Truffle protein and its derived peptides exhibit sleep-promoting effects via regulation of lysosomal autophagy, neurological activity, tyrosine metabolism, and fatty acid elongation.

Black truffle (Tuber sinense) is a famous luxurious mushroom with abundant protein resources. Nevertheless, until now, no single study has explored the potential function of black truffle protein in any animal models. Thus, this study investigated the sleep-promoting effects of truffle albumin (TA) and its hydrolysate (TAH). Then, two novel sleep-enhancing peptides were explored from TAH. Our results showed that TA and TAH significantly prolonged the total sleep time and improved sleep quality of insomnia Drosophila. Additionally, two novel peptides YLDLAPL and YLRPEGDW with strong sleep-enhancing activity were explored by virtual screening and Drosophila with transgenic RNA interference (RNAi) technology. Finally, the transcriptomics analysis investigated potential mechanisms of sleep-enhancing effects in Drosophila: (1) regulation of the autophagic activity by altering the lysosomal protein; (2) up-regulation the genes in the pathway of neuroactive ligand-receptor interaction and promotion the function of neurons; (3) promotion the conversion of tyrosine into neurotransmitters; (4) regulation substrate feeding into the tricarboxylic acid (TCA) cycle and promotion free radical scavenging in neuronal cells; (5) promotion the fatty acid elongation and preservation neuronal cells avoid from oxidation.

Quality characteristics and fibrous structure formation mechanism of walnut protein and wheat gluten meat analogues during high-moisture extrusion cooking process.

Blending two or more materials to create better high-moisture meat analogues has been actively studied in the food science and technology field. Walnut protein is a high-quality plant-based protein resource, yet its full potential remains underexploited. Thus, this study focused on exploring the quality characteristics and fibrous structure formation mechanism of walnut protein (WP) and wheat gluten (WG) meat analogues during high-moisture extrusion cooking process. Results showed that the optimized WP and WG-blended high-moisture meat analogues exhibited a more pronounced anisotropic and oriented fibrous structure. The blending of WP and WG can protect the molecular chains from the thermal transition, and promote the aggregation of protein molecules mainly by enhancing the interaction between hydrophobic interactions and hydrogen bonds, increasing the apparent viscosity and forming protein subunits with larger molecular weights (>100 kDa) to stabilize the newly formed conformation. Additionally, the content of α-helix was the highest among the secondary structures. This study provides a theoretical basis for the application of WG and WP to produce HMMAs with rich fibrous structures.

Theabrownin from Pu-erh Tea Improves DSS-Induced Colitis via Restoring Gut Homeostasis and Inhibiting TLR2&4 Signaling Pathway.

BACKGROUND: Theabrownin (TB) is a dark brown pigment from Pu-erh tea or other dark teas. It is formed by further oxidization of theaflavins and thearubigins, in combination with proteins, polysaccharides, and caffeine etc. TB is a characteristic ingredient and bioactive substance of Pu-erh tea. However, the effects of TB on ulcerative colitis (UC) remains unclear. PURPOSE: This study aims to elucidate the mechanism of TB on UC in terms of recovery of intestinal homeostasis and regulation of toll-like receptor (TLR) 2&4 signaling pathway. METHODS: The colitis models were established by administering 5% dextran sulfate sodium (DSS) to C57BL/6 mice for 5 days to evaluate the therapeutic and preventive effects of TB on UC. Mesalazine was used as a positive control. H&E staining, complete blood count, enzyme-linked immunosorbent assay, immunohistochemistry, flow cytometry, and 16S rRNA sequencing were employed to assess histological changes, blood cells analysis, content of cytokines, expression and distribution of mucin (MUC)2 and TLR2&4, differentiation of CD4+T cells in lamina propria, and changes in intestinal microbiota, respectively. Western blot was utilized to study the relative expression of tight junction proteins and the key proteins in TLR2&4-mediated MyD88-dependent MAPK, NF-κB, and AKT signaling pathways. RESULTS: TB outstanding alleviated colitis, inhibited the release of pro-inflammatory cytokines, reduced white blood cells while increasing red blood cells, hemoglobin, and platelets. TB increased the expression of occludin, claudin-1 and MUC2, effectively restored intestinal barrier function. TB also suppressed differentiation of Th1 and Th17 cells in the colon's lamina propria, increased the fraction of Treg cells, and promoted the balance of Treg/Th17 to tilt towards Tregs. Moreover, TB increased the Firmicutes to Bacteroides (F/B) ratio, as well as the abundance of Akkermansia, Muribaculaceae, and Eubacterium_coprostanoligenes_group at the genus level. In addition, TB inhibited the activation of TLR2&4-mediated MAPK, NF-κB, and AKT signaling pathways in intestinal epithelial cells of DSS-induced mice. CONCLUSION: TB acts in restoring intestinal homeostasis and anti-inflammatory in DSS-induced UC, and exhibiting a preventive effect after long-term use. In a word, TB is a promising beverage, health product and food additive for UC.

Caffeine regulates both osteoclast and osteoblast differentiation via the AKT, NF-κB, and MAPK pathways.

Background: Although caffeine generally offers benefits to human health, its impact on bone metabolism remains unclear. Aim and Methods: This study aimed to systematically evaluate the long-term effects of caffeine administration on osteoclasts, osteoblasts, and ovariectomy-induced postmenopausal osteoporosis (OP). Results: Our in vitro findings revealed that 3.125 and 12.5 µg/mL caffeine inhibited RANKL-mediated osteoclastogenesis in RAW 264.7 cells through the MAPK and NF-κB pathways, accompanied by the inactivation of nuclear translocation of nuclear factor NFATc1. Similarly, 3.125 and 12.5 µg/mL of caffeine modulated MC3T3-E1 osteogenesis via the AKT, MAPK, and NF-κB pathways. However, 50 µg/mL of caffeine promoted the phosphorylation of IκBα, P65, JNK, P38, and AKT, followed by the activation of NFATc1 and the inactivation of Runx2 and Osterix, ultimately disrupting the balance between osteoblastogenesis and osteoclastogenesis. In vivo studies showed that gavage with 55.44 mg/kg caffeine inhibited osteoclastogenesis, promoted osteogenesis, and ameliorated bone loss in ovariectomized mice. Conclusion: Conversely, long-term intake of high-dose caffeine (110.88 mg/kg) disrupted osteogenesis activity and promoted osteoclastogenesis, thereby disturbing bone homeostasis. Collectively, these findings suggest that a moderate caffeine intake (approximately 400 mg in humans) can regulate bone homeostasis by influencing both osteoclasts and osteoblasts. However, long-term high-dose caffeine consumption (approximately 800 mg in humans) could have detrimental effects on the skeletal system.

Recent Approaches to the Formulation, Uses, and Impact of Edible Coatings on Fresh Peach Fruit.

Peaches are among the most well-known fruits in the world due to their appealing taste and high nutritional value. Peach fruit, on the other hand, has a variety of postharvest quality issues like chilling injury symptoms, internal breakdown, weight loss, decay, shriveling, and over-ripeness, which makes a challenging environment for industries and researchers to develop sophisticated strategies for fruit quality preservation and extending shelf life. All over the world, consumers prefer excellent-quality, high-nutritional-value, and long-lasting fresh fruits that are free of chemicals. An eco-friendly solution to this issue is the coating and filming of fresh produce with natural edible materials. The edible coating utilization eliminates the adulteration risk, presents fruit hygienically, and improves aesthetics. Coatings are used in a way that combines food chemistry and preservation technology. This review, therefore, examines a variety of natural coatings (proteins, lipids, polysaccharides, and composite) and their effects on the quality aspects of fresh peach fruit, as well as their advantages and mode of action. From this useful information, the processors could benefit in choosing the suitable edible coating material for a variety of fresh peach fruits and their application on a commercial scale. In addition, prospects of the application of natural coatings on peach fruit and gaps observed in the literature are identified.

Mechanism of action and treatment of type I interferon in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) caused by HBV, HCV infection, and other factors is one of the most common malignancies in the world. Although, percutaneous treatments such as surgery, ethanol injection, radiofrequency ablation, and transcatheter treatments such as arterial chemoembolization are useful for local tumor control, they are not sufficient to improve the prognosis of patients with HCC. External interferon agents that induce interferon-related genes or type I interferon in combination with other drugs can reduce the recurrence rate and improve survival in HCC patients after surgery. Therefore, in this review, we focus on recent advances in the mechanism of action of type I interferons, emerging therapies, and potential therapeutic strategies for the treatment of HCC using IFNs.

Tea Harvesting and Processing Techniques and Its Effect on Phytochemical Profile and Final Quality of Black Tea: A Review.

Tea (Camellia sinensis) has grown for over 300 years and is recognized worldwide as among other well-renowned crops. The quality of black tea depends on plucking (method, standard, season, and intervals), withering and rolling (time and temperature), fermentation (time, temperature, and RH), drying (temperature and method), and storage conditions, which have a high influence on the final quality of black tea. At the rolling stage, the oxidation process is initiated and ends at the early drying stage until the enzymes that transform tea polyphenols into thearubigins (TRs) and theaflavins (TFs) are denatured by heat. By increasing fermentation time, TRs increased, and TF decreased. Each is liable for black tea's brightness, taste, and color. The amino acids and essential oils also grant a distinctive taste and aroma to black tea. Throughout withering, rolling, and fermentation, increases were found in essential oil content, but during drying, a decrease was observed. However, the Maillard reaction, which occurs when amino acids react with sugar during drying, reimburses for this decrease and enhances the flavor and color of black tea. As compared to normal conditions, accelerated storage showed a slight decrease in the total color, TF, and TRs. It is concluded that including plucking, each processing step (adopted technique) and storage system has a remarkable impact on black tea's final quality. To maintain the quality, an advanced mechanism is needed to optimize such factors to produce high-quality black tea, and an objective setting technique should be devised to attain the desirable quality characteristics.

Theabrownin Isolated from Pu-Erh Tea Enhances the Innate Immune and Anti-Inflammatory Effects of RAW264.7 Macrophages via the TLR2/4-Mediated Signaling Pathway.

Theabrownin (TB) is a tea pigment extracted from Pu-erh Tea. The effects of TB on innate immunity and inflammation are not well understood. Herein, the effects of TB on innate immunity are investigated using RAW264.7 macrophages. We found that TB promoted the proliferation of RAW264.7 macrophages, altered their morphology, enhanced their pinocytic and phagocytic ability, and significantly increased their secretion of nitric oxide (NO) and cytokines, all of which enhanced the immune response. Additionally, TB inhibited the release of inflammatory signals in RAW264.7 macrophages primed with lipopolysaccharide (LPS), implying that TB modulates the excessive inflammation induced by bacterial infection. A Western blot showed that TB could activate the toll-like receptor (TLR)2/4-mediated myeloid differentiation factor 88 (MyD88)-dependent mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathway and the TLR2-mediated phosphoinositide 3-kinase (PI3K)-AKT signaling pathway, enhancing the immune functions of RAW264.7 macrophages. TB also inhibited the phosphorylation of core proteins in the MAPK/NF-κB/PI3K-AKT signaling pathway induced by LPS. In addition, we analyzed the transcriptomes of RAW264.7 macrophages, and a Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis revealed that TB modulated thetoll-like receptor signal pathway. A gene ontology (GO) enrichment analysis indicated that TB treatment strongly modulated the immune response and inflammation. As a result, TB-enhanced innate immunity and modulated inflammation via the TLR2/4 signaling pathway.

Pu-erh tea and theabrownin ameliorate metabolic syndrome in mice via potential microbiota-gut-liver-brain interactions.

Metabolic syndrome (MS) is a common metabolic disorder characterized by obesity, insulin resistance, cardiovascular disease and gut microbiota dysbiosis. Pu-erh tea and its ingredient theabrownin have known functions on the reduction of body weight gain and fat accumulation. However, few studies systematicly analyze the different contributions and mechanisms of their anti-metabolic syndrome functions through multi-omics combination analysis. Here, we used metagenomics, transcriptomics and metabolomics technology to investigate the anti-metabolic syndrome mechanism of Pu-erh tea and theabrownin in MS mice. Our results suggested that Pu-erh tea and theabrownin interventions could improve the physiological functions of liver, jejunum and adipose tissues in MS mice. Hepatic transcriptome revealed that both interventions could regulate the circadian rhythm pathway. Glycerophospholipid and linoleic acid metabolism were also modulated by both interventions through serum and brain metabolome analysis. Faecal metagenome demonstrated that both interventions could increase the relative abundance of Clostridiales bacterium 42_27, Blautia coccoides and Firmicutes bacterium ASF500, but decrease the relative abundance of Brevundimonas vesicularis. Otherwise, compared with Pu-erh tea, theabrownin markedly upregulated the levels of hepatic antioxidants (i.e., SOD, GSH), prominently downregulated hepatic inflammatory factors (i.e., IL-1, IL-6, TNF-α) and malondialdehyde oxidant, but modestly reduced obesity-associated short-chain fatty acids in faeces in MS mice. Taken together, our data provided insights into the homogeneous and heterogeneous natural biological functions of theabrownin and Pu-erh tea in the treatment of metabolic syndrome.

Theabrownin-targeted regulation of intestinal microorganisms to improve glucose and lipid metabolism in Goto-Kakizaki rats.

Diabetes is a disease that is characterized by a disturbance of glucose metabolism. Theabrownin (TB) is one of the most active and abundant pigments in Pu-erh tea, and it is a brown pigment with multiple aromatic rings and attached residues of polysaccharides and proteins. TB has been shown to be hypolipidemic and displays fasting blood glucose (FBG)-lowering properties in rats fed a high-fat diet, but the underlying mechanism has not been elucidated. This study aimed to determine the effect of TB in treating diabetes and explore the underlying mechanism of action of intestinal microbes by using Goto-Kakizaki (GK) rats. Diabetic GK rats were treated up to 8 weeks with TB (GK-TB). Following treatment, the body weight, triglyceride (TG) content, fasting blood glucose (FBG) content, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were significantly lower in the GK-TB group than in the GK control group (P < 0.05). Meanwhile, the circulating adiponectin (ADPN), leptin, and glucokinase levels in the serum of the GK-TB group were significantly higher than those in the GK group, while there was little difference in hepatic lipase (HL) and hormone-sensitive triglyceride lipase (HSL) enzyme activities (P > 0.05). Furthermore, with the extension of treatment time, the number of unique intestinal microorganisms in GK rats greatly increased and an interaction among intestinal microorganisms was observed. The Firmicutes/Bacteroides ratio was decreased significantly, and the composition of Actinobacteria and Proteobacteria was increased. The use of multiple omics technologies showed that TB is involved in the targeted regulation of the core characteristic intestinal flora including Bacteroides thetaiotaomicron (BT), Lactobacillus murinus (LM), Parabacteroides distasonis (PD), and Bacteroides_acidifaciens (BA) which improved the glucose and lipid metabolism of GK rats via the AMP-activated protein kinase signaling pathway, insulin signaling pathway, bile secretion and glycerophospholipid metabolism. Intragastric administration of BT, LM, PD, or BA led to a significantly reduced HOMA-IR in GK rats. Furthermore, BT significantly reduced serum lipid TG and total cholesterol (TC) and BA significantly reduced the serum lipid TC and low-density lipoprotein (LDL). PD significantly reduced serum LDL, while the effect of LM was not significant. However, LM and PD significantly increased the content of ADPN in serum. Taken together, our results indicated that the effect of TB on diabetic rats mainly depends on the targeted regulation of intestinal microorganisms and that TB is a functional food component with great potential to treat or prevent diabetes.

Theabrownin isolated from Pu-erh tea regulates Bacteroidetes to improve metabolic syndrome of rats induced by high-fat, high-sugar and high-salt diet.

BACKGROUND: Theabrownin (TB), a high macromolecular compound and a characteristic component of Pu-erh tea, is able to markedly regulate blood lipid and glucose metabolism. We hypothesized that TB could ameliorate metabolic syndrome induced by high-fat, high-sugar and high-salt diet (HFSSD). RESULTS: To test these hypotheses, we fed rats with HFSSD and administered a gavage of TB. HFSSD successfully induced metabolic syndrome in rats. TB significantly improved serum lipid status, prevented obesity and fasting blood glucose (FBG) and glycosylated hemoglobin (GHbAIc) in rats. After TB intervention, Firmicutes/Bacteroides (F/B) ratio was greatly reduced and showed a dose-effect relationship. TB promoted the reproduction of Bacteroidetes such as prevotella_sp._CAG:1031, prevotella_sp._MGM2 and Bacteroides_sartorii, and inhibited the reproduction of Firmicutes such as roseburia_sp._1XD42-69 and roseburia_sp._831b. CONCLUSION: In HFSSD mode, prevotella_sp._CAG:1031 was one of the main dominant characteristic bacteria of TB targeting regulation, while roseburia_sp._1XD42-69 mainly inhibitory intestinal bacteria, which help to reduce body weight, TG and blood sugar levels of HFSSD rats. Glycerophospholipid metabolism, arachidonic acid metabolism, glycolysis/gluconeogenesis and insulin resistance were the critical pathway. TB has a high application potential in reducing the risk of metabolic diseases. © 2022 Society of Chemical Industry.

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.

Effects of theabrownin on serum metabolites and gut microbiome in rats with a high-sugar diet.

Evidence has proven that the gut microbiota is an important environmental factor contributing to obesity by altering host energy harvest and storage. We performed a high-throughput 16S rDNA sequencing association study and serum metabolomics profiling in rats with a high-sugar diet. Our studies revealed that the high sugar diet reduced the diversity of cecal microorganisms, while the combination of theabrownin and the high sugar diet increased the diversity of cecal microorganisms and promoted reproduction of Alloprevotella, Coprostanoligenes_group, Bacteroides, Prevotellaceae_NK3B31_group, Desulfovibrio, Intestinimonas, Alistipes, Bifidobacterium, Phascolarctobacterium, Ruminococcaceae_UCG-010 and Staphylococcus. The combination also inhibited the growth of Lactobacillus, Prevotellaceae_Ga6A1_group and Tyzzerella. The Firmicutes/Bacteroidetes (F/B) ratio can be significantly reduced after the intervention of theabrownin in high sugar diet rats, and the reproduction of Bacteroides acidifaciens (BA) and Staphylococcus saprophyticus subsp. saprophyticus can be promoted. We found that the obesity-associated gut microbial species were linked to the changes in circulating metabolites. Serum levels of deoxycholic acid, cholic acid, 1H-indole-3-acetic acid, 3-indole acrylic acid and melatonin were negatively correlated with BA and Staphylococcus saprophyticus subsp. saprophyticus, but positively correlated with Lactobacillus murinus, Leptum and Gut_metagenome. 2-Hydroxy-6-methylpyridin-3-carboxylic acid, l-homoserine, and 1,7-dimethylxanthine were positively correlated with BA and Staphylococcus saprophyticus subsp. saprophyticus, but negatively correlated with Lactobacillus murinus, Leptum, and Gut_metagenome. In a high sugar diet mode, theabrownin reduced the body weight and triglycerides and improved insulin resistance mainly by targeting the reproduction of intestinal microorganisms such as BA, Staphylococcus saprophyticus subsp. saprophyticus, Lactobacillus murinus, Leptum, Gut_metagenome and so on. A strong correlation between cecal microorganisms and serum metabolites, obesity and insulin resistance was observed. Theabrownin has high potential in reducing the risk of cardiovascular diseases such as diabetes and obesity.

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.

[Study on the UV-quantitative analysis of theabrownins in Pu-Erh tea].

An UV-quantitative analysis method for the theabrownin (TB) in Pu-erh tea and its derived products was established in the present study. The results showed that the Pu-erh tea shows characteristic absorption at the wavelength of 270 nm, which can be used as wavelength for the content determination of TB. The preparation methods of standard TB and standard curve were also established. The determination results show that the method is simple, the results have certain credibility, and the established method can be used for the determination of TB in Pu-erh tea and its derived products.

Influence of different fermentation raw materials on pyrolyzates of Pu-erh tea theabrownin by Curie-point pyrolysis-gas chromatography-mass spectroscopy.

SCOPE: In this study, Pu-erh tea was prepared by solid-state fermentation of the sun-dried green tea, short-fermentation black tea, and black tea. Ultraviolet-visible spectroscopy, infrared spectroscopy and Curie-point pyrolysis-gas chromatography-mass spectroscopy (CP-Py-GC/MS) were used to study the characteristics and chemical compositions of the TB formed in these Pu-erh teas. METHODS AND RESULTS: The pyrolysates of the Pu-erh teas' theabrownin (TB1, TB2, TB3) were analyzed at 386°C using a Curie point pyrolysis instrument. TB1, TB2, and TB3 produced 158, 135 and 148 pyrolysis products, respectively. These compounds could be grouped as follows: alkaloids, 25.23% (TB1), 25.67% (TB2), and 21.91% (TB3); phenols, 24.19% (TB1), 23.08% (TB2), and 29.91% (TB3); nitrogen-compounds, 11.79% (TB1), 11.25% (TB2), and 13.39% (TB3); hydrocarbons, 10.96% (TB1), 10.37% (TB2), and 11.37% (TB3); ketones, 10.34% (TB1), 6.58% (TB2), and 8.22% (TB3); furan, 5.40% (TB1), 4.06% (TB2), and 2.33% (TB3); alcohol, 3.30% (TB1), 4.16% (TB2), and 3.34% (TB3); fatty acids, 2.80% (TB1), 4.03% (TB2), and 1.42% (TB3); esters 2.17% (TB1), 0.99% (TB2) and 2.35% (TB3); and amines 1.61% (TB1), 2.81% (TB2), and 0.86% (TB3). CONCLUSION: Theabrownin mainly contains alkaloids (caffeine), tea pigments, polysaccharides, proteins and lipids. Its precursors include various polyphenols, tea pigments, alkaloids, polysaccharides, proteins and lipids. These compounds in the raw materials impact the chemical composition of theabrownin, and black tea is not a suitable raw fermentation material for Pu-erh tea.

[Spectroscopic and structural characteristics of the main components of Theabrownin in Pu-erh tea].

In the present study, we fractionated the main components of TB in Pu-erh tea by dialysis and investigated their compositions, structures and properties. TB in the Pu-erh tea was fractionated by dialyses using films with different pore sizes. The highest TB concentration was obtained in the fraction with molecular weight species > 25 000 Da. The carboxyl and hydroxyl concentrations also increased in fractions where the molecular weight size selection was highest (i. e. , > 25 000 Da). AFM images revealed that TB particles with different molecular weights had different morphologies and the TB particles appeared as scattered islands or aggregates. CP-MAS NMR experiments revealed that the TB fraction with molecular weight species between 3 500 and 25 000 Da in size was characterized by a polymeric material of polyphenols. This polymeric substance contained primarily multiple benzene rings, polysaccharides, protein residue groups and various other functional groups. After acidic hydrolysis, this fraction formed a black precipitate. CP-MAS NMR found that the precipitate was a polymeric material with multiple benzene rings. CP-GC/MS identified 16 candidate compounds from the pyrolysis products of the black precipitate obtained from the main fraction with molecular weight species between 3 500 and 25 000 Da.

Influence of large molecular polymeric pigments isolated from fermented Zijuan tea on the activity of key enzymes involved in lipid metabolism in rat.

Influence of large molecular polymeric pigments (LMPP) isolated from fermented Zijuan tea on the activity and mRNA expression of key enzymes involved in lipid metabolism in rat was explored. The results show that intragastric infusion of high-dose LMPP (1.215 g/kg body weight) effectively suppressed the elevation in TC and LDL-C (p<0.05), and prevented the reduction in HDL-C (p<0.05), compared with the hyperlipidemia model group. LMPP significantly enhanced the activity of HL and HSL, and increased the HSL mRNA expression in the liver tissue and adipose tissue. High-LMPP treatment significantly reduced the HMG-CoA reductase expression by 56.5% in the liver compared with hyperlipidemia model group. In contrast, LDL-R expression was increased by 120% in the presence of high-LMPP treatment. These results suggest that LMPP have the hypolipidemic effect to some extent and significantly enhance HSL mRNA expression in the liver and adipose tissue, thereby increasing HSL activity in rat.

Effects of enzymatic action on the formation of theabrownin during solid state fermentation of Pu-erh tea.

BACKGROUND: 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. RESULTS: 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. CONCLUSION: 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.

[The molecular composition and spectral properties of polysaccharide isolated from pu-erh tea and its material].

Pu-erh tea, a kind of well-known tea from the ancient time, is originally produced in the Yunnan Lanchan River basin through a special solid state fermentation by fungi. It uses sun-dried green tea as its starting materials. To investigate the variation of composition and spectral properties of polysaccharide during solid state fermentation of pu-erh tea by using Saccharomyces cerevisiae as preponderant starter and using sun-dried green tea as materials in the present study. The results showed that the content of water soluble polysaccharide was increased, and the activity of hydrolase such as cellulase, pectinase and glucomylase were also enhanced. The content of neutral sugar increased with the ferment time increasing and the M(w) of raw polysaccharide showed significant difference during fermentation. The main polysaccharide TPS2 and TPS1 were isolated and purified from pu-erh tea and its materials by DEAE-52 and Sephadex G-150 column chromatography. TPS2 contains the higher content of uronic acid, but TPS1 contains the higher contents of neutral sugar and protein. Monosaccharide analysis by GC-MS revealed that TPS1 and TPS2 were composed of arabinose, galactose, glucose, rhamnose, xylose and mannose with molar ratios of 24.2 : 23.6 : 5.9 : 3.2 : 1.8 : 1.1 and 19.3 : 26.9 : 3.2 : 2.7 : 1.3 : 5.5, respectively. The average molecular weight of TPS1 and TPS2 was 1.68 x 10(4) and 1.21 x 10(4) Daltons, respectively. UV scanning spectrum showed that TPS1 and TPS2 had no characteristic absorption between 200 and 400 nm wavelength, it suggested that they contain trace protein. IR spectrum of TPS1 and TPS2 demonstrated that pyranoid rings were contained in them. As shown in the image of atomic force microscope, the molecular appearance of TPS1 and TPS2 resembled islands and apparently consisted of conglomerations. The height of conglomerations of TPS2 was about 40 nm and the length or width was 0.5-0.8 microm, while the height of conglomerations of TPS1 was about 4nm and the length or width was 0.2-0.4 microm. TPS2 shows sheet conglomerations with rough surface, but TPS1 shows squama conglomerations with smooth surface in the image of scanning electron micrograph. The experimental data suggested that the variation of composition and spectral properties of polysaccharide isolated from pu-erh tea and its materials owed to the action of microorganism and humid and thermal action for long time process.