Theabrownin: a dietary nutraceutical with diverse anticancer mechanisms

Cancer, a highly deadly disease, necessitates safe, cost-effective, and readily accessible treatments to mitigate its impact. Theabrownin (THBR), a polyphenolic pigment found in Pu-erh tea, has garnered attention for its potential benefits in memory, liver health, and inflammation control. By observing different biological activities of THBR, recently researchers have unveiled THBR's promising anticancer properties across various human cancer types. By examining existing studies, it is evident that THBR demonstrates substantial potential in inhibiting cell proliferation and reducing tumour size with minimal harm to normal cells. These effects are achieved through the modulation of key molecular markers such as Bcl-2, Bax, various Caspases, Poly (ADP-ribose) polymerase cleavage (Cl-PARP), and zinc finger E box binding homeobox 1 (ZEB 1). This review aims to provide in-depth insights into THBR's role in cancer research. This review also elucidates the underlying anticancer mechanisms of THBR, offering promise as a novel anticancer drug to alleviate the global cancer burden.

Metabolites and metagenomic analysis reveals the quality of Pu-erh "tea head"

Tea head, a derivative product of Pu-erh tea, are tight tea lumps formed during pile-fermentation. The aim of this study was to reveal the differences of quality-related metabolites and microbial communities between ripened Pu-erh tea (PE-21) and tea heads (CT-21). Compared with PE-21, CT-21 showed a more mellow and smooth taste with slight bitterness and astringency, and can withstand multiple infusions. Metabolites analysis indicated CT-21 had more abundant water-soluble substances (47.39%) and showed significant differences with PE-21 in the main compositions of amino acids, catechins and saccharides which contributed to the viscosity of tea liquor, mellow taste and the tight tea lumps formation. Microbial communities and COG annotation analysis revealed CT-21 had lower abundance of Bacteria (84.05%), and higher abundance of Eukaryota (15.10%), carbohydrate transport and metabolism (8.28%) and glycoside hydrolases (37.36%) compared with PE-21. The different microbial communities may cause metabolites changes, forming distinct flavor of Pu-erh.

Metabolites profiling reveals the dynamic changes of non-volatiles in Pu-erh during Ganpu tea processing

Ganpu is an unique tea product made by Pu-erh tea and citrus peel. In this study, the non-volatiles changes of Pu-erh during Ganpu tea processing were fully analyzed by UPLC-ESI-MS/MS. Total 276 significantly differential metabolites in Pu-erh during Ganpu processing were detected (P < 0.05, VIP > 1), and their change trend were clustered into 8 subclasses by K-means analysis. Metabolites of Pu-erh present at various processes were revealed. 72 differential metabolites (P < 0.05, VIP > 1 and fold change ≥2 or ≤0.5) between any two stages were identified and fixation was the key step with 61 differential metabolites. 39 flavonoids and 2 lignans and coumarins were significantly decreased after fixation, while 5 terpenoids, 3 amino acids, 1 organic acids, 2 nucleotides and derivatives and newly detected jasminoside A (Log2FC = 9.90), picrocrocin (Log2FC = 9.90) and nomilinic acid (Log2FC = 7.56) were significantly increased. The results provided valuable information about the effect of Ganpu processing on dynamic changes of non-volatiles in Pu-erh.

Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry

Mycotoxins and pesticides are the most concerning chemical contaminants that can affect the quality of Pu-erh tea during its production and storage. This study presents a method that can simultaneously determine 31 pesticide residues and six mycotoxins in Pu-erh tea within 11 min using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after QuEChERS extraction. The lower limit of quantification (LOQ) for all analytes ranged between 0.06 and 50 ppb. Recoveries for each pesticide and mycotoxin ranged between 62.0 and 130.3%, with intra- and inter-day precisions lower than 15%. Good linear relationships were obtained, with correlation coefficients of r2 > 0.991 for all analytes. The established method was applied to 31 Pu-erh tea samples, including raw and ripened Pu-erh tea with different storage times. As a result, pesticide residues were not detected in any of the collected samples, and the mycotoxins detected in the samples were well below the official maximum residue limits (MRLs). Notably, the levels of aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were lower than 1 ppb in the samples stored for more than 30 years.

Characterization of volatile metabolites in Pu-erh teas with different storage years by combining GC-E-Nose, GC-MS, and GC-IMS

Storage time is one of the important factors affecting the aroma quality of Pu-erh tea. In this study, the dynamic changes of volatile profiles of Pu-erh teas stored for different years were investigated by combining gas chromatography electronic nose (GC-E-Nose), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-ion mobility spectrometry (GC-IMS). GC-E-Nose combined with partial least squares-discriminant analysis (PLS-DA) realized the rapid discrimination of Pu-erh tea with different storage time (R²Y = 0.992, Q² = 0.968). There were 43 and 91 volatile compounds identified by GC-MS and GC-IMS, respectively. A satisfactory discrimination (R²Y = 0.991, and Q² = 0.966) was achieved by using PLS-DA based on the volatile fingerprints of GC-IMS. Moreover, according to the multivariate analysis of VIP > 1.2 and univariate analysis of p < 0.05, 9 volatile components such as linalool and (E)-2-hexenal were selected as key variables to distinguish Pu-erh teas with different storage years. The results provide theoretical support for the quality control of Pu-erh tea.

Theabrownin of raw and ripened pu-erh tea varies in the alleviation of HFD-induced obesity via the regulation of gut microbiota

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 alleviated colitis-mediated brain dysfunction by promoting butyric acid production

Brain inflammation develops with increased colitis. Pu-erh tea is considered a potential dietary intervention to improve colitis. However, it's unclear whether Pu-erh tea helps alleviate colitis-mediated brain dysfunction. Here, we found that colitis triggered brain dysfunction and increased the risk of depression. Pu-erh tea improved gut-brain barrier function (increased ZO-1 and Occludin) and restored short-chain fatty acids (SCFAs) as well as neurotransmitter release (γ-GABA, 5-HT, and dopamine), which stemmed from the production of butyric acid (BA). Pu-erh tea and BA promoted the production of SCFAs by reshaping the gut microbes (increased Lactobacillus, Akkermansia, Faecalibaculum), thereby downregulating gut inflammatory protein expression (PI3K/AKT/NF-κB). SCFAs, especially BA, intervened directly in the blood-brain barrier via the gut-brain axis to restore neurotransmitter release. Collectively, our results highlighted that increasing BA through Pu-erh tea consumption may be a key mechanism for improving colitis-mediated brain dysfunction by lowering gut inflammation and balancing gut microbe-gut-brain axis homeostasis. These results provide a promising step that might encourage further investigations of Pu-erh tea as a protective agent for brain function in colitis patients.

Effects of Microbial Action and Moist-Heat Action on the Nonvolatile Components of Pu-Erh Tea, as Revealed by Metabolomics

Microbial action and moist-heat action are crucial factors that influence the piling fermentation (PF) of Pu-erh tea. However, their effects on the quality of Pu-erh tea remain unclear. In this study, the effects of spontaneous PF (SPPF) and sterile PF (STPF) on the chemical profile of Pu-erh tea were investigated for the first time, and sun-dried green tea was used as a raw material to determine the factors contributing to the unique quality of Pu-erh tea. The results indicated that the SPPF-processed samples had a stale and mellow taste, whereas the STPF-processed samples had a sweet and mellow taste. Through metabolomics-based analysis, 21 potential markers of microbial action (including kaempferol, quercetin, and dulcitol) and 10 potential markers of moist-heat action (including ellagic acid, β-glucogallin, and ascorbic acid) were screened among 186 differential metabolites. Correlation analysis with taste revealed that metabolites upregulated by moist-heat and microbial action were the main factors contributing to the staler mellow taste of the SPPF-processed samples and the sweeter mellow taste of the STPF-processed samples. Kaempferol, quercetin, and ellagic acid were the main active substances formed under microbial action. This study provides new knowledge regarding the quality formation mechanism of Pu-erh tea.

Pu-erh tea increases the metabolite Cinnabarinic acid to improve circadian rhythm disorder-induced obesity

Obesity is one of the circadian rhythm disorders (CRD)-mediated metabolic disorder syndromes. Pu-erh tea is a viable dietary intervention for CRD, however its effect on CRD-induced obesity is unclear. Here, we found that Pu-erh tea improved obesity in CRD-induced mice, which stemmed from the production of Cinnabarinic acid (CA). CA promoted adipose tissue lipolysis and thermogenic response (HSL, ATGL, Pparα, CKB, UCP1) and increased adipocyte sensitivity to hormones and neurotransmitters by targeting the expression of adipose tissue receptor proteins (Q6KAT8, P51655, A2AKQ0, M0QWX7, Q6ZQ33, and mGluR4). This improved mitochondrial activity and facilitated adipose tissue metabolic processes, thereby accelerating glucolipid metabolism. Also, CA-induced alterations in gut microbes and short-chain fatty acids further improved CRD-mediated lipid accumulation. These results suggest that the increase of CA caused by Pu-erh tea, targeted to adipose tissue via the metabolite-blood circulation-adipose tissue axis, maybe a key mechanism for reducing the development of CRD-induced obesity.

MS-FINDER Assisted in Understanding the Profile of Flavonoids in Temporal Dimension during the Fermentation of Pu-erh Tea

Flavonoid represents a significant class of secondary metabolites in Pu-erh tea with benefits to human health. For a rapid and complete discovery of such compounds, we established a data mining workflow that integrates software MS-DIAL, MS-FINDER, and molecular networking analysis. As a result, 181 flavonoids were tentatively annotated including 22 first found in Pu-erh tea, and two of them were potentially new molecules. The dynamic alteration of these flavonoids during Pu-erh fermentation was further investigated. They all showed a trend of first increasing and then decreasing. Moreover, statistical analysis showed that the first to third pile turnings of the fermentation process had a greater impact on the changes of flavonoids. Partial metabolic pathways were proposed. This study provides a quick and automatic strategy for flavonoid profiling. The temporal dimension of flavonoids during fermentation may serve as a theoretical basis for Pu-erh tea manufacturing technology and study on substance foundation.

Effects of Lightning on Rhizosphere Soil Properties, Bacterial Communities, and Active Components of Camellia sinensis var. assamica

Lightning rods have been developed to prevent damage caused by lightning to organisms. However, the biological effect of the current transmitted into the soil through lightning rods is unknown. In this study, we analyzed the effects of lightning on soil properties, the microbial community, and the active components of Pu-erh tea (Camellia sinensis var. assamica) near lightning rods. The results showed that the contents of organic matter and available potassium, copper, and calcium in rhizosphere soil near the lightning rod were significantly higher than those in control soil (P < 0.05), while the contents of total potassium, phosphorus, iron, magnesium, and aluminum decreased. Lightning significantly increased the bacterial diversity of Pu-erh rhizosphere soil compared to control soil samples (P < 0.05). Sphingomonas, Nitrospira, and Reyranella were significantly enriched in soil samples near the lightning rod compared to soil samples far from the lightning rod. Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that adenosine/AMP kinase, chitodextrinase, flavorubredoxin, nucleotide metabolism, and carbohydrate digestion and absorption were significantly enriched in the rhizosphere soil samples near the lightning rod compared to the control samples (P < 0.05). β diversity analysis indicated the grounding of the lightning rod contributed to the community differentiation of rhizosphere bacteria. Amino acids, polyphenols, and soluble sugar increased in Pu-erh tea near the lightning rod, while the contents of catechin and anthocyanin decreased in Pu-erh tea near the lightning rod compared with the control sample (P < 0.05). Significant correlations were found among microbial indicators, soil properties, and Pu 'er tea components. This study serves as the first report on the effects of lightning rods on soil properties, microecology, and plant metabolism, which promotes the understanding of the biological effects of lightning, and provides a reference for the rational use of lightning resources.

Pu-erh Tea Restored Circadian Rhythm Disruption by Regulating Tryptophan Metabolism

Pu-erh tea is a healthy beverage rich in phytochemicals, and its effect on the risk of inducing circadian rhythm disorders (CRD) is unclear. In this study, healthy mice were given water or 0.25% (w/v) Pu-erh tea for 7 weeks, followed by a 40 day disruption of the light/dark cycle. CRD caused dysregulation of neurotransmitter secretion and clock gene oscillations, intestinal inflammation, and disruption of intestinal microbes and metabolites. Pu-erh tea boosted the indole and 5-hydroxytryptamine pathways of tryptophan metabolism via the gut-liver-brain axis. Furthermore, its metabolites (e.g., IAA, Indole, 5-HT) enhanced hepatic glycolipid metabolism and down-regulated intestinal oxidative stress by improving the brain hormone release. Tryptophan metabolites and bile acids also promoted liver lipid metabolism and inhibited intestinal inflammation (MyD88/NF-κB) via the enterohepatic circulation. Collectively, 0.25% (w/v) Pu-erh tea has the potential to prevent CRD by promoting indole and 5-HT pathways of tryptophan metabolism and signaling interactions in the gut-liver-brain axis.

Investigation and dynamic profiling of oligopeptides, free amino acids and derivatives during Pu-erh tea fermentation by ultra-high performance liquid chromatography tandem mass spectrometry

Microbial fermentation is the critical step of Pu-erh tea manufacture, which will induce dramatic changes in the chemical composition and content of tea. In this research, we applied multi-methods based on UHPLC-Q-TOF/MS to profile the dynamic changes of oligopeptides, free amino acids, and derivatives (OPADs) during Pu-erh fermentation and predicted the potential bioactivities in silico. A total of 60 oligopeptides, 18 free amino acids, and 42 amino acid derivatives were identified, and the contents of most of them decreased after fermentation. But several N-acetyl amino acids increased 7-36 times after fermentation, and they might be the potential inhibitors of neurokinin-1 receptor. Moreover, the results of metamicrobiology showed Aspergillus niger and Aspergillus luchuensis were more prominent to metabolize protein, oligopeptides, and amino acids. Overall, these findings provide valuable insights about dynamic variations of OPADs during Pu-erh tea fermentation and are beneficial for guiding practical fermentation and quality control of Pu-erh tea.

Discriminant Analysis of Pu-Erh Tea of Different Raw Materials Based on Phytochemicals Using Chemometrics

Pu-erh tea processed from the sun-dried green tea leaves can be divided into ancient tea (AT) and terrace tea (TT) according to the source of raw material. However, their similar appearance makes AT present low market identification, resulting in a disruption in the tea market rules of fair trade. Therefore, this study analyzed the classification by principal component analysis/hierarchical clustering analysis and conducted the discriminant model through stepwise Fisher discriminant analysis and decision tree analysis based on the contents of water extract, phenolic components, alkaloid, and amino acids, aiming to investigate whether phytochemicals coupled with chemometric analyses distinguish AT and TT. Results showed that there were good separations between AT and TT, which was caused by 16 components with significant (p < 0.05) differences. The discriminant model of AT and TT was established based on six discriminant variables including water extract, (+)-catechin, (−)-epicatechin, (−)-epigallocatechin, theacrine, and theanine. Among them, water extract comprised multiple soluble solids, representing the thickness of tea infusion. The model had good generalization capability with 100% of performance indexes according to scores of the training set and model set. In conclusion, phytochemicals coupled with chemometrics analyses are a good approach for the identification of different raw materials.

Effect of inoculation with Penicillium chrysogenum on chemical components and fungal communities in fermentation of Pu-erh tea

Developing an effective method to improve the quality of Pu-erh tea is of great scientific and commercial interest. In this work, Penicillium chrysogenum P1 isolated from Pu-erh tea was inoculated in sterilized or unsterilized sun-dreid green tea leaves to develop pure-culture fermentation (PF) and enhanced fermentation (EF) of Pu-erh tea. Spectrophotometry and high performance liquid chromatography determined that contents of free amino acids (FAA), total tea polyphenols and eight polyphenolic compounds in PF were significantly lower than these in non-inoculation control test (CK) (P < 0.05), whereas the contents of soluble sugars and theabrownins (TB) in PF were significantly higher (P < 0.05) than in CK. A total of 416 volatile compounds were detected by headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry. Comparison to CK, 124 compounds in PF were degraded or decreased significantly [Variable importance in projection [(VIP) > 1.0, P < 0.05, fold change (FC) < 0.5], whereas 110 compounds in PF were formed or increased significantly (VIP > 1.0, P < 0.05, FC > 2). Compared with normal fermentation (NF), the levels of gallic acid, (+)-catechin, (-)-epicatechin and 64 volatile compounds in EF were significantly lower (VIP > 1.0, P < 0.05, FC < 0.5), whereas the levels of FAA and 39 volatile compounds were significantly higher (VIP > 1.0, P < 0.05, FC > 2). Amplicon sequencing of fungal internal transcribed spacer 1 (ITS1) revealed that P. chrysogenum P1 didn't become the dominant fungus in EF; while the fungal communities in EF were different from those in NF, in that the relative abundances of Blastobotrys bambusae and P. chrysogenum in EF were higher, and the relative abundances of Aspergillus niger and Kluyveromyces marxianus in EF were lower. Overall, inoculation of P. chrysogenum in unsterilized sun-dreid green tea leaves changed the the fungal communities in fermentation of Pu-erh tea, and chemical compounds in fermented tea leaves, i.e., the levels of TB and the compounds responsible for the stale flavor, e.g., 2-amino-4-methoxybenzothiazole were increased, resulting in improvement of the sensory quality, including mellower taste and stronger stale flavor.

Effects of Different Concentrations of Ganpu Tea on Fecal Microbiota and Short Chain Fatty Acids in Mice

Ganpu tea is composed of tangerine peel and Pu-erh tea. Current research suggests that both products can interact with gut microbes and thus affect health. However, as a kind of compound health food, little information is available about the effect of Ganpu tea on intestinal microorganisms. In this study, the basic physiological parameters (body weight, white adipose tissue and serum fat), the regulation of intestinal microorganisms and content of short-chain fatty acids (SCFAs) in feces of healthy mice were studied. The Ganpu tea can reduce the weight gain of mice and the increase in white adipose tissue (p < 0.01). After the intake of Ganpu tea, the abundance of Bacteroidetes increased (p < 0.05), whereas that of Firmicutes decreased (p < 0.01), indicating the latent capacity of Ganpu tea in adjusting the gut microbiota. Moreover, Ganpu tea differentially affected the content of different types of SCFAs in feces. Ganpu tea at the lowest concentrations showed positive effects on the concentrations of SCFAs such as acetic acid and propionic acid, whereas the concentration of butyric acid was decreased. For branched short-chain fatty acids (BSCFAs) such as isobutyric acid, isovaleric acid, etc., Ganpu tea reduced their concentrations. Our results indicated that Ganpu tea may have positive effects on preventing obesity in humans, but further research is needed before introducing such dietary therapy.

Proteogenomics Study of Blastobotrys adeninivorans TMCC 70007-A Dominant Yeast in the Fermentation Process of Pu-erh Tea

Blastobotrys adeninivorans plays an essential role in pile-fermenting of Pu-erh tea. Its ability to assimilate various carbon and nitrogen sources makes it available for application in a wide range of industry sectors. The genome of B. adeninivorans TMCC 70007 isolated from pile-fermented Pu-erh tea was sequenced and assembled. Proteomics analysis indicated that 4900 proteins in TMCC 70007 were expressed under various culture conditions. Proteogenomics mapping revealed 48 previously unknown genes and corrected 118 gene models predicted by GeneMark-ES. Ortho-proteogenomics analysis identified 17 previously unidentified genes in B. adeninivorans LS3, the first strain with a sequenced genome among the genus Blastobotrys as well. More importantly, five species specific genes were identified from TMCC 70007, which could serve as a barcode for strain typing and were applicable for fermentation process protection of this industrial species. The datasets generated from tea aqueous extract culture not only increased the proteome coverage and accuracy but also contributed to the identification of proteins related to polyphenols and caffeine, which were considered to change greatly during the microbial fermentation of Pu-erh tea. This study provides a proteome perspective on TMCC 70007, which was considered to be an important strain in the production of Pu-erh tea. The systematic proteogenomics analysis not only made a better annotation on the genome of B. adeninivorans TMCC 70007 as previous proteogenomics study but also provided solution for fermentation process protection on valuable industrial species with species specific genes uniquely identified from proteogenomics study.

Rapid characterization of the volatile profiles in Pu-erh tea by gas phase electronic nose and microchamber/thermal extractor combined with TD-GC-MS

Aroma plays an important role in the quality of Pu-erh tea. However, the quality evaluation of Pu-erh tea aroma is heavily relied on the experience of sensory evaluation, and the theoretical research is relatively scarce. In the present work, the volatile compounds in Pu-erh tea were characterized by using gas phase electronic nose (e-nose) and microchamber/thermal extractor (µ-CTE) combined with thermal desorption coupled to gas chromatography-mass spectrometry (TD-GC-MS). A satisfactory discrimination model (R² Y = 0.95, Q²  = 0.807) was obtained by using orthogonal partial least squares discriminant analysis (OPLS-DA) based on the odor fingerprint of different brands of Pu-erh tea. In addition, based on the double criterion of multivariate analysis with VIP >1.0 and univariate analysis with p ≤ 0.001, 39 volatile components were identified to contribute greatly to the discrimination of five brands of Pu-erh tea. The results suggested that gas phase e-nose and µ-CTE combined with TD-GC/MS were simple, rapid techniques to characterize the volatile compounds in Pu-erh tea and were allowed to effectively distinguish different brands of Pu-erh tea, which would provide an important reference on the quality assessment of Pu-erh tea. PRACTICAL APPLICATION: This work demonstrates that the volatile compounds in Pu-erh tea are simply and rapidly characterized by using µ-CTE/TD-GC/MS and gas phase e-nose, allowing to effectively distinguish different brands of Pu-erh tea, which can provide an important reference for the quality assessment and authentication of Pu-erh tea.

Evolution analysis of flavor-active compounds during artificial fermentation of Pu-erh tea

For the urgent need for fermentation control and product quality improvement of Pu-erh tea, gas chromatography-mass spectrometry and odor activity value (OAV) were used to comprehensively investigate the flavor-active compounds during artificial fermentation of Pu-erh tea. A flavor wheel was constructed to expound the sensory attributes evolution during fermentation. With an increased total volatiles content, 43 were significantly up-regulated and 30 were down-regulated among 131 detected volatiles. Key active compounds of three aroma types, namely fresh fragrance, fruit-fungus fragrance and stale-Qu fragrance, were analyzed based on OAV. β-damascenone was firstly found contributing most to the aroma of Pu-erh tea, followed by 1,2,3-methoxybenzene and (E,E)-2,4-nonadienal. γ-terpinene, linalool, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxybenzene, and 4-ethylveratrol were identified as the potential markers responsible for aroma differences among three fermentation stages. Finally the metabolic evolution of key flavor-active compounds were systematically summarized. This study provides significant guidance in fermentation control and new product development of Pu-erh tea.

Pu-erh tea ameliorates obesity and modulates gut microbiota in high fat diet fed mice

Obesity is regarded to be associated with fat accumulation, chronic inflammation, and gut microbiota dysbiosis. Raw and ripened pu-erh tea extract (PETe) have the effect of reducing body weight gain and fat accumulation, which are associated with gut microbiota. However, little is known about the difference of raw and ripened PETe on the regulation of gut microbiota. Here, our results suggested that supplementation of raw and ripened PETe displayed similar anti-obesogenic effect in high fat diet (HFD)-induced obesity mice, by attenuating the body weight gain, fat accumulation, oxidative injury, and low-grade inflammation, improving the glucose tolerance, alleviating the metabolic endotoxemia, and regulating the mRNA and protein expression levels of the lipid metabolism-related genes. 16S rRNA sequencing of fecal samples indicated that raw and ripened PETe intervention displayed different regulatory effect on the HFD-induced gut microbiota dysbiosis at different taxonomic levels. The microbial diversity, the relative abundance of Firmicutes and Bacteroidetes as well as F/B ratio were reversed more closer to normal by ripened PETe. Phylotypes of Bacteroidaceae, Ruminococcaceae, Lachnospiraceae, Muribaculaceae, and Rikenellaceae which are negatively correlated with obesity were enhanced notably by the intervention of ripened PETe, while Erysipelotrichaceae and Lactobacillaceae which have positive correlation with obesity were decreased dramatically. In addition, the treatment of ripened PETe had better effect on the increase of benefical Bacteroides, Alistipes, and Akkemansia and decrease of obesity associated Faecalibaculum and Erysipelatoclostridium (p < 0.05). These findings suggested that pu-erh tea especially ripened pu-erh tea could serve as a great candidate for alleviation of obesity in association with the modulation of gut microbiota.

Effects of bioactive components of Pu-erh tea on gut microbiomes and health: A review

Pu-erh tea is a post-fermentation tea with unique flavor and multiple health benefits. Due to the various microorganisms involved in the post-fermentation process, Pu-erh tea contains highly complex components, which have rich interactions with the gut microbiomes (GMs). Because the structure and homeostasis of GMs are closely related to human wellness and the various diseases progress, the beneficial effects of Pu-erh tea on GMs have a great potential for application in health care. However, there is no systematic summary of the bioactive components of Pu-erh tea, and their effects on the GMs. Here, we review the current studies on the effects of Pu-erh tea and its bioactive components on the structure of GMs as well as on health improvement, and further discuss the relevant quality indicators. This "components - function - indicators" clue will hopefully stimulate the standardization of Pu-erh tea fermentation process and the development of its functional products.

Puerhibacterium puerhi gen. nov., sp. nov., a novel member of the family Promicromonosporaceae, isolated from Pu-erh tea pile-fermentation

A Gram-staining positive aerobic bacterium, designated TLY-12^T, was isolated from the Pu-erh tea pile-fermentation process in Pu'er city, Yunnan, China. Strain TLY-12^T grew at 15-37 °C (optimum, 30 °C), pH 6.0-11.0 (optimum, pH 9.0) and 0-9.0% (w/v) NaCl (optimum, 3.0%). The major cellular fatty acids were anteiso-C_15:0, C_16:0 and iso-C_16:0. The respiratory quinone were menaquinones MK-9 (H₂) and MK-9 (H₄). The polar lipids were phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylinositol (PI), phosphoglycolipid (PGL), glycolipid (GL) and an unidentified phospholipid (PL). The peptidoglycan contained glutamic acid, aspartic acid, alanine and lysine, with the last named being the diagnostic diamino acid. Whole-cell sugars of the isolate were ribose, galactose and glucose. Phylogenetic analyses of 16S rRNA gene showed that this strain belonged to the family Promicromonosporaceae, and was most closely related to Isoptericola cucumis DSM 101603 ^T, which gave sequence similarity of 97.9%. Genome sequencing revealed a genome size of 3.91 Mbp and a G + C content of 75.0%. Average nucleotide identity and digital DNA-DNA hybridization values were all below the species threshold of described Promicromonosporaceae species. Genome phylogenetic analysis showed that strain TLY-12^T formed a separate evolutionary branch, and was parallel to other related genera of Promicromonosporaceae. Based on the phylogenetic, phenotypic, chemotaxonomic and genome pairwise data, strain TLY-12^T is considered to represent a novel species in a new genus in the family Promicromonosporaceae, for which the name Puerhibacterium puerhi gen. nov, sp. nov. is proposed. The type strain is TLY-12^T (= CGMCC 1.17157^T = KCTC 49467^T).

Pu-erh Tea Extract Treatment Could Be an Efficient Way to Enhance the Yield and Nutritional Value of Soybean Sprout

Soybean sprouts are one of the most inexpensive and nutritious food items that can be easily grown year-round. Several studies have been conducted to increase their yield and nutritional values. This study was carried out to examine the effects of Pu-erh tea extracts on the production and nutrients content of soybean sprouts. Soybean seeds were soaked in 1%, 2%, or 3% (w/v) tea extracts, or tap water, before keeping for sprout cultivation; the sprout samples were named PE-1, PE-2, PE-3, and the control, respectively. The sprout yields were increased by up to 17% in PE-2 and PE-3 than in the control. The vitamin C, total free amino acid, total mineral, total isoflavone, total polyphenol, and flavonoid contents as well as the antioxidant potentials of the tea extract-treated sprouts were higher than those of the control. The results indicated that pre-soaking soybean seeds in 2% Pu-erh tea extracts could offer an easy, inexpensive, and efficient way to improve the yield and nutritional value of soybean sprouts.

Integrated proteomics and metabolomics analysis of tea leaves fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus

Post-fermented Pu-erh tea (PFPT) is a microbially-fermented tea with distinct sensory qualities and multiple health benefits. Aspergillus are the dominant fungi in the fermentation and the main contributors to the characteristics of PFPT, so their underlying functions warrant detailed study. Here, tea leaves were fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus, and resulting samples (designated as Asn, Ast and Asf, respectively) were analyzed by proteomic and metabolomic methods. Changes to the composition of flavonoids, glycerophospholipids, organo-oxygen compounds and fatty acids resulting from Aspergillus fermentation were observed. Carbohydrate-active enzymes, e.g., endoglucanases and cellulases, for degradation of cellulose, starch, lignin, pectin, xylan and xyloglucan were identified. Glycoside hydrolase, glycosyltransferases, tannase, laccases, vanillyl-alcohol oxidases and benzoquinone reductase were identified and hypothesized to catalyze hydrolysis, oxidation, polymerization and degradation of phenolic compounds. Together, functions of Aspergillius were demonstrated as production of enzymes to change concentrations and compositions of metabolites in tea leaves.

Gut Microbiome and Metabolome Response of Pu-erh Tea on Metabolism Disorder Induced by Chronic Alcohol Consumption

This study investigated the protective effects of pu-erh tea extract (PTE) on alcohol-induced microbiomic and metabolomic disorders. In chronic alcohol-exposed mice, PTE ameliorated chronic alcoholic consumption-induced oxidative stress, inflammation, lipid accumulation, and liver and colon damage through modulating microbiomic and metabolomic responses. PTE restored the alcohol-induced fecal microbiota dysbiosis by elevating the relative abundance of potentially beneficial bacteria, for example, Bifidobacterium and Allobaculum, and decreasing the relative abundance of potentially harmful bacteria, for example, Helicobacter and Bacteroides. The alcohol-induced metabolomic disorder was modulated by PTE, which was characterized by regulations of lipid metabolism (sphingolipid, glycerophospholipid, and linoleic acid metabolism), amino acid metabolism (phenylalanine and tryptophan metabolism), and purine metabolism. Besides, the bacterial metabolites of phytochemicals in PTE might contribute to the protective effects of PTE. Overall, PTE could be a functional beverage to treat chronic alcohol consumption-induced microbiomic and metabolomic disorders.

Comparison and Risk Assessment for Trace Heavy Metals in Raw Pu-erh Tea with Different Storage Years

This research conducted an exploration of the content of microelements (As, Cr, Cd, Pb, Cu, Zn, Mn, and Hg) in raw Pu-erh tea with different storage years. The contents of As, Cr, Cd, Pb, Cu, Zn, Mn, and Hg were 0.14, 0.82, 0.02, 0.52, 14.59, 33.51, 564.02, and 0.01 μg/g, respectively, and were all less than the national standard limit values in China. The target hazard quotients (THQs) of each heavy metal were all lower than 1, and the value of combined risk hazard index (HI) of all to adults was 0.221, which presents no health risk when consumed properly by adults of the raw Pu-erh tea infusions. Interestingly, there was no significant correlation between the heavy metal element (As, Cr, Cd, Pb, Cu, Zn, Mn, and Hg) contents and the THQ values of raw Pu-erh tea samples and storage years; the correlation coefficients (R²) range from 0.01 to 0.33 and from 0.01 to 0.57, respectively. The result showed that the storage years showed no effect on the exposure risk of heavy metals; the heavy metal elements in tea samples come from the atmosphere and soil.

Production of theophylline via aerobic fermentation of pu-erh tea using tea-derived fungi

Background

Caffeine is one of the most abundant methylxanthines in tea, and it remains stable in processing of general teas. In the secondary metabolism of microorganism, theophylline is the main conversion product in caffeine catabolism through demethylation. Microorganisms, involved in the solid-state fermentation of pu-erh tea, have a certain impact on caffeine level. Inoculating an appropriate starter strain that is able to convert caffeine to theophylline would be an alternative way to obtain theophylline in tea. The purpose of this study was to isolate and identify the effective strain converting caffeine to theophylline in pu-erh tea, and discuss the optimal conditions for theophylline production.

Results

Caffeine content was decreased significantly (p < 0.05) and theophylline content was increased significantly (p < 0.05) during the aerobic fermentation of pu-erh tea. Five dominant fungi were isolated from the aerobic fermentation and identified as Aspergillus niger, Aspergillus sydowii, Aspergillus pallidofulvus, Aspergillus sesamicola and Penicillium mangini, respectively. Especially, A. pallidofulvus, A. sesamicola and P. mangini were detected in pu-erh tea for the first time. All isolates except A. sydowii TET-2, enhanced caffeine content and had no significant influence on theophylline content. In the aerobic fermentation of A. sydowii TET-2, 28.8 mg/g of caffeine was degraded, 93.18% of degraded caffeine was converted to theophylline, and 24.60 mg/g of theophylline was produced. A. sydowii PET-2 could convert caffeine to theophylline significantly, and had application potential in the production of theophylline. The optimum conditions of theophylline production in the aerobic fermentation were 1) initial moisture content of 35% (w/w), 2) inoculation quantity of 8%, and 3) incubation temperature at 35 °C.

Conclusions

For the first time, we find that A. sydowii PET-2 could convert caffeine to theophylline, and has the potential value in theophylline production through aerobic fermentation.

Quality Evaluation of Green and Dark Tea Grade Using Electronic Nose and Multivariate Statistical Analysis

Aroma assessment remains difficult and uncertain in the present sensory assessment system. It is highly desirable to develop a new assessment method to discriminate the quality of various teas in the tea market. In the present work, based on linear discriminant analysis and principal component analysis, the aroma of dry and wet samples of different Xi-hu Longjing and Pu-erh teas were tested and differentiated by electronic noses (e-nose). The results confirm that e-nose can discriminate different priced Xi-hu Longjing tea samples in the range of 80-800 RMB/500 g and varying storage years of Pu-erh tea samples. Furthermore, for the detection of both dry and wet samples of Longjing and Pu-erh teas, the results reveal that all samples have specific aroma characteristics that e-nose can recognize. More importantly, contribution analysis in sensors indicates that nitrogen oxides, methane and alcohols are the characteristic components that contribute to the fragrances of different priced Xi-hu Longjing teas, while nitrogen oxides, aromatic benzene and amines make the fragrances of Pu-erh teas with different storage years disparate. PRACTICAL APPLICATION: This work demonstrates that e-nose can rapidly distinguish tea products with different price levels and varying storage years. With the advantages of ease of use, high portability and flexibility, e-nose will be widely expanded and applied in refined processing and the development of flavored foods.

Theabrownin from Pu-erh tea together with swinging exercise synergistically ameliorates obesity and insulin resistance in rats

PURPOSE

Theabrownin (TB)-containing Pu-erh tea has been shown to be hypolipidemic in rats fed a high-fat diet. Physical exercise such as swinging is also known to reduce obesity. We hypothesized that TB in combination with swinging can synergistically ameliorate obesity and insulin resistance in rats with metabolic syndrome.

METHODS

TB, rosiglitazone, or lovastatin (controls) was administered by gavage to rats fed a diet high in fat, sugar, and salt. A subgroup of the rats was subjected to a 30-min daily swinging exercise regimen, whereas the other rats did not exercise.

RESULTS

Theabrownin in combination with swinging was found to significantly improve serum lipid status and prevent development of obesity and insulin resistance in rats. Liver transcriptomics data suggested that theabrownin activated circadian rhythm, protein kinase A, the adenosine monophosphate-activated protein kinase, and insulin signaling pathways by enhancing cyclic adenosine monophosphate levels and, hence, accelerating nutrient metabolism and the consumption of sugar and fat. The serum dopamine levels in rats increased significantly after exercise. In parallel work, intraperitoneal dopamine injections were shown to significantly reduce weight gain and prevent the elevation in triglyceride levels that would otherwise be induced by the high fat-sugar-salt diet. Theabrownin prevented obesity and insulin resistance mainly by affecting the circadian rhythm, while swinging exercise stimulated the overproduction of dopamine to accelerate metabolism of glucose and lipid.

CONCLUSIONS

Theabrownin and exercise synergistically ameliorated metabolic syndrome in rats and effectively prevented obesity.

Characteristics of probiotic yoghurts supplemented with Pu-erh tea infusion

BACKGROUND

Recently, interest in the development of functional foods enriched with bioactive components has increased. Dairy products supplemented with tea extracts known for their health-promoting properties are good examples of such products. However, most of the scientific studies and applications focus on green tea. The present study was established to estimate the effect of Pu-erh tea supplementation on the viability of starter microorganisms and selected physico-chemical and sensory properties of probiotic ABT-yoghurt.

METHODS

ABT-yoghurts (Lactobacillus acidophilus La-5, Bifidobacterium animalis ssp. lactis BB-12, Streptococcus thermophilus) were produced from cow&rsquo;s milk with 0%, 5%, 10% or 15% (v/v) of Pu-erh tea infusion added before the fermentation stage. The products obtained were subjected to the following analyses one day after production (colour profile) and after 7, 14 and 21 days of cold storage: ferric reducing antioxidant power (FRAP) and anti-radical power (ARP) measured against DPPH radical, titratable acidity, pH, texture parameters (back extrusion test), viability of starter cultures and sensory quality (hedonic scale experiment).

RESULTS

Pu-erh tea supplementation significantly enhanced the antioxidant potential of probiotic yoghurts as a 3&ndash;6.5-fold increase in FRAP and a 10&ndash;24-fold increase in ARP values were observed in comparison to plain ABT-yoghurt. Pu-erh tea slightly enhanced the viability of L. acidophilus and reduced the pH of probiotic yoghurts. Higher concentrations of Pu-erh tea caused decreased firmness and consistency while cohesiveness and index of viscosity remained unaffected upon supplementation. The addition of Pu-erh tea infusion modified the colour and sensory properties of the probiotic yoghurts but the sensory quality of the tea yoghurts was rated lower when compared to the plain one. Among all tea yoghurts, the one with 15% Pu-erh tea additive received the highest scores in sensory assessment.

CONCLUSIONS

Pu-erh tea may be successfully applied as a functional additive to probiotic yoghurts, signifi- cantly enhancing the antioxidant properties of fermented milk and ensuring a high rate of starter bacteria viability during storage. However, the level of fortification must be carefully chosen as some doses negatively influence texture parameters and sensory quality.

Dynamic Profiling of Phenolic Acids during Pu-erh Tea Fermentation Using Derivatization Liquid Chromatography-Mass Spectrometry Approach

Pu-erh tea, a famous traditional Chinese tea with multiple health benefits, is produced by microbial fermentation. It has been reported that major known bioactive compounds in green tea, e.g. epicatechin, epigallocatechin gallate, and theanine, decreased during fermentation. Then which components account for the benefits of Pu-erh tea? Phenolic acids are aromatic secondary metabolites and possess various biological properties. In this research, phenolic acids in Pu-erh tea were investigated qualitatively and quantitatively to reveal the influence of fermentation and their potential effects using 5-(diisopropylamino)amylamine (DIAAA) derivatization-ultrahigh performance liquid chromatography-quadrupole-time-of-flight/mass spectrometry (UHPLC-Q-TOF/MS) approach. A total of 33 phenolic acids were determined, and most of them were detected in Pu-erh tea for the first time. Moreover, gallic acid and theogallin were the major components in ripened and raw Pu-erh tea, respectively. Dynamic profiling revealed the increase of simple phenolic acids and the decrease of most of phenolic acid esters during Pu-erh tea fermentation. These results provided firm basis for practical fermentation and quality control of Pu-erh tea.

Pu-erh Tea Regulates Fatty Acid Metabolism in Mice Under High-Fat Diet

Pu-erh tea has been extensively reported to possess lipid lowering effects but the underlying mechanisms remained unclear. Free fatty acids (FFAs) are generally correlated with the development of obesity, leading to increased risk for type 2 diabetes mellitus and cardiovascular diseases. To investigate whether Pu-erh tea treatment alters FA metabolism, we treated HFD induced obese mice with Pu-erh tea for 22 weeks and analyzed FFA profiles of experimental mice using a UPLC-QTOF-MS platform. Results showed remarkable changes in metabolic phenotypes and FFA compositions in mice treated with or without Pu-erh tea. HFD induced a marked obese phenotype in mice as revealed by significantly increased body weight, liver and adipose tissue weight, lipid levels in serum and liver, and these parameters were markedly reduced by Pu-erh tea treatment. Several FFA or FFA ratios, such as DGLA, palmitoleic acid, and OA/SA ratio, were significantly increased while the levels of SA/PA and AA/DGLA were significantly reduced in HFD-induced obese mice. Interestingly, these differential FFAs or FFA ratios were previous identified as key markers in human obese subjects, and their changes observed in the HFD group were reversed by Pu-erh tea treatment. Moreover, a panel of FFA markers including C20:3 n6/C18:3 n6 and C20:3 n6/C20:2 n6, C18:3 n6/C18:2 n6, C18:3 n3/C18:2 n6 and C24:1 n9/C22:1 n9, which were previously identified as biomarkers in predicting the remission of obesity and diabetes in human subjects who underwent metabolic surgery procedures, were reversed by Pu-erh tea intervention. Pu-erh tea significantly improved glucose homeostasis and insulin tolerance compared to the HFD group. Additionally, Pu-erh tea treatment significantly decreased FFA synthesis genes and increased the expression of genes involved in FFA uptake and β-oxidation including FATP2, FATP5, PPARα, CPT1α, and ACOX-1. These finding confirmed the beneficial effects of Pu-erh tea on regulating lipid and glucose metabolism, and further validated a panel of FFA markers with diagnostic and prognostic value for obesity and diabetes.

Aqueous raw and ripe Pu-erh tea extracts alleviate obesity and alter cecal microbiota composition and function in diet-induced obese rats

Pu-erh tea is attracting increased attention worldwide because of its unique flavor and health effects, but its impact on the composition and function of the gut microbiota remains unclear. The aim of this study was to investigate the effects of aqueous extracts of fermented (ripe) and non-fermented (raw) Pu-erh teas on the composition and function of the intestinal microbiota of rats with diet-induced obesity. We conducted a comparative metagenomic and meta-proteomic investigation of the microbial communities in cecal samples taken from obese rats treated with or without extracts of raw or ripe Pu-erh teas. By analyzing the composition and diversity of 16S rRNA amplicons and expression profiles of 814 distinct proteins, we found that despite differences in the chemical compositions of raw and ripe Pu-erh teas, administration of either tea at two doses (0.15- and 0.40-g/kg body weight) significantly (P < 0.05) increased microbial diversity and changed the composition of cecal microbiota by increasing the relative abundances of Firmicutes and decreasing those of Bacteroidetes. Community metabolic processes, including sucrose metabolism, glycolysis, and syntheses of proteins, rRNAs, and antibiotics were significantly (P < 0.05) promoted or had a tendency (0.10 < P < 0.05) to be promoted due to the enrichment of relevant enzymes. Furthermore, evidence at population, molecular, and metabolic levels indicated that polyphenols of raw Pu-erh tea and their metabolites potentially promote Akkermansia muciniphila growth by stimulating a type II and III secretion system protein, the elongation factor Tu, and a glyceraldehyde-3-phosphate dehydrogenase. This study provides new evidence for the prebiotic effects of Pu-erh tea.

[Progress in research for pharmacological effects of Pu-erh tea]

Pu-erh tea has gradually aroused general concern with social development and people's enhanced awareness of health. Pu-erh tea is rich in multiple active constitute such as flavonoids, catechins, phenolic acids, flavanols polymer, purine alkaloids, and hydrolysable tannin as a microbial-fermented tea.It is reported that Pu-erh tea have a variety of pharmacologically activities, such as anti-hyperlipidemic, anti-diabetic, anti-oxidative, anti-tumor, anti-bacterial, anti-inflammatory, and anti-viral effects. In this paper, the main pharmacological effects of Pu-erh tea are reviewed. We wish this work will provide some references and clues for further research of Pu-erh tea.

Flavanols from the Camellia sinensis var. assamica and their hypoglycemic and hypolipidemic activities

α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (2—17) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro; compound 15 showed moderate inhibitory effect against sucrase with an IC₅₀ value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC₅₀ value of 1.3 μmol/L. Compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC₅₀ values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.

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

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

Serum metabolomics analysis of rat after intragastric infusion of Pu-erh theabrownin

BACKGROUND

The aim was to study the effects of Pu-erh theabrownin (TB) (Mw  > 50 kDa) on the metabolism of rat serum by nuclear magnetic resonance (NMR)-based metabolomics and identify candidate marker metabolites associated with Pu-erh TB, and thus provide fundamental information for a better understanding of the metabolism of Pu-erh tea in animals.

RESULTS

TB infusion induced different changes in endogenous serum metabolites depending on the type of diet. Compared with the control group, the TB infusion group showed significantly reduced serum glycine and choline levels, as well as significantly increased taurine, carnitine and high-density lipoprotein (all P < 0.05). Compared with the high-lipid group, the high-lipid TB infusion group exhibited significantly reduced low-density lipoprotein and acetate levels, as well as significantly increased inositol, carnitine and glycine levels (all P < 0.05).

CONCLUSION

Examination of the variations of these differential expressed metabolites and their individual functions revealed that the TB extract accelerated lipid catabolism in rats and might affect glucose metabolism. Of these, carnitine level significantly increased after intragastric infusion of TB regardless of the type of diet, and activities of carnitine palmitoyltransferases I and II changed significantly, suggesting carnitine may be a candidate serum marker for tracking the metabolism of TB in rats. © 2015 Society of Chemical Industry.

Characterization of thermophilic fungal community associated with pile fermentation of Pu-erh tea

This study aimed to characterize the thermophilic fungi in pile-fermentation process of Pu-erh tea. Physicochemical analyses showed that the high temperature and low pH provided optimal conditions for propagation of fungi. A number of fungi, including Blastobotrys adeninivorans, Thermomyces lanuginosus, Rasamsonia emersonii, Aspergillus fumigatus, Rhizomucor pusillus, Rasamsonia byssochlamydoides, Rasamsonia cylindrospora, Aspergillus tubingensis, Aspergillus niger, Candida tropicalis and Fusarium graminearum were isolated as thermophilic fungi under combination of high temperature and acid culture conditions from Pu-erh tea pile-fermentation. The fungal communities were analyzed by PCR-DGGE. Results revealed that those fungi are closely related to Debaryomyces hansenii, Cladosporium cladosporioides, A. tubingensis, R. emersonii, R. pusillus, A. fumigatus and A. niger, and the last four presented as dominant species in the pile process. These four preponderant thermophilic fungi reached the order of magnitude of 10(7), 10(7), 10(7) and 10(6)copies/g dry tea, respectively, measured by real-time quantitative PCR (q-PCR). The results indicate that the thermophilic fungi play an important role in Pu-erh tea pile fermentation.

Development of LC-MS/MS analysis of cyclic dipeptides and its application to tea extract

2,5-Diketopiperazines (DKPs), also called cyclic dipeptides, have been known to occur in various foods. Recently, DKPs have attracted attentions as bioactive components. There were some reports on analytical methods for DKPs, but the number of analyzed DKPs was only a part of all DKPs and the quantitative performance was not studied in detail. In this study, we selected 31 kinds of DKPs and developed a quantitative and simultaneous analytical method using LC-MS/MS. This method was applied to DKPs determination in Pu-erh tea, post-fermentation tea, and 18 kinds of DKPs were determined at concentration of 0.0017-0.11 ppm. As a result of spiked test, it was concluded that the developed method using LC-MS/MS was useful for estimating DKPs concentration in tea.

Simultaneous determination of free amino acids in Pu-erh tea and their changes during fermentation

Pu-erh ripened tea is produced through a unique microbial fermentation process from the sun-dried leaves of large-leaf tea species (Camellia sinensis (Linn.) var. assamica (Masters) Kitamura) in Yunnan province of China. In this study, the changes of amino acid profiles during fermentation of Pu-erh tea were investigated, based on the improved HPLC-UV method with PITC pre-column derivatization for the simultaneous determination of twenty free amino acids. Results showed that aspartic acid, glutamic acid, arginine, alanine, theanine and tyrosine were the major amino acids in tea samples. Fermentation significantly influenced on the amino acid profiles. The total free amino acid contents significantly decreased during fermentation (p<0.05). Meanwhile, low amount of acrylamide were detected. Its concentration increased after 7-days' fermentation and then decreased gradually. The results provided the useful information for the manipulation of fermentation process according to the changes of amino acids and acrylamide contents in Pu-erh ripened tea.

Fungal isolates from a Pu-erh type tea fermentation and their ability to convert tea polyphenols to theabrownins

The natural microbiota involved in the fermentation influence the quality and taste of fully postfermented teas such as China's Pu-erh tea. Ten microbial isolates representing 6 species were recovered from a solid-state fermentation of a Pu-erh type tea. The isolates were Aspergillus tubingensis, Aspergillus marvanovae, Rhizomucor pusillus, Rhizomucor tauricus, Aspergillus fumigatus, and Candida mogii. With the exception of A. marvanovae and C. mogii, all these microorganisms have been previously reported in solid-state fermentations of native Pu-erh tea. The ability of the isolates for converting the tea polyphenols to bioactive theabrownins in infusions of sun-dried green tea leaves in a submerged fermentation process was subsequently investigated. All isolates except C. mogii TISTR 5938 effectively produced theabrownins in a 4-d fermentation in shake flasks at 40 °C, 250 rpm. A. tubingensis TISTR 3646, A. tubingensis TISTR 3647, A. marvanovae TISTR 3648, and A. fumigatus TISTR 3654 produced theabrownins at particularly high levels of 6.5, 12.4, 11.1, and 8.4 g/L, respectively.

Pu-erh tea inhibits tumor cell growth by down-regulating mutant p53

Pu-erh tea is a kind of fermented tea with the incorporation of microorganisms' metabolites. Unlike green tea, the chemical characteristics and bioactivities of Pu-erh tea are still not well understood. Using water extracts of Pu-erh tea, we analyzed the tumor cell growth inhibition activities on several genetically engineered mouse tumor cell lines. We found that at the concentration that did not affect wild type mouse embryo fibroblasts (MEFs) growth, Pu-erh tea extracts could inhibit tumor cell growth by down-regulated S phase and cause G1 or G2 arrest. Further study showed that Pu-erh tea extracts down-regulated the expression of mutant p53 in tumor cells at the protein level as well as mRNA level. The same concentration of Pu-erh tea solution did not cause p53 stabilization or activation of its downstream pathways in wild type cells. We also found that Pu-erh tea treatment could slightly down-regulate both HSP70 and HSP90 protein levels in tumor cells. These data revealed the action of Pu-erh tea on tumor cells and provided the possible mechanism for Pu-erh tea action, which explained its selectivity in inhibiting tumor cells without affecting wild type cells. Our data sheds light on the application of Pu-erh tea as an anti-tumor agent with low side effects.