Antioxidant activities of crude tea polyphenols, polysaccharides and proteins of selenium-enriched tea and regular green tea

A highly biocompatible and bioactive transdermal nano collagen for enhanced healing of UV-damaged skin

Skin damage caused by excessive UV radiation has gradually become one of the most prevalent skin diseases. Collagen has gradually found applications in the treatment of UV-damaged skin; however, their high molecular weight greatly limits their capacity to permeate the skin barrier and repair the damaged skin. Nano collagen has garnered growing attentions in the mimicking of collagen; while the investigation of its skin permeability and wound-healing capability remains vacancies. Herein, we have for the first time created a highly biocompatible and bioactive transdermal nano collagen demonstrating remarkable transdermal capacity and repair efficacy for UV-damaged skin. The transdermal nano collagen exhibited a stable triple-helix structure, effectively promoting the adhesion and proliferation of fibroblasts. Notably, the transdermal nano collagen displayed exceptional penetration capabilities, permeating fibroblast and healthy skin. Combo evaluations revealed that the transdermal nano collagen contributed to recovering the intensity and TEWL values of UV-damaged skin to normal level. Histological analysis further indicated that transdermal nano collagen significantly accelerated the repair of damaged skin by promoting the collagen regeneration and fibroblasts activation. This highly biocompatible and bioactive transdermal nano collagen provides a novel substituted strategy for the transdermal absorption of collagen, indicating great potential applications in cosmetics and dermatology.

In vitro comparative evaluation of antioxidative effect of selenium alone and in combination with green tea and alpha-tocopherol on the shear bond strength of universal composite resin to enamel after in-office bleaching

Background

Antioxidant application soon after bleaching process increases the shear bond strength (SBS) of composite resin to enamel.

Aims

The aim of the study was to evaluate the antioxidant effects of selenium alone and in combination with alpha-tocopherol (αT) and green tea (GT) on SBS of composite resin to enamel following in-office bleaching with 38% hydrogen peroxide (HP).

Methods

Sixty extracted human single -rooted premolar teeth were cleaned and embedded in acrylic resin blocks at the level of cementoenamel junction(CEJ) followed by bleaching with 38% hydrogen peroxide (HP) and arbitrarily divided into seven groups (n=10) for antioxidant application: Group I (negative control): intact teeth, Group II (positive control): only bleaching, Group III: 10% selenium (Se), Group IV: 10% alpha tocopherol (αT), Group V: 10% αT +10% Se, Group VI: 10% Green tea (GT), Group VII: 10%GT+10% Se. In all groups, self-etch adhesive was applied and composite restoration was done, and specimens were stored in distilled water for 24h followed by SBS evaluation.

Statistical Analysis

One-way analysis of variance and post hoc Tukey's tests were used (P < 0.05).

Results

The highest SBS was found in negative control Group I (intact teeth) and least in positive control Group II (bleached teeth), whereas in experimental groups, Group VII (GT + Se) showed highest followed by Groups V (αT + Se), III (Se), and VI (GT) and least in Group IV (αT).

Conclusion

Combination of selenium with green tea and alpha tocopherol enhanced the SBS of composite resin following in-office bleaching.

Hot Water Extraction of Antioxidants from Tea Leaves—Optimization of Brewing Conditions for Preparing Antioxidant-Rich Tea Drinks

There are billions of tea drinkers around the world. However, the optimized tea-brewing temperature and time conditions for achieving a higher concentration of antioxidants in tea drinks have not been thoroughly studied. Finding out the optimized brewing conditions can benefit tea drinkers significantly. In this work, we have studied ten antioxidants from seven different popular green, Oolong, black, and scented teas using hot water extraction followed by HPLC analysis. The antioxidant yield was evaluated at 25–100 °C with 5 to 720 min of brewing time. Our results show that the extraction efficiency was enhanced by increasing the water temperature and the highest yield of antioxidants was achieved at 100 °C. The antioxidant yield increased with prolonged brewing time. However, the degradation of antioxidants occurred when tea leaves were extracted for 120 to 720 min. Caffeine was found in all seven tea samples. At 100 °C, the caffein concentration in the tea extract ranged from 7.04 to 20.4 mg/g in Rizhao green tea. Longjing green tea contained the highest concentration of antioxidants (88 mg/g) in the 100 °C extract. Epigallocatechin and caffeine were the most abundant compounds found in all tea samples studied, ranging from 4.77 to 26.88 mg/g. The antioxidant yield was enhanced by increasing the extraction time to up to 60–120 min for all ten compounds studied.

Analytical Problems in Separation of Selenomethionine and Its Oxidative Product in HILIC HPLC

Selenomethionine (SeMet) is one of the main selenium forms in foods and supplements. Determining its presence in natural food samples creates difficulties due to possible oxidation processes. The objective of this study was to evaluate the possible degradation of SeMet in water extracts of green teas, one of the most consumed beverages worldwide. Such a medium has not been investigated at this time. The HILIC-HPLC MS/MS method with different stationary phases was used to achieve the satisfactory separation of SeMet and selenomethionine oxide (SeMetO). The addition of dithiothreitol and β-mercaptoethanol, recommended to ensure that SeMet is kept in the reduced form, was also evaluated. The best separation was achieved using the zwitterionic HILIC stationary phase coupled to mass spectrometry and MeOH with water (85/15, v/v) as the eluent. Extraction was done with hot water with the addition of β-mercaptoethanol. The infusions prepared from Lung-Ching teas (from the Zhejiang Province in China) contained the highest concentration of selenium in a typical cup of tea (12.5–17.3 µg L⁻¹). For other tested teas it decreased in the following order: Yunnan > Dilmah > Lipton. For Lung-Ching teas, the sum of concentrations of SeMet and SeMetO corresponded to about 46–63% of the total selenium in their extracts.

Selenium-Containing Proteins/Peptides from Plants: A Review on the Structures and Functions

Selenium is an essential microelement required for biological processes. Traditional selenium supplements (selenite and selenomethionine mainly) remain concerns due to toxicity and bioavailability. In recent decades, biofortification strategies have been applied to produce selenium-enriched edible plants to address the challenges of superior nutritional quality requirements. Plant-derived selenium-containing proteins/peptides offer potential health benefits beyond the basic nutritional requirements of Se. Highly nucleophilic seleno-amino acids, special peptide sequences, and favorable bioavailability contribute to the biological activities of selenium-containing proteins/peptides, such as antioxidant, antihypertensive, anti-inflammatory, and immunomodulatory effects. However, their applications on a commercial scale are insufficient owing to the complexity of purification and identification techniques and the sparse information on bioavailability and metabolism. In this review, selenium status, structural features, bioactivities, structure-activity relationships, and bioavailability, as well as the mechanisms underlying the bioactivities and metabolism of plant-derived selenium-containing proteins/peptides, are summarized and discussed for their nutraceutical use.

Content of selenoaminoacids and catechins in Chinese green teas

In this study, famous Zhejiang teas were evaluated as a well-advertised source of selenium. The 25 samples from provinces around China and Asia were purchased in Warsaw tea shops. The speciation analysis of selenium as well as the evaluation of catechin content in water tea infusions was performed using hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS/MS). It turned out that all of tested samples can be a great source of organic selenium species (no traces of inorganic selenium was found), however, Zhejiang teas did not differ much among others. Such a conclusion can also be drawn when comparing the antioxidant capacity of the tested samples, obtained with the application of four methods (Folin–Ciocalteu method, scavenging of the 2,2-diphenyl-1-picrylhydrazyl radical, hydroxyl radical scavenging and cupric reducing ability assay). What is more, no correlation was found between the selenium content and the antioxidant activity of studied teas. The results obtained for the six samples from Zhejiang Province were very varied, which shows that it is very difficult to interpret the results and compare them with the results of other authors.

Organic selenium derived from chelation of soybean peptide-selenium and its functional properties in vitro and in vivo

Organic selenium has been widely explored as an important source of selenium (Se) supplement due to its low toxicity and easy absorption. In the present study, a new type of organic selenium was fabricated by chelating Se with soybean protein isolate peptides (SPIPs), and its physio-chemical properties, structural characteristics, and antioxidant activities were investigated. Results indicated that the structure of the SPIP molecule was folded and aggregated during the chelation process. SPIP-Se exhibited stronger hydroxyl radical scavenging activity and reducing power than SPIP in vitro. In addition, SPIP-Se could repair the H2O2-induced oxidative damage of Caco-2 cells by enhancing the activities of antioxidant enzymes. The in vivo assay showed that SPIP-Se showed much less toxicity than inorganic Se supplements, and exhibited a more positive effect on the activities of key enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and aspartate aminotransferase (AST). These findings suggest that SPIP-Se could be developed as an effective dietary Se supplement in the food or pharmaceutical field in the future.

Physicochemical Contents, Antioxidant Activities, and Acute Toxicity Assessment of Selenium-Enriched Chinese Kale (Brassica oleracea var. alboglabra L.) Seedlings

The oxidative activities of hydroponically produced Chinese kale (Brassica oleracea var. alboglabra L.) seedlings grown under different concentrations of selenium (Se) biofortification with sodium selenite (Na2SeO3) at 0, 5, 10, 15, and 30 mg·Se/L and different ages (5, 10, and 15 days after germination) were determined by the electron transfer method (DPPH and FTC). Highest antioxidant activities of Se-enriched Chinese kale seedlings (Se-KS) were found in seedlings grown on 30 mg·Se/L, 15 days after germination. The physicochemical contents (moisture, crude fibre, ash, crude protein, and carbohydrate), total Se contents, and Se bioaccessibility and antioxidant activities (after treatment with an in vitro simulated gastrointestinal digestion process) between Se-KS and a control of regular Chinese kale seedlings (R-KS) were compared. The crude protein and total Se contents of the air-dried matter in Se-KS were higher (37 ± 1% and 433 ± 22 mg·Se/kg) than those of the R-KS (33 ± 2% and 17 ± 3 mg·Se/kg). Total Se content and antioxidant activities were strongly correlated in the range from 0.93 to 0.99. Testing acute toxicity, a single dose of the Se-KS was orally administrated to rats at 1250, 2500, and 5000 mg/kg·b.w., which consisted of 0.54, 1.08, and 2.16 mg Se/kg·b.w., respectively. These results demonstrated that Se-KS did not create any toxicological signs and mortality. No abnormal pathological changes in the liver, kidney, and heart were found. The results suggested that the Se-KS could be a good source of organo Se for development as a new Se supplementary product.

Investigation of antioxidant activity of selenium compounds and their mixtures with tea polyphenols

The antioxidant interactions between selenium species and tea polyphenols were investigated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals, cupric reducing antioxidant capacity (CUPRAC) and Folin-Ciocalteu (FC) assay. Se(IV) exhibited the lowest antioxidant properties in comparison to other selenium compounds in all assays. The highest reducing power was obtained for SeMet, while the highest ability to scavenging DPPH radicals for MeSeCys. The results obtained experimentally for the mixtures containing selenium species and green or black tea infusion were compared with theoretical values calculated by adding up the effects of both individual components analyzed separately. The results obtained from each assay clearly show that observed effect is not additive. In almost every case the theoretical value of antioxidant capacity was significantly higher from that obtained from the activity of the binary mixture of black tea infusion with selenium compound decreased in the order: SeMet > Se(IV) > Se(VI) > MeSeCys, while for similar mixtures with green tea infusion: MeSeCys > Se(VI) > SeMet ~ Se(IV).

Chemical composition, antioxidant and antitumor activities of sub-fractions of wild and cultivated Pleurotus ferulae ethanol extracts

Pleurotus ferulae is an edible and medicinal mushroom with various bioactivities. Here, the ethanol extracts of wild and cultivated P. ferulae (PFEE-W and PFEE-C) and their subfractions including petroleum ether (Pe-W/Pe-C), ethyl acetate (Ea-W/Ea-C) and n-butanol (Ba-W/Ba-C) were prepared to evaluate their antioxidant and antitumor activities. Both PFEE-W and PFEE-C show the antioxidant activity and PFEE-W is stronger than PFEE-C. The antioxidant activities of their subfractions are in the following order: Ea > Ba > Pe. Moreover, PFEE-W and PFEE-C significantly inhibit the proliferation of murine melanoma B16 cells, human esophageal cancer Eca-109 cells, human gastric cancer BGC823 cells and human cervical cancer HeLa cells through induction of apoptosis, which partially mediated by reactive oxygen species. The antitumor activities of their subfractions are in the following order: Ea ≥ Pe > Ba. Pe-W shows higher antitumor activity compared with Pe-C, which might be correlated with the difference of their components identified by gas chromatography-mass spectrometry. These results suggest that both wild and cultivated P. ferulae have antioxidant and antitumor activities, and cultivated P. ferulae could be used to replace wild one in some functions.

Structural characterization and evaluation of the antioxidant activities of polysaccharides extracted from Qingzhuan brick tea

The crude tea polysaccharides (CTPS) from Qingzhuan brick tea(QZBT) were extracted and fractionated to afford two fractions, namely TPS-1 and TPS-2. Analyses were conducted concerning the structural characterization and antioxidant activities of these samples. Component analysis revealed that the carbohydrate, uronic acid, protein and polyphenol contents of these samples differed significantly. Fourier transform infrared analysis showed that these samples showed similar characteristic absorption peaks for polysaccharides. Ultraviolet-visible spectroscopy, circular dichroism, scanning electron microscopy and thermogravimetric analyses indicated that there were considerable differences in the presence of protein, surface features, conformational characteristics and thermodynamic behaviors. For antioxidant activities in vitro, CTPS, TPS-1 and TPS-2 exhibited concentration-dependent antioxidant activities, with TPS-2 showing significantly higher antioxidant activity than CTPS and TPS-1. These results provide a scientific and strong foundation for the use of tea polysaccharides(TPS) from QZBT and further research towards the relationships between the characteristics and antioxidant activities of TPS.

Recent advances in tea polysaccharides: Extraction, purification, physicochemical characterization and bioactivities

Tea has a long history of medicinal and dietary use. Tea polysaccharide (TPS) is regarded as one of the main bioactive constituents of tea and is beneficial for health. Over the last decades, considerable efforts have been devoted to the studies on TPS: extraction, structural feature and bioactivity of TPS. However, it has been received much less attention compared with tea polyphenols. In order to provide new insight for further development of TPS in functional foods, in present review we summarize the recent literature, update the information and put forward future perspectives on TPS covering its extraction, purification, quantitative determination techniques as well as physicochemical characterization and bioactivities.

Inhibitory effects of polyphenol-enriched extract from Ziyang tea against human breast cancer MCF-7 cells through reactive oxygen species-dependent mitochondria molecular mechanism

A polyphenol-enriched extract from selenium-enriched Ziyang green tea (ZTP) was selected to evaluate its antitumor effects against human breast cancer MCF-7 cells. In ZTP, (−)-epigallocatechin gallate (28.2%) was identified as the major catechin, followed by (−)-epigallocatechin (5.7%) and (−)-epicatechin gallate (12.6%). ZTP was shown to inhibit MCF-7 cell proliferation (half maximal inhibitory concentration, IC₅₀ = 172.2 μg/mL) by blocking cell-cycle progression at the G0/G1 phase and inducing apoptotic death. Western blotting assay indicated that ZTP induced cell-cycle arrest by upregulation of p53 and reduced the expression of CDK2 in MCF-7 cells. ZTP-caused cell apoptosis was associated with an increase in Bax/Bcl-2 ratio, and activation of caspase-3 and -9. MCF-7 cells treated with ZTP also showed an overproduction of reactive oxygen species, suggesting that reactive oxygen species played an important role in the induction of apoptosis in MCF-7 cells. This is the first report showing that ZTP is a potential novel dietary agent for cancer chemoprevention or chemotherapy.

Combination of selenium-enriched green tea polysaccharides and Huo-ji polysaccharides synergistically enhances antioxidant and immune activity in mice

BACKGROUND

The aim of this study was to investigate the influence of a combination of selenium-enriched green tea polysaccharides (Se-GTP) and Huo-ji polysaccharides (HJP) on the immune function and antioxidant activity in mice.

RESULTS

The results showed that the indices of spleen and thymus were markedly increased, and the activity of natural killer (NK) cell was promoted in mice treated with the combination of Se-GTP and HJP. The combined treatment of Se-GTP and HJP also reduced the content of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in splenocytes. In addition, the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were remarkably enhanced, and malondialdehyde (MDA) levels were significantly reduced in mice treated with combination of Se-GTP and HJP. Furthermore, the combined treatment of Se-GTP and HJP increased nuclear factor erythroid 2-related factor (Nrf2) expression at mRNA and protein levels in splenocytes. The effects of the combination treatment of Se-GTP and HJP in mice were stronger than with Se-GTP or HJP treatment alone.

CONCLUSION

Our study suggests that the combined administration of Se-GTP and HJP can synergistically improve immune function and decrease the oxidative stress by enhancing the mechanisms involved in the clearance of free radicals.

Reviews on Mechanisms of In Vitro Antioxidant Activity of Polysaccharides

It is widely acknowledged that the excessive reactive oxygen species (ROS) or reactive nitrogen species (RNS) induced oxidative stress will cause significant damage to cell structure and biomolecular function, directly or indirectly leading to a number of diseases. The overproduction of ROS/RNS will be balanced by nonenzymatic antioxidants and antioxidant enzymes. Polysaccharide or glycoconjugates derived from natural products are of considerable interest from the viewpoint of potent in vivo and in vitro antioxidant activities recently. Particularly, with regard to the in vitro antioxidant systems, polysaccharides are considered as effective free radical scavenger, reducing agent, and ferrous chelator in most of the reports. However, the underlying mechanisms of these antioxidant actions have not been illustrated systematically and sometimes controversial results appeared among various literatures. To address this issue, we summarized the latest discoveries and advancements in the study of antioxidative polysaccharides and gave a detailed description of the possible mechanisms.

Influence of harvest season on antioxidant activity and constituents of rabbiteye blueberry ( Vaccinium ashei ) leaves

To select rabbiteye blueberry leaves from an appropriate harvest season to develop functional foods, this paper studied the bioactive secondary metabolites and the antioxidant capacity of rabbiteye blueberry leaves from May, September, and November. The results showed the leaves from May had the highest content of total flavonoids (114.21 mg/g) and the leaves from November had the highest content of total polyphenols and proanthocyanidins (425.24 and 243.29 mg/g, respectively). It was further found that blueberry leaves from different seasons have similar bioactive constituents, but their contents are obviously different by HPLC. The rabbiteye blueberry leaves from November had the highest antioxidant capacity, which was well correlated with their highest proanthocyanidin content. The results clarify that the blueberry leaves from different seasons have different contents of bioactive secondary metabolites and different antioxidant activities, which implied that leaves from November should be selected first for utilization in functional foods.

Chromium level and intake from Chinese made tea

Tea is a popular drink around the world. It is also one of the sources of metal intake. The objectives of this study were to assess chromium (Cr) intake from popular green, oolong, black and Pu-erh tea. In total, 128 Chinese made teas were analysed and concentration differences among four types of tea were explored. Black tea contained highest total Cr, which varied between 0.63 and 17.60 mg/kg. The lowest content was found in the green tea samples, between 0.26 and 1.30 mg/kg. Cr(III) and Cr(VI) in black tea were higher than in other types of tea. Cr(III), Cr(VI) and total Cr concentration in different tea infusions were also analysed. The results suggest that drinking tea is an effective way for Cr intake and the risk of adults and children being chronically intoxicated by tea infusions is low.

Comparison of the Roles of Tea Polysaccharides and Polyphenols in Growth Inhibition of Hepatoma H22 Cells in Mice

The effects of tea polysaccharides (TPS) and polyphenols (TPP) on the growth inhibition of hepatoma H22 cells in mice including the roles of them in immune stimulation were investigated. The results showed that TPS and TPP both significantly inhibited the growth of H22 transplantable tumor in mice without statistical difference, both remarkably decreased the spleen index and increased the thymus index compared with that of model group (p<0.05). In addition, TPS and TPP significantly improved the splenocyte proliferation induced by ConA or LPS, and notably enhanced the macrophage phagocytosis towards neutral red. The comparison showed the effect of TPS on immune stimulation was superior to that of TPP to some extent.

Inhibitory effects and molecular mechanisms of selenium-containing tea polysaccharides on human breast cancer MCF-7 cells

Dietary supplementation of selenium-enriched tea is known to have an anticancer health benefit. This study was to investigate the inhibitory effect of selenium-containing tea polysaccharides (Se-GTPs) from a new variety of selenium-enriched Ziyang green tea against human MCF-7 breast cancer cells. Se-GTPs dose-dependently exhibited an effective cell growth inhibition with an IC(50) of 140.1 μg/mL by inducing MCF-7 cancer cells to undergo G2/M phase arrest and apoptosis. The blockade of cell cycle was associated with an up-regulation of p53 expression, but not CDK2. Se-GTPs clearly triggered the mitochondrial apoptotic pathway, as indicated by an increase in Bax/Bcl-2 ratio and subsequent caspase-3 and caspase-9 activation. It was also found that the generation of intracellular ROS is a critical mediator in Se-GTPs-induced cell growth inhibition. These findings suggest that Se-GTPs may serve as a potential novel dietary agent for human breast cancer chemoprevention.

Antioxidant activities and phytochemical study of leaf extracts from 18 indigenous tree species in taiwan

The objective of this study is to assess antioxidant activities of methanolic extracts from the leaves of 18 indigenous tree species in Taiwan. Results revealed that, among 18 species, Acer oliverianum exhibited the best free radical scavenging activities. The IC₅₀ values were 5.8 and 11.8 μg/mL on DPPH radical and superoxide radical scavenging activities, respectively. In addition, A. oliverianum also exhibited the strongest ferrous ion chelating activity. Based on a bioactivity-guided isolation principle, the resulting methanolic crude extracts of A. oliverianum leaves were fractionated to yield soluble fractions of hexane, EtOAc, BuOH, and water. Of these, the EtOAc fraction had the best antioxidant activity. Furthermore, 8 specific phytochemicals were isolated and identified from the EtOAc fraction. Among them, 1,2,3,4,6-O-penta-galloyl-β-D-glucopyranose had the best free radical scavenging activity. These results demonstrate that methanolic extracts and their derived phytochemicals of A. oliverianum leaves have excellent antioxidant activities and thus they have great potential as sources for natural health products.

Correlation of dispersibility of proteins with that of selenium in teas

Selenium-enriched tea was suggested as a possible source of supplemental Se. The result of this study indicates that it is not practicable to make selenium-enriched tea as a beverage like traditional green tea or black tea for the supplementation of selenium in human diet. The selenium dispersibilities of fresh tea leaves, green tea, and black tea highly correlated with those of protein (r(2) = 0.998). The high protein dispersibility (85.0%) of fresh tea leaves in water solution was accompanied by that of selenium (93.8%). Decreases in protein dispersibility of green tea and black tea to 2.5% and 4.2 % coincided with those of selenium to only 8.3% and 10.1%, respectively. The amount (14.90 μg) of selenium in saturated ammonium sulphate (a protein precipitating reagent) precipitate was 83.8% of that (17.79 μg) in fresh tea leaf extract, and after the saturated ammonium sulphate precipitate was dialyzed against distilled water overnight, the amount (14.37 μg) of selenium remaining in the dialyzed precipitate (protein) was still 80.8% of that in the fresh tea leaf extract. However, there were no significant differences (p >0.05) between the amount of selenium in the saturated ammonium sulphate precipitate and that in the saturated ammonium sulphate precipitate that was dialyzed.