ArticleLiterature Review

The mechanisms of weight-cutting effect in Pu-erh tea

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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.

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... 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). ...
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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.
... 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. ...
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.