Determination of tea components with antioxidant activity

Levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in Spain have been evaluated. Chromium, manganese, selenium, and zinc were determined in the samples mineralized with HNO(3) and V(2)O(5), using ETAAS as the analytical technique. The reliability of the procedure was checked by analysis of a certified reference material. Large variations in the trace element composition of teas were observed. The levels ranged from 50.6 to 371.4 ng/g for Cr, from 76.1 to 987.6 microg/g for Mn, from 48.5 to 114.6 ng/g for Se, and from 56.3 to 78.6 ng/g for Zn. The four major catechins [(-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC)], gallic acid (GA), and caffeine were simultaneously determined by a simple and fast HPLC method using a photodiode array detector. In all analyzed samples, EGCG ranged from 1.4 to 103.5 mg/g, EGC from 3.9 to 45.3 mg/g, ECG from 0.2 to 45.6 mg/g, and EC ranged from 0.6 to 21.2 mg/g. These results indicated that green tea has a higher content of catechins than both oolong and fermented teas (red and black teas); the fermentation process during tea manufacturing reduces the levels of catechins significantly. Gallic acid content ranged from 0.039 to 6.7 mg/g; the fermentation process also elevated remarkably gallic acid levels in black teas (mean level of 3.9 +/- 1.5 mg/g). The amount of caffeine in the analyzed samples ranged from 7.5 to 86.6 mg/g, and the lower values were detected in green and oolong teas. This study will be useful for the appraisal of trace elements and antioxidant components in various teas, and it will also be of interest for people who like drinking this beverage.     

In vitro antioxidant activities of barley, husked oat, naked oat, triticale, and buckwheat wastes and their influence on the growth and biomarkers of antioxidant status in rats

The study was aimed at verification of the following hypothesis: differences in antioxidant capacity of diets consisting of different cereals and byproducts affect the antioxidant status of the consumers of these diets. To validate that hypothesis this study investigated the contents of polyphenols and alpha-tocopherol as well as the total antioxidant capacity (TAC) in vitro of cereals and their fractions (barley, husked and naked oat, oat bran, and triticale); the nutritional and antioxidant properties of diets containing these cereals, applied in a 4-week feeding experiment on rats, were also assessed. Among the cereals examined, the highest TAC was reported for barley (13.16 micromol of Trolox/g) and the lowest for naked oat (3.84 micromol of Trolox/g). Compared with cereals, the TAC of buckwheat waste was 2-3 times higher (25.2 micromol of Trolox/g). The antioxidant capacity of diets, calculated in vitro, ranged from 6.35 micromol of Trolox/g for naked oat type diet to 10.51 micromol of Trolox/g for barley type diet. Results of an in vitro study were confirmed in changes of glutathione peroxidase (GPx) activities and the level of thiobarbituric acid-reactive substances (TBARS) in the serum of rats fed diets with the highest and lowest antioxidant capacities in vitro; the barley diet increased the activity of GPx (37.63 units/mL) and decreased the level of TBARS (4.82 microg/g), whereas the naked oat diet had an opposite effect (31.16 units/mL and 5.91 microg/g, respectively).     

Phytochemicals and antioxidant activity of milled fractions of different wheat varieties

The health-promoting effects of whole-grain consumption have been attributed in part to their unique phytochemical contents and profiles that complement those found in fruits and vegetables. Wheat is an important component of the human diet; however, little is known about the phytochemical profiles and total antioxidant activities of milled fractions of different wheat varieties. The objectives of this study were to investigate the distribution of phytochemicals (total phenolics, flavonoids, ferulic acid, and carotenoids) and to determine hydrophilic and lipophilic antioxidant activity in milled fractions (endosperm and bran/germ) of three different wheat varieties, two of which were grown in two environments. Grain samples of each of the wheat varieties were milled into endosperm and bran/germ fractions. Each fraction was extracted and analyzed for total phenolics, ferulic acid, flavonoids, carotenoid contents, and hydrophilic and lipophilic antioxidant activities. Total phenolic content of bran/germ fractions (2867-3120 micromol of gallic acid equiv/100 g) was 15-18-fold higher (p < 0.01) than that of respective endosperm fractions. Ferulic acid content ranged from 1005 to 1130 micromol/100 g in bran/germ fractions and from 15 to 21 micromol/100 g in the endosperm fractions. The bran/germ fraction flavonoid content was 740-940 micromol of catechin equiv/100 g. On average, bran/germ fractions of wheat had 4-fold more lutein, 12-fold more zeaxanthin, and 2-fold more beta-cryptoxanthin than the endosperm fractions. Hydrophilic antioxidant activity of bran/germ samples (7.1-16.4 micromol of vitamin C equiv/g) was 13-27-fold higher than that of the respective endosperm samples. Similarly, lipophilic antioxidant activity was 28-89-fold higher in the bran/germ fractions (1785-4669 nmol of vitamin E equiv/g). Hydrophilic antioxidant activity contribution to the total antioxidant activity (hydrophilic + lipophilic) was >80%. In whole-wheat flour, the bran/germ fraction contributed 83% of the total phenolic content, 79% of the total flavonoid content, 51% of the total lutein, 78% of the total zeaxanthin, 42% of the total beta-cryptoxanthin, 85% of the total hydrophilic antioxidant activity, and 94% of the total lipophilic antioxidant activity. Our results showed that different milled fractions of wheat have different profiles of both hydrophilic and lipophilic phytochemicals. These findings provide information necessary for evaluating contributions to good health and disease prevention from whole-wheat consumption.     

Total polyphenol content and antioxidant capacity of commercially available tea (Camellia sinensis) in Argentina

Tea, Camellia sinensis (L.) O. Kuntze (Theaceae) is cultivated in Argentina in the northeastern region (provinces of Misiones and Corrientes), between 26 degrees and 28 degrees south latitude, the southernmost area of the world where tea is cultivated. The objective of this work was to determine the total polyphenol content and the in vitro antioxidant capacity of green and black tea cultivated and industrialized in Argentina. Twelve samples of eight brands were analyzed. The total polyphenol content was determined according to the International Organization for Standardization method (ISO) 14502-1 for the determination of substances characteristic of green and black tea. The antioxidant capacity was determined by the ferric thiocyanate method (FTC) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging assay. Green tea showed a higher polyphenol content than black tea. The total polyphenol concentration in green tea was found to vary from 21.02 +/- 1.54 to 14.32 +/- 0.45% of gallic acid equivalents (GAE), whereas in black tea, the polyphenol content ranged from 17.62 +/- 0.42 to 8.42 +/- 0.55% of GAE (P < 0.05). A similar profile was observed for the antioxidant capacity determined by both methods. The antioxidant activities were well correlated with the total polyphenol content (r (2) = 0.9935 for the ferric thiocyanate method and r (2) = 0.9141 for the 1,1-diphenyl-2-picrylhydrazyl free-radical scavenging assay). This is the first systematic screening for the quantification of polyphenols and antioxidant activity in tea commercialized in Argentine markets. The results obtained herein allow one to conclude that Argentine tea is of very good quality when compared to teas from other sources.     

A new test method for the evaluation of total antioxidant activity of herbal products

A new test method for measuring the antioxidant power of herbal products, based on solid-phase spectrophotometry using tetrabenzo-[b,f,j,n][1,5,9,13]-tetraazacyclohexadecine-Cu(II) complex immobilized on silica gel, is proposed. The absorbance of the modified sorbent (lambda(max) = 712 nm) increases proportionally to the total antioxidant activity of the sample solution. The method represents an attractive alternative to the mostly used radical scavenging capacity assays, because they generally require complex long-lasting stages to be carried out. The proposed test method is simple ("drop and measure" procedure is applied), rapid (10 min/sample), requires only the monitoring of time and absorbance, and provides good statistical parameters (s(r)相似文献   

The impact of packaging materials on the antioxidant phytochemical stability of aqueous infusions of green tea (Camellia sinensis) and yaupon holly (Ilex vomitoria) during cold storage

Ready to drink (RTD) teas are a growing segment in the beverage category, brought about by improvements in the flavor of these products and healthy market trends driven by consumers. The presented results evaluated the antioxidant phytochemical stability of RTD teas from aqueous infusions of traditional green tea (Camellia sinensis) and a botanical tea from yaupon holly (Ilex vomitoria) as influenced by packaging materials during cold storage. Two common packaging materials for RTD products are glass and polyethylene terephthalate (PET) and have been compared to a retortable pouch (RP), an emerging packaging material for various types of food since it is durable, inexpensive, lightweight, and easy to sterilize. Storage stability was then evaluated for each aqueous infusion prepared at 10 g/L at 90 °C for 10 min and evaluated at 3 °C in the absence of light over 12 weeks. Analyses included quantification and characterization of individual polyphenolics by high-performance liquid chromatography-photodiode array and liquid chromatography-electrospray ionization-mass spectrometry as well as changes in total antioxidant capacity. For green tea, concentrations of the three major flavan-3-ols, epigallocatechin gallate, epigallocatechin, and epicatechin gallate were better retained in glass bottles as compared to other packages over 12 weeks. In yaupon holly, chlorogenic acid and its isomers that were the predominant compounds were generally stable in each packaging material, and a 20.6-fold higher amount of saponin was found as compared to green tea, which caused higher stability of flavonol glycosides present in yaupon holly during storage. The antioxidant capacity of green tea was better retained in glass and PET versus RP, whereas no differences were again observed for yaupon holly. Results highlight the superiority of oxygen-impervious glass packaging, but viable alternatives may be utilizable for RTD teas with variable phytochemical compositions.     

Effect of growing and drying conditions on the phenolic composition of mate teas (Ilex paraguariensis)

Mate tea ( Ilex paraguariensis) has been used for centuries and is widely consumed in Brazil, Argentina, Paraguay, and Uruguay. The aim of the present study was to determine how growing and drying conditions affect the phenolic concentration and antioxidant capacity of 15 Mate teas from forest or plantation cultivations, dried either with hot air or wood smoke. The total polyphenol concentration determined with Folin-Ciocalteu ranged from 100.3 +/- 5.5 to 179.7 +/- 3.6 mg equiv chlorogenic acid/g dry leaves. The antioxidant capacity according to the oxygen radical absorbance capacity assay ranged from 1.5 +/- 0.3 to 4.1 +/- 0.1 mmol Trolox equiv/g dry leaves. Ten phenolic compounds were identified and correlated with antioxidant capacity ( R (2) = 0.80). Principle component analysis and multivariate linear regression were conducted to assess the effect of growing and drying conditions. Sun-exposed (plantation grown) Mate teas exhibited higher levels of all polyphenols as compared to shaded (forest grown) Mate teas ( P < 0.05). Lower rainfall, temperature, and drying conditions had varying effects on the phenolics. On average, plantation grown Mate teas had a greater concentration of phenolics than forest grown teas. Thus, plantation grown Mate teas represent better potential sources for their commercial extraction.     

Total phenol, catechin, and caffeine contents of teas commonly consumed in the United kingdom.

Levels of total phenol, catechins, and caffeine in teas commonly consumed in the United Kingdom have been determined using reversed phase high-performance liquid chromatography. Tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. The resulting data showed considerable variability in both total phenols [80.5-134.9 mg/g of dry matter (DM) in black teas and 87-106.2 mg/g of DM in green teas] and catechins (5.6-47.5, 51.5-84.3, and 8.5-13.9 mg/g of DM in black, green, and fruit teas, respectively); this was most probably a result of differing agronomic conditions, leaf age, and storage during and after transport, as well as the degree of fermentation. Caffeine contents of black teas (22-28 mg/g of DM) were significantly higher than in less fermented green teas (11-20 mg/g of DM). The relative concentration of the five major tea catechins ranked EGCG > ECG > EC > EGC > C. The estimated U.K. dietary intakes of total tea catechins, calculated on the basis of an average tea consumption of three cups of tea (200 mL cup, 1% tea leaves w/v), were 61.5, 92.7, and 405.5 mg/day from fruit teas, black teas, and green teas, respectively. The coefficients of variation were 19.4, 88.6, and 17.3%, respectively, indicating the wide variation in these intakes. The calculated caffeine intake ranged between 92 and 146 mg/day. In addition, many individuals will consume much larger quantities of tea, of various strengths (as determined by the brewing conditions employed). This broad spread of U.K. daily intakes further emphasizes the need for additional research to relate intake and effect in various population groups.     

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.     

Cocoa has more phenolic phytochemicals and a higher antioxidant capacity than teas and red wine

Black tea, green tea, red wine, and cocoa are high in phenolic phytochemicals, among which theaflavin, epigallocatechin gallate, resveratrol, and procyanidin, respectively, have been extensively investigated due to their possible role as chemopreventive agents based on their antioxidant capacities. The present study compared the phenolic and flavonoid contents and total antioxidant capacities of cocoa, black tea, green tea, and red wine. Cocoa contained much higher levels of total phenolics (611 mg of gallic acid equivalents, GAE) and flavonoids (564 mg of epicatechin equivalents, ECE) per serving than black tea (124 mg of GAE and 34 mg of ECE, respectively), green tea (165 mg of GAE and 47 mg of ECE), and red wine (340 mg of GAE and 163 mg of ECE). Total antioxidant activities were measured using the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays and are expressed as vitamin C equivalent antioxidant capacities (VCEACs). Cocoa exhibited the highest antioxidant activity among the samples in ABTS and DPPH assays, with VCEACs of 1128 and 836 mg/serving, respectively. The relative total antioxidant capacities of the samples in both assays were as follows in decreasing order: cocoa > red wine > green tea > black tea. The total antioxidant capacities from ABTS and DPPH assays were highly correlated with phenolic content (r2 = 0.981 and 0.967, respectively) and flavonoid content (r2 = 0.949 and 0.915). These results suggest that cocoa is more beneficial to health than teas and red wine in terms of its higher antioxidant capacity.     

Comparison of the antioxidant activity of commonly consumed polyphenolic beverages (coffee, cocoa, and tea) prepared per cup serving.

In this study, the in vitro low-density lipoprotein oxidation model was used to assess the relative antioxidant activity of the polyphenolic beverages tea, coffee, and cocoa on a cup-serving basis. The beverages were prepared as 0.7-2.5% soluble coffee and 1.5-3.5% cocoa; teas (green, black, or herbal) were prepared as one tea bag infused over 5 min in 220 mL of hot water. Under these standard cup serving conditions, the antioxidant activity as determined by the lag time was in the range of 292-948 min for coffee, 217-444 min for cocoa, 186-338 min for green tea, 67-277 min for black tea, and 6-78 min for herbal tea. Addition of milk did not alter the antioxidant activity. The influence of coffee bean source and degree of roasting was further investigated. Green coffee beans of Robusta coffee exhibited a 2-fold higher antioxidant activity than Arabica coffee, but after roasting this difference was no longer significant. In conclusion, these commonly consumed beverages have a significant antioxidant activity, the highest being soluble coffee on a cup-serving basis.     

Comparison of antioxidant and antimicrobial activities of tilia (Tilia argentea Desf ex DC), sage (Salvia triloba l.), and black tea (Camellia sinensis) extracts

The antioxidant activity of the water extract of Tilia argentea Desf ex DC was determined by the thiocyanate method. The antioxidant activity of the water extract increased with the increasing amount of lyophilized extract (50-400 microg) added into the linoleic acid emulsion. Statistically significant effect was determined in 100 microg and higher amounts. Antioxidant activities of water extracts of tilia (Tilia argentea Desf ex DC), sage (Salvia triloba L.), and two Turkish black teas commercially called Rize tea and young shoot tea (Camellia sinensis) were compared. For comparison studies, 100 microg portions of extracts were added into test samples. All samples were able to show statistically significant antioxidant effect. Both of the tea extracts showed highest antioxidant activities, nevertheless, differences between tilia and sage and tilia and tea were not statistically significant (for both cases p > 0.05). Like antioxidant activity, the reducing power of water extract of Tilia argentea Desf ex DC was also concentration dependent. Even in the presence of 50 microg of extract, the reducing power was significantly higher than that of the control (p < 0.05) in which there was no extract. Unlike antioxidant activity, the highest reducing power activity was shown by sage extract. Among the tea extracts, young shoot extract was the most effective one, however, it had significantly lower activity than sage (p < 0.05). Although tea flower had the lowest reducing power activity, it was higher than that of tilia. But this difference was not statistically significant (p > 0.05). From these results, we could suggest that although the reducing power of a substance may be an indicator of its potential antioxidant activity, there may not always be a linear correlation between these two activities. In addition, antimicrobial activities of each of the above extracts were studied by disk diffusion methods on different test microorganisms. None of the extracts showed antibacterial activity on the studied microorganisms.     

Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity

Processed fruits and vegetables have been long considered to have lower nutritional value than their fresh commodities due to the loss of vitamin C during processing. This research group found vitamin C in apples contributed < 0.4% of total antioxidant activity, indicating most of the activity comes from the natural combination of phytochemicals. This suggests that processed fruits and vegetables may retain their antioxidant activity despite the loss of vitamin C. Here it is shown that thermal processing elevated total antioxidant activity and bioaccessible lycopene content in tomatoes and produced no significant changes in the total phenolics and total flavonoids content, although loss of vitamin C was observed. The raw tomato had 0.76 +/- 0.03 micromol of vitamin C/g of tomato. After 2, 15, and 30 min of heating at 88 degrees C, the vitamin C content significantly dropped to 0.68 +/- 0.02, 0.64 +/- 0.01, and 0.54 +/- 0.02 micromol of vitamin C/g of tomato, respectively (p < 0.01). The raw tomato had 2.01 +/- 0.04 mg of trans-lycopene/g of tomato. After 2, 15, and 30 min of heating at 88 degrees C, the trans-lycopene content had increased to 3.11+/- 0.04, 5.45 +/- 0.02, and 5.32 +/- 0.05 mg of trans-lycopene/g of tomato (p < 0.01). The antioxidant activity of raw tomatoes was 4.13 +/- 0.36 micromol of vitamin C equiv/g of tomato. With heat treatment at 88 degrees C for 2, 15, and 30 min, the total antioxidant activity significantly increased to 5.29 +/- 0.26, 5.53 +/- 0.24, and 6.70 +/- 0.25 micromol of vitamin C equiv/g of tomato, respectively (p < 0.01). There were no significant changes in either total phenolics or total flavonoids. These findings indicate thermal processing enhanced the nutritional value of tomatoes by increasing the bioaccessible lycopene content and total antioxidant activity and are against the notion that processed fruits and vegetables have lower nutritional value than fresh produce. This information may have a significant impact on consumers' food selection by increasing their consumption of fruits and vegetables to reduce the risks of chronic diseases.     

Phytochemical quantification and total antioxidant capacities of emmer (Triticum dicoccon Schrank) and einkorn (Triticum monococcum L.) wheat landraces

In this study, samples of 18 ancient wheat (12 emmer, 6 einkorn) and 2 bread wheat varieties grown in different regions of Turkey were examined for their total phenolics and flavonoids, phenolic acids, lutein, total yellow pigment, and total radical scavenging capacities against ABTS cation. Results showed that health beneficial phytochemicals and total antioxidant capacities were generally significantly different in emmer and einkorn wheat groups. Remarkably higher total antioxidant activity (18.31 +/- 1.31 micromol Trolox equiv/g), total phenolics (6.33 +/- 0.98 micromol gallic acid equiv/g), ferulic acid (662.95 +/- 61.07 microg/g), and flavonoids (1.61 +/- 0.34 micromol catechin equiv/g) content were detected in emmer wheat samples (n = 12), suggesting that they may have high potential for utilization as a novel grain, rich in natural antioxidants. In addition, quite high levels of lutein (7.33 +/- 2.43 microg/g) of einkorn samples (n = 6) hold the potential of developing high-lutein bakery products to considerably raise the dietary intake of carotenoids. These findings for ancient wheat varieties are considered to be very useful in breeding programs for selecting and breeding wheat varieties for higher concentration and better composition of health-beneficial phytochemicals.     

Literature data may underestimate the actual antioxidant capacity of cereals

Several recent articles have reported a significant antioxidant capacity of cereal products, determined in methanolic and ethanolic extracts. The aim of this work was to conduct an assessment of the antioxidant capacity of cereals using both chemical and in vitro digestive enzymatic extraction of antioxidants. Ferric reducing power (FRAP) and free radical scavenging capacity (DPPH) methods were used to determine the antioxidant capacity in wheat flour, bread, raw and boiled rice, wheat bran, and oat bran. The most efficient antioxidant extraction was achieved by using successively acidic methanol/water (50:50 v/v, pH 2) and acetone/water (70:30 v/v). The antioxidant capacity in these extracts ranged from 1.1 to 4.4 micromol Trolox/g dw. A significant amount of hydrolyzable phenolics with a high antioxidant capacity (from 5 to 108 micromol Trolox/g dw) was found in the residues of this aqueous-organic extraction. The antioxidant capacities of these nonextractable polyphenols are usually ignored in the literature, although they may have an antioxidant role in the gastrointestinal tract, especially after colonic fermentation, and may be fermentated to active metabolites. On the other hand, in vitro digestive enzymatic extracts obtained by enzymatic treatments that mimic conditions in the gastrointestinal tract showed that the amount of antioxidants released by the cereal matrix into the human intestine may be higher than the one that can be expected from measurements in the usual aqueous-organic extracts.     

Phenolic constituents and antioxidant activity of Wendita calysina leaves (Burrito), a folk Paraguayan tea

Burrito tea originates from the leaves of Wendita calysina, an indigenous Paraguayan plant, which is commonly consumed in South America and in Western countries. Phytochemical investigation of this species has led to the isolation of 14 constituents, among them 2 new flavanonols, dihydroquercetagetin (1) and 3,5,6,7,4'-pentahydroxyflavanonol (2), in addition to several known methoxyflavones, methoxyflavonols, phenylethanoid glycosides, and benzoic acid derivatives (4-14). All structures were elucidated by ESI-MS and NMR spectroscopic methods. Quantitative determination of phenolic constituents from burrito water infusions has been performed by HPLC-UV-DAD. The total antioxidant activity of the tea was measured by the ABTS(*)(+) radical cation decolorization and chemiluminescence (CL) assays and compared with the values of other commonly used herbal teas (green and black teas, mate, and rooibos).     

Determination of tea polyphenols and caffeine in tea flowers (Camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects

The native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin 3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed by an isocratic HPLC procedure. The levels of total catechins and caffeine were determined in tea flowers collected from 10 different species of Camellia sinensis. The results showed the levels of total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g. Levels of catechins and caffeine in tea leaves and various teas were also determined and ranged from 2 to 126 mg/g and from 23 to 49 mg/g, respectively. Both tea flower and tea leaf extracts exert their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells. Most tea flowers contain less caffeine, but comparable amounts of total catechins, compared to tea leaves and teas. The present study demonstrates that both tea flowers and tea leaves contain appreciable amounts of catechins and caffeine. It is likely that tea flowers might be useful for making alternative tea beverages.     

Polyphenolic compounds, antioxidant capacity, and quinone reductase activity of an aqueous extract of Ardisia compressa in comparison to mate (Ilex paraguariensis) and green (Camellia sinensis) teas

Aqueous extracts of the leaves of Ardisia compressa (AC) have been used in folk medicine to treat various liver disorders including liver cancer. The objective of this study was to partially characterize and determine the total polyphenol content, antioxidant capacity, and quinone reductase activity of A. compressa tea in comparison to mate (Ilex paraguariensis, MT) and green (Camellia sinensis,GT) teas. Total polyphenol content, antioxidant capacity, and phase II enzyme induction capacity were measured by the modified Folin-Ciocalteu, ORAC, and quinone reductase (QR) assays, respectively. The major polyphenols in AC were not catechins. HPLC retention times and standard spikes of AC indicated the presence of gallic acid, epicatechin gallate, ardisin and kaempferol. Using catechin as standard, the total polyphenol value of AC (36.8 +/- 1.1 mg/mg DL) was significantly lower than GT (137.2 +/- 5.8 mg equivalent of (+)-catechin/mg dried leaves, DL) and MT (82.1 +/- 3.8 mg/mg DL) (P < 0.001). Antioxidant capacity (AC, 333; GT, 1346; MT, 1239 mmol Trolox equivalents/g DL) correlated with total polyphenol values (r(2) = 0.86, P < 0.01). AC (4.5-12.5 microg/mL) induced QR enzyme, in Hepa1c1c7 cells, up to 15%. MT and GT showed no induction at the concentrations tested (0.5-10.5 and 0.5-12.5 mg/mL, respectively). These results suggest that AC has a different mechanism of protection against cytotoxicity that is not related to its antioxidant capacity. Further studies are needed to determine such mechanisms and to explore its potential as a chemopreventive or therapeutic agent.     

Phytochemical profiles and antioxidant activity of wheat varieties

Whole grain consumption has been associated with reduced risk of chronic diseases, such as cardiovascular diseases and cancer. These beneficial effects have been attributed to the unique phytochemicals of grains that complement those found in fruits and vegetables. Wheat is one of the major grains in the human diet; however, little is known about the inherent varietal differences in phytochemical profiles, total phenolic and carotenoid contents, or total antioxidant activities of different wheat varieties, which ultimately influence the associated nutritional and health benefits of wheat and wheat products. The objectives of this study were to determine the phytochemical profiles and total antioxidant activity for 11 diverse wheat varieties and experimental lines. The profiles included free, soluble-conjugated, and insoluble-bound forms of total phenolics, flavonoids, and ferulic acids and carotenoid content including lutein, zeaxanthin, and beta-cryptoxanthin. The results showed that total phenolic content (709.8-860.0 micromol of gallic acid equiv/100 g of wheat), total antioxidant activity (37.6-46.4 micromol of vitamin C/g), and total flavonoid content (105.8-141.8 micromol of catechin equiv/100 g of wheat) did not vary greatly among the 11 wheat lines. However, significant differences in total ferulic acid content (p < 0.05) and carotenoid content (p < 0.05) among the varieties were observed, with carotenoid content exhibiting the greatest range of values. Carotenoid content among the 11 wheat varieties exhibited 5-fold, 3-fold, and 12-fold differences in lutein, zeaxanthin, and beta-cryptoxanthin, respectively. A synthetic wheat experimental line, W7985, gave the lowest carotenoid concentrations of any of the genotypes in this study. Such large genotypic differences in carotenoid content may open up new opportunities for breeding wheat varieties with higher nutritional value.     

Nutritional and functional characteristics of seven grades of black tea produced in Turkey

Seven grades of black tea [high-quality black tea (grades 1-3) and low-quality black tea (grades 4-7)], processed by ?AYKUR Tea Processing Plant (Rize, Turkey), were examined for their proximate composition, dietary fiber, minerals, and water-soluble vitamins as well as total phenolic content, various antioxidant assays, phenolics (flavanols, alkoloids, condensed phenolics, and phenolic acids), chlorophylls, and carotenoids. Some variations, albeit to different extents, were observed (p < 0.05) among these parameters in seven grades of black tea. With respect to proximate composition, dietary fiber was the predominant compound (ranging from 49.68 to 54.31 g/100 g), followed by protein, carbohydrate, and, to a lesser extent, ash, moisture, and fat. Thirteen minerals, four water-soluble vitamins, six flavanols, two alkoloids, three condensed phenolics, one phenolic acid, two chlorophylls, and two carotenoids were identified in the seven grades of black tea. Total phenol content ranged from 7.52 to 8.29 g of gallic acid equivalents (GAE)/100 g, being lowest in grade 6 and highest in grade 1. With regard to antioxidant activities, a large variation in oxygen radical absorbance capacity (ORAC) values was observed among all grades of black tea (ranging from 777 μmol of trolox equivalents (TE)/g in grade 7 to 1210 μmol of TE/g in grade 3). The present work suggests that high- and low-quality black teas should not be distinguished on the basis of their nutritional and functional characteristics. The combination of nutritional compounds together with functional characteristics renders combination effects that provide the characteristic quality of each grade of black tea.