Large Yellow Tea Attenuates Macrophage-Related Chronic Inflammation and Metabolic Syndrome in High-Fat Diet Treated Mice

Structural characteristics and biological activity of a water-soluble polysaccharide HDCP-2 from Camellia sinensis

Large-leaf Yellow tea (LYT) is a traditional beverage from Camellia Sinensis (L.) O. Kuntze in China and has unusual health-regulating functions. This investigation explored the structural characteristics of a polysaccharide extracted from LYT, which possesses anti-inflammatory activity. The polysaccharide HDCP-2, obtained through ethanol fractional precipitation and then DEAE-52 anion exchange column, followed by DPPH radical scavenging screening, exhibited a yield of 0.19 %. The HPGPC method indicated that the molecular weight of HDCP-2 is approximately 2.9 × 104 Da. Analysis of the monosaccharide composition revealed that HDCP-2 consisted of mannose, glucose, xylose, and galacturonic acid, and their molar ratio is approximately 0.4:0.5:1.2:0.7. The structure motif of HDCP-2 was probed carefully through methylation analysis, FT-IR, and NMR analysis, which identified the presence of β-d-Xylp(1→, →2, 4)-β-d-Xylp(1→, →3)-β-d-Manp(1→, α-d-Glcp(1→ and →2, 4)-α-d-GalAp(1→ linkages. A CCK-8 kit assay was employed to evaluate the anti-inflammatory action of HDCP-2. These results demonstrated that HDCP-2 could inhibit the migration and proliferation of the MH7A cells and reduce NO production in an inflammatory model induced by TNF-α. The abundant presence of xylose accounted for 39 % of the LYT polysaccharide structure, and its distinctive linking mode (→2, 4)-β-d-Xylp(1→) appears to be the primary contributing factor to its anti-inflammatory effect.

Baltic herring hydrolysates: Identification of peptides, in silico DPP-4 prediction, and their effects on an in vivo mice model of obesity

Baltic herring is the main catch in the Baltic Sea; however, its usage could be improved due to the low processing rate. Previously we have shown that whole Baltic herring hydrolysates (BHH) and herring byproducts hydrolysates (BHBH) by commercial enzymes consisted of bioactive peptides and had moderate bioactivity in in vitro dipeptidyl peptidase (DPP)-4 assay. In this study, we identified the hydrolysate peptides by LC-MS/MS and predicted the potential bioactive DPP-4 inhibitory peptides using in silico tools. Based on abundance, peptide length and stability, 86 peptides from BHBH and 80 peptides from BHH were proposed to be novel DPP-4 inhibitory peptides. BHH was fed to a mice intervention of a high-fat, high-fructose diet to validate the bioactivity. The results of the glucose tolerance and insulin tolerance improved. Plasma DPP-4 activities, C-peptide levels, and HOMA-IR scores significantly decreased, while plasma glucagon-like peptide-1 content increased. In conclusion, BHH is an inexpensive and sustainable source of functional antidiabetic ingredients.

The Effects of Crataegus pinnatifida and Wolfiporia extensa Combination on Diet-Induced Obesity and Gut Microbiota

Obesity is a multifactorial chronic metabolic disease with multiple complications. Crataegus pinnatifida (CP) and Wolfiporia extensa (WE) are traditional functional foods with improving metabolic health properties. This study demonstrated the effect of CP and WE combination on ameliorating obesity induced by a high-fat diet (HFD). Moreover, the CP-WE food pair ameliorated HFD-induced metabolic disorders, including glucose intolerance, insulin resistance, hyperlipidemia, and hepatic steatosis. 16S rRNA gene amplicon sequencing and analysis revealed that CP combined with WE reshaped the composition of gut microbiota in HFD-fed mice. Furthermore, correlation analysis revealed a substantial association between the obesity-related parameters and the shifts in predominant bacterial genera influenced by the food pair intervention. In conclusion, this study demonstrated that the CP-WE food pair ameliorated HFD-induced obesity and reshaped gut microbiota composition, providing a promising approach to combat obesity through specific food combinations.

Study on color, aroma, and taste formation mechanism of large-leaf yellow tea during an innovative manufacturing process

This study used samples processed with an innovative manufacturing process to explore the dynamic changes of large-leaf yellow tea (LYT) in color, aroma, and taste substances, and the quality components were most significantly affected in the stages of first pile-yellowing (FP) and over-fired drying (TD). In this process, the moisture and temperature conditions caused chlorophyll degradation, Maillard reactions, caramelization reactions, and isomerization of phenolic substances, forming the quality of LYT. Specifically, chlorophyll degradation favored the formation of color quality; the taste quality was determined by the content of soluble sugars, amino acids, catechins, etc.; the aroma quality was dependent on the content changes of alcohols and aldehydes, as well as the increase of sweet and roasting aroma substances in the third drying stage. Additionally, twelve key aroma components, including linalool, (E)-β-ionone, 2,3-diethyl-5-methyl-pyrazine, etc., were identified as contributors to revealing LYT rice crust-like and sweet aroma formation mechanism.

GC-MS, GC-O, and sensomics analysis reveals the key odorants underlying the improvement of yellow tea aroma after optimized yellowing

An optimized yellowing process for yellow tea (YT) was recently developed. The study found that the optimized yellowing process caused a significant increase in sweet and floral aromas by 31.3% and 24.0%, respectively. A total of 21 aroma-active compounds were identified using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) combined with sensomics analysis. Quantification of the 15 aroma-active compounds and calculation of odor activity values (OAVs) showed that the OAVs of sweet and floral aroma compounds increased significantly by 986.2% and 46.4%, respectively, after the optimized yellowing process. Sensory-directed aroma reconstitution and omission experiments confirmed that dimethyl sulfide, 3-methylbutanal, β-ionone, β-damascenone, geraniol, phenylacetaldehyde, and linalool were the key odorants in YT after the optimized yellowing process. Odorant addition tests further demonstrated that β-damascenone (OAV 590.4) was the main odorant for YT sweet aroma enhancement, while β-ionone (OAV 884.6) was the main odorant for YT floral aroma enhancement.

Tibetan tea consumption prevents obesity by modulating the cellular composition and metabolic reprogramming of white adipose tissue

Obesity, a global health concern, is linked with numerous metabolic and inflammatory disorders. Tibetan tea, a traditional Chinese beverage rich in theabrownin, is investigated in this study for its potential anti-obesity effects. Our work demonstrates that Tibetan tea consumption in C57BL/6J mice significantly mitigates obesity-related phenotypic changes without altering energy intake. Computational prediction revealed that Tibetan tea consumption reconstructs gene expression in white adipose tissue (WAT), promoting lipid catabolism and thereby increasing energy expenditure. We also note that Tibetan tea suppresses inflammation in WAT, reducing adipocyte hyperplasia and immune cell infiltration. Furthermore, Tibetan tea induces profound metabolic reprogramming, influencing amino acid metabolic pathways, specifically enhancing glutamine synthesis, which in turn suppresses pro-inflammatory chemokine production. These findings highlight Tibetan tea as a potential candidate in obesity prevention, providing a nuanced understanding of its capacity to modulate the cellular composition and metabolic landscape of WAT.

Mechanisms underlying large-leaf yellow tea mediated inhibition of cognitive impairment in the 5xFAD model of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia and is characterized by amyloid-β (Aβ) peptides and hyperphosphorylated Tau proteins. Evidence indicates that AD and type 2 diabetes mellitus (T2DM) share pathophysiological characteristics, including impaired insulin sensitivity. Large-leaf yellow tea (LYT) has been widely recognized for its health benefits, and we previously found that LYT can improve peripheral insulin resistance.

PURPOSE

This study aimed to investigate the protective effects and underlying mechanisms of LYT in the 5xFAD mouse model of AD.

METHODS

HPLC and spectrophotometric methods determined the chemical composition of the LYT extract. 5xFAD mice were treated with LYT supplementation (2 and 4 mg/ml) in drinking water for six months. Barnes and Y mazes were used to evaluate cognitive function, and the open field test assessed anxiety-like behavior. Immunofluorescence, silver, and Nissl staining were used to evaluate the pathological effects of LYT extract. A FRET-based assay assessed β-site APP cleavage enzyme 1 (BACE1) activity, ELISA measured Aβ levels in the brain, and Western blot analyses explored protein expression levels.

RESULTS

Our results revealed that LYT significantly attenuated memory impairment and anxiety levels and alleviated cerebral neural damage. A reduction of senile plaques was also observed in both the cortex and hippocampus. LYT significantly inhibited the activity of BACE1, which resulted in a lower Aβ protein level. In addition, LYT enhanced insulin receptor substrate 1 (IRS-1)-mediated phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT), further suppressed glycogen synthase kinase-3β (GSK3β), and ultimately inhibited hyperphosphorylation of the protein Tau. The inhibitory effect of the LYT extract on the phosphorylation of Tau and BACE1 activity was dose-dependent.

CONCLUSION

LYT improves cognitive ability and reduces Aβ production by inhibiting BACE1 activity. Decreases of Tau protein hyperphosphorylation upon LYT treatment appear to be associated with the regulation of the IRS-1/PI3K/AKT/GSK3β axis. Thus, the findings of this study also provide new evidence that LYT regulates insulin signaling pathways within the central nervous system.

Large yellow tea polysaccharides ameliorate obesity-associated metabolic syndrome by promoting M2 polarization of adipose tissue macrophages

Obesity-induced metabolic syndrome is strongly associated with infiltrated adipose tissue macrophages (ATMs). Large yellow tea, a traditional functional beverage in China, has been shown to possess anti-obesity effects. However, the effect of large yellow tea polysaccharides (LYPs) against obesity-associated metabolic syndrome and their underlying mechanisms remain unclear and must be extensively investigated. In this study, we investigated the ameliorative effect of LYPs on metabolic syndrome using a high-fat diet (HFD)-induced obese mouse model. Our results indicated that LYPs significantly alleviated weight gain, dyslipidemia, glucose intolerance, and insulin resistance. Moreover, LYPs restored the homeostasis of energy metabolism and pancreatic β-cell function. Notably, LYPs promoted M2 polarization of ATMs by regulating the expression of genes and specific cytokines involved in the assembly and secretion of M2 polarization. The improved metabolic syndrome of LYPs might be associated with the modulation of macrophage polarization. These findings suggest that LYPs might be a novel potential therapeutic agent to prevent or treat HFD-induced metabolic disorders by regulating M2 polarization.

Metabolite analysis and sensory evaluation reveal the effect of roasting on the characteristic flavor of large-leaf yellow tea

Roasting is essential for processing large-leaf yellow tea (LYT). However, the effect of the roasting on the metabolic and sensory profiles of LYT remains unknown. Herein, the metabolomics and sensory quality of LYT at five roasting degrees were evaluated by liquid/gas chromatography mass spectrometry and quantitative descriptive analysis. A higher degree of roasting resulted in a significantly stronger crispy rice, fried rice, and smoky-burnt aroma (p < 0.05), which is closely associated with heterocyclic compound accumulation (concentrations: 6.47 ± 0.27 - 1065.00 ± 5.58 µg/g). Amino acids, catechins, flavonoid glycosides and N-ethyl-2-pyrrolidone-substituted flavan-3-ol varied with roasting degree. The enhancement of crispy-rice and burnt flavor coupled with the reduction of bitterness and astringency. Correlations analysis revealed the essential compounds responsible for roasting degree, including 2,3-diethyl-5-methylpyrazine, hexanal, isoleucine, N-ethyl-2-pyrrolidone-substituted flavan-3-ol (EPSF), and others. These findings provide a theoretical basis for improving the specific flavors of LYT.

Yellow tea: more than turning green leaves to yellow

Yellow tea (YT), a slightly-fermented tea originated from Ming Dynasty with distinctive "Three yellows," mild-sweet smell, and mellow taste attributed to the unique yellowing process. Based on current literature and our previous work, we aim to comprehensively illustrate the key processing procedures, characteristic chemical compounds, health benefits and applications, as well as the interlocking relationships among them. Yellowing is the most vital procedure anchored on the organoleptic quality, characteristic chemical components, and bioactivities of YT, which is influenced by temperature, moisture content, duration, and ventilation conditions. Pheophorbides, carotenoids, thearubigins and theabrownins are the major pigments contributing to the "three yellows" appearance. Alcohols, such as terpinol and nerol, are attributed to the refreshing and sweet aroma of bud and small-leaf YT, while heterocyclics and aromatics forming during roasting result in the crispy rice-like large-leaf YT. Hygrothermal effects and enzymatic reactions during yellowing result in the decline of astringent substances. Meanwhile, multiple bioactive compounds such as catechins, ellagitannins, and vitexin, endow YT with antioxidant, anti-metabolic syndrome, anti-cancer, gut microbiota regulation, and organ injury protection effects. Future studies focusing on the standard yellowing process technology, quality evaluation system, and functional factors and mechanisms, possible orientations, and perspectives are guaranteed.

Increased levels of circulating oxidized mitochondrial DNA contribute to chronic inflammation in metabolic syndrome, and MitoQ-based antioxidant therapy alleviates this DNA-induced inflammation

Here, the aim was to investigate the role of circulating oxidized mitochondrial DNA (ox-mtDNA) in metabolic syndrome (MetS)-associated chronic inflammation and evaluate the effect of Mito-Quinone (MitoQ)-based antioxidant therapy on inflammation. A total of 112 MetS patients and 111 healthy control individuals (HCs) were recruited. Peripheral blood was collected, and mononuclear cells (PBMCs) were separated. In a preclinical study, MitoQ, a mitochondrial-targeted antioxidant, was administered to Sprague-Dawley (SD) rats fed a high-fat diet (HFD). In vitro, H₂O₂- or MitoQ-treated HUVECs served as the oxidative or antioxidative cell models to detect the cell-free ox-mtDNA level. Plasma or cell-free ox-mtDNA levels were measured by qPCR. Additionally, THP-1 cells were incubated with plasma cell-free DNA (cfDNA) from MetS patients and HCs or cell-free ox-mtDNA to detect TLR9-NF-κB pathway activation. Plasma ox-mtDNA levels and TLR9 expression levels in PBMCs were increased in MetS patients. In vivo, HFD-fed rats showed elevated plasma ox-mtDNA and TLR9 expression levels in cardiac-residing immune cells, but MitoQ administration attenuated these increases. In vitro, a significant lower level of cell-free ox-mtDNA was detected in MitoQ-treated cells, compared with H₂O₂-treated cells. Coincubation of plasma cfDNA from MetS patients or cell-free ox-mtDNA and THP-1 cells increased TLR9-NF-κB p65 expression, and promoted IL-1β, IL-6 and IL-8 secretion in THP-1 cells. In conclusion, increased circulating ox-mtDNA contributes to chronic inflammation in MetS by activating the TLR9-NF-κB pathway. MitoQ-based antioxidant therapy effectively alleviates inflammation by reducing ox-mtDNA release.

Insights into the Key Odorants in Large-Leaf Yellow Tea (Camellia sinensis) by Application of the Sensomics Approach

Large-leaf yellow tea (LYT) is a yellow tea product with a specific aroma characteristic and is enjoyed with increasing enthusiasm in China. However, its key odorants are still unknown. In this study, 46 odorants in the headspace and vacuum-distillate of the tea infusion were identified via aroma extract dilution analysis. Sixteen compounds were newly found in LYT infusion. They were present in the highest flavor dilution factors together with 2-ethyl-3,5-dimethylpyrazine. All odorants were quantitated to evaluate their own odor activity values (OAVs). High OAVs were found for 2-methylbutanal (malty, 210), (E,E)-2,4-heptandienal (fatty/flowery, 170), 2-methylpropanal (malty, 120) and 2,3-diethyl-5-methylpyrazine (earthy/roasty, 110). An aroma recombinate consisting of 17 odorants (all OAVs ≥ 1) in an odorless nonvolatile LYT matrix mimicked the overall aroma of the original infusion, verifying the successful characterization of key aroma components in a LYT beverage. The knowledge of key odorants obtained showed potential for simplifying industrial flavor optimization of the LYT product.

Effect of brewing conditions on the chemical and sensory profiles of milk tea

The brewing conditions of beverage milk tea determine the taste of milk tea. This study investigated the changes in sensory characteristics and small molecule compounds in milk tea made from large-leaf yellow tea under different brewing conditions by sensory analysis, colorimeter, and LC-MS. The results show that the tea to milk ratio is the most important process affecting the taste, and the color values of b* (+yellow, - blue) can be used to evaluate the taste of milk tea made from large leaf yellow tea. The composition of small molecular compounds is affected by tea to milk ratio, which can change the taste of milk tea. l-cysteine and 8-methylsulfinyloctyl glucosinolate are significantly positively correlated with taste by metabolomics analysis. l-cysteine was used to verify the analysis results by LC-MS. The total acceptance of milk tea is improved by adding l-cysteine at a low level (0.025-0.035 mM).

Structural Characterization and Macrophage Polarization-Modulating Activity of a Novel Polysaccharide from Large Yellow Tea

A novel homogeneous polysaccharide (LYP-S3) that promotes the M2 polarization of macrophages was obtained from large yellow tea by a bioactivity-guided sequential isolation procedure and activity evaluation in the present study. Structural characterization revealed that LYP-S3 has an average molecular weight of 28.6 kDa and is composed of rhamnose, arabinose, galactose, glucose, and galacturonic acid at the molar ratio of 8.08:11.66:11.77:3.96:58.02. The main backbone of LYP-S3 consists of →4)-α-d-GalpA-6-OMe-(1→, β-d-GalpA-(1→, →4)-β-d-Galp-(→1, and →β-d-Galp-(1→, and the branches are composed of α-l-Araf-(→1, →5)-α-l-Araf-(1→, →2,4)-β-l-Rhap-(1→, →2)-β-l-Rhap-(1→, and →4)-β-d-Glcp-(1→. An in vitro bioactivity evaluation assay showed that LYP-S3 remarkably reduced the expression of M1 macrophage markers and increased the expression of M2 macrophage markers. In addition, LYP-S3 inhibited adipocyte differentiation and adipogenesis in 3T3-L1 adipocytes and blocked macrophage migration toward 3T3-L1 adipocytes in the cocultures of bone-marrow-derived monocytes and 3T3-L1 adipocytes. Furthermore, LYP-S3 promoted the M2 polarization of macrophages in cocultures. These findings suggested that LYP-S3 has a potential function in preventing inflammation and obesity.

Baicalein Prevents Fructose-Induced Hepatic Steatosis in Rats: In the Regulation of Fatty Acid De Novo Synthesis, Fatty Acid Elongation and Fatty Acid Oxidation

Non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), hepatic fibrosis and even hepatocellular carcinoma, is a liver disease worldwide without approved therapeutic drugs. Baicalein (BAL), a flavonoid compound extracted from the Traditional Chinese Medicine (TCM) Scutellariae Radix (Scutellaria baicalensis Georgi.), has been used in TCM clinical practice for thousands of years to treat liver diseases due to its "hepatoprotective effect". However, the underlying liver-protecting mechanisms remain largely unknown. Here, we found that oral administration of BAL significantly decreased excess serum levels of triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST) as well as hepatic TG in fructose-fed rats. Attenuation of the increased vacuolization and Oil Red O staining area was evident on hepatic histological examination in BAL-treated rats. Mechanistically, results of RNA-sequencing, western-blot, real-time quantitative PCR (RT-qPCR) and hepatic metabolomics analyses indicated that BAL decreased fructose-induced excessive nuclear expressions of mature sterol regulatory element-binding protein 1c (mSREBP1c) and carbohydrate response element-binding protein (ChREBP), which led to the decline of lipogenic molecules [including fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1), elongation of very long chain fatty acids 6 (ELOVL6), acetyl-CoA carboxylase (ACC)], accompanying with the alternation of hepatic fatty acids composition. Meanwhile, BAL enhanced fatty acid oxidation by activating AMPK/PGC1α signaling axis and PPARα signal pathway, which elicited high expression of carnitine palmitoyl transferase 1α (CPT1α) and Acyl-CoA oxidase 1 (ACO1) in livers of fructose-fed rats, respectively. BAL ameliorated fructose-induced hepatic steatosis, which is associated with regulating fatty acid synthesis, elongation and oxidation.

Comparison of the chemical composition and antioxidant, anti-inflammatory, α-amylase and α-glycosidase inhibitory activities of the supernatant and cream from black tea infusion

Tea cream is a kind of turbid substance commonly existing in tea infusion and tea beverage upon cooling. Herein, a comparative study was conducted on the supernatant and cream from black tea infusion in terms of antioxidant, anti-inflammatory and enzyme inhibitory activities, and chemical composition. Ultraviolet-visible (UV-vis) spectrometry and high-performance liquid chromatography (HPLC) analysis showed that the contents of protein, polyphenols, theaflavins, thearubigins, theabrownins, and caffeine in cream were significantly higher than those in the supernatant. The contents of Al, Ca, Cu, and Fe elements in cream were higher than those in the supernatant. However, higher levels of monosaccharides and free amino acids were detected in the supernatant compared with cream. The ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) based metabolomics analysis revealed that the main marker compounds between the supernatant and the cream were organic acids, phenolic acids, and flavan-3-ols and their oxidation products, flavonol glycosides and amino acids. The cream showed better antioxidant and anti-inflammatory, as well as α-amylase and α-glycosidase inhibitory activities than the supernatant, because it contained higher contents of polyphenols than the supernatant. The present study expanded the new vision towards the cream of black tea infusion.

Lactobacillus rhamnosus Strain LRH05 Intervention Ameliorated Body Weight Gain and Adipose Inflammation via Modulating the Gut Microbiota in High-Fat Diet-Induced Obese Mice

SCOPE

This study aims to investigate the underlying mechanism of a specific probiotic strain on suppression of adipogenesis and inflammatory response in white adipose tissue (WAT) of high-fat diet (HFD)-fed mice.

METHODS AND RESULTS

Eight strains are screened in vitro for candidates of potential probiotics. Lactobacillus rhamnosus LRH05 (LRH05) and Lactobacillus reuteri LR47 (LR47) are screened out with lower triglyceride expression in vitro. The mice are fed a control diet (CD), HFD, or HFD supplemented with a dose of LRH05 or LR47 at 10⁹ CFU per mouse per day for 10 weeks (n = 8), respectively. The results demonstrate that LRH05, but not LR47, significantly reduce body weight gain and the weight of WAT, as well as improve hepatic steatosis and glucose intolerance. LRH05 regulates the Mogat1, Igf-1, Mcp-1, and F4/80 mRNA expression and decreases macrophage infiltration in WAT. LRH05 shows an increase in butyric and propionic acid-producing bacteria, including Lachnoclostridium, Romboutsia, and Fusobacterium that is coincident with the increased fecal propionic acid and butyric acid levels.

CONCLUSION

LRH05 shows a strain-specific effect on ameliorating the pro-inflammatory process by reducing inflammatory macrophage infiltration and the expression of inflammation-related genes in mice. Thus, LRH05 can be considered a potential probiotic strain to prevent obesity.

Effects and mechanisms of tea on obesity

Obesity has become a global health concern. It increases the risk of several diseases, such as type 2 diabetes mellitus, nonalcoholic fatty liver disease, and certain cancers, which threatens human health and increases social economic burden. As one of the most consumed beverages, tea contains various phytochemicals with potent bioactive properties and health-promoting effects, such as antioxidant, immune-regulation, cardiovascular protection and anticancer. Tea and its components are also considered as potential candidates for anti-obesity. Epidemiological studies indicate that regular consumption of tea is beneficial for reducing body fat. In addition, the experimental studies demonstrate that the potential anti-obesity mechanisms of tea are mainly involved in increasing energy expenditure and lipid catabolism, decreasing nutrient digestion and absorption as well as lipid synthesis, and regulating adipocytes, neuroendocrine system and gut microbiota. Moreover, most of clinical studies illustrate that the intake of green tea could reduce body weight and alleviate the obesity. In this review, we focus on the effect of tea and its components on obesity from epidemiological, experimental, and clinical studies, and discuss their potential mechanisms.

Synthesis and Physicochemical Evaluation of Bees' Chitosan-Based Hydrogels Modified with Yellow Tea Extract

The novelty of the research involves designing the measurement methodology aimed at determining the structure-property relationships in the chitosan-based hydrogels containing yellow tea extract. Performed investigations allowed us to determine the swelling properties of hydrogels in selected time intervals, evaluate the mutual interactions between the hydrogels and simulated physiological liquids via pH measurements and directly assess the impact of such interactions on the chemical structure of hydrogels using Fourier transform infrared (FT-IR) spectroscopy and their wettability by the measurements of the flatness of the drop on the surface of the tested samples via the static drop method. Next, the surface morphology of hydrogels was characterized by the Scanning Electron Miscorcopy (SEM) and their elasticity under the tension applied was also verified. It was proved that incubation in simulated physiological liquids resulted in a decrease in contact angles of hydrogels, even by 60%. This also caused their certain degradation which was reflected in lower intensities of bands on FT-IR spectra. Further, 23% v/v yellow tea extract in hydrogel matrices caused the decrease of their tensile strength. An increase in the amount of the crosslinker resulted in a decrease in the sorption capacity of hydrogels wherein their modification caused greater swelling ability. In general, the investigations performed provided much information on the tested materials which may be meaningful considering their application, e.g., as dressing materials.

Ambient Ultraviolet B Signal Modulates Tea Flavor Characteristics via Shifting a Metabolic Flux in Flavonoid Biosynthesis

Tea leaves contain an extraordinarily high level of flavonoids that contribute to tea health benefits and flavor characteristics, but the regulatory mechanism of ambient ultraviolet B (UV-B) on tea flavonoid enrichment remains unclear. Here, we report that ambient UV-B modulates tea quality by inducing a metabolic flux in flavonoid biosynthesis. UV-B absence decreased bitter- and astringent-tasting flavonol glycosides (kaempferol-7-O-glucoside, myricetin-3-O-glucoside, and quercetin-7-O-glucoside) but increased non-galloylated catechins. Conversely, supplementary UV-B increased flavonols and decreased catechins in tea leaves. These responses were achieved via CsHY5, which mediates the UV-B-induced MYB12 activation and binds to the promoters of flavonoid biosynthetic genes (CsFLS, CsLARa, and CsDFRa), leading to flavonoid changes. Transcriptomic data indicated that UV-B-induced tea flavonoid regulation is responsive to multiple biotic and abiotic environmental stresses. These findings improve our understanding of light-regulated tea astringency and bitterness underlying shading effects and seasonal light changes and provide novel insights into tea cultivation management and processing.

Impact of Dietary Flavanols on Microbiota, Immunity and Inflammation in Metabolic Diseases

Flavanols are natural occurring polyphenols abundant in fruits and vegetables to which have been attributed to beneficial effects on health, and also against metabolic diseases, such as diabetes, obesity and metabolic syndrome. These positive properties have been associated to the modulation of different molecular pathways, and importantly, to the regulation of immunological reactions (pro-inflammatory cytokines, chemokines, adhesion molecules, nuclear factor-κB [NF-κB], inducible enzymes), and the activity of cells of the immune system. In addition, flavanols can modulate the composition and function of gut microbiome in a prebiotic-like manner, resulting in the positive regulation of metabolic pathways and immune responses, and reduction of low-grade chronic inflammation. Moreover, the biotransformation of flavanols by gut bacteria increases their bioavailability generating a number of metabolites with potential to affect human metabolism, including during metabolic diseases. However, the exact mechanisms by which flavanols act on the microbiota and immune system to influence health and disease remain unclear, especially in humans where these connections have been scarcely explored. This review seeks to summarize recent advances on the complex interaction of flavanols with gut microbiota, immunity and inflammation focus on metabolic diseases.

Effect of the roasting degree on flavor quality of large-leaf yellow tea

Roasting is crucial for producing large-leaf yellow tea (LYT) as it substantially affects chemical composition and sensory quality. However, the effect of roasting degree on LYT flavor quality is not clear. To investigate the effect of roasting degree on LYT flavor, the odor profiles and sensory evaluations of LYTs produced with small fire, medium fire and old fire roasting (OF) were determined. The OF was essential for the formation of LYT flavor with strong roasted, nutty, woody odors and weak fatty, fruity odors, and retaining high levels of GCG, total volatiles and heterocyclic compounds. Furthermore, the characteristic crispy-rice-like odor was only found in LYT with OF treatment and burnt flavor was missing. 2,3-Diethyl-5-methylpyrazine, trans-β-ionone with odor activity value above 1600 and 39 respectively offered roasted, floral odors, respectively in LYT. The current results provide a scientific basis for understanding the reactions that occur during the conventional production of LYT.

Yellow Tea Stimulates Thermogenesis in Mice through Heterogeneous Browning of Adipose Tissues

SCOPE

Large-leaf yellow tea (YT) exhibits interesting beneficial metabolic effects in previous studies. Here, the authors elucidated the actions of YT on thermogenesis, energy metabolism, and adipocyte metabolic conversion.

METHODS AND RESULTS

Five-week-old male C57BL/6 mice are fed low-fat diet, high-fat diet (HFD), and HFD supplemented with 0.5% or 2.5% YT. After treatment for 10 or 14 weeks, YT enhances energy expenditure, O2 consumption and CO2 production. YT strongly boosts thermogenic program in brown adipose tissue (BAT) and subcutaneous adipose tissue (SAT), while only weakly in epididymal adipose tissue (EAT). These are accompanied by higher body temperature, increased mitochondrial copy numbers, and upregulation of thermogenic genes (Ucp1, Pgc1α, etc.) and proteins. The classic brown adipocyte markers (Eva1, Zic1) are induced only in BAT, while beige adipocyte markers (Tbx1, Tmem26) are boosted only in SAT. Furthermore, subcutaneous-originated preadipocytes are induced by YT in vitro to differentiate to brown-like adipocytes - a browning effect.

CONCLUSION

Dietary YT induces adaptive thermogenesis through increasing mitochondrial biogenesis in EAT, inducing beigeing in SAT and enhancing browning in the BAT.

Ultrasound irradiation alters the spatial structure and improves the antioxidant activity of the yellow tea polysaccharide

In this study, the impact of ultrasound irradiation on the structural characteristics and antioxidant properties of yellow tea polysaccharides with different molecular weights (Mw) were investigated. Native yellow tea polysaccharide containing YTPS-3N, YTPS-5N and YTPS-7N were prepared through precipitation with ethanol at various concentrations of 30%, 50%, and 70%, respectively, and irradiated with high intensity ultrasound (20 kHz) for 55 min to yield yellow tea polysaccharide including YTPS-3U, YTPS-5U and YTPS-7U. The molecular weight (Mw) of YTPS-3N (from 37.7 to 15.1 kDa) and YTPS-5N (from 14.6 to 5.2 kDa) sharply decreased upon ultrasound irradiation, coincidentally particle size (Zavg) was also significantly reduced for YTPS-3N (40%), YTPS-5N (48%) and YTPS-7N (54%). The high-performance liquid chromatography and Fourier transform-infrared spectroscopy analysis revealed a partial degradation of native yellow tea polysaccharide treated with ultrasound, though the monosaccharide composition was not altered. Furthermore, changes in morphology and the breakdown of native yellow tea polysaccharide upon irradiation was confirmed with the circular dichroism spectrum, atomic force and scanning electron microscopy. As a consequence, irradiation of yellow tea polysaccharide increased free radical scavenging activity with YTPS-7U exhibiting the highest levels of 2, 2-diphenyl-1-picrylhydrazyl free radical, superoxide and hydroxyl radicals scavenging activity. These results suggest that the alteration of the spatial structure of yellow tea polysaccharide can enhance its antioxidant activity which is an important property for functional foods or medicines.

Exploring the Antihyperglycemic Chemical Composition and Mechanisms of Tea Using Molecular Docking

Tea, a widely consumed beverage, has long been utilized for promoting human health with a close correlation to hyperglycemia. The Tea Metabolome Database (TMDB), the most complete and comprehensive curated collection of tea compounds data containing 1271 identified small molecule compounds from the tea plant (Camellia sinensis), was established previously by our research team. More recently, our studies have found that various tea types possess an antihyperglycemic effect in mice. However, the bioactive ingredients from tea have potential antihyperglycemic activity and their underlying molecular mechanisms remain unclear. In this study, we used a molecular docking approach to investigate the potential interactions between a selected 747 constituents contained in tea and 11 key protein targets of clinical antihyperglycemic drugs. According to our results, the main antihyperglycemic targets of tea composition were consistent with those of the drug rosiglitazone. The screening results showed that GCG, ECG3'Me, TMDB-01443, and CG had great target binding capacity. The results indicated that these chemicals of tea might affect hyperglycemia by acting on protein targets of rosiglitazone.

Modeling Diet-Induced Metabolic Syndrome in Rodents

Standardized animal models represent one of the most valuable tools available to understand the mechanism underlying the metabolic syndrome (MetS) and to seek for new therapeutic strategies. However, there is considerable variability in the studies conducted with this essential purpose. This review presents an updated discussion of the most recent studies using diverse experimental conditions to induce MetS in rodents with unbalanced diets, discusses the key findings in metabolic outcomes, and critically evaluates what we have been learned from them and how to advance in the field. The study includes scientific reports sourced from the Web of Science and PubMed databases, published between January 2013 and June 2020, which used hypercaloric diets to induce metabolic disorders, and address the impact of the diet on metabolic parameters. The collected data are used as support to discuss variables such as sex, species, and age of the animals, the most favorable type of diet, and the ideal diet length to generate metabolic changes. The experimental characteristics propose herein improve the performance of a preclinical model that resembles the human MetS and will guide researchers to investigate new therapeutic alternatives with confidence and higher translational validity.

Fermented mulberry (Morus alba) leaves suppress high fat diet-induced hepatic steatosis through amelioration of the inflammatory response and autophagy pathway

BACKGROUND

A novel extract of mulberry leaves fermented with Cordyceps militaris (EMfC) is reported to exert anti-obesity activity, although their molecular mechanism during hepatic steatosis has not verified.

METHODS

To investigate the role of inflammation and autophagy during the anti-hepatic steatosis effects of EMfC, we measured alterations in the key parameters for inflammatory response and autophagy pathway in liver tissues of the high fat diet (HFD) treated C57BL/6N mice after exposure to EMfC for 12 weeks.

RESULTS

Significant anti-hepatic steatosis effects, including decreased number of lipid droplets and expression of Klf2 mRNA, were detected in the liver of the HFD + EMfC treated group. The levels of mast cell infiltration, expression of two inflammatory mediators (iNOS and COX-2), and the MAPK signaling pathway were remarkably decreased in the liver of HFD + EMfC treated group as compared to the HFD + Vehicle treated group. Furthermore, a similar inhibitory effect was measured for the expression levels of pro-inflammatory cytokines, including IL-1β, IL-6, TNF-α and NF-κB. The expression level of members in the AKT/mTOR signaling pathway (a central regulator in autophagy) was recovered after treatment with EMfC, and autophagy-related proteins (Beclin and LC3-II) were remarkably decreased in the HFD + EMfC treated group compared to the HFD + Vehicle treated group. Moreover, the HFD + EMfC treated group showed decreased transcript levels of autophagy-regulated genes including Atg4b, Atg5, Atg7 and Atg12.

CONCLUSIONS

Taken together, findings of the present study provide novel evidences that the anti-hepatic steatosis of EMfC is tightly linked to the regulation of the inflammatory response and autophagy pathway in the liver tissue of HFD-induced obesity mice.

Mixtures of Tea and Citrus maxima (pomelo) Alleviate Lipid Deposition in HepG2 Cells Through the AMPK/ACC Signaling Pathway

Tea and citrus maxima are natural, medicinal homologous plants, typically used for making beverages, which have anticancer, antiobesity, and antioxidation properties. Green tea, yellow tea, and black tea were combined with citrus maxima to obtain green tea and Citrus maxima (GTCM), yellow tea and Citrus maxima (YTCM), and black tea and Citrus maxima (BTCM). The biochemical components of these mixtures were analyzed, and their possible effects and mechanisms on relieving liver lipid deposition were explored. The tea polyphenols, free amino acids, phenolamine ratio, and caffeine were comparable in YTCM and GTCM, being significantly higher than those in BTCM. In addition, the content of esterified catechins, nonesterified catechins, and total catechins in YTCM was significantly higher than those in GTCM and BTCM. All three mixtures of Citrus maxima tea significantly reduced lipid deposition in HepG2 cells, with GTCM and YTCM being slightly more effective than BTCM. Regarding the possible mechanism, Western blot analysis revealed that the three Citrus maxima tea mixtures could activate the AMPK/ACC signaling pathway, upregulate the expression of p-AMPK, p-ACC, and CPT-1 proteins, and downregulate the expression of SREBP1c and fatty acid synthase proteins to inhibit fat synthesis, thereby relieving lipid deposition in liver cells. In conclusion, as a novel and healthy beverage, Citrus maxima tea has the potential to alleviate liver lipid deposition, and further could be responsible for obesity treatment.

Secoisolariciresinol diglucoside alleviates hepatic lipid metabolic misalignment involving the endoplasmic reticulum-mitochondrial axis

Secoisolariciresinol diglucoside (SDG) has positive effects on obesity and its complications. We investigated the effects and mechanism of SDG on high-fat and high-fructose diet (HFFD)-induced hepatic lipid metabolic disorders. Supplementation with 40 mg kg^-1 d^-1 SDG for 12 weeks significantly reduced the body weight and the ratio of liver and adipose tissue to body weight in HFFD-fed mice. Serum and hepatic TG, TC, HDL-C, and LDL-C levels became normalized, and hepatic lipid metabolic disorders lessened because of the downregulation of lipid synthesis genes and upregulation of lipid oxidation genes. SDG also alleviated endoplasmic reticulum (ER) stress and mitochondrial dysfunction by regulating the ER stress factors Bip, IRE1α, Xbp1, Atf6, Perk, and Chop and mitochondrial function-related genes Cox5b, Cox7a1, Cox8b, and Cycs. Results with HepG2 cells confirmed that SDG regulated lipid metabolic disorders by the ER stress-Ca²⁺-mitochondrial-associated pathway. Our study provides a strategy for the treatment of obesity and its related comorbidities.

The Pharmacological Activity of Camellia sinensis (‎L.‎) ‎Kuntze‎ on Metabolic and Endocrine Disorders: A Systematic Review

Tea made from Camellia sinensis leaves is one of the most consumed beverages worldwide. This systematic review aims to update Camellia sinensis pharmacological activity on metabolic and endocrine disorders. Inclusion criteria were preclinical and clinical studies of tea extracts and isolated compounds on osteoporosis, hypertension, diabetes, metabolic syndrome, hypercholesterolemia, and obesity written in English between 2014 and 2019 and published in Pubmed, Science Direct, and Scopus. From a total of 1384 studies, 80 reports met inclusion criteria. Most papers were published in 2015 (29.3%) and 2017 (20.6%), conducted in China (28.75%), US (12.5%), and South Korea (10%) and carried out with extracts (67.5%, especially green tea) and isolated compounds (41.25%, especially epigallocatechin gallate). Most pharmacological studies were in vitro and in vivo studies focused on diabetes and obesity. Clinical trials, although they have demonstrated promising results, are very limited. Future research should be aimed at providing more clinical evidence on less studied pathologies such as osteoporosis, hypertension, and metabolic syndrome. Given the close relationship among all endocrine disorders, it would be of interest to find a standard dose of tea or their bioactive constituents that would be beneficial for all of them.

Modulation of Glucose Metabolism by Leaf Tea Constituents: A Systematic Review of Recent Clinical and Pre-clinical Findings

Leaf teas are widely used as a purported treatment for dysregulated glucose homeostasis. The objective of this study was to systematically evaluate the clinical and cellular-metabolic evidence, published between January 2013 and May 2019, and indexed on PubMed, ScienceDirect, and Web of Science, supporting the use of leaf teas for this purpose. Fourteen randomized controlled trials (RCTs) (13 on Camellia sinensis teas) were included, with mixed results, and providing scant mechanistic information. In contrast, 74 animal and cell culture studies focusing on the pancreas, liver, muscle, and adipose tissue yielded mostly positive results and highlighted enhanced insulin signaling as a recurring target associated with the effects of teas on glucose metabolism. We conclude that more studies, including RCTs and pre-clinical studies examining teas from a wider variety of species beyond C. sinensis, are required to establish a stronger evidence base on the use of leaf teas to normalize glucose metabolism.

High Dietary Kuding Tea Extract Supplementation Induces Hepatic Xenobiotic-Metabolizing Enzymes-A 6-Week Feeding Study in Mice

Kuding tea (KT) is a traditional Chinese beverage rich in plant bioactives that may exhibit various health benefits. However, little is known about the safety of KT extract (KTE) when consumed long term at high doses as a dietary supplement. Therefore, in this study, we investigated aspects of the safety of KTE. Male C57BL/6 mice were fed a high-fat, high-fructose, Western-type diet (control) supplemented with either 12.88% γ-cyclodextrin (γCD), 7.12% KTE (comprising 0.15% ursolic acid, UA) encapsulated in 12.88% γCD (KTE-γCD), or 0.15% UA over a 6-week experimental period. The dietary treatments did not affect food intake, body weight or body composition. However, treatment with KTE-γCD, but not γCD and UA, increased liver weight and hepatic fat accumulation, which was accompanied by increased hepatic PPARγ and CD36 mRNA levels. KTE-γCD treatment elevated plasma cholesterol and CYP7A1 mRNA and protein levels compared to those in control mice. KTE-γCD substantially increased the mRNA and protein levels of hepatic CYP3A and GSTA1, which are central to the detoxification of drugs and xenobiotics. Furthermore, we observed a moderate elevation in hepatic CYP3A (5-fold change) and GSTA1 (1.7-fold change) mRNA levels in UA-fed mice. In vitro data collected in HepG2 cells indicated a dose-dependent increase in hepatic cytotoxicity in response to KTE treatment, which may have been partly mediated by UA. Overall, the present data may contribute to the safety assessment of KTE and suggest that KTE encapsulated in γCD affects liver fat storage and the hepatic phase I and phase II responses in mice.

Fuzhuan Brick Tea Attenuates High-Fat Diet-Induced Obesity and Associated Metabolic Disorders by Shaping Gut Microbiota

An increasing amount of evidence suggests that the metabolic improvement of high-fat diet (HFD)-induced obese mice by Fuzhuan brick tea (FBT) is associated with gut microbiota. However, the causalities between FBT and gut microbiota have not yet been elucidated and the underlying mechanisms of action remain unclear. To impart direct evidence for the essential role of gut microbiota in the attenuation of obesity by FBT, the effects of FBT on healthy mice and microbiota-depleted mice that were treated with antibiotics were compared in an HFD-induced obesity mouse model. The results showed that FBT dramatically ameliorated obesity, serum lipid parameters, blood glucose homeostasis, hepatic steatosis, adipocyte hypertrophy, and tissue inflammation. However, the microbiota-depleted mice with single bacterium (Escherichia-Shigella) after antibiotic treatment were resistant to FBT-induced antiobesity and metabolic improvement. The beneficial effects of FBT resulted from its shift on gut microbiota composition and structure in mice. HFD-induced increase in the phyla Firmicutes/Bacteroidetes (F/B) ratio was remarkably restored by FBT. Furthermore, FBT-induced increase in abundances of beneficial bacteria Clostridiaceae, Bacteroidales, and Lachnospiraceae and decreases in harmful Ruminococcaceae, Peptococcaceae, Peptostreptococcaceae, and Erysipelotrichaceae were causal antecedents for FBT to reduce obesity and improve metabolic disorders.

Effects and Mechanisms of Tea for the Prevention and Management of Diabetes Mellitus and Diabetic Complications: An Updated Review

Diabetes mellitus has become a serious and growing public health concern. It has high morbidity and mortality because of its complications, such as diabetic nephropathy, diabetic cardiovascular complication, diabetic neuropathy, diabetic retinopathy, and diabetic hepatopathy. Epidemiological studies revealed that the consumption of tea was inversely associated with the risk of diabetes mellitus and its complications. Experimental studies demonstrated that tea had protective effects against diabetes mellitus and its complications via several possible mechanisms, including enhancing insulin action, ameliorating insulin resistance, activating insulin signaling pathway, protecting islet β-cells, scavenging free radicals, and decreasing inflammation. Moreover, clinical trials also confirmed that tea intervention is effective in patients with diabetes mellitus and its complications. Therefore, in order to highlight the importance of tea in the prevention and management of diabetes mellitus and its complications, this article summarizes and discusses the effects of tea against diabetes mellitus and its complications based on the findings from epidemiological, experimental, and clinical studies, with the special attention paid to the mechanisms of action.

LC-MS-Based Metabolomics Reveals the Chemical Changes of Polyphenols during High-Temperature Roasting of Large-Leaf Yellow Tea

Large-leaf yellow tea (LYT) is made from mature tea leaves with stems and has unique sensory characteristics different from other teas. To study the chemical changes of LYT during processing, samples were collected from each step for quantitative and qualitative analyses by high-performance liquid chromatography and liquid chromatography-mass spectrometry (LC-MS). LC-MS-based nontargeted and targeted metabolomics analyses revealed that the tea sample after roasting was markedly different from samples before roasting, with the levels of epicatechins and free amino acids significantly decreased, but the epimerized catechins increased dramatically. After accounting for common compounds in tea, N-ethyl-2-pyrrolidinone-substituted flavan-3-ols were found to be the marker compounds responsible for the classification of all samples, as they rapidly rose with increasing processing temperature. These findings suggested that the predominant changes in the tea constituents during large-leaf yellow tea roasting were the thermally induced degradation and epimerization of catechins and the formation of N-ethyl-2-pyrrolidinone-substituted flavan-3-ols from l-theanine.

Roasting improves the hypoglycemic effects of a large-leaf yellow tea infusion by enhancing the levels of epimerized catechins that inhibit α-glucosidase

Teas contain bioactive polyphenols, such as (-)-epigallocatechin gallate (EGCG), which is not stable during the processing of tea. EGCG can be epimerized into (-)-gallocatechin gallate (GCG), which is present in very small amounts in fresh tea leaves. An infusion made from roasted large-leaf yellow tea inhibited α-glucosidase more significantly than an infusion of unroasted yellow tea, with IC50 values of 76.08 ± 8.96 and 170.17 ± 33.00 μg mL-1, respectively. After roasting, the content of GCG showed about a 5-fold increase, while EGCG showed a decrease of 56.6%. Of the two main α-glucosidase inhibitors, GCG exhibited a higher inhibitory effect on α-glucosidase than its corresponding epimer (EGCG), whose IC50 value was about 3-fold lower. Modeling of molecular docking suggested that GCG preferably binds to the target α-glucosidase protein; this was confirmed by in vitro protein-polyphenol binding, where GCG had a binding rate about 4 times higher than that of EGCG. Comparative in vivo studies using oral starch tolerance tests in mice verified that GCG exhibited lower postprandial blood glucose compared to EGCG. These results suggest that roasting is a simple and effective way to increase the capacity of large-leaf yellow tea to regulate postprandial blood glucose.