Daxiang Li

Ancha tea (AT) is a type of dark tea processed through dew wetting. This study compared green tea (GT), black tea (BT), and AT, all derived from the same tea cultivar, to examine how processing methods influence chemical composition and health-promoting function. Nontargeted and targeted metabolomics revealed distinct chemical profiles among the three teas. In vitro fermentation with gut microbiota showed that all teas promoted beneficial bacteria, particularly Lactobacillus, while suppressing harmful genera, such as Escherichia-Shigella. All teas also enhanced the production of short-chain fatty acids (SCFAs). Among them, AT exhibited the most pronounced effects, including broader suppression of pro-inflammatory taxa and the highest SCFAs levels. Furthermore, in vivo experiments confirmed that all tea types consistently promoted Lactobacillus species, particularly Lactobacillus acidophilus and Lactobacillus vaginalis. These findings highlight the pivotal role of tea processing in shaping bioactive compound profiles and gut microbiota-modulating potential, with AT demonstrating superior functional properties.

Background: The gut microbiota and its metabolite short-chain fatty acids (SCFAs) regulate host physiology, but whether butyrate, a key SCFA, protects against myocardial injury via the gut–heart axis remains unclear. Objectives: This study aimed to investigate the cardioprotective effect of butyrate in a rat model of isoproterenol (ISO)-induced myocardial injury and to explore its underlying gut–heart mechanism. Methods: In this experimental study, male Sprague-Dawley rats received intragastric butyrate pre-treatment followed by ISO injection to induce myocardial injury. Cardiac function, myocardial remodeling, gut–heart homeostasis, intestinal barrier integrity, and the expression of Tas2r, GPR41/43, and NLRP3 pyroptosis pathway components were assessed. Results: Butyrate pre-treatment significantly restored cardiac function (LVEF increased by 19.67 units; 95% CI, 11.17–28.16; p < 0.001) and ameliorated electrophysiological abnormalities (QTc shortened by 63.21 ms; 95% CI, 45.45–80.97; p < 0.0001). Mechanistically, butyrate suppressed aberrant myocardial Tas2r signaling (Tas2r137 reduced by 1.06 units; 95% CI, 0.37–1.74; p < 0.01), upregulated GPR41/43, inhibited NLRP3 inflammasome activation (NLRP3 reduced by 1.23 units; 95% CI, 0.13–2.33; p < 0.05), and repaired intestinal barrier integrity, thereby reducing bacterial translocation and secondary injury. Conclusions: Butyrate ameliorates ISO-induced myocardial injury through a simultaneous gut–heart mechanism, acting on both the cardiac Tas2r137/GPR41/43-NLRP3 pathway and intestinal barrier protection. These findings identify butyrate as a key functional molecule in gut–heart crosstalk and suggest its potential as a therapeutic agent for myocardial injury.

Background: Obesity is a chronic metabolic disease that has emerged as a major global public health concern. Obesity complications refer to a range of metabolic, neurological and behavioral disorders. Complex interaction mechanisms exist between obesity and the brain, including neuroendocrine regulation, center inflammatory responses, the gut–brain axis, and obesity-related cognitive impairment. Polyphenols are naturally occurring bioactive compounds widely found in plants. Recent research indicates that polyphenols may modulate the brain through multiple pathways, thereby ameliorating obesity complications. However, no data set available to summarize neuroregulatory effects of dietary polyphenols on obesity complication. Methods: The latest data available were collected to review research progress focusing on neuroregulatory roles of polyphenols on obesity complication. Results: This review summarizes the interaction between obesity and the brain and further explores the effects of polyphenols on obesity-related neurological disorders, with particular emphasis on their roles in appetite regulation, central neuroinflammation, brain leptin and insulin resistance, gut–brain axis modulation, and cognitive improvement. Finally, future perspectives are discussed. Conclusions: This paper may provide a new theoretical support and research direction for the potential of polyphenols against obesity-related neurological complications.

Tea offers health benefits, but some teas accumulate high fluoride (F), posing fluorosis risks. However, the roles of individual tea components in regulating F bioavailability remain unclear. This study investigated the effects of major tea constituents on F metabolism in male rats (n = 5/group) administered F (40 mg/L) alone or with graded doses of epigallocatechin gallate (EGCG, 150–450 mg/kg); theaflavins, thearubigins, and theabrownin (TFs, TRs, TB, 200–800 mg/kg each); tea polysaccharides (TPSs, 25–250 mg/kg); and calcium and aluminum (Ca, Al, 800–3200 µg/kg each) via gavage. Pharmacokinetic analysis of plasma F (0–480 min) and fecal F excretion were assessed. The result showed that high-dose EGCG (450 mg/kg) reduced C_max by 61.76% and total exposure (AUC_0–t) by 37.48% compared to the control, while significantly increasing fecal F by 26.79% (p < 0.05). TB (800 mg/kg) delayed F absorption by prolonging T_max from 18 to 30 min and reduced C_max by 35.38% (p < 0.05). TPS (250 mg/kg) decreased C_max by 51.72% and AUC_0–t by 24.38% (p < 0.05). Ca and Al (800–3200 µg/kg) reduced C_max by 39.19–69.62%, and low-dose aluminum (800 µg/kg) increased fecal F by 35.58% (p < 0.05). These findings elucidate distinct roles of tea constituents in mitigating F bioavailability, providing a scientific basis for tea safety assessment and dietary interventions against F overexposure.

Depression has emerged as a major global public health issue. l-theanine exerts notable anxiolytic and antidepressant effects mediated by its blood-brain barrier permeability as well as its anti-inflammatory and antioxidant properties. Nevertheless, the underlying mechanism of its key role remains elusive. In this study, chronic unpredictable mild stress (CUMS) reduced serum neurotransmitter levels in mice, impaired prefrontal cortex (PFC) and colonic barrier function, which induced depressive-like behaviors. l-theanine, especially at a dose of 800 mg/kg, down-regulated gut-brain inflammatory pathways (TLR9/NLRP3/Caspase-1) and restored barrier integrity (ZO-1 and Occludin), reversing CUMS-induced depressive-like behavior. This therapeutic effect was primarily attributed to l-theanine-mediated reshaping of gut microbiota (increased of Lactobacillus and Roseburia) and the restoration of short-chain fatty acids (SCFAs, especially acetic acid, butyric acid, and propionic acid) synthesis and their receptor functions. In summary, the Gut-SCFAs-Brain axis may serve as a potential pathway for l-theanine to improve depression.

Currently, cultivated tea plants are classified into three varieties, namely, C. sinensis var. sinensis, C. sinensis var. assamica, and C. sinensis var. kucha. Three tea varieties made green teas (TVGTs) are widely consumed worldwide. However, a comparative investigation of the beneficial effects, mechanism, and characteristic compounds of TVGTs has not been reported. Here, three representative tea plant varieties, namely, C. sinensis var. sinensis cv. Fuding (FD), C. sinensis var. assamica cv. Yunkang 10 (YK), and C. sinensis var. kucha (KC), planted in the same garden, were used to make green teas utilizing the same standard procedure. Our findings show that the TVGTs effectively improved hyperglycemia, obesity, dyslipidemia, fatty liver, and mesenteric artery (MA) hypercontractility in mice with diabetes and obesity induced by a high-fat diet (HFD) after 11- and 22-week interventions, with YK being the most effective at 22 weeks. Liver lipidomics indicated that the TVGTs restored the glycerophospholipid and sphingolipid balance and reduced triglycerides, with YK demonstrating superior effects. The TVGTs, particularly YK, suppressed triglyceride synthesis through the ARV1-FXR-SHP-SREBP-1c pathway. A chemical profile analysis revealed that YK green tea had enriched active compounds, including caffeine, quinic acid, L-theanine, gallic acid, and catechins, compared with FD and KC green teas, which may contribute to ameliorating diabetic dyslipidemia via synergistic action. As a representative tea variety of C. sinensis var. assamica, YK green tea was found to be superior to the other two green teas in preventing and treating diabetic dyslipidemia, especially with long-term consumption. These data provide important information for tea plant breeders and tea consumers.

Brick tea is a type of post-fermented food that involves microorganisms. Long-term consumption of brick tea exposes consumers to high fluoride levels, which can adversely affect their health. This study explored the feasibility of selective defluorination of Qingzhuan brick tea through membrane separation technology, and pilot production was conducted to produce defluorinated instant brick tea. The concentration of tea polyphenols increased by more than 10 times after nanofiltration, demonstrating the high selectivity of nanofiltration membranes toward fluoride. Defluorination trends were studied at different initial material concentrations (0.5–4%) and operating pressures (0.1–0.5 MPa) under cyclic defluorination. Defluorinated instant brick tea products were also industrially prepared using 300- (DF-300) and 1000-Da (DF-1000) membranes, followed by vacuum freeze-drying. The DF-1000 and DF-300 products exhibited a defluorination rate of 51.46% and 67.96%, respectively. The products have excellent characteristics in terms of color, aroma, and flavor quality, as well as solubility. Gas chromatography–mass spectrometry indicated that the volatile components in the defluorinated instant brick tea were slightly different from those in the original tea, but the key aroma and flavor characteristics of the defluorinated brick tea remained unchanged. Membrane separation provides technical support for the large-scale production of low-fluoride post-fermented tea.

Tea polyphenols have been shown to prevent cardiovascular disease through antioxidant and anti-inflammatory mechanisms. Theogallin, a phenolic acid derived from gallic and quinic acids, is a unique polyphenolic compound found in teas. Its preventive effect on myocardial ischemia-reperfusion (I/R) injury remains unclear. This study utilized an ex vivo model of I/R injury in isolated rat hearts through Langendorff perfusion and an in vivo myocardial injury model through left anterior descending coronary artery (LAD) ligation. In isolated hearts, theogallin pretreatment at both 100 and 200 ng/mL significantly improved hemodynamic parameters following I/R injury. Additionally, in vivo, pretreatment with 20 mg/kg theogallin in LAD ligation rats for 7 days significantly enhanced myocardial contractile function, reduced the release of myocardial enzymes, and decreased infarct size and fibrosis in LAD ligation rats. These protective effects may be attributed to theogallin's ability to inhibit the expression of interleukin-17 (IL-17) receptor A, transcription factor Jun-B (JUNB), Fos-related antigen 1 (FRA1), and matrix metalloproteinase 9 (MMP9) in the IL-17 signaling pathway. These findings suggest that theogallin exerts cardioprotective effects by downregulating the IL-17 signaling pathway in rats with myocardial I/R injury.