Tea and health: preventive and therapeutic usefulness in the elderly?

Persimmon tannin promotes the growth of Saccharomyces cerevisiae under ethanol stress

BACKGROUND

Saccharomyces cerevisiae plays a pivotal role in various industrial processes, including bioethanol production and alcoholic beverage fermentation. However, during these fermentations, yeasts are subjected to various environmental stresses, such as ethanol stress, which hinder cell growth and ethanol production. Genetic manipulations and the addition of natural ingredients rich in antioxidants to the culture have been shown to overcome this. Here, we investigated the potential of persimmon tannins, known for their antioxidative properties, to enhance the ethanol stress tolerance of yeast.

RESULTS

Assessment of the effects of 6.25 mg mL-1 persimmon tannins after 48 h incubation revealed cell viability to be increased by 8.9- and 6.5-fold compared to the control treatment with and without 12.5% ethanol, respectively. Furthermore, persimmon tannins reduced ethanol-induced oxidative stress, including the production of cellular reactive oxygen species and acceleration of lipid peroxidation. However, persimmon tannins could hardly overcome ethanol-induced cell membrane damage.

CONCLUSION

The findings herein indicate the potential of persimmon tannin as a protective agent for increasing yeast tolerance to ethanol stress by restricting oxidative damage but not membrane damage. Overall, this study unveils the implications of persimmon tannins for industries relying on yeast. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Understanding Healthy Eating Habits of Elderly People in a Geriatric Center in Kirkuk City: A Cross-Sectional Study

Background A person's nutritional knowledge has a great influence on their eating habits and nutritional status. Identifying knowledge gaps can lead to educational efforts to reduce the probability of malnutrition and encourage healthy aging. This study aimed to assess older people's knowledge of healthy eating and identify associated factors in the Geriatric Center in Kirkuk City. Methods This was a cross-sectional study conducted from November 5, 2023, to February 25, 2024, at the Geriatric Center in Kirkuk City on 25 older adults who were targeted at the only specialist center in Kirkuk City. All center residents were included (≥60 years old and without severe cognitive impairment). A non-probability, purposive sample was employed in the study. Data were collected using an interview-structured questionnaire. The structured questionnaire consisted of two parts. The first part focused on socio-demographic variables such as age, gender, marital status, education level, and type of work before admission to the center, as well as smoking status, walking, and medical history. The second part related to assessing older people's knowledge of healthy eating using 17 items. Data entry and analysis were performed using SPSS (v 26; IBM Corp., Armonk, NY, US). Data are reported as frequency and percentage and the chi-square test/Fisher exact test was used for categorical variables. The significance level for statistical analysis was set at p<0.05. Results Of the 25 participants included in the study, 20 (80%) were men and 5 (20%) were women. Approximately two-thirds of the 17 (68%) were between 60 and 69 years old, with a mean age of 69.44 ± 5.71 years. Of the 25 older people surveyed, 16 (64%) had low knowledge of healthy eating while 9 (36%) had high knowledge. Knowledge level was significantly associated with age (p = 0.001), gender (p = 0.040), education level (p = 0.006), and smoking status (p = 0.037). Conclusions In the geriatric center in Kirkuk City, the level of knowledge of healthy eating was low. The knowledge level of people tends to be related to factors like age, gender, education level, and smoking status. This, in turn, requires implementing educational programs by healthcare providers at the center to promote knowledge and understanding of healthy diets and practices.

Inhibitory interaction of flavonoids with organic cation transporter 2 and their structure-activity relationships for predicting nephroprotective effects

Organic cation transporter 2 (OCT2) is mainly responsible for the renal secretion of various cationic drugs, closely associated with drug-induced acute kidney injury (AKI). Screening and identifying potent OCT2 inhibitors with little toxicity in natural products in reducing OCT2-mediated AKI is of great value. Flavonoids are enriched in various vegetables, fruits, and herbal products, and some were reported to produce transporter-mediated drug-drug interactions. This study aimed to screen potential inhibitors of OCT2 from 96 flavonoids, assess the nephroprotective effects on cisplatin-induced kidney injury, and clarify the structure-activity relationships of flavonoids with OCT2. Ten flavonoids exhibited significant inhibition (>50%) on OCT2 in OCT2-HEK293 cells. Among them, the six most potent flavonoid inhibitors, including pectolinarigenin, biochanin A, luteolin, chrysin, 6-hydroxyflavone, and 6-methylflavone markedly decreased cisplatin-induced cytotoxicity. Moreover, in cisplatin-induced renal injury models, they also reduced serum blood urea nitrogen (BUN) and creatinine levels to different degrees, the best of which was 6-methylflavone. The pharmacophore model clarified that the aromatic ring, hydrogen bond acceptors, and hydrogen bond donors might play a vital role in the inhibitory effect of flavonoids on OCT2. Thus, our findings would pave the way to predicting the potential risks of flavonoid-containing food/herb-drug interactions in humans and optimizing flavonoid structure to alleviate OCT2-related AKI.

Discriminative Chemical Profiles of Shan Tuyet Tea (Camellia sinensis var. Shan) and Sinensis Tea (Camellia sinensis var. sinensis) Collected in Ta Xua, Son La, Vietnam and Their Correlation With Antioxidant Activity

Chè Shan Tuyet ( Camellia sinensis var. Shan) is one of the precious tea resources of Vietnam; however, there is little research on its chemical composition. The purpose of this study was to characterize the main quality components, such as free amino acids and catechins, in Camellia sinensis var. Shan and Camellia sinensis var. sinensis collected in the high mountain of Ta Xua, Son La, Vietnam by using an amino acid analyzer and liquid chromatography coupled with tandem mass spectrometry, respectively. Principal component analysis (PCA) discrimination analysis of chemical profiles revealed a clear metabolic difference between the young leaves of Shan Tuyet tea and mature leaves of the same variety and of sinensis tea. The amino acids serine, glutamic acid, arginine, ornithine, and aspartic acid contributed mainly to the discrimination and could be considered biomarkers for Shan Tuyet tea. The levels of caffeine and 7 catechins, catechin, catechin 3-gallate, epicatechin, epicatechin-3-gallate, epigallocatechin 3-gallate, gallocatechin, and gallocatechin 3-gallate, in young leaves of Shan Tuyet tea were significantly higher than in the other types. Notably, the pair correlation among catechins revealed strong coefficients of the epistructures and non-epistructures, which suggested that these compounds can be converted naturally to each other. The strong correlation between epicatechin-3-gallate and catechin 3-gallate with antiradical ABTS activity of Shan Tuyet tea leaves indicates that these 2 catechins are mainly responsible for the antioxidant activity. This is the first report on the bioactive compounds of Shan Tuyet tea, as well as its potential for the production of health supplements.

Effect of red light on the composition of metabolites in tea leaves during the withering process using untargeted metabolomics

BACKGROUND

Red light withering significantly improves the sensory flavor qualities of tea, although changes in metabolites during this process have not been systematically studied until now. The present study comprehensively analyzes metabolites in withered tea leaves at 2-h intervals up to 12 h under red light (630 nm) and dark conditions using ultra performance liquid chromatography-high resolution mass spectrometry (untargeted metabolomics).

RESULTS

Ninety-four non-volatile compounds are identified and relatively quantified, including amino acids, catechins, dimeric catechins, flavonol glycosides, glycosidically-bound volatiles, phenolic acids and nucleosides. The results show that amino acids, catechins and dimeric catechins are most affected by red light treatment. Ten free amino acids, theaflavins and theasinensin A increase after red light irradiation, whereas epigallocatechin gallate and catechin fall.

CONCLUSION

The present study provides a comprehensive and systematic profile of the dynamic effects of red light on withering tea and a rationale for its use in tea processing quality control. © 2021 Society of Chemical Industry.

Microbial, physiochemical and functional properties of probiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium bifidum enriched by green tea aqueous extract

In this study, the effect of aqueous extract of green tea on the viability of probiotic bacteria including Lactobacillus acidophilus and Bifidobacterium bifidum and the sensory and physicochemical and functional properties of synbiotic yogurt was investigated during 4 weeks of storage. L. acidophilus and B. bifidum counts did not significantly change in yogurt containing 0.5% and 1% of the extract during storage. Also, the addition of the extract to yogurt highly increased the phenolic compounds, since the amount of phenolic compounds in yogurt containing 0.5% and 1% extract was 660 and 1,123 mg gallic acid/kg, respectively. In addition, a significant increase in the antioxidant activity of yogurt containing green tea extract was observed in comparison with the control. The amount of antioxidant activity increased during 4 weeks of storage, which reached to 4,193 and 7,337 mg BHT eq./kg in probiotic yogurt containing 0.5% and 1% extract, respectively. The acidity increased during 4 weeks of storage, while the pH decreased. Addition of the extract significantly increased the acidity of probiotic yogurt compared with the control (p < .05). In addition, in all studied groups, an increase in syneresis was observed during the study, and the syneresis was greater in yogurt containing aqueous extract of green tea, compared with the control group. Although adding the green tea extract to probiotic yogurt impaired taste, texture, and appearance compared with the plain yogurt, the overall acceptability of these samples was yet above the acceptable level. In conclusion, the results of the study showed that the addition of aqueous extract of green tea increased the antioxidant properties and the amount of phenolic compounds in yogurt, while the viability of probiotic bacteria was not changed. Therefore, the simultaneous use of green tea extract and probiotics in yogurt is recommended as an effective functional food formulation.

Variability of antioxidant properties, catechins, caffeine, L-theanine and other amino acids in different plant parts of Azorean Camellia sinensis

During Camellia sinensis tea processing, manufacturers usually remove the internodes, which are classified as waste. This study presents the first determination of plant part contribution, particularly internodes, to green tea quality, in order to find the best blend to maximize impact on human health. Catechins, caffeine and free amino acid (FAA) profiles were determined by RP-HPLC/DAD, total phenolics (TPC) and total flavonoids (TFC) by Folin-Ciocalteu and colorimetric methodologies, respectively, and antioxidant activities by free radical-scavenging activity (FRSA), ferric-reducing antioxidant power (FRAP) and ferrous ion-chelating (FIC) methods. Individual esterified catechins content decreased as follows: epicatechin-3-gallate > epigallocatechin-3-gallate ≫ gallocatecin-3-gallate, and epicatechin derivatives content ranged from 63.91 to 91.22% of total catechins. Caffeine content was higher in internodes. L-theanine, histidine, asparagine, phenylalanine, glutamic acid and methionine were the major FAAs, and internodes contained the highest amounts of L-theanine and histidine (17 and 13.73 mg/g of sample, respectively). TPC ranged from 201.51 to 265.48 mg gallic acid equivalents/g dry extract (DE) and TFC ranged from 23.84 to 72.02 mg rutin equivalents/g DE. Internodes presented the lowest FRSA (EC₅₀ = 6.10–13.50 μg/mL), FRAP (EC₅₀ = 5.70–11.40 μg/mL) and FIC activity (36.96–79.21%). Bud presented the highest FRSA and FRAP, and bud+1st+2^ndleaves + internodes the highest FIC activity. The results revealed the potential contribution of the internodes to green tea quality and, consequently, to human health.

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Metabolites variability is observed in different parts of Azorean Camellia sinensis.

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Camellia sinensis plant parts are good sources of polyphenols (catechins).

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Internodes are not useless tea plant waste but a valuable tea quality component.

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Theanine is the major amino acid in Camellia sinensis particularly in internodes.

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Addition of internodes to the tea leaves have significative impact on human health.

A Combination of Essential Fatty Acids, Panax Ginseng Extract, and Green Tea Catechins Modifies Brain fMRI Signals in Healthy Older Adults

OBJECTIVES

To assess the effects of a combination of omega 3 essential fatty acids, green tea catechins, and ginsenosides on cognition and brain functioning in healthy older adults.

DESIGN

Double-blind, placebo-controlled, crossover design randomized controlled trial with 26-day intervention phases and a 30-day washout period.

SETTING

The Institute for Dementia Research and Prevention at the Pennington Biomedical Research Center.

PARTICIPANTS

Ten independently-living, cognitively-healthy older adults (mean age: 67.3 + 2.01 years).

INTERVENTION

Daily consumption of an investigational product (trade name "Cerbella TM") consisting of an emulsified liquid combination of standardized fish oil, panax ginseng extract, and green tea catechins in a flavored base of lecithin phospholipids optimized to maximize bioavailability of the active ingredients.

MEASUREMENTS

Before and after supplementation with the investigational product or placebo, participants completed cognitive tests including the Mini Mental State Exam (MMSE), Stroop test, Digit Symbol Substitution Test (DSST), and Immediate and Delayed Recall tests, as well as functional magnetic resonance imaging (fMRI) during a standard cognitive task switching paradigm.

RESULTS

Performance on the MMSE, Stroop test, and DSST increased significantly over one month of supplementation with the investigational product (one-sample t tests, p<.05) although differences between these changes and corresponding changes during supplementation with placebo were not significant (two-sample t tests, p>.05). During supplementation with the investigational product, brain activation during task performance increased significantly more than during supplementation with placebo in brain regions known to be activated by this task (anterior and posterior cingulate cortex). Functional connectivity during task execution between task regions (middle frontal gyrus and anterior cingulate cortex) increased significantly during supplementation with the investigational product, relative to placebo. Functional connectivity during rest between task regions (precentral gyrus and middle frontal gyrus) and default mode network regions (medial frontal gyrus and precuneus) decreased during supplementation with the investigational product relative to placebo, suggesting greater segregation of task and rest related brain activity.

CONCLUSION

One-month supplementation with a combination of omega 3 essential fatty acids, green tea catechins, and ginsenosides was associated with suggestive changes in cognitive functioning as well as modification of brain activation and brain functional connectivity in cognitively healthy older adults.

Colletotrichum gloeosporioides- Contaminated Tea Infusion Blocks Lipids Reduction and Induces Kidney Damage in Mice

When the homogenate of fresh tea tree leaves was fermented to produce black tea beverage, the Colletotrichum gloeosporioides (main pathogen or endophyte of Camellia sinensis) may be mixed into the fermentation liquor. However, it was unclear whether C. gloeosporioides-contaminated tea beverage would damage human health. Therefore, we investigated the changes of functional components and the influences on mice. C. gloeosporioides was added to the green tea infusion. After cultivation of 48 h, tea polyphenols, caffeine, and L-theanine decreased by 31.0, 26.2, and 8.3%, respectively. The contaminated tea infusion showed brown stain, and produced a group of toxic materials named phthalic acid esters. The animal study showed that green tea without contamination significantly decreased levels of alanine aminotransferase, triglycerides, free fatty acids, low-density lipoprotein, and increased insulin level compared with obese mice. On the contrary, contaminated tea lost the effects on these indicators. Furthermore, the urea nitrogen and serum creatinine levels significantly increased in the contaminated tea-drinking mice. Altogether, our results indicate that C. gloeosporioides contamination can reduce the amount of functional components of green tea. Therefore, it inhibits some health-care function of lipid-lowering. In addition, the toxic components in contaminated tea infusion might induce renal damage.

De novo transcriptome assembly of the wild relative of tea tree (Camellia taliensis) and comparative analysis with tea transcriptome identified putative genes associated with tea quality and stress response

Background

Camellia taliensis is one of the most important wild relatives of cultivated tea tree, C. sinensis. The species extensively occupies mountainous habitats representing a wide-range abiotic tolerance and biotic resistance and thus harbors valuable gene resources that may greatly benefit genetic improvement of cultivated tea tree. However, owning to a large genome size of ~3 Gb and structurally complex genome, there are fairly limited genetic information and particularly few genomic resources publicly available for this species. To better understand the key pathways determining tea flavor and enhance tea tree breeding programs, we performed a high-throughput transcriptome sequencing for C. taliensis.

Results

In this study, approximate 241.5 million high-quality paired-end reads, accounting for ~24 Gb of sequence data, were generated from tender shoots, young leaves, flower buds and flowers using Illumina HiSeq 2000 platform. De novo assembly with further processing and filtering yielded a set of 67,923 transcripts with an average length of 685 bp and an N50 of 995 bp. Based on sequence similarity searches against public databases, a total of 39,475 transcripts were annotated with gene descriptions, conserved protein domains or gene ontology (GO) terms. Candidate genes for major metabolic pathways involved in tea quality were identified and experimentally validated using RT-qPCR. Further gene expression profiles showed that they are differentially regulated at different developmental stages. To gain insights into the evolution of these genes, we aligned them to the previously cloned orthologous genes in C. sinensis, and found that considerable nucleotide variation within several genes involved in important secondary metabolic biosynthesis pathways, of which flavone synthase II gene (FNSII) is the most variable between these two species. Moreover, comparative analyses revealed that C. taliensis shows a remarkable expansion of LEA genes, compared to C. sinensis, which might contribute to the observed stronger stress resistance of C. taliensis.

Conclusion

We reported the first large-coverage transcriptome datasets for C. taliensis using the next-generation sequencing technology. Such comprehensive EST datasets provide an unprecedented opportunity for identifying genes involved in several major metabolic pathways and will accelerate functional genomic studies and genetic improvement efforts of tea trees in the future.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1494-4) contains supplementary material, which is available to authorized users.

Effects of extreme climate events on tea (Camellia sinensis) functional quality validate indigenous farmer knowledge and sensory preferences in tropical China

Climate change is impacting agro-ecosystems, crops, and farmer livelihoods in communities worldwide. While it is well understood that more frequent and intense climate events in many areas are resulting in a decline in crop yields, the impact on crop quality is less acknowledged, yet it is critical for food systems that benefit both farmers and consumers through high-quality products. This study examines tea (Camellia sinensis; Theaceae), the world's most widely consumed beverage after water, as a study system to measure effects of seasonal precipitation variability on crop functional quality and associated farmer knowledge, preferences, and livelihoods. Sampling was conducted in a major tea producing area of China during an extreme drought through the onset of the East Asian Monsoon in order to capture effects of extreme climate events that are likely to become more frequent with climate change. Compared to the spring drought, tea growth during the monsoon period was up to 50% higher. Concurrently, concentrations of catechin and methylxanthine secondary metabolites, major compounds that determine tea functional quality, were up to 50% lower during the monsoon while total phenolic concentrations and antioxidant activity increased. The inverse relationship between tea growth and concentrations of individual secondary metabolites suggests a dilution effect of precipitation on tea quality. The decrease in concentrations of tea secondary metabolites was accompanied by reduced farmer preference on the basis of sensory characteristics as well as a decline of up to 50% in household income from tea sales. Farmer surveys indicate a high degree of agreement regarding climate patterns and the effects of precipitation on tea yields and quality. Extrapolating findings from this seasonal study to long-term climate scenario projections suggests that farmers and consumers face variable implications with forecasted precipitation scenarios and calls for research on management practices to facilitate climate adaptation for sustainable crop production.

Effects of Oolong tea polyphenols, EGCG, and EGCG3″Me on pancreatic α-amylase activity in vitro

In order to investigate the inhibitory effects and possible mechanisms of Oolong tea polyphenols, (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) on pancreatic α-amylase, the inhibition, enzyme kinetics, ultraviolet (UV) absorption spectrum and fluorescence spectrum of α-amylase were investigated. The results showed that Oolong tea polyphenols, EGCG, and EGCG3″Me all exhibited inhibitory effects against α-amylase, and their half inhibitory concentration (IC50) values were 0.375, 0.350, and 0.572 mg/mL, respectively. The results of Lineweaver-Burk double reciprocal plot indicated that the inhibitory types of Oolong tea polyphenols and EGCG were competitive, whereas EGCG3″Me was in a noncompetitive pattern. Oolong tea polyphenols, EGCG, and EGCG3″Me all induced red-shift of UV absorbance and quenching of fluorescence of α-amylase, suggesting possible changes in the conformation of α-amylase. The differences of inhibitory effects and inhibition types for EGCG and EGCG3″Me might be due to their structural difference (the hydroxyl group at C-3 in D ring of EGCG substituted by methoxy group, forming EGCG3″Me).

Preventive effect of theanine intake on stress-induced impairments of hippocamapal long-term potentiation and recognition memory

Theanine, γ-glutamylethylamide, is one of the major amino acid components in green tea. On the basis of the preventive effect of theanine intake after birth on mild stress-induced attenuation of hippocamapal CA1 long-term potentiation (LTP), the present study evaluated the effect of theanine intake after weaning on stress-induced impairments of LTP and recognition memory. Young rats were fed water containing 0.3% theanine for 3 weeks after weaning and subjected to water immersion stress for 30min, which was more severe than tail suspension stress for 30s used previously. Serum corticosterone levels were lower in theanine-administered rats than in the control rats even after exposure to stress. CA1 LTP induced by a 100-Hz tetanus for 1s was inhibited in the presence of 2-amino-5-phosphonovalerate (APV), an N-methyl-d-aspartate (NMDA) receptor antagonist, in hippocampal slices from the control rats and was attenuated by water immersion stress. In contrast, CA1 LTP was not significantly inhibited in the presence of APV in hippocampal slices from theanine-administered rats and was not attenuated by the stress. Furthermore, object recognition memory was impaired in the control rats, but not in theanine-administered rats. The present study indicates the preventive effect of theanine intake after weaning on stress-induced impairments of hippocampal LTP and recognition memory. It is likely that the modification of corticosterone secretion after theanine intake is involved in the preventive effect.

Factors associated with low bone density among women with major depressive disorder

OBJECTIVE

Previous studies have suggested that depression might be associated with low bone mineral density (BMD) in women with depression. The aim of this study was to investigate the association between the BMD of women with major depressive disorder and correlated factors.

METHOD

This prospective cross-sectional study explored the association between bone density and major depressive disorder in women. One hundred women diagnosed with major depressive disorder were enrolled. The diagnoses were made by board-certificated psychiatrists using the Mini International Neuropsychiatric Interview (MINI). The Beck Depression Inventory (BDI) was administered. The bone density of the hip was measured with dual X-ray densitometry (DEXA) using a Hologic Delphi QDR-2000 densitometer.

RESULTS

We found age, family history of osteoporosis, consumption of coffee, and consumption of tea to be associated with low BMD in single-variate analysis. Depression was also related to BMD, in that the worse the depression, the lower the BMD. Multi-variate analysis by linear regression revealed an equation of BMD = 0.91 - 0.004 x (severity of depression) + 0.07 x (tea consumption)--0.06 x (family history of osteoporosis)--0.04 x age.

CONCLUSION

These results suggest that depression is associated with lower BMD, and the associated factors should be considered in depressive women. The findings of this research may be useful for improving the care of women with major depressive disorder in terms of developing appropriate and effective care plans.

Green tea for weight loss and weight maintenance in overweight or obese adults

BACKGROUND

Preparations of green tea are used as aids in weight loss and weight maintenance. Catechins and caffeine, both contained in green tea, are each believed to have a role in increasing energy metabolism, which may lead to weight loss. A number of randomised controlled trials (RCTs) evaluating the role of green tea in weight loss have been published; however, the efficacy of green tea preparations in weight loss remains unclear.

OBJECTIVES

To assess the efficacy and safety of green tea preparations for weight loss and weight maintenance in overweight or obese adults.

SEARCH METHODS

We searched the following databases from inception to specified date as well as reference lists of relevant articles: The Cochrane Library (Issue 12, 2011), MEDLINE (December 2011), EMBASE (December 2011), CINAHL (January 2012), AMED (January 2012), Biological Abstracts (January 2012), IBIDS (August 2010), Obesity+ (January 2012), IPA (January 2012) and Web of Science (December 2011). Current Controlled Trials with links to other databases of ongoing trials was also searched.

SELECTION CRITERIA

RCTs of at least 12 weeks' duration comparing green tea preparations to a control in overweight or obese adults.

DATA COLLECTION AND ANALYSIS

Three authors independently extracted data, assessed studies for risk of bias and quality, with differences resolved by consensus. Heterogeneity of included studies was assessed visually using forest plots and quantified using the I(2) statistic. We synthesised data using meta-analysis and descriptive analysis as appropriate; subgroup and sensitivity analyses were conducted. Adverse effects reported in studies were recorded.

MAIN RESULTS

Due to the level of heterogeneity among studies, studies were divided into two groups; those conducted in Japan and those conducted outside Japan. Study length ranged between 12 and 13 weeks. Meta-analysis of six studies conducted outside Japan showed a mean difference (MD) in weight loss of -0.04 kg (95% CI -0.5 to 0.4; P = 0.88; I(2) = 18%; 532 participants). The eight studies conducted in Japan were not similar enough to allow pooling of results and MD in weight loss ranged from -0.2 kg to -3.5 kg (1030 participants) in favour of green tea preparations. Meta-analysis of studies measuring change in body mass index (BMI) conducted outside Japan showed a MD in BMI of -0.2 kg/m(2) (95% CI -0.5 to 0.1; P = 0.21; I(2) = 38%; 222 participants). Differences among the eight studies conducted in Japan did not allow pooling of results and showed a reduction in BMI ranging from no effect to -1.3 kg/m(2) (1030 participants), in favour of green tea preparations over control. Meta-analysis of five studies conducted outside Japan and measuring waist circumference reported a MD of -0.2 cm (95% CI -1.4 to 0.9; P = 0.70; I(2) = 58%; 404 participants). Differences among the eight studies conducted in Japan did not allow pooling of results and showed effects on waist circumference ranging from a gain of 1 cm to a loss of 3.3 cm (1030 participants). Meta-analysis for three weight loss studies, conducted outside Japan, with waist-to-hip ratio data (144 participants) yielded no significant change (MD 0; 95% CI -0.02 to 0.01). Analysis of two studies conducted to determine if green tea could help to maintain weight after a period of weight loss (184 participants) showed a change in weight loss of 0.6 to -1.6 kg, a change in BMI from 0.2 to -0.5 kg/m(2) and a change in waist circumference from 0.3 to -1.7 cm. In the eight studies that recorded adverse events, four reported adverse events that were mild to moderate, with the exception of two (green tea preparations group) that required hospitalisation (reported as not associated with the intervention). Nine studies reported on compliance/adherence, one study assessed attitude towards eating as part of the health-related quality of life outcome. No studies reported on patient satisfaction, morbidity or cost.

AUTHORS' CONCLUSIONS

Green tea preparations appear to induce a small, statistically non-significant weight loss in overweight or obese adults. Because the amount of weight loss is small, it is not likely to be clinically important. Green tea had no significant effect on the maintenance of weight loss. Of those studies recording information on adverse events, only two identified an adverse event requiring hospitalisation. The remaining adverse events were judged to be mild to moderate.

Unique induction of CA1 LTP components after intake of theanine, an amino acid in tea leaves and its effect on stress response

Theanine, γ-glutamylethylamide, is one of the major amino acid components in green tea. This study was undertaken to evaluate the effect of theanine intake on long-term potentiation (LTP) induction at hippocampal CA1 synapses and exposure to acute stress. Young rats were fed water containing 0.3% theanine after birth.

KEY FINDINGS

Serum corticosterone level was markedly decreased by theanine intake. Because this decrease can modify synaptic plasticity, the effect of theanine intake was examined focused on CA1 LTP induction. CA1 LTP induced by a 100-Hz tetanus for 1 s was almost the same extent in hippocampal slices from theanine-administered rats, whereas that induced by a 200-Hz tetanus for 1 s was significantly attenuated. 2-Amino-5-phosphonovalerate (APV), an N-methyl-D: -aspartate (NMDA) receptor antagonist, significantly attenuated CA1 LTP induced by a 200-Hz tetanus in the control rats, but not in theanine-administered rats. Interestingly, APV completely blocked CA1 LTP induced by a 100-Hz tetanus in the control rats, while scarcely blocking it in theanine-administered rats. These results indicate that theanine intake reduces NMDA receptor-dependent CA1 LTP, while increasing NMDA receptor-independent CA1 LTP. Furthermore, neither 100-Hz tetanus-induced LTP nor 200-Hz tetanus-induced LTP was attenuated in theanine-administered rats after exposure to tail suspension stress, suggesting that the lack of NMDA receptor-dependent CA1 LTP by theanine intake is involved in ameliorating the attenuation of CA1 LTP after tail suspension. This study is the first to indicate that theanine intake modifies the mechanism of CA1 LTP induction.

Preparation, preliminary characterization, antioxidant, hepatoprotective and antitumor activities of polysaccharides from the flower of tea plant (Camellia sinensis)

In the present study, the crude polysaccharides from the flowers of tea plant (Camellia sinensis) (TFPS) were prepared with hot water and further fractionated on a DEAE-52 cellulose chromatography to afford three purified fractions of TFPS-1, TFPS-2 and TFPS-3. Then, their preliminary structures, antioxidant and antitumor activities in vitro and hepatoprotective activity in vivo were investigated. Compared with TFPS-2 and TFPS-3, TFPS-1 had relative higher content of sulfate and relative complicated monosaccharide composition. In addition, TFPS-1 and TFPS-3 showed relative stronger antioxidant activity and inhibitory activity on the growth of human gastric cancer BGC-823 cells. For hepatoprotective activity in vivo, we demonstrated that crude TFPS significantly prevented the increase of serum alanine aminotransferase and aspartate aminotransferase levels, reduced the formation of malondialdehyde and enhanced the activities of superoxide dismutase and glutathione peroxidase in carbon tetrachloride-induced liver injury mice. The results suggested that TFPS should be a potent natural polymer with antioxidant, hepatoprotective and antitumor activities.

Facilitated neurogenesis in the developing hippocampus after intake of theanine, an amino acid in tea leaves, and object recognition memory

Theanine, γ-glutamylethylamide, is one of the major amino acid components in green tea. In this study, cognitive function and the related mechanism were examined in theanine-administered young rats. Newborn rats were fed theanine through dams, which were fed water containing 0.3% theanine, and then fed water containing 0.3% theanine after weaning. Theanine level in the brain was under the detectable limit 6 weeks after the start of theanine administration. Theanine administration did not influence locomotor activity in the open-field test. However, rearing behavior was significantly increased in theanine-administered rats, suggesting that exploratory activity is increased by theanine intake. Furthermore, object recognition memory was enhanced in theanine-administered rats. The increase in exploratory activity in the open-field test seems to be associated with the enhanced object recognition memory after theanine administration. On the other hand, long-term potentiation (LTP) induction at the perforant path-granule cell synapse was not changed by theanine administration. To check hippocampal neurogenesis, BrdU was injected into rats 3 weeks after the start of theanine administration, and brain-derived neurotropic factor (BDNF) level was significantly increased at this time. Theanine intake significantly increased the number of BrdU-, Ki67-, and DCX-labeled cells in the granule cell layer 6 weeks after the start of theanine administration. This study indicates that 0.3% theanine administration facilitates neurogenesis in the developing hippocampus followed by enhanced recognition memory. Theanine intake may be of benefit to the postnatal development of hippocampal function.

New perspectives on chinese herbal medicine (zhong-yao) research and development

Synthetic chemical drugs, while being efficacious in the clinical management of many diseases, are often associated with undesirable side effects in patients. It is now clear that the need of therapeutic intervention in many clinical conditions cannot be satisfactorily met by synthetic chemical drugs. Since the research and development of new chemical drugs remain time-consuming, capital-intensive and risky, much effort has been put in the search for alternative routes for drug discovery in China. This narrative review illustrates various approaches to the research and drug discovery in Chinese herbal medicine. Although this article focuses on Chinese traditional drugs, it is also conducive to the development of other traditional remedies and innovative drug discovery.

Changes of constituents and activity to apoptosis and cell cycle during fermentation of tea

Tea is believed to be beneficial for health, and the effects of the fermentation process on its contributions to apoptosis and cell cycle arrest of gastric cancer cells have not been completely investigated. In this study, the chemical components in green tea, black tea and pu-erh tea aqueous extracts were analyzed and compared. The polysaccharide and caffeine levels were substantially higher in the fermented black tea and pu-erh tea, while the polyphenol level was higher in the unfermented green tea. Hence, a treatment of tea aqueous extract and the components, which are emerging as promising anticancer agents, were pursued to determine whether this treatment could lead to enhance apoptosis and cell cycle arrest. In the human gastric cancer cell line SGC-7901, the cell viability and flow cytometry analysis for apoptotic cells indicated effects in a dose-dependent inhibition manner for the three tea treatment groups. The apoptosis rates were found to be elevated after 48 h of treatment with 31.2, 125, and 500 μg/mL of green tea extract, the higher catechins content may be involved in the mechanism. Cell cycle was arrested in S phase in the fermented black tea and pu-erh tea, and the populations were significantly decreased in G2/M phases, possibly due to the oxidation of tea polyphenols, which causes an increase of theabrownins. CCC-HEL-1 normal cells were not sensitive to tea extract. These findings suggest that the fermentation process causes changes of the compounds which might be involved in the changes of cell proliferation inhibition, apoptosis induction and cell cycle arrest.

Reactive oxygen and nitrogen species in normal physiological processes

Abstract Reactive oxygen species (ROS) and reactive nitrogen species have generally been considered as being highly reactive and cytotoxic molecules. Besides their noxious effects, ROS participate in physiological processes in a carefully regulated manner. By way of example, microbicidal ROS are produced in professional phagocytes, ROS function as short-lived messengers having a role in signal transduction and, among other processes, participate in the synthesis of the iodothyronine hormones, reproduction, apoptosis and necrosis. Because of their ability to mediate a crosstalk between key molecules, their role might be dual (at least in some cases). The levels of ROS increase from a certain age, being associated with various diseases typical of senescence. The aim of this review is to summarize the recent findings on the physiological role of ROS. Other issues addressed are an increase in ROS levels during ageing, and the possibility of the physiological nature of this process.