绿茶和红茶多酚对大鼠脂肪分化相关基因表达影响的比较研究

目的:比较绿茶多酚(GTP)和红茶多酚(BTP)抗肥胖作用及其分子机制。方法:将实验大鼠分为空白对照组,高脂饲料+GTP组,高脂饲料+BTP组,高脂饲料组,定期检测体重,喂饲3个月后,观察脂肪组织和血脂水平变化,并提取附睾脂肪组织,应用RT-PCR技术观察与脂肪细胞分化相关的基因pref-1,aP2,TNF-α,瘦素,PPAR-γ,C/EBP-α在mRNA水平的表达。结果:GTP和BTP均能明显降低体重,减少脂肪。同时,GTP和BTP均能显著地抑制脂肪细胞特殊标记物aP2,TNF-α,瘦素,但两者之间无统计学差异。此外,GTP还上调前脂肪细胞标记物pref-1,且下调转录因子PPAR-γ。结论:GTP和BTP均可通过调节与脂肪细胞分化相关的基因,逆转脂肪细胞的分化,达到抗肥胖的作用,且GTP抗肥胖作用强于BTP。     

Green tea polyphenols provide photoprotection, increase microcirculation, and modulate skin properties of women

Dietary constituents including polyphenols and carotenoids contribute to endogenous photoprotection and modulate skin characteristics related to structure and function of the tissue. Animal and in-vitro studies indicate that green tea polyphenols affect skin properties. In a 12-wk, double-blind, placebo-controlled study, 60 female volunteers were randomized to an intervention or control group. Participants consumed either a beverage with green tea polyphenols providing 1402 mg total catechins/d or a control beverage. Skin photoprotection, structure, and function were measured at baseline (wk 0), wk 6, and wk 12. Following exposure of the skin areas to 1.25 minimal erythemal dose of radiation from a solar simulator, UV-induced erythema decreased significantly in the intervention group by 16 and 25% after 6 and 12 wk, respectively. Skin structural characteristics that were positively affected included elasticity, roughness, scaling, density, and water homeostasis. Intake of the green tea polyphenol beverage for 12 wk increased blood flow and oxygen delivery to the skin. Likewise, in a separate, randomized, double-blind, single-dose (0.5, 1.0, and 2.0 g) study of green tea polyphenols, blood flow was maximized at 30 min after ingestion. In summary, green tea polyphenols delivered in a beverage were shown to protect skin against harmful UV radiation and helped to improve overall skin quality of women.     

Green tea composition, consumption, and polyphenol chemistry.

Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. Green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavanols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. Green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.     

Antimetastatic Properties of Tea Polyphenols

Abstract

Metastasis of cells from primary site to distant organs involves a series of sequential steps, and molecules responsible for all these events are understandably considered as potential targets for metastasis management. Tea polyphenols, the secondary metabolites of the tea leaf Camellia sinensis, are increasingly being studied for their antimetastatic properties. In this article, effects of green tea polyphenols (GTP) and black tea polyphenols (BTP) on the molecules and events involved in metastasis are discussed in detail. As tea is a very popular beverage, tea polyphenols are expected to be potential chemopreventive agents that can be taken with normal diet and can be nontoxic due to their natural origin. However, individual variations in metabolic pathways, bioavailability, dose, and toxicity are some important factors that can modify the effectiveness of tea polyphenols within the human system.     

Randomized controlled trial for an effect of green tea consumption on insulin resistance and inflammation markers

To study the effects of the intake of green tea and polyphenols, which are a component of green tea, on insulin resistance and systemic inflammation, a randomized controlled trial was conducted on 66 patients aged 32-73 y (53 males and 13 females) with borderline diabetes or diabetes. Subjects in the intervention group were asked to take a packet of green tea extracts/powder containing 544 mg polyphenols (456 mg catechins) daily, which was a dose that could be taken without difficulty, and were asked to divide the green tea extracts/powder in a packet into 3 or 4 fractions dissolved in hot water everyday and to take a fraction after every meal or snack for 2 mo, in addition to daily food intake. The subjects in the control group were simply followed. To calculate the level of green tea polyphenol intake that the subject usually drank at home, the subject was asked to taste 3 teas of different strengths (1, 2 and 3%) and the tea that was closest to the one that the subject drank at home, was selected by each subject. After 2 mo, the mean daily polyphenol intake in the intervention group was 747 mg, which was significantly higher than that of 469 mg in the control group. In the intervention group, the body weight, BMI, systolic and diastolic blood pressures, blood glucose level, Hb A1c level, insulin level and HOMA index after taking the supplementation for 2 mo, were lower than the respective value before intervention: however, these parameters in the intervention group at 2 mo did not significantly differ from those in the control group. Within the intervention group, changes in insulin level tended to be associated with changes in polyphenol intake. In addition, changes in BMI were associated with changes in blood glucose level and insulin level. In conclusion, the daily supplementary intake of 500 mg green tea polyphenols did not have clear effects on blood glucose level, Hb A1c level, insulin resistance or inflammation markers. The positive correlation between the level of polyphenol intake and insulin level warrants further studies on the effect of green tea on insulin resistance.     

Black tea prevents cigarette smoke-induced oxidative damage of proteins in guinea pigs

Cigarette smoke (CS) causes oxidative damage and tea polyphenols have strong antioxidant properties. Therefore, we studied the effect of a black tea (BT) infusion on CS-induced oxidative damage of proteins both in vitro and in vivo. In the in vitro experiment, bovine serum albumin (BSA) or a guinea pig tissue microsomal suspension was incubated with an aqueous extract of CS (CS-solution) in the presence or absence of the BT infusion. Protein oxidation was measured by immunoblotting of the dinitrophenylhydrazone derivatives of the protein carbonyls followed by densitometric scanning. Protein degradation was assessed by SDS-PAGE. BT prevented (P < 0.05) CS-induced oxidation of BSA and oxidative degradation of guinea pig lung, liver and heart microsomal proteins. This was also observed when the BT infusion was replaced by its components, i.e, flavonols, theaflavins, thearubigins and catechins. BT prevented microsomal protein degradation by inhibiting oxidative modification of the proteins. The antioxidant effect of BT was similar to that of green tea. In the in vivo experiment, partially ascorbate-deficient guinea pigs were subjected to CS exposure from 5 cigarettes/(guinea pig. d) for 7 d and given water or the BT infusion (20 g/L) to drink. Guinea pigs exposed to CS and given water had extensive oxidation accompanied by 39, 40 and 30% losses (P < 0.05) of microsomal proteins of lung, liver and heart, respectively. However, when the CS-exposed guinea pigs consumed the BT infusion instead of water, the oxidation of microsomal proteins was reduced (P < 0.05) approximately 90, 97 and 70% in lung, liver and heart, respectively. Protein loss was reduced (P < 0.05) approximately 92, 98 and 90% in lung, liver and heart, respectively. The results, if extrapolated to humans, would indicate that regular intake of tea may protect smokers from CS-induced oxidative damage and consequent degenerative diseases.     

Effect of increased tea consumption on oxidative DNA damage among smokers: a randomized controlled study

Tea drinking has been associated with decreased occurrence of cancer and heart disease. One potential mechanism for these findings is the strong antioxidant effect of tea polyphenols. A phase II randomized controlled tea intervention trial was designed to study the effect of high consumption (4 cups/d) of decaffeinated green or black tea on oxidative DNA damage as measured by urinary 8-hydroxydeoxyguanosine (8-OHdG) among smokers over a 4-mo period. A total of 143 heavy smokers, aged 18-79 y, were randomized to drink either green or black tea or water. Levels of plasma and urinary catechins and urinary 8-OHdG were measured monthly. A total of 133 of 143 smokers completed the 4-mo intervention. Multiple linear regression models were used to estimate the main effects and interaction effect of green and black tea consumption on creatinine-adjusted urinary 8-OHdG, with or without adjustment for potential confounders. Plasma and urinary levels of catechins rose significantly in the green tea group compared with the other two groups. Assessment of urinary 8-OHdG after adjustment for baseline measurements and other potential confounders revealed a highly significant decrease in urinary 8-OHdG (-31%) after 4 mo of drinking decaffeinated green tea (P = 0.002). No change in urinary 8-OHdG was seen among smokers assigned to the black tea group. These data suggest that regular green tea drinking might protect smokers from oxidative damages and could reduce cancer risk or other diseases caused by free radicals associated with smoking.     

Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages

The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.     

Bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement

BACKGROUND: Green and black tea polyphenols have been extensively studied as cancer chemopreventive agents. Many in vitro experiments have supported their strong antioxidant activity. Additional in vivo studies are needed to examine the pharmacokinetic relation of absorption and antioxidant activity of tea polyphenols administered in the form of green or black tea or tea extract supplements. OBJECTIVE: The purpose of this study was to compare the pharmacokinetic disposition of tea polyphenols and their effect on the antioxidant capacity in plasma 8 h after a bolus consumption of either green tea, black tea, or a green tea extract supplement. DESIGN: Thirty healthy subjects were randomly assigned to 3 different sequences of green tea, black tea, or a green tea extract supplement in a 3 x 3 crossover design with a 1-wk washout period in between treatments. RESULTS: Flavanol absorption was enhanced when tea polyphenols were administered as a green tea supplement in capsule form and led to a small but significant increase in plasma antioxidant activity compared with when tea polyphenols were consumed as black tea or green tea. All 3 interventions provided similar amounts of (-)-epigallocatechin-3-gallate. CONCLUSIONS: Our observations suggest that green tea extract supplements retain the beneficial effects of green and black tea and may be used in future chemoprevention studies to provide a large dose of tea polyphenols without the side effects of caffeine associated with green and black tea beverages.     

Comparative Study and Partial Characterization of Azorean Green Tea Polyphenols

Tea is grown in about 30 countries, including Azores Islands, and is the most widely consumed beverage worldwide. Green tea polyphenols (GTP) are the major water-soluble components in a cup of tea (Camellia sinensis (L.) O. Kuntze). The content of the Azorean GTP was determined by RP-HPLC with UV detection and compared with that of different origin samples. The Azorean GTP extraction yield was also determined using different extraction times from 10 to 60 min at 70°C, and also at different temperatures from 50 to 100°C, at a constant extraction time of 40 min. Quantitative determination of the total epicatechin derivatives and epigallocatechin gallate (EGCG) of different green teas were also compared with that of Azorean green tea. The EGCG:caffeine ratio was high in Azorean green tea as compared with others, which suggested a good source of a chemopreventive agent. The aroma of different green tea samples were compared using the SPME/GC-headspace methodology.     

Acute effects of ingestion of black tea on postprandial platelet aggregation in human subjects

Results of population studies suggest that black tea can reduce cardiovascular risk. Effects of black-tea polyphenols to reduce platelet aggregability may help to explain any benefits. Given that black tea is often consumed with and after meals, and man spends much of his life in the postprandial state, the objective of the present study was to investigate the acute effects of ingestion of black tea on postprandial platelet aggregation ex vivo. Twenty healthy participants had platelet aggregation and blood lipids assessed before and 4 h after the ingestion of 50 g dairy fat on two occasions in random order, corresponding to black tea or hot water. Black tea or hot water (one cup) was consumed immediately following the dairy fat, then after 15 and 30 h. Platelet aggregation ex vivo was assessed in platelet-rich plasma in response to three concentrations of collagen (0.2, 0.6, 20 microg/ml) and ADP (2, 4, 8 microM). Urinary concentrations of 4-O-methylgallic acid were used as an indicator that tea polyphenols were absorbed. Serum total cholesterol and triacylglycerol concentrations increased significantly 4 h after ingesting the dairy fat, but there was no significant difference between black tea and hot-water treatments on the cholesterol or triacylglycerol responses. Urinary 4-O-methylgallic acid concentrations were significantly increased following ingestion of black tea (P=0.0001) but not water. Black tea in comparison to hot water did not inhibit collagen or ADP-induced postprandial platelet aggregation. The results of this study do not support the suggestion that reduced postprandial platelet aggregability contributes to any benefits of black tea on cardiovascular risk.     

Tea components: antimutagenic and anticarcinogenic effects.

BACKGROUND. Tea from the Camellia sinensis species of the Theaceae family is one of the most ancient and, next to water, the most widely consumed beverage in the world. Since tea contains several polyphenols and since several other naturally occurring dietary polyphenols have shown antimutagenic effects in bacteria and anticarcinogenic effects in animal bioassay systems, we studied whether polyphenols extracted from Chinese green tea (GTP) also possess antimutagenic and anticarcinogenic effects. RESULTS. GTP and its constituent epicatechin derivatives were found to interact with hepatic cytochrome P450 (P450) and inhibited the P450-dependent mixed-function oxidase enzymes in skin and liver. GTP and its epicatechin derivatives exhibited antimutagenic effects in several test systems. GTP showed substantial anti-skin-tumor-initiating and anti-skin-tumor-promoting activities when assessed in murine skin tumorigenesis bioassay systems. In these model systems polyaromatic hydrocarbons, benzo[a]pyrene (BP), 3-methyl-cholanthrene, 7,12-dimethylbenz[a]anthracene, and (+)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (an ultimate carcinogenic metabolite of BP) were used as model skin carcinogens. The feeding of GTP in drinking water to SKH-1 hairless mice also afforded significant protection against ultraviolet-B-radiation-induced skin photocarcinogenesis. CONCLUSIONS. These data suggest that tea components possess antimutagenic and anticarcinogenic effects, and that they could protect humans against the risk of cancer by environmental agents.     

绿茶及其有效成分对肾性高血压大鼠左室肥厚抑制作用的研究

目的研究绿茶及其提取物对肾性高血压大鼠左室肥厚的抑制作用机制。方法雄性Wistar大鼠160只,体重180~220g,随机分为5组,建立二肾一夹法大鼠肾性高血压左室肥厚模型:假手术组(SHAM)和手术组(2K1C)正常饮水;手术+绿茶组(2K1C+GT)饮用2%绿茶水;手术+茶多酚组(2K1C+TP)饮用0.1%茶多酚水;手术+EGCG组(2K1C+EGCG)饮用0.05%EGCG水,术后即给予不同浓度的绿茶及其提取物,持续8周直至实验结束。结果与假手术组比较,手术组和各饮茶组血压、左心室与体重比值(LVW/BW)和左心室壁厚度(LVWT)均显著升高(P<0.01)。而与手术组相比,不同浓度的绿茶及其有效成分(2%绿茶、0.1%茶多酚、0.05%EGCG)左心室重/体重(LVW/BW)、左心室壁厚度显著降低,抗氧化酶(SOD和GSH-Px)的活性升高,活性氧自由基(ROS)以及Ras和ERK1/2蛋白表达降低,但对大鼠收缩压无显著性影响。结论绿茶及其提取物对肾性高血压大鼠左室肥厚有抑制作用,其机制可能是由于茶及其有效成分具有抗氧化活性,能够清除ROS,以及对Ras-MAPK信号传导通路的调控有关。     

A single dose of tea with or without milk increases plasma antioxidant activity in humans

OBJECTIVE: To investigate the effect of black and green tea consumption, with and without milk, on the plasma antioxidant activity in humans. DESIGN: In a complete cross-over design, 21 healthy volunteers (10 male, 11 female) received a single dose of black tea, green tea (2 g tea solids in 300 ml water) or water with or without milk. Blood samples were obtained at baseline and at several time points up to 2 h post-tea drinking. Plasma was analysed for total catechins and antioxidant activity, using the ferric reducing ability of plasma (FRAP) assay. RESULTS: Consumption of black tea resulted in a significant increase in plasma antioxidant activity reaching maximal levels at about 60 min. A larger increase was observed after consumption of green tea. As anticipated from the higher catechin concentration in green tea, the rise in plasma total catechins was significantly higher after consumption of green tea when compared to black tea. Addition of milk to black or green tea did not affect the observed increases in plasma antioxidant activity. CONCLUSIONS: Consumption of a single dose of black or green tea induces a significant rise in plasma antioxidant activity in vivo. Addition of milk to tea does not abolish this increase. Whether the observed increases in plasma antioxidant activity after a single dose of tea prevent in vivo oxidative damage remains to be established. European Journal of Clinical Nutrition (2000) 54, 87-92     

Can black tea influence plasma total homocysteine concentrations?

BACKGROUND: Polyphenols can act as acceptors of methyl groups during the metabolism of methionine to homocysteine. This may result in elevations in plasma total homocysteine (tHcy) concentrations after ingestion of polyphenol-rich beverages such as tea. OBJECTIVES: Our major objective was to determine whether regular, moderate-to-high intakes of black tea alter tHcy concentrations. We also assessed the relation between the degree of O-methylation of tea-derived polyphenols and the change in tHcy with regular ingestion of tea. DESIGN: Twenty-two subjects completed a randomized, controlled crossover study. Subjects consumed 1250 mL black tea/d (5 cups each containing 2 g tea leaves in 250 mL boiled water) and 1250 mL hot water/d for 4 wk each. Fasting tHcy concentrations and 24-h urinary excretion of 4-O-methylgallic acid (4OMGA, the major O-methylated metabolite of gallic acid) were measured at the end of each period. 4OMGA was used as a marker of overall O-methylation of tea-derived polyphenols. RESULTS: Black tea did not significantly alter mean (+/- SEM) tHcy concentrations (9.9 +/- 0.5 and 10.0 +/- 0.5 micro mol/L for the hot water and black tea periods, respectively). However, the increased excretion of 4OMGA as a consequence of black tea consumption was positively associated with the change in tHcy from the hot water period to the black tea period (r = 0.55, P = 0.008). Subjects in the bottom quartile of increase in 4OMGA excretion had a significant decrease in tHcy (-0.28 +/- 0.10 micro mol/L; P = 0.046), and those in the top quartile had a significant increase in tHcy (0.78 +/- 0.16 micro mol/L; P = 0.005). CONCLUSIONS: Overall, regular ingestion of black tea did not alter mean tHcy concentrations. However, individual differences in O-methylation of polyphenolic compounds may influence the ultimate effects of black tea on tHcy.     

绿茶多酚对胰岛素抵抗模型大鼠血脂与血压的效应及其机制

目的:利用胰岛素抵抗模型大鼠,探究绿茶多酚(greenteapolyphenols,GTP)调脂降压作用及其作用机制。方法:高脂、高糖和高盐饲料饲养大鼠,饲养6w时,给予GTP,1次/d,连续6w,并于处理前,处理6w和12w测定大鼠血压,以及各组大鼠空腹血糖、血脂、胰岛素水平及血中MDA、TNF-α、Renin、AngⅡ水平和SOD活性。结果:GTP可显著降低胰岛素抵抗模型大鼠血压和血脂,并提高胰岛素敏感指数;同时,降低血中AngⅡ、MDA、TNF-α水平,升高SOD活性。结论:GTP对胰岛素抵抗时发生的高血脂和高血压具有调脂和降压作用,其作用机制与其抗氧化,抑制AngⅡ和TNF-α因子生成有关。     

How should we assess the effects of exposure to dietary polyphenols in vitro?

Human intervention studies have provided clear evidence that dietary polyphenols (eg, flavonoids--eg, flavonols--and isoflavones) are at least partly absorbed and that they have the potential to exert biological effects. Biological activity of polyphenols is often assessed by using cultured cells as tissue models; in almost all such studies, cells are treated with aglycones or polyphenol-rich extracts (derived from plants and foods), and data are reported at concentrations that elicited a response. There are 2 inherent flaws in such an approach. First, plasma and tissues are not exposed in vivo to polyphenols in these forms. Several human studies have identified the nature of polyphenol conjugates in vivo and have shown that dietary polyphenols undergo extensive modification during first-pass metabolism so that the forms reaching the blood and tissues are, in general, neither aglycones (except for green tea catechins) nor the same as the dietary source. Polyphenols are present as conjugates of glucuronate or sulfate, with or without methylation of the catechol functional group. As a consequence, the polyphenol conjugates are likely to possess different biological properties and distribution patterns within tissues and cells than do polyphenol aglycones. Although deconjugation can potentially occur in vivo to produce aglycone, it occurs only at certain sites. Second, the polyphenol concentrations tested should be of the same order as the maximum plasma concentrations attained after a polyphenol-rich meal, which are in the range of 0.1-10 micromol/L. For correct interpretation of results, future efforts to define biological activities of polyphenols must make use of the available data concerning bioavailability and metabolism in humans.     

Decaffeinated green and black tea polyphenols decrease weight gain and alter microbiome populations and function in diet-induced obese mice

Purpose

Decaffeinated green tea (GT) and black tea (BT) polyphenols inhibit weight gain in mice fed an obesogenic diet. Since the intestinal microflora is an important contributor to obesity, it was the objective of this study to determine whether the intestinal microflora plays a role in the anti-obesogenic effect of GT and BT.

Methods

C57BL/6J mice were fed a high-fat/high-sucrose diet (HF/HS, 32% energy from fat; 25% energy from sucrose) or the same diet supplemented with 0.25% GTP or BTP or a low-fat/high-sucrose (LF/HS, 10.6% energy from fat, 25% energy from sucrose) diet for 4 weeks. Bacterial composition was assessed by MiSeq sequencing of the 16S rRNA gene.

Results

GTP and BTP diets resulted in a decrease of cecum Firmicutes and increase in Bacteroidetes. The relative proportions of Blautia, Bryantella, Collinsella, Lactobacillus, Marvinbryantia, Turicibacter, Barnesiella, and Parabacteroides were significantly correlated with weight loss induced by tea extracts. BTP increased the relative proportion of Pseudobutyrivibrio and intestinal formation of short-chain fatty acids (SCFA) analyzed by gas chromatography. Cecum propionic acid content was significantly correlated with the relative proportion of Pseudobutyrivibrio. GTP and BTP induced a significant increase in hepatic 5′adenosylmonophosphate-activated protein kinase (AMPK) phosphorylation by 70 and 289%, respectively (P < 0.05) determined by Western blot.

Conclusion

In summary, both BTP and GTP induced weight loss in association with alteration of the microbiota and increased hepatic AMPK phosphorylation. We hypothesize that BTP increased pAMPK through increased intestinal SCFA production, while GTPs increased hepatic AMPK through GTP present in the liver.