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Abstract

A new popular way of making tea, especially in Taiwan, is to steep leaves in cold water. Here we investigate whether antioxidant activity of teas may be affected by hot or cold water steeping and if this correlates with their polyphenol content and metal-chelating activity. A set of five loose tea samples, consisting of unblended and blended teas, was analysed following their infusion in either hot water (90 °C, 7 min) or cold water (room temperature, 2 h). Antioxidant activity, measured as hydrogen-donating ability, using the ABTS· and DMPD assays, showed no significant differences among hot or cold teas, except in the case of white tea, where significantly higher values were obtained after cold water steeping, a recurrent finding in this study. The antioxidant activity of the teas correlates well with their total phenolic content and metal-chelating activity. Cold teas were, however, generally better inhibitors of in vitro LDL conjugated diene formation and of loss in tryptophan fluorescence. The results of this study contribute to gaining further knowledge on how the potential health benefits of this popular beverage may be maximised by the different methods of preparation.

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... The preparation method also influences the antioxidant properties of tea. Studies on the impact of tea brewing techniques on flavonoid, catechin, thearubigin and theaflavin content in the black tea extracts have demonstrated that with increased brewing time the content of polyphenol compounds increased as well [10]. The temperature at which tea is brewed also influences its antioxidant properties. ...
... No total antioxidant capacity TEAC values determined by EPR spectroscopy were found in the literature. However, TEAC values obtained in this work are congruent with the values determined through the use of other research methods [1,10,23]. TEAC values found in literature varied between 143 and 3100 (µmol Trolox/100 mL) for black tea [1,10,16,21,24], between 480 and 6200 (µmol TE/100 mL) for green tea [16,17,21] and between 728 and 1205 (µmol Trolox/100 mL) for earl grey tea [17]. ...
... However, TEAC values obtained in this work are congruent with the values determined through the use of other research methods [1,10,23]. TEAC values found in literature varied between 143 and 3100 (µmol Trolox/100 mL) for black tea [1,10,16,21,24], between 480 and 6200 (µmol TE/100 mL) for green tea [16,17,21] and between 728 and 1205 (µmol Trolox/100 mL) for earl grey tea [17]. ...
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The antioxidant properties of different types of tea—green, black and earl grey—were investigated using the EPR spectroscopy method based on a new semi-empirical mathematical model and on a single EPR spectroscopy measurement. The obtained values of the antioxidant capacity were correlated with the bioactive ingredient content identified through the NMR spectroscopy. Moreover, an attempt was made to determine what impact on the antioxidant properties of tea does adding sugar, milk, lemon and honey have. All studied teas exhibited antioxidant properties. The best DPPH free radical scavengers were green teas. Adding sugar, milk and lemon juice to tea did not significantly impact the antioxidant properties of the infusion; adding honey, however, caused an increase in the total antioxidant capacity of the infusion. The aromatic proton content correlates positively with the antioxidant capacity value.
... If results from TPC, TTC and TFC are taken alto-gether, tested servings could be presented as follows -green teas > instant coffees > red wines > black teas > Turkish coffees, pointing out that green teas serving is the richest in investigated compounds. Several studies reported green teas as a greater source of phenolic compounds when compared with black teas ( Carloni et al., 2013 ;Venditti et al., 2010 ;Zhao et al., 2019 ). Same as our findings, other authors also showed a higher content of total phenolics and flavonoids in instant coffee when compared to Turkish coffee ( Gorjanovi ć et al., 2017 ;Pérez-Hernández et al., 2012 ). ...
... On the other hand, green tea servings had a significantly higher content of all tested flavanols, catechin epicatechin and epigallocatechin gallate, when compared with black teas. This is probably due to the fact that during fermentation which occurs in production of black tea, polyphenols undergo enzymatic oxidation and catechins are transformed to theaflavins and thearubigins ( Venditti et al., 2010 ;Zhao et al., 2019 ). It could be also suggested that hydrolysable tannins are present more in black teas, while condensed tannins might be an attribute of green teas. ...
... However, if an overproduction of reactive species occurs, these highly reactive molecules will cause oxidative degradation of proteins, nucleic acids, carbohydrates and fatty acids, leading to oxidative stress, the basis of many pathological con- ditions. For instance, LDL oxidation mediated by free metal ions in the walls of arteries is considered to trigger the formation of atherosclerotic plaque leading to coronary heart diseases, damaged proteins can misfold losing their activity or accumulate in the brain and be the cause of neurodegenerative processes, DNA mutations are the onset of carcinogenesis, while the decrease in the antioxidant mechanisms is the most accepted theory of aging ( Pham-Huy et al., 2008 ;Venditti et al., 2010 ;Yashin et al., 2013 ). Since various mechanisms are implicated in the detrimental effects of oxidative stress, different assays should be conducted in order to elucidate how antioxidants counteract free rad-icals. ...
Article
This study compared the phenolic profile and antioxidant activity, expressed by real serving's concentrations, of most popular plant-based drinks: coffee, tea and wine. Popular brands of coffees, black and green teas and red wines were subjected to LC–MS/MS analysis of 47 phenolic compounds known for their beneficial effect on human health, measurement of total phenolic, tannins and flavonoids contents as well as various in vitro antioxidant assays. Each drink group was characterized by specific compounds and an analogy was drawn between composition and exhibited antioxidant activity. With only phenolic acids and coumarins detected in their composition, coffees showed moderate antioxidant activity in all assays. Teas had the highest antioxidant potential, particularly green tea, with great amounts of gallic and ellagic acids, hyperoside, quercetin 3-O-glucoside, rutin, kaempferol 3-O-glucoside, vitexin, catechin, epicatechin and epigallocatechin gallate present in servings. Red wines showed good antioxidant activity, with great similarity in detected compounds to teas with a few exceptions – myricetin, resveratrol and vanillic acid. By results from this study, it could be concluded that green tea 200 mL serving, when compared with the same of black tea, Turkish and instant coffee, and red wine, has the highest antioxidant activity and content of beneficial polyphenols.
... Indeed, in vitro and in vivo studies have explored a wide range of herbal teas revealing antioxidant properties and potential clinical benefits in chronic conditions, including diabetes, high blood pressure, obesity (Chandrasekara & Shahidi, 2018;Poswal et al., 2019) and cancer (Talib et al., 2020). However, the composition of these infusions varies not only according to the plant species but also according to the brewing conditions (time, temperature) adopted (Venditti et al., 2010;Castiglioni et al., 2015;Damiani et al., 2019). In previous studies, we demonstrated that the brewing conditions of infusions from C. sinensis (common tea) and Aspalathus linearis (rooibos tea) influence the polyphenol content and in vitro antioxidant capacity, and that cold infusions showed similar or higher polyphenol content and antioxidant capacity than the traditionally prepared hot beverages (Venditti et al., 2010;Damiani et al., 2019). ...
... However, the composition of these infusions varies not only according to the plant species but also according to the brewing conditions (time, temperature) adopted (Venditti et al., 2010;Castiglioni et al., 2015;Damiani et al., 2019). In previous studies, we demonstrated that the brewing conditions of infusions from C. sinensis (common tea) and Aspalathus linearis (rooibos tea) influence the polyphenol content and in vitro antioxidant capacity, and that cold infusions showed similar or higher polyphenol content and antioxidant capacity than the traditionally prepared hot beverages (Venditti et al., 2010;Damiani et al., 2019). ...
... The cold infusions (C) were prepared in the same way as the RT ones, but they were kept under continuous stirring at 4°C overnight. These infusion conditions were chosen based on those previously reported in the literature and which reflect standard brewing conditions for the preparation of a cup of tea (Venditti et al., 2010;Castiglioni et al., 2015;Damiani et al., 2019). The rooibos (R), stigmas (St) and black (Bt) teas were prepared using the hot (H) infusion method. ...
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Saffron production from Crocus sativus flowers produces large amounts of by-products that may represent an excellent source of polyphenols. The aim of this work was to evaluate infusions originating from different brewing processes and from different saffron flower portions, in terms of both functional and sensory traits. For this aim, total polyphenols and total flavonoids, in vitro antioxidant assays and an untargeted phenolic profiling were applied. In general, tepals showed higher polyphenols and flavonoids content than stamen infusions, and their bioactives content depended more on brewing temperature than brewing time. These findings were consistent with both antioxidant capacity and phenolic profiling. Multivariate statistics highlighted polyphenols discriminating ‘boiled’ vs. ‘cold’ infusions, being mainly flavonoids, phenolic acids and the alkylphenol 5-pentadecylresorcinol (showing a strong down-accumulation at the higher brewing temperatures). Positive correlations could be highlighted between anthocyanins, flavones, flavonols and lignans, and the in-vitro antioxidant assays. In general, cold brewing was successful in extracting phenolic compounds and provided better sensory properties, thus indicating that this may represent a valuable strategy to develop saffron-based functional beverages with better consumers’ acceptability.
... Moreover, there are further factors to be considered, such as the time of infusion or particle size. In addition, the phytochemical composition of tea is affected by the cultivation conditions, including agricultural practices, location, cultivar, the life cycle of tea leaf, and shelf-life during storage [34,35]. However, the appropriate dose levels of phenolic compounds required for the physiological activity of the human body cannot be identified from the reported findings. ...
... However, the appropriate dose levels of phenolic compounds required for the physiological activity of the human body cannot be identified from the reported findings. Green teas have been studied extensively for their flavonoid and phenolic acid contents and antioxidant activity [2,6,34]. Unfortunately, there is only little data on the undigested residues of matcha tea. ...
... High temperatures responded to a higher yield of caffeine. In addition, the age of green leaves is also a very important factor, as young leaves contain higher caffeine contents when compared to old leaves [1,28,34]. For instance, the levels of caffeine in green teas ranged between 26.7-38.1 mg/g at the extraction conditions of 80 • C and 20 min [3]. ...
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This study investigates the effects of in vitro digestion on the antioxidant activity and release of phenolics, xanthine alkaloids, and L-theanine contents of matcha. It establishes digestibility values between 61.2–65.8%. Considering native matcha, the rutin content (303–479 µg/g) reached higher values than catechin (10.2–23.1 µg/g). Chlorogenic acid (2090–2460 µg/g) was determined as predominant. Rutin, quercetin, ferulic, ellagic, and caffeic acid were the least-released phenolics, and their remaining residues reached 76–84%. Protocatechuic, hydroxybenzoic acid, epigallocatechin, and epigallocatechin-3-gallate were the best-released phenolics, with the remaining residues under 1%. Caffeine, L-theanine, and theobromine contents in native matcha reached 16.1, 9.85, and 0.27 mg/g, respectively. Only caffeine (3.66–5.26 mg/g) and L-theanine (0.09–0.15 mg/g) were monitored in the undigested residue, representing 13 and 0.1% of the remaining part, respectively. A chemiluminescence assay showed that water-soluble antioxidants showed significant antioxidant activity in native matcha, while lipid-soluble compounds showed higher antioxidant activity in the undigested samples. Cinnamic and neochlorogenic acids were determined as the main contributors to the ACW values in the undigested matcha, epicatechin, and quercetin in the ACL fraction. The application of the digestion process reduced the antioxidant activity by more than 94%. SEM has proved specific digestion patterns of in vitro digestibility of matcha.
... In Ireland, 2 of 10 Canada, and the United Kingdom, black tea is mostly prepared using boiling water and consumed with milk and often sugar. A black tea infusion made with a cold steeping temperature (4 or 25 • C) for 2 h has become popular in Taiwan [8,9]. Determining the optimal method of infusing black tea is crucial to achieving high antioxidant activity. ...
... Black tea produced using a short-duration, hot water extraction method exhibited the highest antioxidant activity. This result concurred with reports by Khokhar and Magnusdottir [6], Venditti et al. [8], and Hajiaghaalipour et al. [9]. However, few reports have discussed the effects of the water-tea leaves ratio on the antioxidant activity of black tea. ...
... The results indicate that no difference is observable among these IC 50 values with weight ratios from 25 to 500, as shown in Figure 2. The IC 50 for DPPH scavenging ability ranged from 30.4 ± 3.3 to 26.6 ± 3.9 µg/mL. Therefore, the black tea infusion was fixed with a 100:1 weight ratio for determining the antioxidant capacity in this study to allow comparison with previous reports [6,8,[20][21][22]. ...
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This study determined antioxidant activity in terms of the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging ability and total phenolic content of black tea under different infusion and storage conditions. High performance liquid chromatography analysis identified caffeine, (−)-epigallocatechin, (−)-epicatechin-3-gallate, (−)-epigallocatechin-3-gallate and (−)-gallocatechin-3-gallate in the tea sample. The water–tea leaves weight ratio did not affect the DPPH scavenging ability. However, infusion temperature affected the DPPH scavenging activity and the total phenolic content. In the present study, the 50% inhibitory concentrations (IC50) for DPPH of black tea infused at 60 to 100 °C ranged from 100.0 ± 13.7 to 28.4 ± 4.8 μg/mL. The total phenolic content of black tea steeped at 60 to 100 °C ranged from 50.4 ± 5.2 to 178.6 ± 16.4 mg gallic acid equivalent/g dry leaf. Black tea exhibited increased antioxidant activity when the infusion temperature was increased. Regarding short-term storage, the DPPH scavenging ability and total phenolic content of black tea did not significantly change within 15 days. This result was consistent for storage temperatures of 4, 9, and 25 °C.
... [2][3][4] The medicinal and health properties of tea are well known and have been widely explored. [5] Many studies have also confirmed that tea is anti-carcinogenic, [6] antioxidant, [7][8][9] anti-mutagenicity, [10] antibacterial, [11] antitumor, [12] anti-cariogenic, [13] lowers blood cholesterol, [14] inhibits a rise in blood pressure, [1,15] inhibits increase in blood glucose, [16] and delays aging. [1,17] Thus, tea has been beneficiated effects on several diseases, such as neurodegenerative, cardiovascular, diabetes, obesity, and basically to pathology involving oxidative stress. ...
... The Pouchong tea samples used in this study were obtained from local tea shops (Pinlin District, New Taipei City, Taiwan). The infusions were prepared following the protocols of Venditti et al. (2010) [5] with some modifications. Cold brewed tea infusion was prepared by adding 150 mL of deionized water to 3.0 g of tea and leaving the infusions at 5°C for 1, 2, 4, 6, 8, 10, 12, 14, and 16 h. ...
... The Pouchong tea samples used in this study were obtained from local tea shops (Pinlin District, New Taipei City, Taiwan). The infusions were prepared following the protocols of Venditti et al. (2010) [5] with some modifications. Cold brewed tea infusion was prepared by adding 150 mL of deionized water to 3.0 g of tea and leaving the infusions at 5°C for 1, 2, 4, 6, 8, 10, 12, 14, and 16 h. ...
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The health-maintaining effects of tea on the human body have been widely proven, even with the tea prepared by brewing tea leaves in cold water becoming a new choice other than hot water. In this research, quality and the antioxidant properties of the Pouchong tea infusions prepared with cold water and hot water were determined and explored their relationships under a consumer hedonic test. The results showed that the chemical components of cold tea infusions increased with increasing duration of brewing, and a maximal increment was observed during the first 2 h of brewing. All chemical components under investigation, except caffeine, were found to be higher in the cold tea infusions over 8 h as compared in the hot tea infusions. The antioxidant ability of cold tea infusion increased with increasing duration of brewing and approached the plateau after 12 hours. The chemical components showed a significantly positive correlation with the antioxidant activities (P < .01). Regarding the sensory analysis-consumer hedonic test, the cold tea infusions of 10, 12, and 14 h of brewing had the highest score in taste, the highest score in total acceptability, and the most popular in aroma, respectively. ARTICLE HISTORY
... The presence of the following polyphenolic derivatives in the two types of extracts (methanolic and ethanolic) obtained from the three investigated Equisetum samples was confirmed by the liquid chromatography technique: chlorogenic acid, caffeic acid, ferulic acid, as well as glycosylated derivatives of quercetin and luteolin. Such active principles have also been identified by other authors in extracts obtained by various methods from E. arvense [13,17,22,23]. According to the spectral and quantitative analysis, the flavonoid components quantified in the samples are presented briefly in Table 1. ...
... The ferrous ion is present in serum and intracellular fluid in extremely small amounts, but when its concentration increases and its protein binding capacity is low, it may be involved in pathological phenomena [22]. At the cellular level, it participates in the Fenton and Haber-Weiss reactions of hydroxyl radical generation, one of the most aggressive free radicals involved in the occurrence of oxidative stress [23]. ...
Article
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The sterile stems belonging to the Equisetum species are often used in traditional medicine of various nations, including Romanians. They are highly efficient in treating urinary tract infections, cardiovascular diseases, respiratory tract infections, and medical skin conditions due to their content of polyphenolic derivatives that have been isolated. In this regard, this study aimed to provide the chemical composition of the extracts obtained from the Equisetum species (E. pratense, E. sylvaticum, E. telmateia) and to investigate the biological action in vitro and in vivo. For the chemical characterization of the analyzed Equisetum species extracts, studies were performed by using ultra-high-performance liquid chromatography (UHPLC-DAD). In vitro evaluation of the antioxidant activity of the plant extracts obtained from these species of Equisetum genus was determined. The neuroprotective activity of these three ethanolic extracts from the Equisetum species using zebrafish tests was determined in vivo. All obtained results were statistically significant. The results indicate that E. sylvaticum extract has a significant antioxidant activity; whereas, E. pratense extract had anxiolytic and antidepressant effects significantly higher than the other two extracts used. All these determinations indicate promising results for the antioxidant in vitro tests and neuroprotective activity of in vivo tests, particularly mediated by their active principles.
... Green tea is consumed by two thirds of the world's population (7). Considering the increasing interest in the health properties of tea, especially those with its antioxidant capacity, and taking into account the different types of teas, and the different methods to prepare a cup of tea in different countries which may affect the content of active ingredients in the final preparation of this beverage, it becomes necessary to evaluate the antioxidant activity to determine the changes between process (8). ...
... These results are similar to those reported by Venditti E. and Bacchetti T, they compared the TPC in hot and cold teas and found that always TPC is higher in hot than in cold for green tea extracts, except in the case of white tea, where TPC is significantly higher in cold extracts than in the hot ones. In addition, TPC, in white tea prepared through cold water steeping, is significantly higher than in all other teas prepared in the same way (8). TPC of hot and cold tea extracts obtained in this study generally covers a range of 2.53 -127.74 mg GAE/g per sample, which matches the range of 43.21 -139.02 ...
Article
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Background: Tea (Camellia sinensis) is the most highly consumed beverage in the world in addition to water. The most common way of preparation is by immersing the tea bag in hot or cold water. In Colombia, it is a recent trend and the market is growing continuously. Objectives: The objective of this study is to compare the antioxidant characteristics of four brands of green tea sold in Colombia at room and hot-temperature in relation to the preparation conditions. Methods: Four commercial brands of green tea (Oriental®, Lipton®, Hindú®, Jaibel®) were used in an aqueous extraction at two temperatures: Cold tea extract (25°C) and hot tea extract (80°C). Total polyphenol concentration (TPC) was determined by Folin-Ciocalteu method; Total flavonoid content (TFC) was determined by spectrophotometric method and the antioxidant capacity was determined by two methods: DPPH radical capture assay, and the oxygen radical absorbance capacity (ORAC) assay. Finally, a method to quantify the catechins of the tea extracts, high performance liquid chromatography (HPLC) was applied. Results: The TPC vary between: 2.53-14.63 mg GAE/ g sample for cold tea extract and 29.34-55.06mg GAE/g sample for hot tea extract. The TFC vary between: 2.67-7.08mg CE/g per sample for the cold tea extract and 5.43-8.41 mg CE/ g sample for hot tea extract. A similar profile assays: for cold tea extract: 22.36 - 41.29 mg TE /g sample for DPPH and 22.95-46.25mg TE/g sample for ORAC. Similarly, for hot tea extract the following ranges were: 38.50 - 110.01 mg TE/g sample for DPPH and 23.40- 113.60 mg TE/g sample for ORAC. In general, the values obtained in each assay for each brand were as follows: Oriental®> Lipton®> Hindú®> Jaibel®. The chromatographic profiles showed the presence of ten compounds. Conclusions: These results confirm that the aqueous extraction of green tea at 80°C leads to the formation of infusions made up of compounds with higher antioxidant capacity in comparison with extractions at room temperature.
... Green tea is consumed by two thirds of the world's population (7). Considering the increasing interest in the health properties of tea, especially those with its antioxidant capacity, and taking into account the different types of teas, and the different methods to prepare a cup of tea in different countries which may affect the content of active ingredients in the final preparation of this beverage, it becomes necessary to evaluate the antioxidant activity to determine the changes between process (8). ...
... These results are similar to those reported by Venditti E. and Bacchetti T, they compared the TPC in hot and cold teas and found that always TPC is higher in hot than in cold for green tea extracts, except in the case of white tea, where TPC is significantly higher in cold extracts than in the hot ones. In addition, TPC, in white tea prepared through cold water steeping, is significantly higher than in all other teas prepared in the same way (8). TPC of hot and cold tea extracts obtained in this study generally covers a range of 2.53 -127.74 mg GAE/g per sample, which matches the range of 43.21 -139.02 ...
Article
Full-text available
Background: Tea (Camellia sinensis) is the most highly consumed beverage in the world in addition to water. The most common way of preparation is by immersing the tea bag in hot or cold water. In Colom-bia, it is a recent trend and the market is growing continuously. Objectives: The objective of this study is to compare the antioxidant characteristics of four brands of green tea sold in Colombia at room and hot-temperature in relation to the preparation conditions. Methods: Four commercial brands of green tea (Oriental ® , Lipton ® , Hindú ® , Jaibel ®) were used in an aqueous extraction at two temperatures: Cold tea extract (25°C) and hot tea extract (80°C). Total polyphenol concentration (TPC) was determined by Folin-Ciocalteu method; Total flavonoid content (TFC) was determined by spectrophotometric method and the antioxidant capacity was determined by two methods: DPPH radical capture assay, and the oxygen radical absorbance capacity (ORAC) assay. Finally, a method to quantify the catechins of the tea extracts, high performance liquid chromatography (HPLC) was applied. Results: The TPC vary between: 2.53-14.63 mg GAE/ g sample for cold tea extract and 29.34-55.06 mg GAE/g sample for hot tea extract. The TFC vary between: 2.67-7.08 mg CE/g per sample for the cold tea extract and 5.43-8.41 mg CE/ g sample for hot tea extract. A similar profile assays: for cold tea extract: 22.36-41.29 mg TE /g sample for DPPH and 22.95-46.25 mg TE/g sample for ORAC. Similarly, for hot tea extract the following ranges were: 38.50-110.01 mg TE/g sample for DPPH and 23.40-113.60 mg TE/g sample for ORAC. In general, the values obtained in each assay for each brand were as follows: Oriental ® > Lipton ® > Hindú ® > Jaibel ®. The chromatographic profiles showed the presence of ten compounds. Conclusions: These results confirm that the aqueous extraction of green tea at 80°C leads to the formation of infusions made up of compounds with higher antioxidant capacity in comparison with extractions at room temperature.
... Metal chelation assay was applied after Venditti et al. [28]. A total of 0.2 mL of the sample solution, containing different concentrations of GBSE and reaction mixture, containing 0.74 mL of 0.1 M acetate buffer (pH 5.25), and 0.02 mL of 2 mM ferrous sulfate solution in 0.2 M hydrochloric acid were mixed for 10-15 s. ...
... In our experiment, GBSE at a concentration of 0.25 mg/mL chelated only 0.9% of iron ions; however, it should be noted that the values given by the authors for the chelation of iron ions from the standard EDTA chelator differ significantly from those obtained by us. Thus, the authors find that at a concentration of 0.2 mg/mL (0.68 mM) EDTA chelates 51.2% of iron ions, and we obtain 99.3% chelation of iron ions at 0.5 mM EDTA [28]. In our opinion, it is necessary to establish standard methods for laboratory measurement and calculation of the antioxidant and other pharmacological properties of plant extracts for proper comparison and outlining of the expected therapeutic results. ...
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Oxidative stress underlies the pathogenesis of many diseases, which determines the interest in natural substances with antioxidant properties. Ginkgo biloba L. leaves are well known and widely used in the pharmaceutical industry, but the therapeutic properties of the seeds are less studied. This study aimed to identify the chromatographic profile and to evaluate the antioxidant properties of methanol extract from seeds of G. biloba (GBSE). In the GBSE, flavonoids and terpenes were found as terpenes predominated. The GBSE antioxidant capacity determined by 2,2 azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and 1-diphenyl-2-picrylhydrazyl (DPPH) methods were equal to 1.34% and 0.58% of the activity of reference substance Trolox, respectively. The results of the ferric reducing antioxidant power method showed that the effect of concentration 1 mg/mL (w/v) GBSE was equal to 7.418 mM FeSO4 used as a standard. The cupric reducing antioxidant capacity activity of the GBSE was found to be 215.39 µmol Trolox/g GBSE and is presented as Trolox equivalent. The metal chelation effect of 1 mg/mL (w/v) GBSE was equal to that obtained for 0.018 mM EDTA. In conclusion, GBSE showed a good ability to neutralize ABTS and DPPH radicals and could have a beneficial effect in pathological conditions with oxidative stress etiology.
... The presence of the following polyphenolic derivatives in the two types of extracts (methanolic and ethanolic) obtained from the three investigated Equisetum samples was confirmed by the liquid chromatography technique: chlorogenic acid, caffeic acid, ferulic acid, as well as glycosylated derivatives of quercetin and luteolin. Such active principles have also been identified by other authors in extracts obtained by various methods from E. arvense [13,17,22,23]. According to the spectral and quantitative analysis, the flavonoid components quantified in the samples are presented briefly in Table 1. ...
... The ferrous ion is present in serum and intracellular fluid in extremely small amounts, but when its concentration increases and its protein binding capacity is low, it may be involved in pathological phenomena [22]. At the cellular level, it participates in the Fenton and Haber-Weiss reactions of hydroxyl radical generation, one of the most aggressive free radicals involved in the occurrence of oxidative stress [23]. ...
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Full-text available
Citation: Batir-Marin, D.; Boev, M.; Cioanca, O.; Mircea, C.; Burlec, A.F.; Beppe, G.J.; Spac, A.; Corciova, A.; Hritcu, L.; Hancianu, M. Neuroprotective and Antioxidant Enhancing Properties of Selective Equisetum Extracts. Molecules 2021, 26, 2565. https://doi.org/10.3390/ molecules26092565 Academic Editor: Simona Rapposelli
... Given the growing interest in the health properties of tea, especially those with antioxidant power, and given the different types of tea and the different methods of preparing a cup of tea in different countries, which can affect the active ingredient content in the final preparation of this beverage, it becomes necessary to assess antioxidant activity to determine changes between processes (Venditti et al., 2010). For this reason, this study was conducted to determine the total phenolic compounds, flavonoid content, and antioxidant capacity of five different brands of tea sold in Mali and prepared "Malian style". ...
... However, at the level of total phenolic compounds, the cumulative content of FD, SD and TD is higher than that of WM (p-value=0.026). This may be due to the fact that total phenolic compounds are better extracted hot than cold (Ramírez-Aristizabal et al., 2017;Venditti et al., 2010). Also, this demonstrates that the way green tea is prepared as it is done in the grins does not impact the amount of phenolic compounds and flavonoids in green tea. ...
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The tea consumption has become an important part of the Malian's habits. As a result, an image of tea preparation and consumption among Malians has become widely diffused; tea is offered in three successive glasses: the first drink (FD), the second drink (SD) and the third drink (TD). However, no study has been carried out on the antioxidant potential of this type of green tea preparation. The objective of this work was to evaluate the quality of the preparation methods of green tea (Camellia sinensis) as performed in grins. Thus, a Journal of Food Studies 27 phytochemical screening was carried out, the quantitative estimation of total polyphenols was performed by the method of Folin-Ciocalteu and that of flavonoids by using the aluminum trichloride. The in vitro antioxidant activity of the different tea extracts (macerated and decocted) was determined by the DPPH method. Thus, the presence of several metabolites was revealed in these tea extracts and the cumulative contents of phenolic compounds in the green tea extracts found in the glasses were 150.67 ±7.87 mg EAG/g, while 140.67 ±2.37 mg EAG/g were collected in the macerated extract (WM). Both types of extracts showed similar levels of flavonoids. The antioxidant activity of FD in all tea samples was statistically identical to that of the extracts (WM) from tea samples A and D (p-values > 0.05). It appears from this preliminary study that neither the total phenolic compound contents nor the antioxidant activity would be impacted by the way Malian green tea is prepared.
... We found that the brewing conditions of tea indeed influences the polyphenol content and in vitro antioxidant capacity of the infusions. This was especially evident for white tea, which produced cold infusions with consistently higher polyphenol content and antioxidant capacity than the traditionally prepared hot beverage [14][15][16][17]. ...
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Consumption of rooibos (Aspalathus linearis) as herbal tea is growing in popularity worldwide and its health-promoting attributes are mainly ascribed to its phenolic composition, which may be affected by the brewing conditions used. An aspect so far overlooked is the impact of cold brewing vs regular brewing and microwave boiling on the poly(phenolic) profile and in vitro antioxidant capacity of infusions prepared from red (‘fermented’, oxidized) and green (‘unfermented’, unoxidized) rooibos, the purpose of the present study. By using an untargeted metabolomics-based approach (UHPLC-QTOF mass spectrometry), 187 phenolic compounds were putatively annotated in both rooibos types, with flavonoids, tyrosols, and phenolic acids the most represented type of phenolic classes. Multivariate statistics (OPLS-DA) highlighted the phenolic classes most affected by the brewing conditions. Similar antioxidant capacities (ORAC and ABTS assays) were observed between cold- and regular-brewed green rooibos and boiled-brewed red rooibos. However, boiling green and red rooibos delivered infusions with the highest antioxidant capacities and total polyphenol content. The polyphenol content strongly correlated with the in vitro antioxidant capacities, especially for flavonoids and phenolic acids. These results contribute to a better understanding of the impact of the preparation method on the potential health benefits of rooibos tea.
... Steeping of tea leaves releases 69-85% of their bio-actives within 3-5 min in hot water in case of both black or green tea [34]. Many studies illustrate the effect of diverse types of steeping on the polyphenols [14,35]. Comparable outcomes to these were observed by Damiani et al. [36] concerning infusions of white tea and their impact on tea components extracted besides its antioxidant activity. ...
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Purpose Coffee leaves, generally considered as an agri-waste are traditionally consumed as coffee leaf tea and are known to have medicinal properties. Leaves were valorized by exploring effects of different drying and steeping methods on its phytochemicals and formulation of a functional beverage. Methods The efficiency of drying systems such as sun, shade, and cross-flow (45 ± 1 °C), on drying kinetics, phytochemicals, volatiles and antioxidant potentials from coffee leaves were analysed. Subsequently, effect of steeping processes like hot infusions, cold infusions and cold brew on the physiochemical properties, phytochemical profile and sensory attributes of the functional beverage from coffee leaves were studied. Results Cross-flow drying was significant based on kinetics, rapid drying rate, moisture ratio, modelled successfully by Page equation (R² = 0.998). Chlorogenic acid (32–33 mg/g) was one of the major phytochemicals followed by quercetin (2–4 mg/g), caffeine (2–5 mg/g) and trigonelline (3–8 mg/g) contributing to significant antioxidant activities. Methyl salicylate is key volatile imparting warm-spicy aroma. Hot infusions (HI) asserted significant yield (47.7%), pH (6.54), Brix (1.3), phenolics (89.9 mg/g) and other phytochemicals ensued by cold infusions and cold brew with an appealing hue. The principal component analysis renders HI as superior steeping process with enhanced sensory profile. Conclusion Thus, the study provides insights on valorising coffee leaves in designing a functional beverage that finds new avenues in the coffee industry. Graphical Abstract
... White tea inhibits lipid peroxidation, thereby constrains oxidative damage to tissues of diabetic patients. Anti-oxidant activities of white tea and the level of its catechins or polyphenols are higher compared to green or black tea [18,59]. ...
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Background and aims Diabetes Mellitus (D.M.) is a chronic metabolic disease characterized by hyperglycemia due to insufficient or inefficient insulin secretory response that has become a widespread epidemic primarily due to the increasing prevalence and incidence of type 2 diabetes. Phytochemicals such as flavonoids and regular physical activity have recently attracted attention to developing new anti-diabetic drugs or alternative therapy to control diabetes. The aim of this study was to compare effects of dietary Flavonol consumption in white tea, with or without aerobic training, among patients with type 2 diabetes mellitus as a randomized trial. Methods 49 women with T2D were randomly assigned into groups including control, white tea, aerobic training, and aerobic training + white tea. The interventions were carried out for six months. Weight, Body Mass Index (BMI), body Fat, peak oxygen consumption (VO2Max), and Blood Pressure were evaluated at both the first and last days of the research period. Blood samples were withdrawn on the same days via venipuncture to test blood glucose, insulin, low-density lipoprotein (LDL), high-density lipoprotein (HDL), cholesterol, and triglycerides (T.G.). Results Characteristics analysis showed significant improvements in treated groups. In addition, glucose, insulin, LDL, Cholesterol, and T.G. were significantly reduced while HDL was remarkably increased in treated groups compared to pre-experiment values or the diabetic control group. Conclusion Collectively, white tea combined with aerobic training favorably affects glycemic parameters, lipid profile, blood pressure, and VO2Max in six months in women with T2D. Registered under Clinical Trials.gov Identifier no. NCT00123456.
... During the fermentation process polyphenol oxidase enzyme of the leaves comes to the contact of catechins and leads to the conversion of catechins to their dimmer and polymers known as theaflavins and thearubigins, which affects the ORAC values [22]. In present study green tea showed higher antioxidant activity as compared to black teas which is in well agreement with some other previous studies [23,24] while insignificant studies reported that black teas are better than green ones [25,26]. ...
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The aim of present study is to investigate Total phenol content (TPC), Anti-inflammatory, Anti-allergic and Antioxidant activity (AA) in differently processed Camellia Sinensis (tea) of Bangladesh. TPC varied in the range of 1056.74 (branded tea)-2348.60 (green tea) mg GAE/g respectively. Radical scavenging activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) was found in the range of 1269.91-2432.76 µmol TE/ g while total Oxygen Radical Absorbance Capacity (ORAC) value in the range of 1262.81-2834.51 µmol TE/g. Both green and organic tea showed highest ORAC value when brewed for 5 min in boiling water extract while tea BT-2 and branded (mirzapur) tea exhibited highest ORAC value for 10 min brewing. Anti-inflammatory activity potential was found in the order of green tea> tea BT-2> organic tea> branded tea where both green and organic tea exhibited dose-response relationship. Anti-allergic activity ranged from (60.9-83%) with highest and lowest in green and branded tea respectively.
... Individual phenolic compounds identified by Damiani et al. (2014) were also higher in cold water extractions than in hot water extractions. Their study also showed that the antioxidant activity of the cold water extracts ranged from 17 to 30 mmol TE/ L, which was higher than in hot water extracts, where the antioxidant activity ranged from 5 to 16 mmol TE / L. In their study involving white tea, black tea, oolong, green tea and lyons tea, Venditti et al. (2010) found that only cold water extracts of white tea had significantly (p ≤ 0.05) higher polyphenols compared with hot water extracts; the same trend was observed in the current study in the antioxidant activity of the extracts using the ABTS method. ...
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The positive health benefits associated with tea are made possible by the antioxidant activity of phenolic compounds present in tea. The total phenolic content and antioxidant activity of bush tea (Athrixia phylicoides DC.) and special tea (Monsonia burkeana) were studied. The extractions were done in triplicate using cold water (5, 10 and 15 minutes), hot water (5, 10 and 15 minutes), 95% acetone, 95% methanol and 95% hexane. The experiments were arranged in a complete randomised design (CRD), and samples were extracted in triplicates in each treatment. Results demonstrated that total phenolic content ranged from 2.83 mg GAE / 100 g to 4.93 mg GAE / 100 g for bush tea and 2.60 mg GAE / 100 g to 6.24 mg GAE / 100 g for special tea. The ABTS antioxidant activity ranged from 34.41 μmol TE / g to 58.34 μmol TE / g in bush tea and 86.49 μmol TE / g to 197.46 μmol TE / g in special tea. The DPPH antioxidant activity in bush tea ranged from 59.87 μmol TE / g to 77.17 μmol TE / g and in special tea from 93.78 μmol TE / g to 109.13 μmol TE / g. Special tea had significantly higher total phenols and antioxidant activity (p<0.05) than bush tea. Hot water extractions were found to be comparable to chemical solvent extractions. This suggests that the potential benefits associated with consumption of beverages containing phenolic compounds can be expected from the consumption of these teas.
... The Chinese are mostly preparing green tea leaves by brewing in hot water (70-80 °C) and usually repeatedly brewed seven times. However, the most common way is steeping green tea leaves using a hot water at the temperature at 70-100 °C for 1-20 min [7][8][9]. The development of green tea as a pharmaceutical product needs a proper extraction procedure. ...
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Objective: This study was intended to optimize the extraction condition using central composite design.Methods: Central composite cesign with three independent variables, namely water temperature, brewing time, and brewing number were used to obtain the optimum extraction condition. Two dependent variables, namely yield of extraction and epigallocatechingallate level were used as a response parameter. Epigallocatechin gallate level was determined by using high-performance liquid chromatography method.Results: Extraction yield was varied from 0.30 g to 0.72 g. All variables, namely water temperature, brewing time, and brewing number were able to increase the extraction yield. Epigallocatechingallate level was varied from 190.23 mg/g to 301.74 mg/g. Water temperature, brewing time, and both interaction were able to increase the epigallocatechin gallate level in green tea extract.Conclusion: Optimum extraction condition was shown using hot water at a temperature of 95 °C for 20 min and two-times infusions. The condition obtained extraction yield and epigallocatechingallate of 0.70 g and 286.87 mg/g dry weight, respectively.
... Previous studies have shown that extraction temperature affects the chemical compositions of extracts and hence, their bioactivities. For instance, higher concentrations of phenolics were obtained from white tea (Venditti et al., 2010) and Pleurotus citrinopileatus (Chen et al., 2016) extracted at low temperatures (room temperature and 4°C, respectively) compared to high temperatures (90-100°C). These extracts also had higher antioxidant capacity. ...
... The capacity of the investigated extracts to chelate ferrous ions was determined according to the method described by Venditti et al. with slight modifications [29]. Briefly, the ferrous ion forms with ferrozine a complex with maximum absorbance at 562 nm. ...
... Phenolic compounds of various plants are the main class of natural antioxidants and there is a relationship between antioxidant activity of tissues and phenolic content of plants (Lizcano et al., 2010;Wu et al., 2011). Results of the study showed that the total phenolic content and antioxidant activity of some species of the Asteraceae family were affected by plant species properties and the other factors (Tuberoso et al., 2010;Messaoud and Boussaid, 2011;Venditti et al., 2010;Goncalves et al., 2013). ...
Article
Medicnal and aromatic plants are used in different fields depending on the amount of antioxidant and phenolic substances they have. This study was conducted to determine the antioxidant enzyme activity and phenolic contents of some species of the Asteraceae family (Achillea biebersteinii Afan., Achillea millefolium L., Achillea nobilis L., Artemisia absinthium L., Artemisia alba Turra., Artemisia dracunculus L., Artemisia santanicum L., Artemisia vulgaris L., Carthamus tinctorius L., Centaurea cyanus L., Echinacea pallida Nutt., Echinacea purpurea L. Moench., Grindelia robusta Nutt., Helianthus annuus L., Helichrysum plicatum L., İnula helenium L. and Santolina chamaecyparissus L.) for medicines, additive food supplement and cosmetic sector. In, this study, the antioxidant amount of some medicinal and aromatic plants with different properties belonging to Asteraceae family and hormones, phenolic substance and vitamin C and vitamin E were determined. E. purpurea, A. nobilis, G. robusta and S. chamaecyparissus species have more antioxidant, enzymes, hormones and some phenolic substances such as vitamin C and vitamin E, than other species in Asteracae. According to study result, highest amount of gibberellic acid, salicylic acid, indole acetic acid (IAA), abscisic acid (ABA), catalase (CAT) enzyme activity, peroxidase (POD) enzyme activity, superoksid dismutase (SOD) enzyme activity, ascorbate peroxidase (AxPOD) enzyme activity, malondialdehyte (MDA), hydrogen peroxide, total antioxidant, total phenolic, total carotenoid amount, vitamin E contents, vitamin C contents, chlorogenic acid contents, caffeic acids, chloric acid and proantocyanidin were determined in the A. millefolium (819.46 ng μl ⁻¹ ), A. dracunculus (91.29 ng μl ⁻¹ ), S. cyparissus L. (1985.08 enzyme unit (EU) g leaf ⁻¹ ), S. chamaecyparissus (415.22 EU g leaf ⁻¹ ) E. purpurea (83.78 EU g leaf ⁻¹ ), A. nobilis (41.91 EU g leaf ⁻¹ ), S. chamaecyparissus (140.85 nmol g ⁻¹ ), E. purpurea (10.49 μmol g ⁻¹ ) A. nobilis (1464 μmol Trolox Equivalents (TE) per g ⁻¹ ), E. purpurea (13.34 mg gallic acid (GA) per g ⁻¹ fresh weight (FW)), E. purpurea (29.41 g vitamine A 100 ⁻¹ ), G. robusta (33.63 g-Alfa tocopherol eg 100 g ⁻¹ ), A. nobilis (20.70 g 100g ⁻¹ ), E. purpurea (13.51 mg g ⁻¹ fw), A. nobilis and S. chamaecyparissus (1.83 mg g ⁻¹ fw), S. chamaecyparissus (143.84 mg g ⁻¹ fw) and A. nobilis (83.63%) species, respectively. According to the results obtained, it is determined that there are significant changes in the contents of the medicinal and aromatic plants depending on the region and climatic conditions.
... 2004). Unlike the other types, white tea was reported to exhibit a greater antioxidant activity when tea leaves were exposed to steeping in water at room temperature for 2 hr instead of hot infusion at 90 C for 7 min (Damiani, Bacchetti, Padella, Tiano, & Carloni, 2014;Venditti et al., 2010). Higher extraction time has been demonstrated when extractions were assisted by hot infusion. ...
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Changes in functional characteristics of cold brewed white tea were quantified in response to high pressure processing (HPP). The multiple functional responses of total phenolic content (TPC), total antioxidant activity (TAA), and total caffeine content (TCC) were optimized using Box–Behnken design. Operational HPP conditions involved the ranges of pressure (300–500 MPa), solid (tea leaves)/liquid (water) ratio (SLR; 1–3%), and brewing time (120–600 s). Tea leaves/water ratio was determined as the most important factor with the highest rate of change per 1% increase in SLR for TPC (645.8 mg/L), TCC (11.48%), and TAA (5.09%). The optimum conditions were achieved using 300 MPa, 2.2% SLR, and 600 s brewing time and resulted in 91.9% TAA, 1949.2 mg/L TPC, and 17.5% TCC. APP appeared to be a promising alternative novel technique to minimize TCC and maximize TAA and TPC of cold brewed white tea simultaneously. Practical applications The present study quantifies the multiple health‐related responses of cold brewed white tea to high pressure processing (HPP). The HPP approach adopted in the study provides cold brewed white tea with good quality and is cost‐effective in terms of small‐to‐large scale food industries. Joint optimization results can be used to improve the operational conditions of cold brewed white tea by related food processors.
... As compared to the standard (Table 2) in two different extraction temperatures was presented in Figure 5. The temperature extraction, in this study, significantly affected the antioxidant activity of green tea which in accordance as explained by [16]. ...
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The determination of the antioxidant activity in green tea using FRAP essays developed in a Microfluidic Paper-Based Analytical Device (μPADs) was observed. μPAD was prepared on the chromatographic paper with a suitable pattern and then printed using a solid ink printer. The solid printing was intended to obtain a hydrophobic barrier and a hydrophilic channel on the chromatographic paper. A preliminary study was done to determine the optimum time and temperature used on the penetration of obtaining the hydrophobic barrier to avoid leakage in the channel. Optimization of temperature and time was calculated by the average velocity, the optimum condition was obtained at 120 °C for 90 seconds with an average speed of 0.1 mm.s ⁻¹ . The green tea samples were prepared by extracting its active compound using demineralized water at 25 °C and 90 °C with 2 hours of immersion time. For the measurement of antioxidant activities, the analysis was carried out by placing 0.5 μl in the detection zone and 5 μl samples into the sample zone μPAD. Then, the color reaction product, which propagates from the sample zone to the detection zone, is processed by Image J software to measure color intensity in CMYK mode. Extracts of green tea samples at 25 °C and 90 °C has a significant difference in antioxidant activity. These results indicate that the method developed in this work can be used as an alternative method for analyzing antioxidant activity in green tea extract. The results of the average amount of antioxidant activity in green tea samples were shown with Fe ²⁺ concentration. High-speed detection, low cost, high accuracy, and ease of use can be attributed to the advantages of our μPAD method.
... This is especially true for powdery products that are susceptible to falsification, counterfeiting or imitation, as it is more difficult to prove authenticity after comminution [6][7][8][9]. In addition, blending of tea leaves or powders is commonly used for processing to guarantee a constant tea quality and compensate for deviations caused by cultivation and environment [10,11]. However, this blending practice could also easily be misused. ...
Article
Food testing is of great importance to the food industry and organizations to verify the authenticity claims, to prove the quality of raw materials and products, and to ensure food safety. The market prices of vanilla differed by a factor of about 20 in the last three decades. Therefore the risk of adulteration and counterfeiting of vanilla products is high. Instead of commonly used target analyses and sum parameter assays, a complementary non-target multi-imaging effect-directed screening was developed, which provided a new perspective on the wide range of vanilla product qualities on the market. Planar chromatography was combined with effect-directed assays, and the obtained biological and biochemical profiles of 32 vanilla products from nine different categories revealed a variety of active ingredients. Depending on the region, typical vanilla product profiles and activity patterns were obtained for pods, tinctures, paste (inner part), oleoresin and powder. However, some vanilla products showed additional active compounds and a different intensity pattern. The assessment of differences in the activity patterns pointed to highly active compounds, which were not detected at UV/Vis/FLD but first via the assays. This effect-directed profiling bridges the gap from analytical food chemistry to food toxicology, and thus, makes an important contribution to consumer safety. In the same way, it would accelerate investigations for Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) according to Regulation (EC) No. 1907/2006. The vanilla product profiles substantially differed from those of vanilla aroma or products containing synthetic vanillin or vanilla-flavored food products. Bioactive compounds of interest were online eluted and further characterized via HPTLC−HRMS, which allowed their tentative assignment. After purchase of the standards, these were successfully confirmed by co-chromatography. Quantification of vanillin across nine different product categories revealed levels ranging from 1 µg/g to 36 mg/g with a mean repeatability of 1.9%. The synthetic ethylvanillin was not detected in the investigated samples in significant concentrations.
... The potential to chelate ferrous ions was determined for the investigated extracts according to the method described by Venditti et al. with some modifications [54,55]. The ferrous ions form with ferrozine a complex with maximum absorbance at 562 nm. ...
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Zinnia elegans (syn. Zinnia violacea) is a common ornamental plant of the Asteraceae family, widely cultivated for the impressive range of flower colors and persistent bloom. Given its uncomplicated cultivation and high adaptability to harsh landscape conditions, we investigated the potential use of Z. elegans as a source of valuable secondary metabolites. Preliminary classification of compounds found in a methanolic extract obtained from inflorescences of Z. elegans cv. Caroussel was accomplished using HR LC-MS techniques. The extract was then subjected to solid-phase extraction and separation using Sephadex LH-20 column chromatography, which resulted in several fractions further investigated for their antioxidant properties through lipoxygenase inhibition and metal chelating activity assays. Moreover, following additional purification procedures, structures of some active ingredients were established by NMR spectroscopy. The investigated fractions contained polyphenolic compounds such as chlorogenic acids and apigenin, kaempferol, and quercetin glycosides. Antioxidant assays showed that certain fractions exhibit moderate 15-LOX inhibition (Fr 2, IC50 = 18.98 μg/mL) and metal chelation (e.g., Fr 1-2, EC50 = 0.714–1.037 mg/mL) activities as compared to positive controls (20.25 μg/mL for kaempferol and 0.068 mg/mL for EDTA, respectively). For Fr 2, the 15-LOX inhibition activity seems to be related to the abundance of kaempferol glycosides. The NMR analyses revealed the presence of a kaempferol 3-O-glycoside, and a guanidine alkaloid previously not described in this species.
... It is non-fermented tea and usually protected from sunlight to avoid polyphenol degradation. It is exclusively prepared from very young tea leaves and/or only buds, which are harvested before being fully open and are processed by air drying (Venditti et al., 2010). This less extended processing confers to white tea its special and highly appreciated odour and flavour characteristics (Müller et al., 2010 andRusak et al., 2008). ...
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The present study was conducted to develop quality-full white tea manufacturing protocol by using of different clone with their different combinations in respect. In the experiment, most interesting thing was that, white tea of T1 treatment had best flavour which was the result of using only V1 clone but had less Strength and less astringency. Whereas on the basis of overall quality category, T3 treatment (35.62a) gave the best (Excellent Quality Category) white tea followed by T1 treatment (33.89b), T6 treatment (33.75b) and T4 (33.41) gave Above Average Quality Category white tea. But T2 (31.65c) and T5 (31.45c) produced Average Quality Category white tea.
... The polyphenol in our study was higher than the ones reported by Anon, 2008 despite the fact that the material that was used in our study was 1 bud +1 lea. (Vendetti et al, 2010 observed that levels of total polyphenols changed with steeping time of the tea leaves in water (Cold or hot). He observed that total polyphenol content is always higher in hot teas than in cold tea especially green tea. ...
... After water, tea is the second most highly consumed beverage worldwide (Venditti et al. 2010). It is an infusion obtained from leaves of Camellia sinensis and is consumed by two-thirds of the world's population (Łuczaj and Skrzydlewska 2005). ...
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Tannin acyl hydrolase, commonly known as tannase, is found as an intracellular or extracellular enzyme. Filamentous fungi were reported to dominate among all tannase-producing microorganisms. Despite its long history and numerous publications, tannase is still considered one of the costly industrial enzymes. The production and applications of tannase have been extensively studied; researches related to strain isolation and improvement, process development, and applications of tannases have resulted in a great number of scientific publications. The enzyme has potential uses in the treatment of tannery or industrial effluents. This chapter presents an overview of the natural substrate of tannins, fungal production of tannins, production of tannase by fermentation, and tannase applications in food and other industrial products.
... Enzymatic extraction promotes extraction and improves the flavor of the extract [7], but prolonged treatment time leads to quality deterioration [8]. Several studies have reported the effects of extraction temperature, time, and method on the quality of tea infusion [34][35][36][37][38]. The tea infusion obtained using hot water showed better scavenging of free radicals than that obtained using cold water, and the extraction yield increased with increasing temperature and time. ...
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Tannase is widely used in tea beverage processing because of its ability to catalyze the hydrolysis of hydrolysable tannins or gallic acid esters and effectively improve the quality of tea extracts through enzymatic extraction. A new thermophilic tannase was cloned from Aspergillus niger FJ0118 and characterized. The tannase exhibited an optimal reaction temperature of 80 °C and retained 89.6% of the initial activity after incubation at 60 °C for 2 h. The enzymatic extraction of green tea at high temperature (70 °C) for a short time (40 min) was devised on the basis of the superior thermal stability of tannase. The enzymatic reaction significantly increased the total polyphenol content of green tea extract from 137 g•kg −1 to 291 g•kg −1. The enzymatic reaction effectively degraded the ester catechins into non-ester catechins compared with the water extraction method. Results suggested that the thermally stable tannase exhibited potential applications in the enzymatic extraction of green tea beverage.
... where Ac is the absorbance of the blank probe, containing 200 µL of sodium/acetate buffer instead of the sample, while As is the absorbance of the sample solution [102]. ...
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The wastewater from the distillation of rose oils is discharged directly into the soil because it has a limited potential for future applications. The aim of the present study was to determine in vitro the chromatographic profile, redox-modulating capacity, and antineoplastic activity of wastewater obtained by distillation of essential oils from the Bulgarian Rosa alba L., Rosa damascena Mill., Rosa gallica L., and Rosa centifolia L. We applied UHPLC-HRMS for chromatographic analysis of rose wastewaters, studied their metal-chelating and Fe(III)-reducing ability, and performed MTT assay for the evaluation of cytotoxic potential against three tumorigenic (HEPG2—hepatocellular adenocarcinoma, A-375—malignant melanoma, A-431—non-melanoma epidermoid squamous skin carcinoma) and one non-tumorigenic human cell lines (HaCaT—immortalized keratinocytes). The median inhibitory concentrations (IC50) were calculated with nonlinear modeling using the MAPLE® platform. The potential of the wastewaters to induce apoptosis was also examined. Mono-, di-, and acylated glycosides of quercetin and kaempferol, ellagic acid and its derivatives as main chemical components, and gallic acid and its derivatives—such as catechin and epicatechin—were identified. The redox-modulating capacity of the samples (TPTZ test) showed that all four wastewaters exhibited the properties of excellent heavy metal cleaners, but did not exert very strong cytotoxic effects. The lowest IC50 rate was provided in wastewater from R. centifolia (34–35 µg/mL of gallic acid equivalents after a 72 h period for all cell lines). At 24 and 48 hours, the most resistant cell line was HEPG2, followed by HaCaT. After 72 h of exposure, the IC50 values were similar for tumor and normal cells. Still, R. damascena had a selectivity index over 2.0 regarding A-431 non-melanoma skin cancer cells, showing a good toxicological safety profile in addition to moderate activity—IC50 of 35 µg/mL polyphenols. The obtained results related to wastewaters acquired after the distillation of essential oils from the Bulgarian R. alba, R. damascena, R. gallica, and R. centifolia direct our attention to further studies for in-depth elucidation of their application as detoxifying agents under oxidative damage conditions in other experimental datasets.
... However, it is worth pointing out that the polyphenols in our study showed to be more stable than in Komes et al.'s [9] study, and temperature did not have a significant influence on their concentration. Other studies have noted that using lower brewing temperatures but longer extraction times for plant material can increase antioxidant activity by protecting specific polyphenolic fractions [40,41]. ...
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Matcha green tea (Camellia sinensis), which originates from Japan, is commonly considered as particularly beneficial to health. A large content of polyphenols, amino acids (mainly tannins) and caffeine potentially increase the antioxidant properties of the drink. The aim of the study was to determine the antioxidant potential and the content of substances with an antioxidant effect-vitamin C, total polyphenol content including flavonoids-in infusions made from Traditional Matcha (from the first and second harvests) and Daily Matcha (from the second and third harvests) at different temperatures. The infusions were made by pouring 100 mL of distilled water once at various temperatures (25 • C, 70 • C, 80 • C and 90 • C) over 1.75 g of the plant material. Matcha tea is characterized by a high level of antioxidant substances (flavonoids 1968.8 mg/L; polyphenols 1765.1 mg/L; vitamin C 44.8 mg/L) as well as antioxidant potential (41.2% DPPH (10× dilution); 6129.5 µM Fe(II)/dm 3 FRAP). The concentration of these compounds depends on the time at which the plant material was harvested as well as on the temperature of water used to prepare the infusions. For most parameters, the highest values were observed in infusions prepared at 90 • C and from the daily Matcha.
... *To whom correspondence should be addressed Phone: +234 8034684871; e-mail: makakins2001@yahoo.com Introduction Tea (Camellia sinensis (L.) Kuntze)) drink is the second most consumed drink worldwide after water [1,2]. Tea plant is a member of the Theaceae family and were originally cultivated in Asian countries and have found usage in traditional medicine [3,4]. ...
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The effects of extraction temperature, time and concentration (powder to solvent ratio) on extraction of flavonoids and polyphenols from tea using aqueous, aqueous ethanolic and absolute ethanolic solvents were investigated using response surface methodology. Concentration had the most significant influence on the extraction of the tea antioxidants. For both the aqueous and absolute ethanolic solvents, the extraction of polyphenols and flavonoids was maximised at temperatures close to the highest extraction temperatures investigated. Aqueous extraction of flavonoids and polyphenols was optimised at 92.01°C and 95.75 °C, respectively and the absolute ethanolic extraction was optimised at 69.50 °C and 70.00 °C, respectively. A comparison of the three extraction solvents based on the single response optimisation approach indicated that aqueous extraction gave extract with highest total flavonoids (26697.2 mg CE/L) content while aqueous ethanolic extraction gave extract with the highest total phenols content (4068.76 mg GAE/L). The study also suggests that pH, hue index and absorbance of extracts at 510 and 610 nm could be used for developing rapid prediction protocols for tea polyphenols and flavonoids.
... This is especially true for powdery products that are susceptible to falsification, counterfeiting or imitation, as it is more difficult to prove authenticity after comminution [6][7][8][9]. In addition, blending of tea leaves or powders is commonly used for processing to guarantee a constant tea quality and compensate for deviations caused by cultivation and environment [10,11]. However, this blending practice could also easily be misused. ...
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The antioxidative activity of Camelia sinensis tea and especially powdered tea extracts on the market, among others used as added value in functional foods, can considerably vary due to not only natural variance, but also adulteration and falsification. Thus, an effect-directed profiling was developed to prove the functional effects or health-promoting claims. It took 3–12 min per sample, depending on the assay incubation time, for 21 separations in parallel. Used as a fast product quality control, it can detect known and unknown bioactive compounds. Twenty tea extracts and a reference mixture of 11-bioactive compounds were investigated in parallel under the same chromatographic conditions by a newly developed reversed phase high-performance thin-layer chromatographic method. In eight planar on-surface assays, effect-directed tea profiles were revealed. Catechins and theaflavins turned out to be not only highly active, but also multi-potent compounds, able to act in a broad range of metabolic pathways. The flavan-3-ols acted as radical scavengers (DPPH· assay), antibacterials against Gram-positive Bacillus subtilis bacteria, and inhibitors of tyrosinase, α-glucosidase, β-glucosidase, and acetylcholinesterase. Further effects against Gram-negative Aliivibrio fischeri bacteria and β-glucuronidase were assigned to other components in the powdered tea extracts. According to their specifications, the activity responses of the powdered tea extracts were higher than in mere leaf extracts of green, white and black tea. The multi-imaging and effect-directed profiling was not only able to identify known functional food ingredients, but also to detect unknown bioactive compounds (including bioactive contaminants, residues or adulterations).
... In addition, environmental factors, such as the drying technique, storage conditions, and the plant organ used as the source and the moisture content are parameters that could influence the phytochemical content of a plant [35,36]. Furthermore, the extraction process appears to affect the total phenolic content and antioxidant activity of the plants [3,[37][38][39][40][41]. ...
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Lantana rhodesiensis Moldenke is a plant widely used to treat diseases, such as rheumatism, diabetes, and malaria in traditional medicine. To better understand the traditional uses of this plant, a phytochemical study was undertaken, revealing a higher proportion of polyphenols, including flavonoids in L. rhodesiensis leaf extract and moderate proportion in stem and root extracts. The antioxidant activity of the extracts was also determined using three different assays: the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, the FRAP method (Ferric-reducing antiox-idant power) and the β-carotene bleaching test. The anti-malarial activity of each extract was also evaluated using asexual erythrocyte stages of Plasmodium falciparum, chloroquine-sensitive strain 3D7. The results showed that the leaf extract exhibited higher antioxidant and anti-malarial activities in comparison with the stem and root extracts, probably due to the presence of higher quantities of polyphenols including flavonoids in the leaves. A positive linear correlation was established between the phenolic compound content (total polyphenols including flavonoids and tannins; and total flavonoids) and the antioxidant activity of all extracts. Furthermore, four flavones were isolated from leaf dichloromethane and ethyl acetate fractions: a new flavone named rhodescine (5,6,3',5'-tetrahydroxy-7,4'-dimethoxyflavone) (1), 5-hydroxy-6,7,3',4',5'-pentamethoxyflavone (2), 5-hydroxy-6,7,3′,4′-tetramethoxyflavone (3), and 5,6,3'-trihydroxy-7,4'-dimethoxyflavone (4). Their structures were elucidated by 1 H, 13 C NMR, COSY, HSQC, HMBC, and MS-EI spectral methods. Aside from compound 2, all other molecules were described for the first time in this plant species.
... It is derived from the leaves of Camellia sinensis (the tea plant) (2). According to different production procedure, there are three various main types of teas: black, green and oolong (3), which are taken variously in different countries (4).About 76-78% of the consumers in the world prefer black tea (5). Reactive oxygen spices may cause wide range of damages to biological systems (6). ...
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Tea is an important dietary source of flavanols and flavonols. In vitro and animal studies provide strong evidence that tea polyphenols may possess the bioactivity to affect the pathogenesis of several chronic diseases, especially cardiovascular disease and cancer. However, the results from epidemiological and clinical studies of the relationship between tea and health are mixed. International correlations do not support this relationship although several, better controlled case-referent and cohort studies suggest an association with a moderate reduction in the risk of chronic disease. Conflicting results between human studies may arise, in part, from confounding by socioeconomic and lifestyle factors as well as by inadequate methodology to define tea preparation and intake. Clinical trials employing putative intermediary indicators of disease, particularly biomarkers of oxidative stress status, suggest tea polyphenols could play a role in the pathogenesis of cancer and heart disease.
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A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.
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A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
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In order to study the biological activities of tea preparations and purified tea polyphenols, their growth inhibitory effects were investigated using four human cancer cell lines. Growth inhibition was measured by [ 3 H]thymidine incorporation after 48 h of treatment. The green tea catechins (-)-epigallocatechin-3-gallate (EGCG) and (-)-epigallocatechin (EGC) displayed strong growth inhibitory effects against lung tumor cell lines H661 and H1299, with estimated IC 50 values of 22 μM, but were less effective against lung cancer cell line H441 and colon cancer cell line HT-29 with IC 50 values 2- to 3-fold higher. (-)-Epicatechin-3-gallate, had lower activities, and (-)-epicatechin was even less effective. Preparations of green tea polyphenols and theaflavins had higher activities than extracts of green tea and decaffeinated green tea. The results suggest that the growth inhibitory activity of tea extracts is caused by the activities of different tea polyphenols. Exposure of H661 cells to 30 μM EGCG, EGC or theaflavins for 24 h led to the induction of apoptosis as determined by an annexin V apoptosis assay, showing apoptosis indices of 23, 26 and 8%, respectively; with 100 μM of these compounds, the apoptosis indices were 82, 76 and 78%, respectively. Incubation of H661 cells with EGCG also induced a dose-dependent formation of H 2 O 2 . Addition of H 2 O 2 to H661 cells caused apoptosis in a manner similar to that caused by EGCG. The EGCG-induced apoptosis in H661 cells was completely inhibited by exogenously added catalase (50 units/ml). These results suggest that tea polyphenol-induced production of H 2 O 2 may mediate apoptosis and that this may contribute to the growth inhibitory activities of tea polyphenols in vitro.
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Catechins are the main ingredients of green tea extracts and have been shown to possess versatile biological activities, including antimicrobial. We determined that the catechins inhibit bacterial DNA gyrase by binding to the ATP binding site of the gyrase B subunit. In the group of four tested catechins, epigallocatechin gallate (EGCG) had the highest activity, followed by epicatechin gallate (ECG) and epigallocatechin (EGC). Specific binding to the N-terminal 24 kDa fragment of gyrase B was determined by fluorescence spectroscopy and confirmed using heteronuclear two-dimensional NMR spectroscopy of the EGCG-15N-labeled gyrase B fragment complex. Protein residues affected by binding to EGCG were identified through chemical shift perturbation. Molecular docking calculations suggest that the benzopyran ring of EGCG penetrates deeply into the active site while the galloyl moiety anchors it to the cleft through interactions with its hydroxyl groups, which explains the higher activity of EGCG and ECG.
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Increase in coarser plucking standards significantly (P<0.05) depressed levels of theaflavin (TF; μmol/g), total colour and brightness (spectrophotometer) of black tea. But total thearubigins (TR) TRSI, TRSII and brightness (taster) levels did not significantly (P<0.05) change with plucking standards. Increasing fermentation duration led to rise in TF (μmol/g), total TR, total colour, TRSI and TRSII, liquor brightness (taster) but not liquor brightness determined by spectrophotometer method (P<0.05). Correlation analysis showed that total TR and TRSII had negative correlations (r=−0.66 and −0.77, P<0.01), respectively, while total TF levels had positive correlation with taster brightness (r=0.57, P<0.01). Total TF level had highest correlation with spectrophotometer liquor brightness (r=0.87, P<0.01) for a single substance. TRSII and total TR gave an r of 0.86 indicating that the two groups of substances were strongly correlated to each other. Regression analysis showed that the direct linear model gave the best fit for the sample data studied. The coefficient of multiple determination (R2) was 0.606 in linear model I for the tasters’ liquor brightness. Thus, the independent variables TF and total TR explained 60.6% of the total variation in liquor brightness scores observed. When TRSI and TRSII were included in the linear model II instead of total TR, but with TF maintained, the coefficient of multiple determination improved to 78.9%. This confirmed that the brightness attribute of black tea, assessed by the taster, could best be explained by the combination of TF and TRSII and that TRSI had a lesser role in the tasters’ evaluation of liquor brightness. Indeed, the test statistic in linear model I showed that the coefficient of TF positively and significantly influenced liquor brightness at P<0.01 whereas the coefficient of total TR negatively and significantly influenced liquor brightness (P<0.0001). However, in linear model II the effect of total TR on the taster brightness was clearly unmasked and the influence of each individual component well elucidated. The coefficient of TRSII was negative and significantly explained liquor brightness at 0.01% level (P<0.0001). The coefficient of TRSI was negative but insignificant. Hence it has no discernible influence on the taster liquor brightness. The coefficient of TF was positive and significantly explained taster liquor brightness (P<0.01). Thus, TF and TRSII explain taster liquor brightness and the lower the level of TRSII the higher the score for brightness. The situation for spectrophotometer brightness was somewhat different. The coefficient of multiple determination was 0.896 in linear model I. Thus, TF and total TR explained 89.6% of the variation in spectrophotometer brightness. The coefficient of TF was positive whereas that of total TR was negative. Both coefficients were significant (P<0.0001). When TRSI and TRSII were included in the linear model II instead of total TR, R2 improved to 91%. Unlike for the tasters’ brightness, the coefficient of TRSI was now significant (P<0.05). The coefficient of TRSII was negative and significant (P<0.01) whereas the coefficient of TF was positive and significant (P<0.0001). The differences in the contributions of TRSI and TRSII to black tea liquor brightness and the observed discrepancy between the test methods, due to variations in plucking standards and fermentation duration, are discussed.
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A novel method for measuring the antioxidant activity using N,N-dimethyl-p-phenylenediamine (DMPD) was developed. The radical cation of this compound gives a stable colored solution and a linear inhibition of color formation can be observed in the presence of 0.2−11 μg of TROLOX. The experimental protocol, which is rapid and inexpensive, ensures sensitivity and reproducibility in the measure of antioxidant activity of hydrophilic compounds. The effectiveness of the DMPD method on real foods was verified by evaluating the antioxidant ability of wine samples coming from different areas of Campania, Italy. Antioxidant capacity of wines is strictly related to the amount of phenolic compounds. The results obtained by the DMPD method are very similar to those obtained on the same samples when the radical cation of 2,2‘-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (Miller et al., 1996) was used. Keywords: Antioxidant activity; DMPD; radical cation; ABTS; wine
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Publisher Summary This chapter discusses the screening of dietary carotenoids and carotenoid-rich fruit extracts for antioxidant activities applying 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization assay. The decolorization of the ABTS radical cation is an efficient, accurate assay for screening the antioxidant activities of lipophilic substances and food extracts. The inhibitory response of the radical cation is proportional to the antioxidant concentration, and the time point selected (2.5 min) for the analysis explains that this is an ideal measuring point when the reaction is complete. Results for the carotenoids are of the same order as previously reported data using alternative systems for generating the ABTS .+ radical cation. It is essential to examine the relative bioavailability, absorption, and hypoactivity of dietary carotenoids and flavonoids/phenolics to understand the importance of these diverse nutritional components in the maintenance of health and disease prevention. The chapter concludes with a discussion of trolox reference standard for relative antioxidant activities.
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Publisher Summary This chapter discusses the analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Analyses of the Folin-Ciocalteu (FC) type are convenient, simple, and require only common equipment and have produced a large body of comparable data. Under proper conditions, the assay is inclusive of monophenols and gives predictable reactions with the types of phenols found in nature. Because different phenols react to different degrees, expression of the results as a single number—such as milligrams per liter gallic acid equivalence—is necessarily arbitrary. Because the reaction is independent, quantitative, and predictable, analysis of a mixture of phenols can be recalculated in terms of any other standard. The assay measures all compounds readily oxidizable under the reaction conditions and its very inclusiveness allows certain substances to also react that are either not phenols or seldom thought of as phenols (e.g., proteins). Judicious use of the assay—with consideration of potential interferences in particular samples and prior study if necessary—can lead to very informative results. Aggregate analysis of this type is an important supplement to and often more informative than reems of data difficult to summarize from various techniques, such as high-performance liquid chromatography (HPLC) that separate a large number of individual compounds .The predictable reaction of components in a mixture makes it possible to determine a single reactant by other means and to calculate its contribution to the total FC phenol content. Relative insensitivity of the FC analysis to many adsorbents and precipitants makes differential assay—before and after several different treatments—informative.
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Immobilized bovine serum albumin (BSA) binds tannins selectively at pH 4. Monomeric polyphenolic substances such as gallic acid, chlorogenic acid and catechol do not interact with the protein under these conditions. The protein-tannin complexes are dissociated by organic solvents such as methanol or dimethylformamide and the released tannins may be recovered in pure form. These principles have been utilized in the design of an analytical method which utilizes small columns of Sepharose-BSA to achieve separation between the two groups of compounds.
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Prostate cancer (PCa) is the most frequently diagnosed malignancy and the second leading cause of cancer-related deaths in American males with similar trends in many western countries. The existing treatment approaches and surgical intervention have not been able to effectively cope with this dreaded disease. For these reasons, it is necessary to intensify our efforts for a better understanding of the disease process and for the development of novel approaches for its prevention and treatment. Based on considerable evidence from in vivo and in vitro data and epidemiological studies, in recent years the beverage tea has gained considerable attention for reducing the risk of several cancers. Much of the cancer preventive effects of tea, especially green tea appear to be mediated by the polyphenols present therein. Geographical evidence suggests that the incidence and occurrence of PCa is lower in populations that consume tea regularly. This evidence suggests that tea polyphenols could be extrapolated to optimize their chemopreventive properties against PCa. PCa represents an excellent candidate disease for chemoprevention because it is typically diagnosed in men over 50 years of age and therefore, even a modest delay in neoplastic development achieved through pharmacological or nutritional intervention could result in a substantial reduction in the incidence of clinically detectable disease. In this review we address the issue of possible use of tea, especially green tea, for the prevention as well as treatment of PCa.
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The antioxidant activity of aqueous extracts of rooibos tea (unfermented, semi-fermented and fermented) was compared with that of green, oolong and black teas. The α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging and β-carotene bleaching methods were used to determine the antioxidant activity of extracts prepared in a similar manner and diluted to the same amount of soluble solids. All the tea extracts were strong inhibitors of β-carotene bleaching as well as highly active hydrogen donors to the DPPH radical. Antioxidant activity as assessed with the β-carotene bleaching method decreased in the order: green > black > oolong > fermented rooibos > unfermented rooibos > semifermented rooibos. However, antioxidant activity as assessed by the DPPH radical scavenging method decreased in the order: green > unfermented rooibos > fermented rooibos > semifermented rooibos > black > oolong.
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A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
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Oxidative modification of LDL is accompanied by a number of compositional and structural changes, including increased electrophoretic mobility, increased density, fragmentation of apolipoprotein B, hydrolysis of phosphatidylcholine, derivatization of lysine amino groups, and generation of fluorescent adducts due to covalent binding of lipid oxidation products to apo B. In addition, oxidation of LDL has been shown to result in numerous changes in its biologic properties that could have pathogenetic importance, including accelerated uptake in macrophages, cytotoxicity, and chemotactic activity for monocytes. The present article summarizes very recent developments related to the mechanism of oxidation of LDL by cells, receptor-mediated uptake of oxidized LDL in macrophages, the mechanism of phosphatidylcholine hydrolysis during LDL oxidation, and other biologic actions of oxidized LDL including cytotoxicity, altered eicosanoid metabolism, and effects on the secretion of growth factors and chemotactic factors. In addition, this review will examine the evidence for the presence of oxidized LDL in vivo and the evidence that oxidized LDL plays a pathogenetic role in atherosclerosis.
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Density gradient ultracentrifugation in the swing out rotor has been successfully applied to fractionation of the major lipoprotein species and their subspecies; however, it requires a minimum of 24–36 h to complete the separation of the major lipoprotein fractions in plasma. This chapter describes 13 separate vertical spin procedures for the preparative separation of a number of different plasma lipoproteins and a method for the quantitative analysis of lipoprotein cholesterol from plasma separated by single vertical spin (SVS) density gradient ultracentrifugation. The vertical rotor works on the principle that compression of the gradient geometry by the vertical rotor when at speed shortens spin time over more conventional ultracentrifugation techniques without loss of resolution. The single vertical spin procedure has a number of advantages over the more conventional methods including decreased spin time, decreased lipoprotein degradation, and good resolution. But there are certain disadvantages of this method also, such as wall adherence of VLDL and albumin, resolution, and plasma volume limit per rotor. However, the chapter addresses solutions to the problems of single vertical spin ultracentrifugation such as angled-head rotors.
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The association of some natural and synthetic polyphenols with beta-glucosidase was examined and some observations on the chemical nature of the complex were made.