) was determined by GFAAS following acid mineralization using HNO(3)-H(2)SO(4)-HClO(4). On validation, the method yielded a recovery rate of 99 +/- 1.08%. Results indicated that breakfast cereals are rich in Cr, with contents ranging between 0.09 +/- 0.04 and 0.55 +/- 0.08 microg.g(-)(1) and a mean content of 0.23 +/- 0.12 microg.g(-)(1). Consumption of breakfast cereals by children and adolescents in Spain could supply a Cr intake of 6.9 microg/d, i.e., 3.45-13.8% of the ESSADI and 19.72% of the RDI.