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The mechanisms of weight-cutting effect in Pu-erh tea
Abstract
Originally grown and produced in southern of Yunnan, China, Pu-erh tea has a long history and carries rich cultural connotations. Consumption of Pu-erh has been thought to possess numerous health benefits including weight-loss, lowering of blood glucose levels, and preventing cardiovascular diseases. Research on humans, rodents, and cell lines have each confirmed that Pu-erh tea indeed displays weight-loss and blood lipid lowering effects. The main bioactive components, such as theabrownin (TB), polysaccharides, polyphenols, and statins, may down-regulate the biosynthesis of fat and up-regulate the oxidation of fat to cut weight and reduce the content of lipids in blood. Here, we summarize current progress on understanding the mechanisms and bioactive components of Pu-erh's weight-cutting effects as well as highlighting current weaknesses in the field in order to suggest possible solutions for future research on Pu-erh tea.
... the beginning of the treatment, PTE treatment did not show an effect on lowering body weight. However, PTE reduced OVX-induced body weight gain in rats only after 6 weeks of treatment, suggesting that long-term tea drinking has a positive effect on weight loss, which is consistent with the results of previous studies (Zou et al., 2012). Notably, osteoporosis results from an imbalance related to faster bone resorption than bone formation. ...
Background and Objective: Tea drinking is associated with positive effects on bone health and may protect against osteoporosis, especially in elderly women. Pu-erh tea has many beneficial effects on human health; however, whether Pu-erh tea has anti-osteoporotic potential remains unclear. Thus, we investigated the effects of Pu-erh tea extract (PTE) on ovariectomy-induced osteoporosis in rats and on osteoclastogenesis in vitro.
Methods: Female Wistar rats were divided into six groups: the sham, model, and Xian-Ling-Gu-Bao capsule (XLGB) groups, and the low-, medium-, and high-dose PTE groups. Ovariectomized (OVX) rats were used as an animal model of osteoporosis. The animals were intragastrically administered distilled water, XLGB, or different concentrations of PTE for 13 weeks. Body weight, blood biochemical indicators, relative organ coefficients, femoral bone mineral density (BMD), bone biomechanical properties, and bone microarchitecture were examined and analyzed. Additionally, the in vitro effects of PTE on osteoclastic activities were investigated using the RAW 264.7 cell line as an osteoclast differentiation model. The effects of PTE on osteoclast differentiation and the expression of osteoclast-specific genes and proteins were determined.
Results: PTE reduced OVX-induced body weight gain after 6 weeks of treatment, and the high-dose exerted a significant effect. High-dose PTE significantly ameliorated OVX-induced estradiol (E2) deficiency. PTE treatment maintained calcium and phosphorus homeostasis and improved other blood biochemical parameters to various degrees. In addition, PTE treatment improved organ coefficients of the femur, uterus, and vagina and improved femoral BMD and bone biomechanical properties. PTE treatment strikingly ameliorated bone microarchitecture. Moreover, in the in vitro studies, osteoclast differentiation using the differentiation cell model was significantly inhibited by PTE without cytotoxic effects. Additionally, PTE efficaciously suppressed the expression of key osteoclast-specific genes and proteins.
Conclusion: PTE can ameliorate ovariectomy-induced osteoporosis in rats and suppress osteoclastogenesis in vitro.
... Numerous studies have been conducted on these effects, including in vivo, in vitro and clinical studies. In general, studies on humans (Fujita & Yamagami, 2007Li et al., 2009), animals (Cao et al., 2011;Ding et al., 2015;Gong, Peng, Chen, Gao, & Zhou, 2010;Hou et al., 2009;Hwang, Lin, Chen, Liuchuang, & Shiao, 2003), and cell lines (Lu & Hwang, 2008;Way et al., 2009) have all confirmed that Pu-erh tea has lipid-lowering effects (Zou, Ding, & Liang, 2012). ...
In this study, successive extractions of the Pu-erh tea were performed utilising water, chloroform, ethyl acetate, and n-butanol. The different extracts were investigated for regulation of transcription factors involved in lipid metabolism including Farnesoid X Receptor (FXR), Liver X-activated Receptor (LXR), and the Peroxisome Proliferator-Activated Receptor (PPARγ and PPARδ) using reporter gene assays. The data indicated that the ethyl acetate extract had the strongest activation potential for FXR and PPARδ, and Fraction 6 from the ethyl acetate extract obtained by column chromatography had the highest hypolipidaemic potential. Further chromatographic separation of Fraction 6 led to the isolation of 7 flavonoids, and their contents varied between 7.6 and 51.8mg/g. Additionally, sixty-four chemical constituents were identified from Fraction 6 by UPLC-MS/MS and their relative amounts were determined by the ion intensity. These results showed that the flavonoids were the major bioactive compounds in Pu-erh tea responsible for its hypolipidaemic effects.
Purpose
Pu-erh tea can be classified into raw pu-erh tea and ripened pu-erh tea. Theabrownin (TB) is one of the major components of pu-erh tea. The difference of the anti-obesity activity between raw pu-erh tea TB (R-TB) and ripened pu-erh tea TB (F-TB) has not been comprehensively investigated yet. Therefore, this article aimed to systemically study the anti-obesity activity and the underlying mechanism of R-TB and F-TB.
Method
High-fat diet (HFD)-induced C57BL/6J mice with obesity were gavaged with R-TB or F-TB to assess the effect of R-TB and F-TB on the amelioration of obesity, the expression of lipid metabolism-related genes, and the regulation of gut flora imbalance.
Results
Administration of both R-TB and F-TB could suppress body weight gain, improve insulin sensitivity and glucose homeostasis, regulate the lipid level and reduce the chronic inflammation in obese mice. The underlying anti-obesity mechanism of R-TB and F-TB might involve the regulation of lipogenesis and lipolysis, amelioration of the gut microbiota disorder and promotion of microbial metabolism. Interestingly, R-TB was more efficient in the regulation of blood glucose, reduction of inflammation and suppression of partial adipogenesis-related genes and protein, while F-TB was more effective in the inhibition of lipolysis-related genes and protein. In addition, F-TB might be more effective in adjusting the dysbacteria caused by HFD back to normal by promoting the proliferation of the beneficial microbiota, such as Lactobacillus and Lachnospiraceae_NK4A136_group.
Conclusion
Taken together, both R-TB and F-TB had the potential to be developed as beneficial dietary supplements or functional foods for ameliorating obesity and obesity-related metabolic disorders, but their effects and the ability to regulate the intestinal flora varied.
Pu-erh tea has been used for thousands of years to treat metabolic diseases. Recognized in Shen Nong's Herbal Classic, a compendium kept by the first traditional Chinese practitioners, it is still highly valued for its hypocholesterolemic and hypolipidemic effects. This review reports the processing and bioactive components of pu-erh tea. Recent human and animal studies of pu-erh tea and its potential therapeutic mechanisms have also been summarized. The interaction of liver and gut microbiome regulates the pu-erh tea biotransformation and endogenous metabolism, and thus contributes to the health benefits.
Fuzhuan brick tea has received increasing attention in recent years owing to its benefits for non-alcoholic fatty liver disease (NAFLD) and associated metabolic syndrome. For exploring the ameliorative mechanism, the liver proteomes from three groups of rats fed either a normal control diet (NCD), a high fat diet (HFD), or a HFD supplemented with high-dose FTE (HFD+HFTE) were comprehensively compared by quantitative proteomics using 2DE-LC-MS/MS. This is the first study of the effects of tea aqueous extract on the liver proteome of rats suffering from metabolic syndrome. The results showed that 57 proteins displayed more than 1.5-fold differences in at least one of two comparisons of HFD versus NCD and HFD versus HFD+HFTE due to HFD feeding and FTE treatment, respectively. Of them, over 75% of proteins exhibited a similar tendency of expression in the two comparisons, meaning FTE was able to correct HFD effects on rat livers. By function analyses, an extensive list of proteins were involved in sugar and lipid metabolism. Compared with HFD-fed rats, the reduced lipogenesis and enhanced β-oxidation, tricarboxylic acid cycle and respiratory chain in HFD+HFTE-fed rats, which mainly contributed to ameliorate hepatic fat accumulation and associated NAFLD. Additionally, some putative drug targets were also revealed such as COX2, PGAM1, ACACB, FAS and ECHS1. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Puerh tea has been proposed to promote weight loss and favorably modify glucose, insulin and blood lipids. This study tested the effect of daily Puerh tea consumption for 3 months on weight and body mass index (BMI), and select metabolic parameters. The effect of daily Puerh tea intake on weight, BMI and changes in glucose, HbA1c and lipids was evaluated in patients with metabolic syndrome. The patients (N = 70) were randomized into two groups: those taking Puerh tea extract capsule (333 mg Puerh tea extract) three times a day and those taking a placebo tea for 3 months. There was a decrease in body weight of 1.3 kg in the Puerh tea group (p = 0.077) versus 0.23 kg in the placebo arm (p = 0.186). There was also a slight decrease in BMI 0.47 kg/m(2) in the Puerh tea group (p = 0.076) versus 0.09 kg/m(2) in the placebo arm (p = 0.185), suggesting a trend of weight change, but without statistical significance. Subgroup analysis of the male patients demonstrated statistically significant improvements in body weight reduction (p = 0.004) and BMI (p = 0.004). However, the change in other metabolic parameters (cholesterol or triglyceride) or HbA1c was not statistically significant. Intake of Puerh tea for 3 months was associated with a slight reduction in body weight and BMI, especially in the male patients. Therefore, daily Puerh tea consumption may be an alternative choice to modify body weight. Copyright © 2014 John Wiley & Sons, Ltd.
A simple and fast HPLC method using a photodiode array detector was developed for simultaneous determination of four major catechins, gallic acid and caffeine. After multiple extractions with aqueous methanol and acidic methanol solutions, tea extract was separated within 20 min using a methanol-acetate-water buffer gradient elution system on a C(18) column. The sample extraction data demonstrated that the single extraction used in the previous studies with aqueous acetonitrile or methanol is not sufficient; the multiple extraction procedure is essential for the quantitative analysis of catechins, phenolic acids and caffeine in teas. Several green, Oolong, black and pu-erh teas were successfully analyzed by this method. The analytical results obtained indicated that green teas contain higher content of catechins [(-)-epigallocatechin gallate, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epicatechin] than both Oolong, pu-erh and black teas because fermentation process during the tea manufacturing reduced the levels of catechins significantly. The fermentation process also remarkably elevated the levels of gallic acid in full-fermented pu-erh and black teas. Another interesting finding is the low level of caffeine in Oolong teas, especially in Fujian Oolong tea.
The aim of this study was to evaluate tea polyphenol and purine alkaloid contents of pu-erh tea (Camellia assamica) in a fermentation solid system with Aspergillus niger and Aspergillus fumigatu. In addition, the objective was to find the major intermediate product during fermentation by HPLC-MS(n) analysis. The results showed the change of catechin, ester-catechins and gallic acid by quantitative analysis. In the early stages, the contents of ester-catechins were lightly increased. Then, ester-catechins were gradually degraded to produce catechins and gallic acid. Furthermore, a major metabolic intermediate compound of catechins was observed and elucidated by HPLC-DAD-MS(n) analysis. This study provided a reliable dynamic data description and metabolic pathway of tea polyphenols for postfermented pu-erh tea.
Although green tea extract has been reported to suppress hyperlipidemia, it is unclear how tea extracts prepared from green, oolong, black and pu-erh teas modulate fatty acid synthase expression in rats fed on a high-fructose diet. In this animal study, we evaluated the hypolipidemic and hypoleptinemia effect of these four different tea leaves fed to male Wistar rats for 12 weeks. The results showed that a fructose-rich diet significantly elevated serum triacylglycerols, cholesterol, insulin, and leptin concentrations, as compared with those in the control group. Interestingly, consuming tea leaves for 12 weeks almost normalized the serum triacylglycerols concentrations. Again, rats fed with fructose/green tea and fructose/pu-erh tea showed the greatest reduction in serum TG, cholesterol, insulin and leptin levels. In contrast, serum cholesterol and insulin concentrations of the fructose/oolong tea-fed rats did not normalize. The relative epididymal adipose tissue weight was lower in all rats supplemented with tea leaves than those fed with fructose alone. There was molecular evidence of improved lipid homeostasis according to fatty acid synthase (FAS) protein expression. Furthermore, supplementation of green, black, and pu-erh tea leaves significantly decreased hepatic FAS mRNA and protein levels, and increased AMPK phosphorylation, compared with those of rats fed with fructose only. These findings suggest that the intake of green, black, and pu-erh tea leaves ameliorated the fructose-induced hyperlipidemia and hyperleptinemia state in part through the suppression of FAS protein levels and increased AMPK phosphorylation.
Pu-erh tea is a popular beverage in southwestern China and South Asian countries. To explain the differences of aged pu-erh tea and ripened pu-erh tea, the chemical constituents of these teas were identified by HPLC-DAD-ESI-MS(n). In addition, HPLC was used to determine the contents of the major polyphenols, gallic acid, caffeine, and theobromine, in various types of teas. These results showed that the majority of chemical constituents in ripened pu-erh tea and aged pu-erh tea were similar, but the contents of catechins and gallic acid presented significant differences between these two teas. After fermentation by microorganism, the levels of catechins in ripened pu-erh tea were decreased, but the contents of gallic acid and caffeine were conversely elevated compared with aged pu-erh tea.
Dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. Although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, GABA, and other amino acids has not been developed in one HPLC system. In this paper are analyzed the free amino acid contents of theanine and GABA in different teas (green tea, black tea, oolong tea, Pu-erh tea, and GABA tea) with a dabsylation and reverse phase high-performance liquid chromatography (HPLC) system coupled with a detector at 425 nm absorbance. Two reverse phase columns, Hypersil GOLD and Zorbax ODS, were used and gave different resolutions of dabsyl amino acids in the gradient elution program. The data suggest that the tea source or the steps of tea-making may contribute to the theanine contents variations. High theanine contents of high-mountain tea were observed in both green tea and oolong tea. Furthermore, the raw (natural fermented) Pu-erh tea contained more theanine than ripe (wet fermented) Pu-erh tea, and the GABA contents in normal teas were generally lower than that in GABA tea.
Theabrownin (TB) is a main bioactive component in Pu-erh tea, and the total amount is between 100 and 140 g kg(-1). However, reports on the mechanism of formation of TB are sparse because it has a high molecular weight and complex composition. Hence, the mechanism of formation of TB in Pu-erh tea during solid state fermentation was investigated using an exogenous enzyme method.
It was found that, in the presence of exogenous enzymes, the tea liquor prepared from the resulting leaves changed considerably in colour. In addition, the TB, total carbohydrate, polysaccharide, amino acid and protein contents were all increased, while the tea polyphenol content decreased sharply; the surfaces of leaves before fermentation appeared to be smooth and intact, and the structures of the cell, cellulose and lignin were complete, while after fermentation their surfaces were covered by microorganisms and the structures of the cells were largely disrupted.
The enzymatic actions are closely related to the compositional changes occurring during Pu-erh tea manufacture, and its quality. Enzymes produced by microorganisms were found to be the main cause of TB formation during the fermentation of Pu-erh tea.
Theabrownin (TB), one of the main bioactive components in pu-erh tea, has a significant blood lipid-lowering effect in hyperlipidemic rats. Therefore, it was hypothesized that TB would regulate the activity of key enzymes involved in lipid metabolism and accelerate the catabolism of exogenous cholesterol in rats fed a high fat diet. A total of 90 Sprague-Dawley rats were randomly divided into a normal control group (Group I), a high fat diet group (Group II), and high-fat diet plus TB group (Group III). A total of 10 rats were selected from each group and killed at 15, 30, or 45 d after starting the study for analysis. After feeding 45 d, the contents of TC, TG, and LDL-C levels in Group II were increased by 54.9%, 93.1%, and 134.3% compared with those in Group III, respectively, and the content of HDL-C in Group II was decreased by 55.7%. These effects were inhibited in the rats in Group III, which exhibited no significant differences in these levels compared with Group I, indicating that TB can prevent hyperlipidemia in rats fed a high fat diet. TB enhanced the activity of hepatic lipase and hormone-sensitive triglyceride lipase (HSL) and increased the HSL mRNA expression in liver tissue and epididymis tissue. The HL activity in serum of Group III was increased by 147.6% compared with that in Group II. The content of cholesterol and bile acid in the feces of rats was increased by 21.11- and 4.08-fold by TB. It suggested that TB could promote the transformation and excretion of dietary cholesterol of rats in vivo.
Two commercial Pu-erh teas, 15-year-old Ta-Huang-In and 25-year-old Ta-Hon-In, were used for screening some species of fungi, yeasts, and bacteria, and six of them were isolated and identified as Actinoplanes aurantiacus, Actinoplanes pallidoaurantiacus, Actinoplanes purpeobrunneus, Streptomyces bacillaris, Streptomyces cavourensis subsp. cavourensis, and Streptomyces cinereus. They were selected for inoculated into the tea leaves (Yun Nan from China, TTES-12 and C. S. Oolong from Taiwan) and fermented for 180 days. The total polyphenols and GABA content, and DPPH radical scavenging effects were determined to examine the tea infusion quality. The samples inoculated with S. cinereus had the highest total polyphenols content and maximum capacity to scavenge DPPH radicals; the highest GABA content was obtained while the sample inoculated with S. bacillaris. Further comparison of these samples with two commercial Pu-erh teas of different ages (Ta-Huang-In, 15-year storage and Ta-Hon-In, 25-year storage) showed that DPPH radical scavenging activity and GABA content of S. bacillaris and S. cinereus fermented tea leaf were higher than these two commercial teas. Sensory evaluation also demonstrated that the taste, flavor, and overall acceptance did not had significant differences between the experimental tea leaves and commercial samples. The present studies revealed that the fresh tea leaves inoculated with the suitable microbes in short period of time will possess a high-quality tea infusion as long-term storage Pu-erh tea.
Liquid chromatography-mass and multivariate analyses were employed to measure the composition of pu-erh teas and to determine the general changes in the compositional patterns of pu-erh teas during postfermentation. Principle component analysis of pu-erh teas indicated two large distinct clusters in the score plot: ripened pu-erh teas and raw pu-erh teas. The raw pu-erh teas contained more antioxidant compounds compared to ripened pu-erh teas. As a result, the raw pu-erh teas showed significantly higher antioxidant activities than the ripened pu-erh teas in the 1,1-diphenyl-2-picrylhydrazyl, Trolox equivalent antioxidant capacity, and ferric reducing antioxidant power assays. In addition, raw pu-erh teas showed significantly higher NO inhibitory and cell protective activities than the ripened pu-erh teas. Significant correlations between compounds and postfermentation year were observed in raw pu-erh teas; epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and quinic acid were decreased and gallic acid was increased in a year-dependent manner. The antioxidant activity was shown to decrease as the number of antioxidant compounds in raw pu-erh tea decreased. These findings indicate that a metabolomic approach is a useful tool for analyzing manufacturing type, postfermentation year, and antioxidant activity of pu-erh tea.
Metagenomics is an emerging field focused on characterizing the structures, functions and dynamic operations of microbial communities sampled in their native habitats without the need for culture. Here, we present findings from a 16S rRNA gene sequence- and whole community DNA shotgun sequencing-based analysis of the adult human gut microbiomes of lean and obese mono- and dizygotic twins. Our findings indicate that a core microbiome can be found at the gene level, despite large variation in community membership, and that variations from the core are associated with obesity. These findings have implications for ongoing Human Microbiome Project(s), and highlight important challenges to the field of metagenomics.
In the present study, we successively extracted the pu-erh raw tea with methanol (PR-1), chloroform (PR-2), ethyl acetate (PR-3), n-butanol (PR-4), and water (PR-5). Among these extracts, PR-3 extract contained ingredients with the most effective hypolipidemic potential and was further purified by column chromatography. Moreover, chronic administration of PR-3 provoked a significant reduction in levels of serum triglyceride and low-density lipoprotein (LDL) in rats. Our study demonstrated that fraction 5 from the PR-3 extract (PR-3-5s) showed a hypolipidemic effect in human hepatoma HepG2 cells. PR-3-5s decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) by stimulating AMP-activated protein kinase (AMPK) through the LKB1 pathway. Moreover, PR-3-5s blocked the progression of the cell cycle at the G1 phase by inducing p53 expression and in turn upregulating p21 expression.
Pu-erh tea is believed to possess many beneficial health effects since it is a natural source of cardioprotective lipid lowering and antioxidant compounds, although, the major constituents putatively responsible for these beneficial effects remain unknown. In this study, we examined the effects of two commonly consumed forms of Pu-erh tea, fermented and unfermented, on weight gain, serum levels of lipids and lipoprotein, lipid oxidation, and blood antioxidant enzymes in a rat hyperlipidemia model. Hyperlipidemic rats were treated with water extracts of either 0.5, 1.5 or 3.0 mg/kg fermented or unfermented Pu-erh tea. Serum low density lipoprotein-cholesterol (LDL-C) and triglyceride levels were significantly lowered by tea extract compared to the control group. (p < 0.05) and in most cases were indistinguishable from rats fed normal chow, basal diet. Conversely, levels of high density lipoprotein-cholesterol (HDL-C) were elevated in the groups given daily doses of tea extract (p < 0.05). Compared to the hyperlipidemic control group, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in serum were significantly elevated in Pu-erh tea-treated groups while levels of malondiadehyde (a byproduct of lipid peroxidation) decreased in the same groups. These effects were most pronounced in the groups treated with the highest dose of fermented Pu-erh tea extract. Our results suggest that Pu-erh tea exerts strong antioxidative and lipid-lowering effects and therefore can be used to reduce the risk of cardiovascular disorders.
In this study, the chemical constituents of pu-erh tea, black tea, and green tea, as well as those of pu-erh tea products of different ages, were analyzed and compared using a chemical profiling approach. Differences in tea processing resulted in differences in the chemical constituents and the color of tea infusions. Human biological responses to pu-erh tea ingestion were also studied by using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) in conjunction with multivariate statistical techniques. Metabolic alterations during and after pu-erh tea ingestion were characterized by increased urinary excretion of 5-hydroxytryptophan, inositol, and 4-methoxyphenylacetic acid, along with reduced excretion of 3-chlorotyrosine and creatinine. This study highlights the potential for metabonomic technology to assess nutritional interventions and is an important step toward a full understanding of pu-erh tea and its influence on human metabolism.
Water-extracted Chinese black tea (Pu-Ehr) exerts a precipitating effect on mixed bile salt micelles in foods. The amount of black tea extract (BTE) effective for hypercholesterolemia (HC) was examined in humans.
Animals (test 1) and humans (tests 2-5) were given BTE in the following studies: (test 1) an acute 2-week toxicity test conducted in mice with 2,000 mg/kg BTE or saline; (test 2) a dose-finding 8-week toxicity study with excessive BTE ingestion (0.75 or 1 g/day) in 10 healthy and 10 borderline HC subjects; (test 3) a 1-day acute toxicity test using a (10 g) single-bolus study (n = 10); (test 4) a 5-week long-term safety test (5 g/day, n = 11), and (test 5) a 4-month noncomparative study in 21 HC patients ingesting 1 g/day.
The safety study showed no changes in hematological or relevant biochemical parameters in both mice and humans in the acute and long-term toxicity tests. In test 5, significant reductions in total and low-density lipoprotein cholesterol levels accompanied by significant decreases in body weight were observed without affecting other biochemical parameters.
BTE significantly reduced blood cholesterol levels in humans and may prove safe and useful in preventing and improving metabolic syndrome-induced arteriosclerosis and/or obesity.
The effect of water extracts of Pu-Erh tea (products of Yunnan district, China, preserved for 2 or 20 years) and of green tea (products of Shizuoka prefecture, Japan) on lipid level, tissue weight, lipoprotein lipase (LPL) and adrenalin-induced lipolytic (AIL) activity in rats were examined. Female Wistar rats (8 weeks old) were fed a diet containing 1% cholesterol and given the above tea extracts in drinking water for 8 or 16 weeks ad libitum. The levels of plasma cholesterol ester in rats given Pu-Erh tea or green tea were significantly lower than those of control rats after 6-8 weeks, though the difference became smallar after 10 weeks. The triglyceride (TG) level in plasma was also low in rats given Pu-Erh tea for 16 weeks. This effect on TG was not observed in the case of green tea. Among 6 organs or tissues of rats examined, the weight of abdominal adipose tissue was significantly lower in rat fed Pu-Erh tea for 16 weeks. The LPL activity in abdominal adipose tissue tended to be low (though not statistically significant), while the activity of AIL was significantly elevated in rats given Pu-Erh tea for 8 or 16 weeks. A negative correlation was observed between AIL activity and the ratio of adipose tissue/body weight. These data suggest that the successive administration of Pu-Erh tea could stimulate the degradation of TG in adipose tissue and thereby decrease its weight.
Chinese teas with different degrees of fermentation were examined for their effect on diet-induced hypercholesterolemia in rats. The teas tested were Chinese Green tea, Jasmine, Iron Buddha, Oolong and Pu erh. Hypercholesterolemia was induced by feeding rats with a cholesterol-enriched diet for 1 week. They were then treated with different tea extracts together with a cholesterol-enriched diet for another 8 weeks. Chinese Green tea and Jasmine tea, both with a minimum degree of fermentation, were found to have significant serum and liver cholesterol lowering effects. They also reduced the increase in liver weight due to lipid deposition. All tea treatments lowered the atherogenic index and increased the HDL-total cholesterol ratio, while HDL-cholesterol and triglyceride levels were not significantly affected. Analysis of catechin levels in tea extracts showed that the individual catechin component in Chinese Green tea and Jasmine tea were significantly higher than the others. (-)-Epicatechin gallate and (-)-epigallocatechin gallate in the tea extracts may account for their hypocholesterolemic effect.
The four major commercial teas, oolong, black, pu-erh, and green teas, have been manufactured in southeast Asia. In this study, we evaluated the growth suppressive and hypolipidemic effect of these four different tea leaves by oral feeding to male Sprague-Dawley rats for 30 weeks. The results showed that the suppression of body weights of tea leaves-fed groups were in the order: oolong tea > pu-erh tea > black tea > green tea. Pu-erh tea and oolong tea could lower the levels of triglyceride more significantly than that of green tea and black tea, but pu-erh tea and green tea were more efficient than oolong tea and black tea in lowering the level of total cholesterol. In lipoprotein, 4% pu-erh tea could increase the level of HDL-C and decrease the level of LDL-C, but other teas simply decrease the levels of both. The activity of antioxidant enzyme SOD is increased in all tea-fed groups as compared to the basal diet-fed group. Finally, relative weight ratios of liver to epididylmal adipose tissue were lower in feeding oolong tea and pu-erh tea groups. On the basis of these findings, it seemed that the fully fermented pu-erh and black tea leaves and partially fermented oolong tea leaves were more effective on their growth suppressive and hypolipidemic effects as compared to the nonfermented green tea leaves.
Gallic acid and its structurally related compounds are found widely distributed in fruits and plants. Gallic acid, and its catechin derivatives are also present as one of the main phenolic components of both black and green tea. Esters of gallic acid have a diverse range of industrial uses, as antioxidants in food, in cosmetics and in the pharmaceutical industry. In addition, gallic acid is employed as a source material for inks, paints and colour developers. Studies utilising these compounds have found them to possess many potential therapeutic properties including anti-cancer and antimicrobial properties. In this review, studies of the effects of gallic acid, its esters, and gallic acid catechin derivatives on Phase I and Phase II enzymes are examined. Many published reports of the effects of the in vitro effects of gallic acid and its derivatives on drug metabolising enzymes concern effects directly on substrate (generally drug or mutagen) metabolism or indirectly through observed effects in Ames tests. In the case of the Ames test an antimutagenic effect may be observed through inhibition of CYP activation of indirectly acting mutagens and/or by scavenging of metabolically generated mutagenic electrophiles. There has been considerable interest in the in vivo effects of the gallate esters because of their incorporation into foodstuffs as antioxidants and in the catechin gallates with their potential role as chemoprotective agents. Principally an induction of Phase II enzymes has been observed however more recent studies using HepG2 cells and primary cultures of human hepatocytes provide evidence for the overall complexity of actions of individual components versus complex mixtures, such as those in food. Further systematic studies of mechanisms of induction and inhibition of drug metabolising enzymes by this group of compounds are warranted in the light of their distribution and consequent ingestion, current uses and suggested therapeutic potential. However, it must be noted that numerous constituents of foodstuffs have been found to be potent modulators of xenobiotic metabolism and the net human health effects may depend on concentrations of individual components and individual genetic makeup.
Bag teas, packed 3g of ground black, green, oolong, paochoung and pu-erh tea leaves (the particle size used was 1-2mm), were steeped in 150 mL of 70, 85 or 100 degrees C hot water to study the effects of the number of steeping (the same bag tea was steeped repeatedly eight times, 30s each time, as done in China for making ceremonial tea) and varied steeping durations (0.5-4 min) on caffeine, catechins and gallic acid in tea infusions. The changes in tea infusions during storage at 4 or 25 degrees C for 0-48 h and the variations in these compounds of bag tea infused with 150 mL of 4 or 25 degrees C cold water for 0.5-16 h were also investigated. A HPLC method with a C18 column and a step gradient solvent system consisting of acetonitrile and 0.9% acetic acid in deionized water was used for analysis. Results for all kinds of tea samples showed that the second tea infusion contained the highest contents of caffeine, catechins and gallic acid when bag teas were steeped in 70 degrees C water. It was different from that steeped at 85 and 100 degrees C, the highest contents existed in the first infusion. These compounds decreased gradually in later infusions. Higher amounts of caffeine, catechins and gallic acid could be released from bag teas as hotter water was used. As steeping duration prolonged, these ingredients increased progressively, however, their levels were lower than that cumulated from the infusions with the identical bag tea prepared recurrently at the same temperature and time points. (-)-Gallocatechin gallate and (+)-catechin existed in these tea infusions rarely and could not be detected until a certain amount of them infusing. Except gallic acid that showed a significant increase and caffeine that exhibited no significant change, all kinds of catechins decreased appreciably after tea infusions were stored at 25 degrees C for 36 h; nevertheless, all of them showed no evident changes at 4 degrees C storage. The caffeine, catechins and gallic acid in tea infused with cold water also increased with increasing duration. Their contents in 25 degrees C steeped tea were higher than that made at 4 degrees C; moreover, their infusion rates from bag teas to cold water were markedly lower than that steeped in hot water. Infusing efficiencies of non-gallated catechins were higher than gallated catechins under cold water steeping.
Besides cancer prevention, the hypolipidemic effects of tea have been well studied in animals and humans. Recently, statin has been identified in Pu-erh tea extract. Clinical trials have confirmed that statin decreases the incidence of major coronary and cerebrovascular events and this may be due to its hypolipidemic and antiinflammatory effects. Since a good Pu-erh tea needs longer storage (10 years or more) of fermentation to enhance the flavor and fragrance, we screened microorganisms from two Pu-erh teas, 20 and 25 years old. Species of fungi and bacteria strains that contributed to a good taste of Pu-erh tea were isolated. The effect of fermentation was investigated by inoculating fresh tea leaves with individual strains of isolated microorganisms. Results showed that statin, total polyphenol content, and the scavenging activities of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals increased during fermentation. Tea leaves inoculated with Streptomyces bacillaris strain R9 had the highest polyphenol content (3.3 mg/100 g) and scavenging ability to DPPH radicals (92%). Streptomyces cinereus strain Y11 was equally good for polyphenol content but yielded the highest amount of statin (1012 ng/g) after 42 days of fermentation. Interestingly, the statin content of fresh tea leaves fermented with strain R9 or Y11 after 180 days was much higher (4- and 8-fold, respectively) than that of the 25-year-old Pu-erh tea (513 ng/g) as measured by the HPLC method. Similarly, these two strains also increased the content of gamma-aminobutyric acid (GABA) 5.7- and 4.7-fold in tea fermented for 180 days as compared with the fresh leaves (1270 microg/g) and that were higher than that of the Pu-erh tea (4900 microg/g). Taken together, the present results indicate that tea short-term fermented with S. bacillaris or S. cinereus enhances the color and content of statin, GABA, and polyphenols.