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1.
Enzymatic Oxidation of Tea Catechins and Its Mechanism.
Abudureheman, B, Yu, X, Fang, D, Zhang, H
Molecules (Basel, Switzerland). 2022;(3)
Abstract
Tea (Camellia sinensis, Theaceae) is one of the most widely consumed beverages in the world. The three major types of tea, green tea, oolong tea, and black tea, differ in terms of the manufacture and chemical composition. Catechins, theaflavins, and thearubigins have been identified as the major components in tea. Other minor oligomers have also been found in tea. Different kinds of ring fission and formation elucidate the major transformed pathways of tea catechins to their dimers and polymers. The present review summarizes the data concerning the enzymatic oxidation of catechins, their dimers, and thearubigins in tea.
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2.
Preparation, structure, and properties of tea polysaccharide.
Fan, Y, Zhou, X, Huang, G
Chemical biology & drug design. 2022;(1):75-82
Abstract
Tea polysaccharide is a kind of acid glycoprotein complex extracted from tea. Tea polysaccharide has a variety of biological activities, especially the hypoglycemic effect is outstanding. It is good for human health. Tea polysaccharides have been extensively studied over the past few decades. The advantages and disadvantages of water extraction, enzyme-assisted extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and supercritical fluid extraction were described. At the same time, the structure and biological activity of tea polysaccharide were also summarized. The development of tea polysaccharide was prospected.
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3.
Tea intake and cardiovascular disease: an umbrella review.
Keller, A, Wallace, TC
Annals of medicine. 2021;(1):929-944
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Abstract
Brewed tea (Camellia sinensis) is a major dietary source of flavonoids, in particular flavan-3-ols. Tea consumption has been suggested to be inversely associated with a decreased risk of cardiovascular disease (CVD). Several biological mechanisms support the inverse relationship between tea flavonoid intake and CVD risk. Given the recent accumulating evidence from various systematic reviews regarding the role of tea as a beverage in reducing CVD risk and severity, we conducted an umbrella review to describe and critically evaluate the totality of evidence to date. We searched the PubMed, Web of Science, Cochrane Database of Systematic Reviews, and BIOSIS databases for systematic reviews published between January 1, 2010 and February 22, 2020 reporting relationships between tea (C. sinensis) consumption and CVD mortality, CVD diagnosis or incidence, CVD events, stroke events, blood pressure, endothelial function, blood lipids and triglycerides, and inflammatory markers. Herein, we describe results from 23 included systematic reviews. Consistently consuming 2 cups of unsweet tea per day offers the right levels of flavonoids to potentially decrease CVD risk and its progression. This is supported by the consistency between a recent high-quality systematic review and dose-response meta-analyses of population-based studies demonstrating beneficial effects of consumption on CVD mortality, CVD events and stroke events and medium- to high-quality systematic reviews of intervention studies that further elucidate potential benefits on both validated (i.e., SBP, DBP, total cholesterol, and LDL-cholesterol) and emerging risk biomarkers of CVD (TNF-ɑ and IL-6). On the basis of this umbrella review, the consumption of tea as a beverage did not seem to be harmful to health; therefore, the benefits of moderate consumption likely outweigh risk. Future large, clinical intervention studies will provide better mechanistic insight with the ability to confirm the outcome effects shown across observational studies. The review protocol was registered on PROSPERO (https://www.crd.york.ac.uk/PROSPERO/) as CRD42020218159.KEY MESSAGESIt is reasonable to judge that 2 cups of unsweet tea per day has the potential to decrease CVD risk and progression due to its flavonoid content.The primary side effects of tea documented in human studies are hepatotoxicity and gastrointestinal disturbances (i.e., vomiting and diarrhea) after high-dose supplemental intake.Additional clinical research is needed to fully elucidate the effects of tea flavonoids on markers of CVD, as many studies were under-powered to detect changes.[Figure: see text].
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The interaction between tea polyphenols and host intestinal microorganisms: an effective way to prevent psychiatric disorders.
Sun, Q, Cheng, L, Zhang, X, Wu, Z, Weng, P
Food & function. 2021;(3):952-962
Abstract
Tea polyphenols (TP) are the most bioactive components in tea extracts. It has been reported that TP can regulate the composition and the function of the intestinal flora. Meanwhile, intestinal microorganisms improve the bioavailability of TP, and the corresponding metabolites of TP can regulate intestinal micro-ecology and promote human health more effectively. The dysfunction of the microbiota-gut-brain axis is the main pathological basis of depression, and its abnormality may be the direct cause and potential influencing factor of psychiatric disorders. The interrelationship between TP and intestinal microorganisms is discussed in this review, which will enable us to better evaluate the potential preventive effects of TP on psychiatric disorders by modulating host intestinal microorganisms.
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5.
The Neuroprotective Effect of Tea Polyphenols on the Regulation of Intestinal Flora.
Zhang, Z, Zhang, Y, Li, J, Fu, C, Zhang, X
Molecules (Basel, Switzerland). 2021;(12)
Abstract
Tea polyphenols (TPs) are the general compounds of natural polyhydroxyphenols extracted in tea. Although a large number of studies have shown that TPs have obvious neuroprotective and neuro repair effects, they are limited due to the low bioavailability in vivo. However, TPs can act indirectly on the central nervous system by affecting the "microflora-gut-brain axis", in which the microbiota and its composition represent a factor that determines brain health. Bidirectional communication between the intestinal microflora and the brain (microbe-gut-brain axis) occurs through a variety of pathways, including the vagus nerve, immune system, neuroendocrine pathways, and bacteria-derived metabolites. This axis has been shown to influence neurotransmission and behavior, which is usually associated with neuropsychiatric disorders. In this review, we discuss that TPs and their metabolites may provide benefits by restoring the imbalance of intestinal microbiota and that TPs are metabolized by intestinal flora, to provide a new idea for TPs to play a neuroprotective role by regulating intestinal flora.
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6.
Possibility that the Onset of Autism Spectrum Disorder is Induced by Failure of the Glutamine-Glutamate Cycle.
Kawada, K, Kuramoto, N, Mimori, S
Current molecular pharmacology. 2021;(2):170-174
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disease, and the number of patients has increased rapidly in recent years. The causes of ASD involve both genetic and environmental factors, but the details of causation have not yet been fully elucidated. Many reports have investigated genetic factors related to synapse formation, and alcohol and tobacco have been reported as environmental factors. This review focuses on endoplasmic reticulum stress and amino acid cycle abnormalities (particularly glutamine and glutamate) induced by many environmental factors. In the ASD model, since endoplasmic reticulum stress is high in the brain from before birth, it is clear that endoplasmic reticulum stress is involved in the development of ASD. On the other hand, one report states that excessive excitation of neurons is caused by the onset of ASD. The glutamine- glutamate cycle is performed between neurons and glial cells and controls the concentration of glutamate and GABA in the brain. These neurotransmitters are also known to control synapse formation and are important in constructing neural circuits. Theanine is a derivative of glutamine and a natural component of green tea. Theanine inhibits glutamine uptake in the glutamine-glutamate cycle via slc38a1 without affecting glutamate; therefore, we believe that theanine may prevent the onset of ASD by changing the balance of glutamine and glutamate in the brain.
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7.
Green Tea Epigallocatechin-3-gallate (EGCG) Targeting Protein Misfolding in Drug Discovery for Neurodegenerative Diseases.
Gonçalves, PB, Sodero, ACR, Cordeiro, Y
Biomolecules. 2021;(5)
Abstract
The potential to treat neurodegenerative diseases (NDs) of the major bioactive compound of green tea, epigallocatechin-3-gallate (EGCG), is well documented. Numerous findings now suggest that EGCG targets protein misfolding and aggregation, a common cause and pathological mechanism in many NDs. Several studies have shown that EGCG interacts with misfolded proteins such as amyloid beta-peptide (Aβ), linked to Alzheimer's disease (AD), and α-synuclein, linked to Parkinson's disease (PD). To date, NDs constitute a serious public health problem, causing a financial burden for health care systems worldwide. Although current treatments provide symptomatic relief, they do not stop or even slow the progression of these devastating disorders. Therefore, there is an urgent need to develop effective drugs for these incurable ailments. It is expected that targeting protein misfolding can serve as a therapeutic strategy for many NDs since protein misfolding is a common cause of neurodegeneration. In this context, EGCG may offer great potential opportunities in drug discovery for NDs. Therefore, this review critically discusses the role of EGCG in NDs drug discovery and provides updated information on the scientific evidence that EGCG can potentially be used to treat many of these fatal brain disorders.
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8.
Chemistry and Pharmacology of Natural Catechins from Camellia sinensis as Anti-MRSA Agents.
Gaur, R, Bao, GH
Current topics in medicinal chemistry. 2021;(17):1519-1537
Abstract
Tea, a worldwide popular beverage rich in polyphenols, contributes to the prevention of many diseases and thus is beneficial to human health. Tea is a product through processing the fresh leaves picked from the plant Camellia sinensis (C. sinensis, genus Camellia section Thea). To date, systematic studies have been conducted on the phytochemicals from more than 20 tea varieties and related tea products, resulting in the structural determination of over 400 constituents viz. different types of polyphenols, purines, and their derivatives, mono to tetra-terpenoids, and minor other phytomolecules. These various tea phytochemicals contribute to the anti-oxidative effects, anti-diabetes, anti-inflammation, anti-cancer, blood lipid reduction, neuroprotection, anti-Alzheimer's disease, hepatoprotection, and anti-microbial activities, etc. Staphylococcus aureus (S. aureus), the significant human pathogens, could cause nosocomial and community-acquired infections, which is also responsible for various infectious diseases from mild to severe life-threatening conditions, such as bacteremia (bloodstream infection), endocarditis (heart valves infection), pneumonia, and meningitis (brain infection), leading to 2% clinical disease in of all patient admissions. The multidrug resistance (MDR) and antibiotics losing efficacy, esp. in methicillin resistance Staphylococcus aureus (MRSA) urge for novel antimicrobial agents. The MRSA strains are resistant to the entire class of β-lactam antibiotics and limit effective treatment, leading to still spread of staphylococcal infections. MRSA also exhibits resistance to cephalosporins, macrolides, fluoroquinolones, aminoglycosides, and glycopeptides (teicoplanine and vancomycin), leading to resistant strains-glycopeptide resistant strain (GRSA) and glycopeptide intermediate (GISA) S. aureus. In this review, chemical constituents responsible for the anti-MRSA activity of tea are explored.
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The anti-allergic potential of tea: a review of its components, mechanisms and risks.
Li, QS, Wang, YQ, Liang, YR, Lu, JL
Food & function. 2021;(1):57-69
Abstract
Allergy is an immune-mediated disease with increasing prevalence worldwide. Regular treatment with glucocorticoids and antihistamine drugs for allergy patients is palliative rather than permanent. Daily use of dietary anti-allergic natural products is a superior way to prevent allergy and alleviate the threat. Tea, as a health-promoting beverage, has multiple compounds with immunomodulatory ability. Persuasive evidence has shown the anti-allergic ability of tea against asthma, food allergy, atopic dermatitis and anaphylaxis. Recent advances in potential anti-allergic ability of tea and anti-allergic compounds in tea have been reviewed in this paper. Tea exerts its anti-allergic effect mainly by reducing IgE and histamine levels, decreasing FcεRI expression, regulating the balance of Th1/Th2/Th17/Treg cells and inhibiting related transcription factors. Further research perspectives are also discussed.
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10.
Antiviral activity of green tea and black tea polyphenols in prophylaxis and treatment of COVID-19: A review.
Mhatre, S, Srivastava, T, Naik, S, Patravale, V
Phytomedicine : international journal of phytotherapy and phytopharmacology. 2021;:153286
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Abstract
BACKGROUND The rapid spread of novel coronavirus called SARS-CoV-2 or nCoV has caused countries all over the world to impose lockdowns and undertake stringent preventive measures. This new positive-sense single-stranded RNA strain of coronavirus spreads through droplets of saliva and nasal discharge. PURPOSE US FDA has authorized the emergency use of Remdesivir looking at the increasing number of cases of COVID-19, however there is still no drug approved to treat COVID-19. An alternative way of treatment could be the use of naturally derived molecules with known antiviral properties. METHOD We reviewed the antiviral activities of two polyphenols derived from tea, epigallocatechin-3-gallate (EGCG) from green tea and theaflavins from black tea. Both green tea and black tea polyphenols have been reported to exhibit antiviral activities against various viruses, especially positive-sense single-stranded RNA viruses. RESULTS Recent studies have revealed the possible binding sites present on SARS-CoV-2 and studied their interactions with tea polyphenols. EGCG and theaflavins, especially theaflavin-3,3'-digallate (TF3) have shown a significant interaction with the receptors under consideration in this review. Some docking studies further emphasize on the activity of these polyphenols against COVID-19. CONCLUSION This review summarizes the available reports and evidences which support the use of tea polyphenols as potential candidates in prophylaxis and treatment of COVID-19.