Variations of antioxidant properties and NO scavenging abilities during fermentation of tea

The neuroprotective effect of traditional Chinese medicinal plants-A critical review

Neurodegenerative and neuropsychiatric diseases are increasingly affecting individuals' quality of life, thus increasing their cost to social and health systems. These diseases have overlapping mechanisms, such as oxidative stress, protein aggregation, neuroinflammation, neurotransmission impairment, mitochondrial dysfunction, and excitotoxicity. Currently, there is no cure for neurodegenerative diseases, and the available therapies have adverse effects and low efficacy. For neuropsychiatric disorders, such as depression, the current therapies are not adequate to one-third of the patients, the so-called treatment-resistant patients. So, searching for new treatments is fundamental. Medicinal plants appear as a strong alternative and complement towards new treatment protocols, as they have been used for health purposes for thousands of years. Thus, the main goal of this review is to revisit the neuroprotective potential of some of the most predominant medicinal plants (and one fungus) used in traditional Chinese medicine (TCM), focusing on their proven mechanisms of action and their chemical compositions, to give clues on how they can be useful against neurodegeneration progression.

Distribution of trace metals in a soil-tea leaves-tea infusion system: characteristics, translocation and health risk assessment

The effects of metal pollution on tea are of great concern to consumers. We apply Geographic information systems technology to study the distribution of heavy metal elements in tea plantation ecosystems in Jiangsu Province, explore the relationships among metals in the soil, tea leaves and tea infusions, and assess the human safety risks of metals. The concentrations of nine metals in a soil-tea leaves-tea infusion system were studied at 100 randomly selected tea plantations in Jiangsu Province, China. Concentrations of selected metals, zinc (Zn), nickel (Ni), manganese (Mn), chromium (Cr) and copper (Cu), were quantified using an inductively coupled plasma-optical emission spectrometer (ICP-OES), and cadmium (Cd), arsenic (As), plumbum (Pb) and mercury (Hg) were quantified using inductively coupled plasma-mass spectrometry (ICP-MS). Arc-Map 10.3 was used for the spatial analysis of metals in soil, tea leaves and tea infusions. We found that the contents of Mn, Ni and Zn are high level in soil, tea leaves and tea infusions. The Mn level showed a spatial distribution pattern with greater concentrations at the junction of Nanjing and Yangzhou, southwest of Changzhou and west of Suzhou. The hazard index (HI) values in north-central Nanjing, southern Suzhou, southwestern Changzhou and northern Lianyungang were relatively greater. The Zn, Ni, Mn, Cr and Cu levels in the soil-tea infusion system were 17.3, 45.5, 54.5, 1.5 and 14.3%, respectively. The order of the leaching rates of the elements was Ni > Cr > Zn > Mn > Cu. The relative contribution ratios of HI were in the order of Mn > Ni > Cu > Zn > Cr > Pb > Cd > As > Hg. In tea infusions, the Mn level has the greatest potential health risks to consumers. Moreover, using C_soil it was inferred that the safety thresholds of Zn, Ni, Mn, Cr and Cu in soil were 27,700, 50, 1230, 493,000 and 16,800 mg L^-1, respectively. The content of heavy metals in soil and tea varies greatly in different regions of Jiangsu Province, 92% of the soil has heavy metal content that meets the requirements of pollution-free tea gardens, 91% of tea samples met the requirements of green food tea. The thresholds for Ni (50 mg L^-1) and Mn (1230 mg L^-1) can be used as maximum limits in tea plantation soils. The consumption of tea infusions did not pose metal-related risks to human health.

Dietary Theabrownin Supplementation Improves Production Performance and Egg Quality by Promoting Intestinal Health and Antioxidant Capacity in Laying Hens

Theabrownin, an activated and ample pigment in Pu-erh tea, is known to exert antiobesity and antihyperlipidemic effects in humans, mice, and rats. In this study, we aimed to explore the effects of theabrownin (TB) dietary supplementation on production performance, egg quality, intestinal health, and antioxidant capacities in laying hens. In total, 160 Lohmann laying hens (25 weeks old) were randomly split into four groups (each group 40 hens), namely the CONT (control, basal diet + 0 mg/kg TB), TB1 (basal diet + 100 mg/kg TB), TB2 (basal diet + 200 mg/kg TB), and TB4 (basal diet + 400 mg/kg TB) groups, respectively. These were supplemented with TB for 12 weeks. The results showed that the TB1 group exhibited a significantly higher laying rate during 9 to 12 weeks and higher egg weight and feed conversion efficiency (lower FCR) during 5 to 8 weeks and in the overall period (1 to 12 weeks) than the CONT group (p < 0.05). Compared with the CONT group, the eggs from the TB4 group had higher albumen height and Haugh unit than those from the other treatment groups after the 8th and 12th week; notably, the same was also observed in the TB1 and TB2 groups but only after the 12th week (p < 0.05). The albumen quality (albumen height and Haugh unit) after 3 weeks of storage was significantly higher in the TB1, TB2 and TB4 groups than in the CONT group (p < 0.05). Furthermore, TB supplementation lowered the serum levels of total cholesterol and total triglyceride (p < 0.05). Expression analysis revealed that TB2 and TB4 groups had reduced expression of tumor necrosis factor-α (p < 0.05), while TB1, TB2, and TB4 had significantly decreased expression of interleukin-1β and IL-6 (p < 0.05). Conversely, zonula occludens-1, claudin-1, and mucin-2 were upregulated in the TB2 and TB4 groups (p < 0.05). Meanwhile, dietary TB supplementation ameliorated the antioxidant status of the ovary and the magnum, showing a significant reduction in malondialdehyde and 8-hydroxydeoxyguanosine levels in the magnum, the upregulation of glutathione in the ovary, and superoxide dismutase and catalase in the magnum (p < 0.05). Overall, dietary supplementation with TB (>100 mg/kg) improved production performance and egg storage quality by improving the intestinal health and antioxidant capacities of the reproductive system in laying hens.

Application of BRAFO-tiered approach for health benefit-risk assessment of dark tea consumption in China

Dark tea, a unique tea fermented primarily in China, has numerous potential beneficial effects. However, harmful substances present in dark tea have provoked significant concern. To conduct a quantitative benefit-risk assessment of dark tea for Chinese residents and provide guidance on rational consumption, a framework of Benefit-Risk Analysis for Foods (BRAFO) and meta-analysis was applied to construct a disability-adjusted life year (DALY). Based on the BRAFO-tiered approach, a reference scenario (no intake) and an alternative scenario (intake of 3 cups/day) were determined. The overall health impacts of dark tea were simulated by comparing the risks of fluoride and AF with benefits of reduced-risk to coronary heart disease (CHD) and diabetes in different scenarios. Three cups of fermented tea consumed per day decreased risks of CHD and diabetes by 8.16% and 12.77% respectively. After quantitative integration of information, the ultimate net health effect was found to be -1958.827 illustrating that the benefits of drinking three cups of dark tea per day outweigh the risks. However, considering the uncertainties in the process, decision-makers should proceed with caution, consulting additional well-conducted studies and further managing harmful substances in dark tea.

Kombucha Tea-A Double Power of Bioactive Compounds from Tea and Symbiotic Culture of Bacteria and Yeasts (SCOBY)

Kombucha is a low alcoholic beverage with high content of bioactive compounds derived from plant material (tea, juices, herb extracts) and metabolic activity of microorganisms (acetic acid bacteria, lactic acid bacteria and yeasts). Currently, it attracts an increasing number of consumers due to its health-promoting properties. This review focuses on aspects significantly affecting the bioactive compound content and biological activities of Kombucha tea. The literature review shows that the drink is characterized by a high content of bioactive compounds, strong antioxidant, and antimicrobial properties. Factors that substantially affect these activities are the tea type and its brewing parameters, the composition of the SCOBY, as well as the fermentation parameters. On the other hand, Kombucha fermentation is characterized by many unknowns, which result, inter alia, from different methods of tea extraction, diverse, often undefined compositions of microorganisms used in the fermentation, as well as the lack of clearly defined effects of microorganisms on bioactive compounds contained in tea, and therefore the health-promoting properties of the final product. The article indicates the shortcomings in the current research in the field of Kombucha, as well as future perspectives on improving the health-promoting activities of this fermented drink.

Paternal bisphenol A exposure induces testis and sperm pathologies in mice offspring: Possibly due to oxidative stress?

Bisphenol A (BPA), an endocrine and metabolic disruptor, is widely used to manufacture polycarbonate plastics and epoxy resins. Accumulating evidence suggests that paternal BPA exposure adversely affects male germlines and results in atypical reproductive phenotypes that might persist for generations to come. Our study investigated this exposure on testicular architecture and sperm quality in mouse offspring, and characterised underlying molecular mechanism(s). A total of 18 immature male Swiss albino mice (3.5 weeks old) were randomly divided into three groups and treated as follows: Group I, no treatment (sham control); Group II, sterile corn oil only (vehicle control); Group III, BPA (400 μg/kg) in sterile corn oil. At 9.5 weeks old, F0 males were mated with unexposed females. F0 offspring (F1 generation) were monitored for postnatal development for 10 weeks. At 11.5 weeks old, the animals were sacrificed to examine testicular architecture, sperm parameters, including DNA integrity, and oxidative stress biomarkers. Results showed that BPA significantly induced changes in the body and testis weights of the F0 and F1 generation BPA lineages compared to F0 and F1 generation control lineages. A decrease in sperm count and motility with further, increased sperm abnormalities, no or few sperm DNA alterations and elevated levels of MDA, PC and NO were recorded. Similar effects were found in BPA exposed F0 males, but were more pronounced in the F0 offspring. In addition, BPA caused alterations in the testicular architecture. These pathological changes extended transgenerationally to F1 generation males’ mice, but the pathological changes were more pronounced in the F1 generation. Our findings demonstrate that the biological and health BPA impacts do not end in paternal adults, but are passed on to offspring generations. Hence, linking observed testis and sperm abnormalities in the F1 generation to BPA exposure of their parental line was evident in this work. The findings also illustrate that oxidative stress appears to be a molecular component of the testis and sperm pathologies.

The Remarkable Antioxidant and Anti-Inflammatory Potential of the Extracts of the Brown Alga Cystoseira amentacea var. stricta

Inflammation and oxidative stress are part of the complex biological responses of body tissues to harmful stimuli. In recent years, due to the increased understanding that oxidative stress is implicated in several diseases, pharmaceutical industries have invested in the research and development of new antioxidant compounds, especially from marine environment sources. Marine seaweeds have shown the presence of many bioactive secondary metabolites, with great potentialities from both the nutraceutical and the biomedical point of view. In this study, 50%-ethanolic and DMSO extracts from the species C. amentacea var. stricta were obtained for the first time from seaweeds collected in the Ligurian Sea (north-western Mediterranean). The bioactive properties of these extracts were then investigated, in terms of quantification of specific antioxidant activities by relevant ROS scavenging spectrophotometric tests, and of anti-inflammatory properties in LPS-stimulated macrophages by evaluation of inhibition of inflammatory cytokines and mediators. The data obtained in this study demonstrate a strong anti-inflammatory effect of both C. amentacea extracts (DMSO and ethanolic). The extracts showed a very low grade of toxicity on RAW 264.7 macrophages and L929 fibroblasts and a plethora of antioxidant and anti-inflammatory effects that were for the first time thoroughly investigated. The two extracts were able to scavenge OH and NO radicals (OH EC50 between 392 and 454 μg/mL; NO EC50 between 546 and 1293 μg/mL), to partially rescue H2O2-induced RAW 264.7 macrophages cell death, to abate intracellular ROS production in H2O2-stimulated macrophages and fibroblasts and to strongly inhibit LPS-induced inflammatory mediators, such as NO production and IL-1α, IL-6, cyclooxygenase-2 and inducible NO synthase gene expression in RAW 264.7 macrophages. These results pave the way, for the future use of C. amentacea metabolites, as an example, as antioxidant food additives in antiaging formulations as well as in cosmetic lenitive lotions for inflamed and/or damaged skin.

Origanum vulgare L. extract-mediated synthesis of silver nanoparticles, their characterization and antibacterial activities

Plant extracts serve as reducing and coating agents and are, therefore, commonly employed for the generation of silver (Ag) nanoparticles (NPs). Plant extract mediated synthesis of Ag NPs is a green, environmentally friendly and cost-effective technique which offers a new and potential alternative to chemically synthesized NPs, decreasing the utilization of hazardous and toxic chemicals and protecting the environment. Origanum vulgare L. extracts were evaluated for total flavonoid and phenol content. The free radical scavenging activity was determined employing 2,2-diphenyl-1-picrylhydrazyl assay. Ag NPs were produced exploiting ethanolic extracts of O. vulgare L. leaves. The generation of Ag NPs was carried out both in light and dark conditions. The biosynthesized Ag NPs were characterized employing microscopic and spectroscopic techniques. Antibacterial activities of Ag NPs were determined following appropriate methods. The results revealed that energy of photons was required to reduce Ag+ to Ag0. According to scanning electron microscopy reports, biologically formed Ag NPs ranged in size from 1 to 50 nmand were presented instability causing aggregation. They indicated that O. vulgare L. extracts were rich in flavonoids and phenols and exhibited strong antioxidant activity. Ag NPs exhibited good antibacterial activity immediately after production. Gram-positive strains showed higher sensitivity to Ag NPs compared to Gram-negative stains. Ag NPs can serve as an effective antibacterial agent against antibiotic-resistant strains. The kanamycin-resistant strain was more sensitive to Ag NPs than the ampicillin-resistant strain. Thus, Origanum extract-mediated synthesized Ag NPs can be recommended as alternative effective antibacterial agents, but their activity depended on bacterial species and strains.

Natural compounds attenuate heavy metal-induced PC12 cell damage

Objectives

To investigate the neuroprotective effects of six natural compounds (caffeine, gallic acid, resveratrol, epigallocatechin gallate [EGCG], L-ascorbic acid and alpha tocopherol [Vitamin E] on heavy metal-induced cell damage in rat PC12 cells.

Methods

In this in vitro experiment, rat PC12 cells were exposed to four heavy metals (CdCl₂, HgCl₂, CoCl₂ and PbCl₂) at different concentrations and cell apoptosis, necrosis and oxidative stress were assessed with and without the addition of the six natural compounds.

Results

The metals decreased cell viability but the natural compounds attenuated their effects on apoptosis, necrosis and reactive oxygen species (ROS) levels. Mitochondrial protein changes were involved in the regulation.

Conclusion

Overall, the natural compounds did provide protection against the metal-induced PC12 cell damage. These data suggest that natural compounds may have therapeutic potential against metal-induced neurodegenerative disease.

Anti-oxidative effects of catechins and theaflavins on glutamate-induced HT22 cell damage

Background: Glutamate is an excitatory neurotransmitter that is involved in cell stress caused by oxidation. Polyphenolic compounds display various potential neuroprotective properties due to their ability to donate electrons and hydrogen atoms. Method: In this study, we evaluate the protective effect towards glutamate-induced HT22 cell damage. Two families of polyphenolic compounds are investigated, including the monomer polyphenol catechins, as well as the dimerized theaflavins. The cell apoptosis and intercellular ROS production are quantified by flow cytometry, and the protective mechanism is evaluated by quantifying the expression of cell apoptosis and energy related proteins. Result: Both sets of compounds protect cells against glutamate-induced oxidative stress, partially restore the cell viability, and prevent cells from apoptosis via bcl-2 and bax regulation, and attenuate intercellular ROS production. We demonstrate here that the protective effect is mediated by multiple factors, including reducing intracellular Ca²⁺ concentration, increasing glutathione level and related enzyme activity. Thus, the phosphorylation of AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK) show inverse correlation of activity after catechins and theaflavins stimulation. Conclusion: These results suggest both catechins and theaflavins compounds protect cells from glutamate-induced damage via cell apoptosis-related proteins and indirect regulation of cellular energy enzymes. These natural sourced antioxidants provide potential therapeutic agents for glutamate accumulation and toxicity related diseases.

Methionine Augments Antioxidant Activity of Rice Protein during Gastrointestinal Digestion

To elucidate the influence of methionine, which is an essential sulfur-containing amino acid, on the antioxidant activity of rice protein (RP), methionine was added to RP (RM). The addition of methionine to RM0.5, RM1.0, RM1.5, RM2.0, and RM2.5 was 0.5-, 1.0-, 1.5-, 2.0-, and 2.5-fold of methionine of RP, respectively. Using the in vitro digestive system, the antioxidant capacities of scavenging free radicals (superoxide; nitric oxide; 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, ABTS), chelating metal (iron), and reducing power were investigated in the hydrolysates of RP and RMs. Upon pepsin-pancreatin digestion, the weakest antioxidant capacity was produced by RP. With the addition of methionine, RMs exhibited more excellent responses to free radical scavenging activities and reducing power than RP, whereas RMs did not produce the marked enhancements in iron chelating activity as compared to RP. The present study demonstrated that RMs differently exerted the free radical scavenging activities that emerged in the protein hydrolysates, in which the strongest scavenging capacities for ABTS, superoxide, and nitric oxide were RM1.5, RM2.0, and RM2.5, respectively. Results suggested that the availability of methionine is a critical factor to augment antioxidant ability of RP in the in vitro gastrointestinal tract.

Attenuated glutamate induced ROS production by antioxidative compounds in neural cell lines

Glutamate is an excitatory neurotransmitter involved in neural function. Excess accumulation of intercellular glutamate leads to increasing concentration of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in neuronal cells. In this study, we investigated the antioxidant activity of several typical superior compounds among four neuronal cells, and determined the scavenging activity of free radicals. The in vivo assay was also carried out to compare the protective effect of glutamate-induced cell damage. Hierarchical clustering analysis was used to identify the common properties. Glutamate induced neurotoxicity and ROS production, suggesting glutamate cytotoxicity was related to oxidative stress and widely exists in different cell lines. Those screening compounds exhibited strong antioxidant ability, but low cytotoxicity to neuronal cells, acting as agents against neurodegenerative diseases. Finally, a hierarchical clustering analysis assay indicated that hyperoside and rutin hydrate are the most effective compounds for attenuating intercellular ROS levels. The results suggested the activity more or less relies on structure, rather than residues. These data generate new supporting ideas to remove intracellular ROS and the identified compounds serve as potential therapeutic agents in multiple neurological diseases.

Glutamate is an excitatory neurotransmitter involved in neural function.

Epigallocatechin Gallate Is the Most Effective Catechin Against Antioxidant Stress via Hydrogen Peroxide and Radical Scavenging Activity

Background

Hydrogen peroxide-induced neuronal oxidative stress is a serious threat to the nervous system. Catechins and related compounds are effective radical scavengers that protect against nerve cell damage.

Material/Methods

Here, we investigated the antioxidant property of various catechins in protecting against hydrogen peroxide, as well as their radical-scavenging activity.

Result

We found that catechins treatment effectively protected HT22 cells against H₂O₂-induced cell viability by decreasing and attenuating reactive oxidative species production in different proportions. In addition, all tested catechins performed radical scavenging activity, and partially removed the free radicals. Among all investigated catechins, epigallocatechin gallate was the most effective against ROS production and had the strongest radical-scavenging activity. These results suggest that beneficial effects were strongly related with structure of catechins, mainly because of the hydroxyl and galloyl groups.

Conclusions

In conclusion, epigallocatechin gallate is the most effective antioxidant polyphenol against hydrogen peroxide and radical-scavenging activity.

Protective effect of Pu-erh tea extracts against ethanol-induced gastric mucosal damage in rats

Pu-erh tea has become a focus of research due to its reported biological activities, including anti-oxidation, anti-inflammation and anti-immunosenescence. The present study was performed to evaluate the potential gastroprotective function of Pu-erh tea extracts against ethanol-induced gastric mucosal damage in rats. Sprague Dawley rats were randomly divided into seven groups: A normal control, a model control, a cimetidine (0.08 g/kg) group, three Pu-erh tea extracts groups (low, moderate and high-dose; 0.50, 1.00 and 1.50 g/kg, respectively, and a green tea powder (1.00 g/kg) group. The normal and model groups were pre-treated with distilled water while the other groups were respectively administered cimetidine, Pu-erh tea extracts and green tea powder for 14 days. Then, absolute ethanol was orally administered to the rats of all groups excluding the normal controls. The effects of the pretreatments on gastric mucosal injury were evaluated by gross assessment of gastric lesions, examination of histopathology and determination of myeloperoxidase (MPO) activity and asymmetric arginine (ADMA) concentration in gastric mucosal homogenate. Pre-treatment with cimetidine or Pu-erh tea extracts markedly suppressed the formation of ethanol-induced gastric lesions. Furthermore, clear decreases in MPO activity and ADMA concentration in the gastric mucosal homogenate were observed following pretreatment with cimetidine or Pu-erh tea extracts. The anti-gastric ulcer activity of green tea was less than that of Pu-erh tea. Overall, these effects of Pu-erh tea extracts may be due to potential functions in protecting the gastric mucus layer and suppressing inflammation.

In vitro and in vivo assessment of anti-hyperglycemic and antioxidant effects of Oak leaves (Quercus convallata and Quercus arizonica) infusions and fermented beverages

The aim of this study was to evaluate the anti-hyperglycemic and antioxidant effects of oak leaves infusions and fermented beverages from Quercus convallata and Q. arizonica in vitro and in vivo. Female C57BL/6 mice fed with high saturated fat and fructose diet-induced obesity were treated with oak leaves beverages (200 μL/per day equivalent to 15mg of lyophilized sample/Kg of body weight for infusions and 31mg of lyophilized sample/Kg of body weight for fermented beverages) for 3months and an oral glucose tolerance test (OGTT) was performed. Blood plasma was obtained for determination of glucose, lipid profile, and oxidative stress markers (ABTS, nitric oxide, and ORAC assays). Insulin resistance was estimated using the product of triglycerides and glucose (TyG). Oak leaves infusions and fermented beverages exhibited exerted inhibition of α-amylase (8-15% and 5-9%, respectively) and α-glucosidase (98% and 99%, respectively) enzymes. After OGTT, the groups treated with either oak leaves infusions or fermented beverages showed lower glucose levels compared with the obesity control group (18%) and a similar glucose tolerance to healthy control group. On long-term evaluation, intervention groups showed a significant reduction in fasting glucose concentrations (41-50% for oak leaves infusions and 52-66% for fermented beverages) and TyG index (4.2-4.6% for oak leaves infusions and 5.9-7.5% for fermented beverages) compared with the obese control group. Oak leaves infusions and fermented beverages had antioxidant potential in vitro and scavenging activity for radicals such as peroxyl and peroxynitrite anions. Our results suggest anti-hyperglycemic and antioxidant effects of beverages prepared with leaves of Quercus species in vitro and in vivo.

Environmentally toxicant exposures induced intragenerational transmission of liver abnormalities in mice

Environmental toxicants such as chemicals, heavy metals, and pesticides have been shown to promote transgenerational inheritance of abnormal phenotypes and/or diseases to multiple subsequent generations following parental and/or ancestral exposures. This study was designed to examine the potential transgenerational action of the environmental toxicant trichloroethane (TCE) on transmission of liver abnormality, and to elucidate the molecular etiology of hepatocyte cell damage. A total of thirty two healthy immature female albino mice were randomly divided into three equal groups as follows: a sham group, which did not receive any treatment; a vehicle group, which received corn oil alone, and TCE treated group (3 weeks, 100 μg/kg i.p., every 4^th day). The F0 and F1 generation control and TCE populations were sacrificed at the age of four months, and various abnormalities histpathologically investigated. Cell death and oxidative stress indices were also measured. The present study provides experimental evidence for the inheritance of environmentally induced liver abnormalities in mice. The results of this study show that exposure to the TCE promoted adult onset liver abnormalities in F0 female mice as well as unexposed F1 generation offspring. It is the first study to report a transgenerational liver abnormalities in the F1 generation mice through maternal line prior to gestation. This finding was based on careful evaluation of liver histopathological abnormalities, apoptosis of hepatocytes, and measurements of oxidative stress biomarkers (lipid peroxidation, protein carbonylation, and nitric oxide) in control and TCE populations. There was an increase in liver histopathological abnormalities, cell death, and oxidative lipid damage in F0 and F1 hepatic tissues of TCE treated group. In conclusion, this study showed that the biological and health impacts of environmental toxicant TCE do not end in maternal adults, but are passed on to offspring generations. Hence, linking observed liver abnormality in the offspring to environmental exposure of their parental line. This study also illustrated that oxidative stress and apoptosis appear to be a molecular component of the hepatocyte cell injury.

In vitro α-glucosidase inhibitory activity of isolated fractions from water extract of Qingzhuan dark tea

BACKGROUND

Natural products have being used as potential inhibitors against carbohydrate-hydrolyzing enzymes to treat diabetes mellitus. Chinese dark tea has various interesting bioactivities. In this study, the active compounds from Qingzhuan dark tea were separated and their anti-diabetic activity was examined using an in vitro enzymatic model.

METHODS

The chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions of a Chinese dark tea (Qingzhuan tea) were prepared by successively isolating the water extract with different solvents and their in vitro inhibitory activities against α-glucosidase were assessed. The fraction with the highest inhibitory activity was further characterized to obtain the main active components of Qingzhuan tea.

RESULTS

The ethyl acetate fraction had the greatest inhibitory effect on α-glucosidase, followed by n-butanol, sediment and residual aqua fractions (with the IC₅₀ values of 0.26 mg/mL, 2.94 mg/mL, 3.02 mg/mL, and 5.24 mg/mL, respectively), mainly due to the high content of polyphenols. Among the eight subfractions (QEF1-8) isolated from the ethyl acetate fraction, QEF8 fraction showed the highest α-glucosidase inhibitory potential in a competitive inhibitory manner (the K _i value of 77.10 μg/mL). HPLC-MS analysis revealed that (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) were the predominant active components in QEF8.

CONCLUSION

These results indicated that Qingzhuan tea extracts exerted potent inhibitory effects against α-glucosidase, EGCG and ECG were likely responsible for the inhibitory activity in Qingzhuan tea. Qingzhuan tea may be recommended as an oral antidiabetic diet.

Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activity of Eucalyptus camaldulensis and Litsea glaucescens Infusions Fermented with Kombucha Consortium

Physicochemical properties, consumer acceptance, antioxidant and angiotensin-converting enzyme (ACE) inhibitory activities of infusions and fermented beverages of Eucalyptus camaldulensis and Litsea glaucescens were compared. Among physicochemical parameters, only the pH of fermented beverages decreased compared with the unfermented infusions. No relevant changes were reported in consumer preference between infusions and fermented beverages. Phenolic profile measured by UPLC MS/MS analysis demonstrated significant concentration changes of these compounds in plant infusions and fermented beverages. Fermentation induced a decrease in the concentration required to stabilize 50% of DPPH radical (i.e. lower IC50). Additionally, it enhanced the antioxidant activity measured by the nitric oxide scavenging assay (14% of E. camaldulensis and 49% of L. glaucescens); whereas relevant improvements in the fermented beverage were not observed in the lipid oxidation assay compared with unfermented infusions. The same behaviour was observed in the inhibitory activity of ACE; however, both infusions and fermented beverages had lower IC50 than positive control (captopril). The present study demonstrated that fermentation has an influence on the concentration of phenolics and their potential bioactivity. E. camaldulensis and L. glaucescens can be considered as natural sources of biocompounds with antihypertensive potential used either as infusions or fermented beverages.

Pu-erh Tea Protects the Nervous System by Inhibiting the Expression of Metabotropic Glutamate Receptor 5

Glutamate is one of the major excitatory neurotransmitters of the CNS and is essential for numerous key neuronal functions. However, excess glutamate causes massive neuronal death and brain damage owing to excitotoxicity via the glutamate receptors. Metabotropic glutamate receptor 5 (mGluR5) is one of the glutamate receptors and represents a promising target for studying neuroprotective agents of potential application in neurodegenerative diseases. Pu-erh tea, a fermented tea, mainly produced in Yunnan province, China, has beneficial effects, including the accommodation of the CNS. In this study, pu-erh tea markedly decreased the transcription and translation of mGluR5 compared to those by black and green teas. Pu-erh tea also inhibited the expression of Homer, one of the synaptic scaffolding proteins binding to mGluR5. Pu-erh tea protected neural cells from necrosis via blocked Ca²⁺ influx and inhibited protein kinase C (PKC) activation induced by excess glutamate. Pu-erh tea relieved rat epilepsy induced by LiCl-pilocarpine in behavioural and physiological assays. Pu-erh tea also decreased the expression of mGluR5 in the hippocampus. These results show that the inhibition of mGluR5 plays a role in protecting neural cells from glutamate. The results also indicate that pu-erh tea contains biological compounds binding transcription factors and inhibiting the expression of mGluR5 and identify pu-erh tea as a novel natural neuroprotective agent.

The effect of tea fermentation on rosmarinic acid and antioxidant properties using selected in vitro sprout culture of Orthosiphon aristatus as a model study

Orthosiphon aristatus, an Indonesian medicinal plant, is normally used as a traditional herbal tea. Recently, this plant has begun to attract attention due to its antioxidant properties. However, little is known about tea fermentation effect on antioxidant properties of this plant. Thus, to extend the tea fermentation study, in vitro sprout culture of this plant was established as a new feature model. This model plant was selected based on three reasons. Firstly, as a native tropical plant, to grow this plant in sub-tropic area is considered difficult. Secondly, the in vitro sprout culture is more genetically stable compared to other types of in vitro cultures. Thirdly, results showed that this in vitro sprout culture grew faster and produced higher biomass than in vitro tissue culture. Both characteristics are important in producing tea leaves. Accordingly, the aim of the current study was twofold. First was to establish high rosmarinic acid line of in vitro sprout culture of Orthosiphon aristatus by elicitation. Second was to evaluate the effect of tea fermentation on antioxidant properties of this plant. Results showed that yeast extract (5 g/L) elicitation resulted in the highest production of rosmarinic acid. This elicited plant was subjected to partial and full tea fermentation. Results revealed that both tea fermentations decreased the level of rosmarinic acid, total phenolic compounds, flavonoids, and flavonols. These decreases were concomitant with reduced antioxidant activities as measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, Trolox equivalent antioxidant capacity (TEAC), and Superoxide dismutase (SOD)-like activity assays. HPLC results showed that the longer the tea fermentation was, the greater reduction rosmarinic acid was found. High correlation value of 0.922 between rosmarinic acid and antioxidant activities was also observed. These results indicated that rosmarinic acid is the major contributor to the antioxidant activities of Orthosiphon aristatus. These results may provide useful information, in particular, for the food and pharmaceutical industries in the development of functional foods desiring maximum potential health benefits from Orthosiphon aristatus.

Pu-erh tea reduces nitric oxide levels in rats by inhibiting inducible nitric oxide synthase expression through toll-like receptor 4

Pu-erh tea undergoes a unique fermentation process and contains theabrownins, polysaccharides and caffeine; although it is unclear about which component is associated with the down regulation of nitric oxide levels or how this process is mediated. To address this question we examined the effects of pu-erh tea on nitric oxide synthase (NOS) genes. Cohorts of rats were separately given four-week treatments of water as control, pu-erh tea, or the tea components: theabrownins, caffeine or polysaccharides. Five experimental groups were injected with lipopolysaccharides (LPS) to induce nitric oxide (NO) production, while the corresponding five control groups were injected with saline as a negative control. The serum and liver NO concentrations were examined and the NOS expression of both mRNA and protein was measured in liver. The results showed that the rats which were fed pu-erh tea or polysaccharides had lower levels of NO which corresponded with the down-regulation of inducible nitric oxide synthase (iNOS) expression. We further demonstrate that this effect is mediated through reduction of Toll-like receptor 4 (TLR4) signaling. Thus we find that the polysaccharide components in pu-erh tea reduce NO levels in an animal model by inhibiting the iNOS expression via signaling through TLR4.