Revealing the variances in color formation and bioactivities of seven catechin monomers throughout the enzymatic reaction by colorimetric and mass spectrometry.

The capacity differences of seven catechin monomers to produce colors after treating with catechin-free extract were investigated. After 240-min reaction, only (-)-epicatechin (EC) and (+)-catechin (C) presented obvious luminous red color with L* values of 63.32-71.73, a* values of 37.13-46.44, and b* values of 65.64-69.99. Meanwhile, the decrease rate of EC and C was 43.52 %-50.35 %, which were significantly lower than those of other catechin monomers (85.91 %-100 %). The oxidized products of catechin monomers were analyzed by ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry coupled with diode array detector, wherein dehydro-dimers and -trimers (oxidative coupling products of catechins' A-B ring) were found to be the major chromogenic compounds of EC and C. Additionally, the antioxidant capacity of catechin monomers only decreased after 30-min reaction, while along with further enzymatic reaction, catechin monomers presented comparable oxyradical scavenging ability (e.g., the DPPH inhibitory rates of catechin monomers were in the range of 24.42 %-50.77 %) to vitamin C (positive control, DPPH inhibitory rate was 27.66 %). Meanwhile, the inhibitory effects of most catechin monomers on α-glucosidase were enhanced in different degrees. These results provided basis for the development of enzymatically-oxidized catechin monomers as functional food color additives.

Exploring core functional fungi driving the metabolic conversion in the industrial pile fermentation of Qingzhuan tea.

The distinct sensory quality of Qingzhuan tea is mainly formed in pile fermentation by a group of functional microorganisms but the core functional ones was poorly characterized. Therefore, this study investigated the dynamic changes in the fungal community and metabolic profile by integrating microbiomics and metabolomics, and explored the core functional fungi driving the metabolic conversion in the industrial pile fermentation of Qingzhuan tea. Indicated by microbiomics analysis, Aspergillus dominated the entire pile-fermentation process, while Thermoascus, Rasamsonia, and Cylindrium successively abounded in the different stages of the pile fermentation. A total of 50 differentially changed metabolites were identified, with the hydrolysis of galloyl/polymeric catechins, biosynthesis of theabrownins, oxidation of catechins, N-ethyl-2-pyrrolidinone substitution of catechins, and deglycosylation of flavonoid glucosides. Nine fungal genera were identified as core functional fungi, in which Aspergillus linked to the hydrolysis of polymeric catechins and insoluble polysaccharides as well as biosynthesis of theabrownins, while Thermoascus participated in the biosynthesis of theabrownins, deglycosylation of flavonoid glucosides, and N-ethyl-2-pyrrolidinone substitution of catechins. These findings would advance our understanding of the quality formation of Qingzhuan tea and provide a benchmark for precise inoculation for its quality improvement.

Effects of foliar selenium application on Se accumulation, elements uptake, nutrition quality, sensory quality and antioxidant response in summer-autumn tea.

Summer-autumn tea is characterized by high polyphenol content and low amino acid content, resulting in bitter and astringent teast. However, these qualities often lead to low economic benefits, ultimately resulting in a wastage of tea resources. The study focused on evaluating the effects of foliar spraying of glucosamine selenium (GLN-Se) on summer-autumn tea. This foliar fertilizer was applied to tea leaves to assess its impact on plant development, nutritional quality, elemental uptake, organoleptic quality, and antioxidant responses. The results revealed that GlcN-Se enhanced photosynthesis and yield by improving the antioxidant system. Additionally, the concentration of GlcN-Se positively correlated with the total and organic selenium contents in tea. The foliar application of GlcN-Se reduced toxic heavy metal content and increased the levels of macronutrients and micronutrients, which facilitated adaptation to environmental changes and abiotic stresses. Furthermore, GlcN-Se significantly improved both non-volatile and volatile components of tea leaves, resulting in a sweet aftertaste and nectar aroma in the tea soup. To conclude, the accurate and rational application of exogenous GlcN-Se can effectively enhance the selenium content and biochemical status of tea. This improvement leads to enhanced nutritional quality and sensory characteristics, making it highly significant for the tea industry.

A target-triggered ultra-sensitive aptasensor for simultaneous detection of Cd2+ and Hg2+ using MWCNTs-Au NPs modified electrode.

A sensitive electrochemical assay for simultaneously detecting cadmium ion (Cd2+) and mercury ion (Hg2+) with the aptamer as recognition unit was established, in which methylene blue (MB) and target-triggered in-situ generated Ag nanoclusters (Ag NCs) were identified as signal reporters. Multi-walled carbon nanotubes and gold nanoparticles composites were prepared with polyethyleneimine to amplify electrical signals of screen-printed electrodes. Due to the particular base sequences, MB labeled Cd2+ aptamer paired with ssDNA through T-Hg-T structure with Hg2+. Notably, the C-rich structure in ssDNA acted as a template for the generation of Ag NCs, which could induce differential pulse voltammetry signals corresponding to Hg2+ concentrations. This electrochemical aptasensor exhibited detection limits of 94.01 pg/mL and 15.74 pg/mL for Cd2+ and Hg2+, respectively. The developed aptasensor allowed for practical application to tea and vegetable samples with satisfactory accuracy. This work possesses potential in developing biosensing technologies for simultaneous determination of multiple heavy metals.

Preparation, Characterization, and Antioxidant Properties of Selenium-Enriched Tea Peptides.

The research on the activity of selenium (Se)-enriched agricultural products is receiving increasing attention since Se was recognized for its antioxidant activities and for its enhancement of immunity in trace elements. In this study, antioxidant Se-containing peptides, namely, Se-TAPepI-1 and Se-TAPepI-2, were optimally separated and prepared from Se-enriched tea protein hydrolysates by ultrafiltration and Sephadex G-25 purification, and subsequently, their physicochemical properties, oligopeptide sequence, and potential antioxidant mechanism were analyzed. Through the optimization of enzymatic hydrolysis conditions, the Se-enriched tea protein hydrolyzed by papain exhibited a better free radical scavenging activity. After separation and purification of hydrolysates, the two peptide fractions obtained showed significant differences in selenium content, amino acid composition, apparent morphology, peptide sequence, and free radical scavenging activity. Therein, two peptides from Se-TAPepI-1 included LPMFG (563.27 Da) and YPQSFIR (909.47 Da), and three peptides from Se-TAPepI-2 included GVNVPYK (775.42 Da), KGGPGG (552.24 Da), and GDEPPIVK (853.45 Da). Se-TAPepI-1 and Se-TAPepI-2 could ameliorate the cell peroxidation damage and inflammation by regulating NRF2/ARE pathway expression. Comparably, Se-TAPepI-1 showed a better regulatory effect than Se-TAPepI-2 due to their higher Se content, typical amino acid composition and sequence, higher surface roughness, and a looser arrangement in their apparent morphology. These results expanded the functional activities of tea peptide and provided the theoretical basis for the development of Se-containing peptides from Se-enriched tea as a potential natural source of antioxidant dietary supplements.

Effective chloride ion resistance of aluminum powder through interface electric field designing.

Pure aluminium (Al) powder is widely used in aerospace fields as fuel while its corrosion mechanisms and anti-corrosion strategies are not thoroughly studied. Herein, corrosion mechanisms of Al nanoparticles are revealed by density functional theory (DFT) and experiments. Moreover, by utilizing the behaviour of ions moving in the electric field, an interfacial electric field is designed to endow spherical aluminium powder (sAl) with high anti-corrosion for chloride ions (Cl-). Because TiO2 presents lower electrostatic potential than Al2O3 which is on the surface of sAl, the prepared core@shell structural material (sAl@TiO2) holds an interfacial electric field and its direction is from TiO2 to Al2O3. The electric field repels the Cl- adsorption on the surface of sAl@TiO2, bringing about superior Cl- anti-corrosion.

Amelioration Effects and Regulatory Mechanisms of Different Tea Active Ingredients on DSS-Induced Colitis.

The potential biological function of tea and its active components on colitis has attracted wide attention. In this study, different tea active ingredients including tea polyphenols (TPPs), tea polysaccharides (TPSs), theabrownin (TB), and theanine (TA) have been compared in the intervention of dextran sulfate sodium (DSS)-induced colitis in mice. Specifically, TPP showed the greatest effect on colitis since it reduced 60.87% of disease activity index (DAI) compared to that of the DSS-induced colitis group, followed by the reduction of 39.13% of TPS and 28.26% of TB on DAI, whereas there was no obvious alleviative effect of TA on colitis. TPP, TPS, and TB could regulate the composition and abundance of gut microbiota to increase the content of short-chain fatty acids (SCFAs) and enhance intestinal barrier function. Further evidence was observed that TPP and TPS regulated the activation of Nrf2/ARE and the TLR4/MyD88/NF-κB P65 pathway to alleviate the colitis. Results of cell experiments demonstrated that TPP showed the greatest antiapoptosis and mitochondrial function protective capability among the tea ingredients via inhibiting the Cytc/Cleaved-caspase-3 signaling pathway. In summary, the superior anticolitis activity of TPP compared to TPS and TB is primarily attributed to its unique upregulation of the abundance of Akkermansia and its ability to regulate the mitochondrial function.

Ultrasensitive Fluorescence Platform Based on AgNPs In Situ-Incorporated Zr-MOFs for the Detection of Organophosphorus Pesticides.

Organophosphorus pesticides (OPPs) are extensively used in agricultural production, and the contamination caused by their residues has raised significant concerns regarding potential threats to human health. Herein, a novel fluorescence nanoprobe based on an enzyme-mediated silver nanoparticle-modified metal organic framework (AgNPs@PCN-224) was successfully prepared for the rapid detection of OPPs. Initially, AgNPs@PCN-224 were synthesized by reducing silver nitrate (AgNO3) using sodium borohydride (NaBH4) embedded into luminescent PCN-224. This triggered the inner filter effect, leading to fluorescence quenching. Meanwhile, under the catalysis of acetylcholinesterase (AChE) and choline oxidase (CHO), acetylcholine (ATCh) was decomposed to hydrogen peroxide (H2O2), which could destroy AgNPs to form Ag+ released from PCN-224 for fluorescence recovery. Instead, fenitrothion, an OPP, inhibited AChE activity, allowing the quenched fluorescence to be reactivated. Under the current optimum conditions, the fluorescence intensity had a good correlation (Y = -728.5370X + 2178.4248, R2 = 0.9869) over a dynamic range of fenitrothion concentrations from 0.1 to 500 ng/mL, with an LOD of 0.037 ng/mL. In addition, the anti-interference ability and robustness of the proposed sensor was verified for the monitoring of fenitrothion in tea with recoveries of 87.67-103.72% and the relative standard deviations (RSD) < 5.43%, indicating that the system has excellent prospects for OPP determination in practical applications. Furthermore, this work provides a universal platform for screening other enzyme inhibitors to detect OPPs.

High-Performance Au@Ag Nanorods Substrate for SERS Detection of Malachite Green in Aquatic Products.

In order to improve the detection performance of surface-enhanced Raman scattering (SERS), a low-cost Au@Ag nanorods (Au@Ag NRs) substrate with a good SERS enhancement effect was developed and applied to the detection of malachite green (MG) in aquaculture water and crayfish. By comparing the SERS signal enhancement effect of five kinds of Au@Ag NRs substrates with different silver layer thickness on 4-mercaptobenzoic acid (4-MBA) solution, it was found that the substrate prepared with 100 µL AgNO3 had the smallest aspect ratio (3.27) and the thickest Ag layer (4.1 nm). However, it showed a good signal enhancement effect, and achieved a detection of 4-MBA as low as 1 × 10-11 M, which was 8.7 times higher than that of the AuNRs substrate. In addition, the Au@Ag NRs substrate developed in this study was used for SRES detection of MG in crayfish; its detection limit was 1.58 × 10-9 M. The developed Au@Ag NRs sensor had the advantages of stable SERS signal, uniform size and low cost, which provided a new tool for SERS signal enhancement and highly sensitive SERS detection method development.

State-of-the-art review of theabrownins: from preparation, structural characterization to health-promoting benefits.

As far as health benefit is concerned, dark tea is one of the best beverages in the world. Theabrownins are the major ingredient contributing to the health benefits of dark tea and known as "the soft gold in dark tea." A growing body of evidence indicated that theabrownins are macromolecular pigments with reddish-brown color and mellow taste, and mainly derived from the oxidative polymerization of tea polyphenols. Theabrownins are the main active ingredients in dark tea which brings multiple health-promoting effects in modulating lipid metabolism, reducing body weight gain, attenuating diabetes, mitigating NAFLD, scavenging ROS, and preventing tumors. More importantly, it's their substantial generation in microbial fermentation that endows dark tea with much stronger hypolipidemic effect compared with other types of tea. This review firstly summarizes the most recent findings on the preparation, structural characteristics, and health-promoting effects of theabrownins, emphasizing the underlying molecular mechanism, especially the different mechanisms behind the effect of theabrownins-mediated gut microbiota on the host's multiple health-promoting benefits. Furthermore, this review points out the main limitations of current research and potential future research directions, hoping to provide updated scientific evidence for their better theoretical research and industrial utilization.

Green preparation, safety control and intelligent processing of high-quality tea extract.

Tea contains a variety of bioactive components, including catechins, amino acids, tea pigments, caffeine and tea polysaccharides, which exhibit multiple biological activities. These functional components in tea provide a variety of unique flavors, such as bitterness, astringency, sourness, sweetness and umami, which meet the demand of people for natural plant drinks with health benefits and pleasant flavor. Meanwhile, the traditional process of tea plantation, manufacturing and circulation are often accompanied by the safety problems of pesticide residue, heavy metal, organic solvents and other exogenous risks. High-quality tea extract refers to the special tea extract obtained by enriching the specific components of tea. Through green and efficient extraction technologies, diversed high-quality tea extracts such as high-fragrance and high-amino acid tea extracts, low-caffeine and high-catechin tea extracts, high-bioavailability and high-theaflavin tea extracts, high-antioxidant and high-tea polysaccharide tea extracts, high-umami-taste and low-bitter and astringent taste tea extracts are produced. Furthermore, rapid detection, green control and intelligent processing are applied to monitor the quality of tea in real-time, which guarantee the stability and safety of high-quality tea extracts with enhanced efficiency. These emerging technologies will realize the functionalization and specialization of high-quality tea extracts, and promote the sustainable development of tea industry.

Main high-quality tea extracts and their preparation methods were introduced.Potential pollutants in the processing of tea extracts and their detection methods were proposed.Emerging intelligent processing technologies of tea extract were summarized.The applications of high-quality tea extracts in food industry were explored.Future trends of tea extracts and relevant suggestions were presented.

Time-Resolved FRET-Based Immunosensor for the Ultrasensitive and Rapid Detection of Cd2.

The detection of heavy metals in food is beneficial to public health. Herein, a new time-resolved fluorescent immunosensor based on the Förster resonance energy transfer (FRET) was proposed to rapidly detect a cadmium ion (Cd2+). After coupling with an antigen and a monoclonal antibody (mAb), respectively, the synthesized europium (III)-chelate-doped polystyrene time-resolved fluorescence microsphere-antigen (Eu-antigen) and gold nanoflowers-mAb (GNFs-mAb) interacted by antigen-antibody combination to quench fluorescence through FRET. Under optimal conditions, the Eu-GNF immunosensing platform provided a quick response to Cd2+ within 30 min. The limit of detection was 0.29 ng/mL with a linear range of 1-500 ng/mL. This immunosensor was further validated via graphite furnace atomic absorption spectrometry and exhibited satisfactory recovery for the detection of Cd2+ in four kinds of tea samples (98.82-108.01%). Thus, this strategy provides a good paradigm for the rapid and high-throughput detection of heavy metals in field testing.

Detection methods, migration patterns, and health effects of pesticide residues in tea.

Due to its rich health benefits and unique cultural charm, tea drinking is increasingly popular with the public in modern society. The safety of tea is the top priority that affects the development of tea industry and the health of consumers. During the process of tea growth, pesticides are used to prevent the invasion of pests and diseases with maintaining high quality and stable yield. Because hot water brewing is the traditional way of tea consumption, water is the main carrier for pesticide residues in tea into human body accompanied by potential risks. In this review, pesticides used in tea gardens are divided into two categories according to their solubility, among which water-soluble pesticides pose a greater risk. We summarized the methods of the sample pretreatment and detection of pesticide residues and expounded the migration patterns and influencing factors of tea throughout the process of growth, processing, storage, and consumption. Moreover, the toxicity and safety of pesticide residues and diseases caused by human intake were analyzed. The risk assessment and traceability of pesticide residues in tea were carried out, and potential eco-friendly improvement strategies were proposed. The review is expected to provide a valuable reference for reducing risks of pesticide residues in tea and ensuring the safety of tea consumption.

Facet-dependence of Fe3O4 for enhancing osteogenic differentiation of BMSCs.

Herein, the facet-dependence of Fe3O4 for enhancing osteogenic differentiation is demonstrated for the first time. Experimental results and density functional theory calculations reveal that Fe3O4 with exposed (42̄2) facets has greater potential in inducing osteogenic differentiation of stem cells compared with that with exposed (400) facets. Moreover, the mechanisms underlying this phenomenon are revealed.

Transcriptional profiling of long noncoding RNAs associated with flower color formation in Ipomoea nil.

MAIN CONCLUSION: LncRNAs regulate flower color formation in Ipomoea nil via vacuolar pH, TCA cycle, and oxidative phosphorylation pathways. The significance of long noncoding RNA (lncRNA) in diverse biological processes is crucial in plant kingdoms. Although study on lncRNAs has been extensive in mammals and model plants, lncRNAs have not been identified in Ipomoea nil (I. nil). In this study, we employed whole transcriptome strand-specific RNA sequencing to identify 11,203 expressed lncRNA candidates, including 961 known lncRNA and 10,242 novel lncRNA in the I. nil genome. These lncRNAs in I. nil had fewer exons and were generally shorter in length compared to mRNA genes. Totally, 1141 different expression lncRNAs (DELs) were significantly identified between white and red flowers. The functional analysis indicated that lncRNA-targeted genes were enriched in the TCA cycle, photosynthesis, and oxidative phosphorylation-related pathway, which was also found in differentially expressed genes (DEGs) functional enrichments. LncRNAs can regulate transcriptional levels through cis- or trans-acting mechanisms. LncRNA cis-targeted genes were significantly enriched in potassium and lysosome. For trans-lncRNA, two energy metabolism pathways, TCA cycles and oxidative phosphorylation, were identified from positive association pairs of trans-lncRNA and mRNA. This research advances our understanding of lncRNAs and their role in flower color development, providing valuable insights for future selective breeding of I. nil.

Study on the Interaction Mechanism of Theaflavin with Whey Protein: Multi-Spectroscopy Analysis and Molecular Docking.

The interaction mechanism of whey proteins with theaflavin (TF1) in black tea was analyzed using multi-spectroscopy analysis and molecular docking simulations. The influence of TF1 on the structure of bovine serum albumin (BSA), ß-lactoglobulin (ß-Lg), and α-lactoalbumin (α-La) was examined in this work using the interaction of TF1 with these proteins. Fluorescence and ultraviolet-visible (UV-vis) absorption spectroscopy revealed that TF1 could interact with BSA, ß-Lg and α-La through a static quenching mechanism. Furthermore, circular dichroism (CD) experiments revealed that TF1 altered the secondary structure of BSA, ß-Lg and α-La. Molecular docking demonstrated that the interaction of TF1 with BSA/ß-Lg/α-La was dominated by hydrogen bonding and hydrophobic interaction. The binding energies were -10.1 kcal mol-1, -8.4 kcal mol-1 and -10.4 kcal mol-1, respectively. The results provide a theoretical basis for investigating the mechanism of interaction between tea pigments and protein. Moreover, the findings offered technical support for the future development of functional foods that combine tea active ingredients with milk protein. Future research will focus on the effects of food processing methods and different food systems on the interaction between TF1 and whey protein, as well as the physicochemical stability, functional characteristics, and bioavailability of the complexes in vitro or in vivo.

Regulation of glucolipid metabolism and gut microbiota by green and black teas in hyperglycemic mice.

A high-sugar and -fat diet (HSFD) has become a primary risk factor for diabetes, and dietary intervention shows a substantial effect on the prevention and management of hyperglycemia. In this study, the chemical compositions of the aqueous extracts of stir-fried green tea (GT) and congou black tea (BT) were compared. Moreover, their potential mechanisms and regulatory effects on hepatic glycolipid metabolism and gut microbiota disorders in hyperglycemic mice were further explored. Our results show that GT or BT intervention had a prominent regulatory effect on glycolipid metabolism. Moreover, they could significantly regulate the levels of serum metabolic signatures, the activities of key enzymes in liver glucose metabolism, and the expression of genes or proteins related to glycolipid metabolism via activating the IRS-1-PI3K/AKT-GLUT2 signaling pathway. Significantly, GT or BT administration adjusted the composition and diversity of the gut microbiota, mainly reflecting a significant increase in the abundance of beneficial bacteria (including Allobaculum, Lactobacillus, and Turicibacter) and reducing the abundance of harmful or conditionally pathogenic bacteria (mainly including Clostridiales and Bacteroides). Our results suggest that dietary supplementation with GT or BT could exert a practical anti-diabetic effect. Meanwhile, BT intervention showed a better regulation effect on glycolipid metabolism. This study reveals that GT and BT have excellent potential for developing anti-diabetic food.

Preparation, Identification and Preliminary Application of the Fenvalerate Monoclonal Antibody in Six Kinds of Dark Tea.

Fenvalerate has the advantages of a broad insecticidal spectrum, high efficiency, low toxicity and low cost, and it is widely used in agriculture, especially in tea, resulting in the accumulation of fenvalerate residues in tea and the environment, posing a serious threat to human health. Therefore, the timely monitoring of fenvalerate residue dynamics is vital for ensuring the health of humans and the ecological environment, and it is necessary for establishing a fast, reliable, accurate and on-site method for detecting fenvalerate residues. Based on the methods of immunology, biochemistry and molecular biology, mammalian spleen cells, myeloma cells and mice were used as experimental materials to establish a rapid detection method of an enzyme-linked immunosorbent assay to detect the residues of fenvalerate in dark tea. Three cell lines-1B6, 2A11 and 5G2-that can stably secrete fenvalerate antibodies were obtained by McAb technology, and their sensitivities (IC50) were 36.6 ng/mL, 24.3 ng/mL and 21.7 ng/mL, respectively. The cross-reaction rates of the pyrethroid structural analogs were all below 0.6%. Six dark teas were used to detect the practical application of fenvalerate monoclonal antibodies. The sensitivity IC50 of the anti-fenvalerate McAb in PBS with 30% methanol is 29.12 ng/mL. Furthermore, a latex microsphere immunochromatographic test strip with an LOD of 10.0 ng/mL and an LDR of 18.9-357 ng/mL was preliminarily developed. A specific and sensitive monoclonal antibody for fenvalerate was successfully prepared and applied to detect fenvalerate in dark teas (Pu'er tea, Liupao tea, Fu Brick tea, Qingzhuan tea, Enshi dark tea and selenium-enriched Enshi dark tea). A latex microsphere immunochromatographic test strip was developed for the preparation of rapid detection test strips of fenvalerate.

Regulatory Effects and Molecular Mechanisms of Tea and Its Active Compounds on Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease, is a multifactorial disease resulting from the interaction between environment, genetic background, and metabolic stress. Most treatments for NAFLD include dietary intervention and exercise show limited efficacy due to the complex mechanisms involved in NAFLD. Meanwhile, drug therapy is accompanied by serious side effects. The development of high-efficiency natural supplements is a sustainable strategy for the prevention and treatment of NAFLD. As the second most consumed beverage, tea has health benefits that have been widely recognized. Nevertheless, the intervention of tea active compounds in NAFLD has received limited attention. Tea contains abundant bioactive compounds with potential effects on NAFLD, such as catechins, flavonoids, theanine, tea pigments, and tea polysaccharides. We reviewed the intrinsic and environmental factors and pathogenic mechanisms that affect the occurrence and development of NAFLD, and summarized the influences of exercise, drugs, diet, and tea drinking on NAFLD. On this basis, we further analyzed the potential effects and molecular regulatory mechanisms of tea active compounds on NAFLD and proposed future development directions. This review hopes to provide novel insights into the development and application of tea active compounds in the prevention and treatment of NAFLD.

Recent advances in the utilization of tea active ingredients to regulate sleep through neuroendocrine pathway, immune system and intestinal microbiota.

Sleep disorders have received widespread attention nowadays, which have been promoted by the accelerated pace of life, unhealthy diets and lack of exercise in modern society. The chemical medications to improve sleep has shown serious side effects and risks with high costs. Therefore, it is urgent to develop efficient nutraceuticals from natural sources to ensure sleep quality as a sustainable strategy. As the second most consumed beverage worldwide, the health-promoting effects of tea have long been widely recognized. However, the modulatory effect of teas on sleep disorders has received much less attention. Tea contains various natural sleep-modulating active ingredients such as L-theanine (LTA), caffeine, tea polyphenols (TPP), tea pigments, tea polysaccharides (TPS) and γ-aminobutyric acid (GABA). This review focuses on the potential influence and main regulating mechanisms of different tea active ingredients on sleep, including being absorbed by the small intestine and then cross the blood-brain barrier to act on neurons in the brain as neurotransmitters, manipulating the immune system and further affect sleep-wake cycle by regulating the levels of cytokines, and controlling the gut microbes to maintain the homeostasis of circadian rhythm. Current research progress and limitations are summarized and several future development directions are also proposed. This review hopes to provide new insights into the future elucidation of the sleep-regulating mechanisms of different teas and their natural active ingredients and the development of tea-based functional foods for alleviating sleep disorders. HighlightsNatural sleep-modulating active ingredients in tea have been summarized.Influences of drinking tea or tea active ingredients on sleep are reviewed.Three main regulating mechanisms of tea active ingredients on sleep are explained.The associations among nervous system, immune system and intestinal microbiota are investigated.The potential of developing delivery carriers for tea active ingredients is proposed.