Gen info
- Tea has a history of culinary and medicinal use for the past 50 centuries. It is the second most consumed drink after water. It has been consumed socially since 3000 BC. From time immemorial, tea has been regarded as a healthy beverage. In Lost Property of Medicinal Herbs, an ancient book in China's Chang Dynasty recorded that while various medicines are cure for different diseases, 'green tea is the cure to all.' (2)
 - Camellia sinensis is a species of evergreen shrub or small tree in the flowering plant family Tracheae. Its leaves, leaf buds, and stems can be used to produce tea.
Common names include tea plant, tea shrub or tea tree. (It is unrelated to
Melaleuca alternifolia the source of tea tree oil, or the genus Leptospermum commonly called tea tree.) (35)
- White tea, yellow tea, green tea, oolong, dark tea (which includes pu-erh tea) and black tea are all harvested from one of the two major varieties grown today, Camellia sinensis var. sinensis and C. sinensis var. assamica. They are processed differently to attain varying degrees of oxidation resulting in the color variations, with black tea being the most oxidized, and white the least. (35)
- Kukicha (twig tea) is also from C. sinensis, but uses twigs and stems rather than leaves. (35)
-Taxonomy / Etymology: The genus name Camellia derives from the Latinized name of Rev. Georg Kamel, SJ (1661-1706), a Moravian-born Jesuit lay brother, pharmacist, and missionary to the Philippines. The genus name was chosen by Carl Linnaeus in 1753 to honor Kamel's contributions to botany, even though Kamel did not discover or name this plant, or any Camellia, and Linnaeus considered the plant a Thea, rather than Camellia. In 1818, Robert Sweet shifted all former Thea species to the genus Camellia. The species name sinensis refers mean "from China" in Latin. (35)
- There are hundreds, if not thousands of cultivars.
- Tea is sometimes categorized according to level of "fermentation": Unfermented (green and white), partially fermented (oolong), and fermented (black) tea.
However, rather than fermentation, the process is that of "oxidation", meaning 'exposure to air", a reaction catalyzed by the enzyme polyphenol oxidase. Green tea is produced by rolling of the leaves, steaming to minimized oxidation and inactivate polyphenol oxidase prior to drying. Black tea leaves, after leaves are rolled, which disrupts cellular compartmentation and brings phenolic compounds in contact with polyphenol oxidases, undergo oxidation for 90-120 minutes. Oolong tea undergoes shorter "fermentation" than black tea, with a taste and color between green and black teas. White tea is made from very young tea leaves or buds covered with tiny, silvery hairs, harvested only once a year in early spring, which are steamed and dried immediately after picking to prevent oxidation, giving it a light and delicate taste. (45)
Botany
• Tsa is a shrub, about a meter or more high. Branches are smooth. Buds are silky. Leaves are elliptic-oblong, 7.5 to 20 centimeters long, 3.5 to 6 centimeters wide, tapering at either end, with toothed margins. Flowers are white, about 3 centimeters in diameter. Fruit is leathery, 3-celled capsule, each capsule containing a seed. Seeds are nearly spherical, obtusely angled, smooth, pale brown, about 2 centimeters in diameter.
Distribution
- Introduced shortly before 1905.
- Scattered cultivation in the Baguio area.
- Originally from the triangle of countries of South China, Assam (northeastern India) and Cambodia.
- Planted in almost all tropical and subtropical regions of the world, but especially economically cultivated in China, Japan, India, Sri Lanka and Indonesia.
- Cultivated, not naturalized.
- Assam, China South-Central, China Southeast, East Himalaya, Hainan, Laos, Myanmar, Thailand, Vietnam (22)
 Constituents
- Tea leaves, depending on source and fermentation process, yield: caffeine 0.9 to 50/0 caffeine, free or bound with glycosides; 0.05% theobromine; some theophylline; purine derivatives xanthine, methylxanthine, and adenine; tanning agents (tannin, polyphenols, gallic acid, and catechin derivatives), and chlorophyll (in fresh or unfermented leaves).
- Also yields vitamins (A, B2, C, D, P, nicotinic acid), minerals (manganese), and carbohydrates (dextrin, pectin), and essential oils (providing aroma).
- Phytochemical screening of leaves yielded alkaloids, flavonoids, steroids, and tannins. One gram of C. sinensis leaf extract yielded 0.7 gm of phenolic compounds, 14 mg of flavonoid, and 0.11 gram of reducing power. (see study below) (24)
- Phytochemical screening of various extracts yielded flavanoids, glycosides, tannins, phenolic compounds, carbohydrates, amino acids, and proteins. (see study below) (32)
- The major phenolic compounds in tea leaves are catechins (also known as flavan-3-ols,) and their derivatives, which constitute 30% of their dry weight. Main catechins in white tea are: (-)-epi-catechin (EC), (-)-epigallocatechin (EGC), collectively known as favanol monomers, (-)-epicatechin 3-gallate (ECG), and (-)-epi-gallocatechin 3-gallate (EGCG), which are flavanol gallates. (45)
 Properties
- Natural scent of the tea is from a fragrant volatile oil.
- Essential oil is both euphoriant and calming.
- Stimulant effect of the tea from the caffeine and theobromine and small amounts of alkaloids.
- Considered astringent, cardiotonic, diuretic, expectorant, stimulant.
- Considered nutraceutical, anti-inflammatory, immunostimulatory, insulin-enhancing, chemopreventive, antimicrobial, antihypertensive.
- Fresh leaves contain four to five times more essential oil as dried or fermented leaves.
- Compared to coffee, the stimulant effect of tea's caffeine manifest more slowly and persist longer, as the caffeine from tea must be liberated from tannic and glycosidic bonding.
• Color of Tea: Green tea, black tea, white tea, yellow tea and pu-erh tea are all derived from the same plant, Camellia sinensis. The differences are the results of processing rather than subspecies used or how it is grown. Varying levels of oxidation changes the color, flavor, and chemistry, even medicinal use. (29) Pu-erh tea is a variety of fermented tea produced in Yunnan province, China. Fermentation involves microbial fermentation and oxidation of the tea leaves. (31)
- Studies have suggested antioxidant, antidiabetic, hypolipidemic, antiviral, antimicrobial, antivenom, antithrombotic, nephroprotective, genoprotective, anticancer, antifungal, antiarthritic, wound healing, antidandruff, anticariogenic, anti-inflammatory, immunomodulatory, anti-anaphylactic, mast cell stabilizing, CNS stimulant, anticoagulant, anti-platelet aggregation, anti-adenovirus, anti-obesity properties.
Parts used
Leaves
Uses
Edibility / Culinary
- Leaves are edible.
- Green tea made from steamed and dried leaves; black tea from fermented and dried leaves.
- Tea extracts used for flavoring alcoholic beverages, dairy desserts, candy, baked goods, pastries and puddings.
- Fixed oil from the seeds sometimes used in making margarine.
Folkloric
- Recorded as early in the 6th century as a Chinese herbal medicine, recommended particularly for people who slept too long. It was used to promote blood circulation, promote excretion of alcohol and other harmful substances, invigorate the skin, promote digestion, combat tiredness and depression, among many others. Strong infusions were used as external applications for skin ailments, eruptions, abrasions and athlete's foot.
-
Decoction of leaves used as stimulant and to relieve fatigue.
- Used to soothe headaches, aid digestion.
Others
- Essential oil from fermented and dried leaves used for perfumery and food flavoring.
- Edible oil made from the seed.
- Residual cake containing saponin are made into little round balls, used by Chinese for washing hair.
- Tea seed oil used in the manufacture of sanctuary or signal oil for burning purposes.
- Dye: A source of varied food colors - black, green orange, yellow.
- Wood: moderately hard, makes into a good walking stick.
Legend
- The tea plant is rich in rituals and legends. A monk version of its origin tells of Bodhidhama, a Buddhist disciple, afflicted with sleepiness, easily falling to sleep while meditating. Angered that he could not keep his eye open, he cut off his eyelids and cast them to the ground. On the ground, the first tea plant grew, its leaves resembling the eyelids. The monks noticed the animating power of beverages made from the leaves, and soon, it because a ritual drink before meditation.
Studies
• Antioxidant: Tea contains flavonoids with its beneficial antioxidant effects.
• Anti-Diabetic / Decreased Insulin Resistance: Study on the water extract of Thea sinensis suggest the antidiabetic activity is derived, at least in part, from a decrease in plasma insulin, due to decreased insulin resistance. (3) Study showed Camellia sinensis, Momordica charantia, and Cinnamomum species effectively reduced insulin resistance in animal models involving different molecular mechanisms. (33)
• Genital Warts: Polyphenon E®, a proprietary extract of green tea, has been approved in the U.S. for external topical use for genital warts caused by human papilloma virus.
• Cardiovascular Benefits: Early studies suggest that regular intake of green tea may help reduce the risk of heart attacks or atherosclerosis. Further clinical trials are needed before firm recommendations.
• Hypolipidemic: Animal studies and limited human research suggest benefits of green tea on cholesterol and triglyceride levels. (•) In a double-blind crossover study of green tea (Camellia sinensis) in patients with dyslipidemias, a beneficial effect was demonstrated with a significant reduction of total cholesterol (3.9% reduction / p<0.006) and LDL-cholesterol (4.5% reduction / p<0.026). There was no significant influence on HDL-cholesterol, triglycerides, and Apo-B levels. (10)
• Lactose Intolerance: Study results suggest the lactose content of milk was reduced by adding tea extracts and suggests that with milk-related gastrointestinal problems have milk with herbal tea extracts. (5)
• Saponins / Alcohol Absorption and Metabolism: Study showed the seed saponins of T sinensis seem to suppress alcohol absorption by slowing gastric emptying and inhibiting absorption across the cell membranes of the digestive tract. (6)
• Effect on Drug Metabolizing Enzymes: Study on decaffeinated green tea is unlikely to alter the disposition of medications primarily dependent on the CYP2D6 and CYP3A4 pathways of metabolism. (7)
• Antimicrobial: Study of extracts showed the highest % yield with chloroform followed by petroleum ether, methanol and diethyl ether. Organisms inhibited were P aeruginosa, B subtilis, S dysenteria, E coli, Yersinia, S typhi among others. Results indicate tea extracts have promising antibacterial activity, especially for intestinal microorganisms causing diarrhea and dysentery. (8) A methanolic extract of Camellia sinensis leaves showed antimicrobial activity against B. subtilis and Enterococcus sp. (see constituents above) (24)
• Colds and Flu / T Cell Function: Study of a proprietary formulation of Camellia sinensis show it to be a safe and effective dietary supplement for preventing cold and flu symptoms and for enhancing T cell function. (9)
• Inhibitory Effect on Venom Neuromuscular Blockade: Study of Camellia sinensis extract showed an inhibitory effect against the neuromuscular blockade induced by the South American rattlesnake Crotalus durissus terrificus venom. Although the mechanism is unclear, theaflavins is suspected to be significantly involved. (11)
• Thea sinensis Melanin: Melanin extracted from Thea sinensis is a high molecular part of tea polyphenols with physiochemical characteristics similar to typical melanin. TSM has exhibited a wide range of biochemical and pharmacological activities - antioxidant, free radical scavenging, immunomodulatory, as well as protective activity against toxic substances - snake venoms, benzidine, among others.
• Nephroprotective / Cisplatin-Induced Nephrotoxicity: Thea sinensis melanin pre-administration can prevent the renal toxic effects of cisplatin as evidenced by inhibition of BUN elevation, prevention of oxidative stress, complete blockade of cisplatin-induced elevation of S creatinine.(13)
• Hepatoprotective Against Acetaminophen-Induced Hepatic Injury: Study showed melanin derived from Thea sinensis leaves has protective effects against hepatic injury induced by NAPAP (N-acetyl-p-aminophenol). (14)
• Antioxidant / Radioprotector: Study evaluated the effect of black tea extract against consequences of radiation exposure. The BTE scavenged free radicals and dose-dependently inhibited Fenton reaction-mediated 2-deoxyribose degradation and lipid peroxidation. Extract also exhibited maximum protection against radiation-induced damage in V79 cells. It is possible the key player in radioprotection is elimination of ROS. (16)
• Neurochemical and Behavioral Effects: Study was designed to monitor the effects of green tea extracts in male albino rats for neurochemical and behavioral effects. Results showed decreased in food intake, increase in locomotive activities, anxiolytic effects, and increase in dopamine and serotonin turnover. (17)
• Genoprotective: Study evaluated the genoprotective effects of two types of green tea in an in-vitro and human supplementation trial. In-vitro testing of tea-treated cells showed increased resistance of lymphocytic DNA to H2O2-induced challenge. In the supplementation trial, a significant increase in resistance was also observed. Results showed significant genoprotective effects and evidence for green tea as a "functional food." (18)
• Antioxidant / α-Glucosidase and α-Amylase Inhibitory Activities: Study of tea fruit peel extracts showed antioxidant activities on DPPH, ABTS, and reducing activity. Various extracts also exhibited excellent inhibitory activity against α-glucosidase and mild inhibition of α-amylase activity. (19)
• Antioxidant / Tea Flowers: Study of tea flower extract and fractions exhibited inhibitory effects on hydroxyl radicals and DPPH radicals. Flavones, polyphenols, and catechin contents were highest in the EE and EEA fractions. (20)
• Modulation of Telomerase in Collagen-Induced Arthritis: Study evaluated the therapeutic potency of Camellia sinensis stew in an experimental model of rheumatoid arthritis in Leis rats. Evidence suggests telomerase is involved in the pathogenesis of rheumatoid arthritis. The CSS significantly reduce paw edema. Histopath findings showed reduced inflammatory responses and bone erosion in joints of the treated rats. There was also significant reduction of telomerase activity. (25)
• Review / Anticancer: Study reports on a total of 27 systematic reviews and/or meta-analyses that investigated the association between green tea consumption and cancer risk. In general, there was an inverse association for green tea consumption and risk of gastrointestinal, esophageal (women), lung (non-smoking women), ovarian, prostate, and breast cancer. Evidence for a protective role of tea consumption on development of cancers of the liver, colorectum, pancreas, urinary tract, prostate, glioma, lymphoma, and leukemia was insufficient. (26)
• Interactions: Green tea can act as an antioxidant and induced superoxide dismutase enzyme which can scavenge free oxygen radicals generated by radiotherapy. In a pharmacokinetic study in rats and in vitro, green tea consumption has been reported to increase the plasma concentration of 5-FU. (26)
• Wound Healing Potential: Study evaluated the effects of topical application of C. sinensis extract on the rate of wound closure and histology of wound area. Wounds treated with extract and Intrasite gel healed significantly earlier. Histological exam showed the wounds had less scar, with less inflammatory cells and more collagen and angiogenesis. (27)
• Comparison of Antioxidative Effects of Green and Black Tea: Study evaluated the comparative effects of black and green tea extracts in rats challenged with sodium oxalate to induce lipid peroxidation. Results showed the tea extracts have antioxidant properties and that the green tea extract is more potent. (28) Green tea, the unoxidized leaf of C. sinensis, contains nearly 4000 bioactive compounds. Its health benefits is largely attributed to catechins (flavanols), together with flavonols (kaempferol, quercetin, and myricetin), which together make up 30 to 40% of fresh green tea leaves d/w. Green tea contains higher polyphenol and lower caffeine content than black tea. In contrast, black tea is fully oxidized, with higher caffeine content that makes up about 2-5% of dried leaf weight. (30)
• Antifungal / Anti-Dandruff: Study evaluated the in vitro antifungal activity of various extracts of Camellia sinensis and Acacia sinuate against dandruff causing Pityrosporum ovale. At concentrations of 10, 5, and 2.5 mg/ml, extracts of C. sinensis exhibited greater inhibitory effect on Pityrosporum ovale compared to A. sinuate. (see constituents above) (32)
• Toxicity Studies / Leaves: (1) Study of Camellia sinensis leaf extract (2 g/kg; 1.94 mL/kg) administered orally in Sprague-Dawley rats showed a minimum lethal dose >2 g/kg. Results showed no mortality. (2) The oral LD50 for rats was >2 g/kg for C. sinensis leaf extract (both green and black tea). (3) Dermal LD50 was >1860 mg/kg rats. There was slight to moderate erythema reported. (4) Camellia sinensis caused no adverse effects administered orally to pregnant rats up to 1336 mg/mL in drinking water. (5) FDA considered C. sinensis as GRAS for use as food additive. (34)
• Catechins / EGCG: Clinical evidence has shown catechins are one of the major compounds found in Camellia sinensis with beneficial effects on many human diseases. The primary catechin is epigallocatechin-3-gallate (EGCG), which acts as antioxidant, anti-angiogenic, and anti-tumor agent. EGCG has chemopreventive activities as it induces apoptosis, arrests cell growth, activates killer caspases and suppresses the oncogenic transcription factors. EGCG acts on multiple signal transduction pathways like P13/AKT, JAK/STAT, and MAPK. Black tea extracts contain polyphenol-rich compounds such as astheaflavins and thearubigins, and flavonol-3-ol, which are potent anti-oncogenic compounds. (36)
• Green Tea Benefits on Oral and Periodontal Health / Review: Review reports on the therapeutic properties of Green tea on oral and periodontal health. A pilot clinical study showed the application of green tea catechins via a slow release delivery system had a bactericidal effect and was effective in improving periodontal status. Green tea extract from leaves have bee used as mouthwash for treating and periodontal disease. Green tea has been suggested to inhibit plaque formation and dental caries. Its modulation of immune system function suggests a possibility that its catechins may reduce cancer risks in humans. The review suggests an explicit association between consumption of green tea and oral health. (37)
• Green Tea and Cancer Prevention / Review of Epidemiological Studies and Randomized Trials: Review summarizes the beneficial effects of green tea on cancer prevention. Forty-three epidemiological studies, four randomized trials and one meta-analysis were identified. Overall quality of the studies were evaluated as good or moderate. While some evidence suggests that green tea has beneficial effects on gastrointestinal cancers, the findings are not consistent. Although green tea may have beneficial effects on cancer prevention, further studies such as large and long term cohort studies and clinical trials are warranted. (38)
• Anti-Cariogenic: Various components in green and black tea, beverages made by infusing appropriately processed dried leaves of C. sinensis, notably simple catechins, have in vitro properties that suggest anti-cariogenic activity via: (1) a direct bactericidal effect against Streptococcus mutans and S. sobrinus; (2) prevention of bacterial adherence to teeth; (3) inhibition of glucosyl transferase that limits the biosynthesis of sticky glucan; (4) inhibition of human and bacterial amylases. Studies in animal models suggest these invitro effects can prevent dental caries. Limited clinical trials have suggested regular tea drinking may reduce the incidence and severity of dental caries. (39)
• Prevention of Cold and Flu Symptoms / Enhancement of γδ T Cell Function / Randomized Controlled Trial: A randomized, double-blind, placebo-controlled study evaluated if a specific formulation of C. sinensis can prevent illness and symptoms due to cold and flu, and enhance gamma delta T cell function. Proprietary formulation of green tea capsules or placebo, twice daily for 3 months were used. Results showed 32.1% fewer subjects with symptoms, 22.9% fewer overall illnesses of at least 2 days duration, and 35.6% fewer symptom days, compared to placebo subjects. Results showed the formulation is a safe and effective dietary supplement for preventing cold and flu symptoms, and for enhancing gamma-delta T cell function. (40)
• Toxicological Concerns with Green Tea: Many studies have showed green tea (GT) to have great potential to manage central nervous system, cardiovascular, metabolic disorders, cancer and inflammatory disorders. Study reports on the toxicity of GT and its main constituents in acute, subchronic, and chronic states. The most important side effects reported are hepatotoxicity and gastrointestinal disorders, especially when consumed on an empty stomach. Green tea and its main components are not major teratogenic, mutagenic, or carcinogenic substances. There is limited data on use during pregnancy, and should be used with caution in pregnancy breastfeeding and susceptible people. GT components have a wide variety of drug interactions. GT also has selective cytotoxicity on cancerous cells with potential as adjuvant substance in cancer therapy. (41) There are no reports on clinical toxicity on health hazard of drinking large amount of green tea daily. A level of no observed adverse effects (NOAEL) on three preparations was 2000 mg/kg/day. Another study demonstrated GTC-H (green tea catechin-heat sterilized) did not affect embryonic development in ICR mice. These data provide basis for the safe application of GT extract in food production. A 2010 in vivo experiment in mice reported a 138-times increase of ALT after high-dose EGCG of 1500 mg/kg i.g. for 7 days, a toxic dos much higher than normal tea consumption. The safe intake for adults should be controlled below 338 mg EGCG/day. (51)
• Thrombolytic / Antibacterial / Antioxidant / Leaves: Study evaluated the antibacterial, thrombolytic, and antioxidant activities of crude water, ethanol and acetone extracts of C. sinensis or green tea leaves in vitro. Clot lysis effect % was statistically significant (p<0.0001) compared to control. Leaves showed moderate clot lysis activity of 45.60. 37/68. and 30.51% respectively, compared to standard streptokinase at 87.15%. By simple agar diffusion method using ten pathogenic bacteria, the aqueous and ethanol extracts showed moderate activity against seven pathogens, and the acetone extract, against eight bacteria tested. The extracts showed varying degrees of antioxidant activity by DPPH assay, 88.32%, 78.80%, and 61.69% with water, ethanol, and acetone extracts, respectively. The aqueous extract and ethanol extract showed total flavonoid contents of 78.16 and 65.99 µg/mg. The water extract of green tea leaves showed highest total phenol content of 160 mg GAE/gm followed by ethanol 123,33 and acetone 95.73 mg GAE/g extract. (42)
• Mouthwash for Oral Care / Review: Study explored three scientific databases with keywords of tea, dental care, C. sinensis, and mouthwashes and found 69 relevant studies including 41 randomized controlled trials (RCTs), which proposed antimicrobial, antiplaque, analgesic indications for tea formulations. Several RCTs assessed the synergistic efficacy of C. sinensis in combination with other herbal or chemical ingredients in mouthwash formulations such as chlorhexidine (CHX) Xylitol, Aloe vera, etc. C. sinensis mouthwashes have shown acceptable efficacy fin the management of various oral pathologies. Camellia sinensis products are able to act as antiseptic, anti-plaque, and anti-inflammatory agents with potential as useful mouthwashes in future clinical studies and practice. (43)
• Green Tea as Mouthwash for Plaque-Induced Gingivitis / Clinical Trial: A single blinded placebo controlled clinical trial assessed the efficacy of Green tea mouthwash on plaque-induced gingivitis as the most common form of periodontal disease. High school female students with chronic generalized plaque-induced gingivitis received either 5cc of Green tea 5% two times daily or normal saline, and measuring gingival index, plaque index, and bleeding index after five weeks. A significant improvement was observed in all periodontal indices during the study (p<0.001). Results suggest GT mouthwash may be a safe and feasible adjunct treatment for inflammatory periodontal diseases. (44)
• Effect in Dyslipidemias / Green Tea / Clinical Trial: A prospective double-blind crossover study evaluated the effects of green tea in patients with dyslipidemias. Study included 33 patients aged 21-71 on a low fat diets (25-35% of total calories and 200 mg of cholesterol daily) were randomized with 250 mg capsules of green tea or placebo for 16 weeks (8 weeks of green tea, 8 weeks of placebo). Results demonstrated a beneficial effect of green tea, with significant reduction of total cholesterol and LDL-cholesterol levels in 8 weeks. (46)
• Comparative Antioxidative Effects of Green and Black Tea: Study did a comparative study on antioxidative effects of green and black tea, using measures of serum levels of malondialdehyde, reduced ascorbic acid, catalase, cholesterol, phospholipid, AST, ALT, and ALP. Cholesterol to phospholipid ratio was increased from 0.14 in control to 0.47 and 0.51 by black and green tea extracts, respectively. Results suggest tea extracts have antioxidant properties and green tea extract more potent than black tea. (47)
• Effect on Halitosis / Review: Study evaluated the clinical effects of green tea on halitosis through a systematic review of available literature on clinical trials. Two studies selected according to inclusion criteria suggests statistically significant early effect. Some invivo and invitro studies support the efffectiveness of green tea on reducing halitosis. An invitro study showed ability of GT to remove odorant sulfurs, and showed the intensifying effect of adding herbal acetone powder to GT to reduce halitosis. In an invivo study, GT reduced hydrogen sulfide (H2S) and methyl mercaptan (CH3SH) concentration specifically after consumption, which is important because CH3SH is more related to halitosis than H2S. One study showed long-term effect of green tea mouthwash. Review suggests green tea can reduce halitosis through rinsing and antimicrobial effect. (48)
• Effect on Burn Wound Healing: Study evaluated the effect of green tea ethanolic extract on burn wound healing process in male Wistar rats. Results showed significant effect of Vaseline+0.6% green tea extract in decreasing the burn area. Clinical trials in humans were suggested with its potential as a natural, low cost, easily available treatment for type II burns. (49)
• Silver Nanoparticles / Leaves: Study reports on the simple, efficient, and environmentally friendly synthesis of silver nanoparticles using leaves extract of C. sinensis. The green synthesized NPs have potential for use in many fields such as cosmetics, food, and medicine. (50)
• Mechanisms of Antidiabetic Effect: Current studies have shown the antidiabetic effect of green tea is achieved via four mechanisms: (1) Improving insulin resistance: GT polyphenols can increase insulin sensitivity rats by increasing the absorption of glucose by adipocytes and their ability to bind to insulin. (2) Improving glucose metabolism: This mechanism is related to the increase in glycogen content in the liver and change of activity of key enzymes in glucose metabolism. (3) Promoting Insulin secretion:The water-soluble polysaccharide 7WA isolated from leaves could promote insulin secretion with a significant hypoglycemic effect through a possible mechanism of cAMP-PKA dependent pathway. (4) Improving diabetic complications: Impaired cardiac function in diabetes is closely related to hyperglycemia. GT extract (300 mg/k i.g. for 4 weeks) could significantly reduce blood sugar, lipid peroxide, triglyceride level, and degree of protein glycosylation in the heart of diabetic rats. EGCG treatment showed significant inhibiting effects on neural tube defects in diabetic pregnant mice with defect rate decrease from 29.5% to 2%. This could be related to EGCG that can inhibit hypermethylation of DNA by blocking increased expression and activity of DNA methyltransferase in maternal diabetic mice. (51)
• Nephroprotective / Antimicrobial / of Antidiabetic Effect: Study evaluated the potential nephroprotective and antibacterial activity of leaves of C. sinensis and Hibiscus sabdariffa calyces, in vitro measuring antibacterial activity and in vivo measuring nonenzymatic kidney markers of dysfunction after induction of nephrotoxicity by gentamicin. GT showed antimicrobial activity against MRSA with inhibition zone of 19.67 mm and MIC 1.25 mg/mL, compared with standard vancomycin at 18.00 mg/mL. Both plants showed nephroprotective effect evidenced by reduction in elevated nonenzymatic markers. Results suggest green tea has dual effects: antimicrobial and nephroprotective. (52)
• Neurochemical and Behavioral Effects of Green Tea / Serotonin and Dopamine Turnover: Green tea has been suggested as a potential candidate for treatment of obesity, stress, depression, Parkinson's disease, and other disorders. Study evaluated the effects of green tea in male albino Wistar rats. After 5 weeks, decreased food intake was noted, along with increased locomotive activity, anxiolytic effects in elevated plus maze, and an increase in dopamine and serotonin turnover. The beneficial effects may be due to alteration of serotonin and/or dopamine metabolism (53)
• Immunomodulatory Effects of Black Tea: Immunomodulatory effects of tea are recognized as it stimulates the proliferation of cultured human peripheral blood mononuclear cells. Study evaluated the immunomodulatory and anti-inflammatory activities of black tea in a rat model and in human peripheral mononuclear cells using 10% and 20% black tea decoction. Acute anti-inflammatory activity was evaluated using carrageenan and dextran and chronic anti-inflammatory (immunomodulatory) effects were evaluated in complete Freunds adjuvant-induced arthritis model. Black tea decoction (10 and 20%) showed significant anti-inflammatory effects (64.8% and 77% reduction, respectively) on carrageenan-induced acute inflammatory models (rat paw edema) comparable to standard indomethacin (89.1%). Using MTT assay on human peripheral mononuclear cells, black tea increased the maximum number of lymphocytes, and maximum number of viable cells (T-lymphocytes) was observed at 20% at 72h. Results suggest black tea has anti-inflammatory and immunomodulatory potential. (54)
• Carcinogenicity / Tannin Fractions: In a 1976 study, bioassays of several plant extracts were performed and fractions prepared from them. Fourteen extracts and fractions from 6 plants were injected s.c. into NIH black rats. The tannin fractions from Quercus falcata pagodaefolia, Diospyros virginiana, and Camellia sinensis were very active and produced tumors at the injection site in 66% or more of treated animals. Tannin fractions from 3 other plants and total aqueous extracts from 5 of 6 tested plants were also tumorigenic. The induced tumors were malignant fibrous histiocytomas, similar to those encountered in humans. Experiment indicated possibility of induction of tumor in man by the tested plant materials. (55)
• Applications in Cosmetics / Review: Review collected reports on properties of the tea plant, its extracts and preparations in cosmetology, as skin care products and treatment of selected dermatological diseases. Tea leaves are the richest source of catechins among plants, while also delivering caffeine, a purine alkaloid of high cosmetic significance. Tea plant does not have any confirmed allergenic or irritating effects on topical use. Tea metabolites have been shown to have synergistic actions with other antioxidants and preserving properties towards cosmetic formulations. It has been mentioned to have anti-aging, skin and hair-care, and slimming properties, along with skin microcirculation enhancement and photoprotection against harmful effects of UV irradiation. In terms of cosmetic applications, it is still insufficiently studied. (56)
• Chemopreventive and Chemotherapeutic in Breast Cancer / Review: Review is an overview of breast cancer chemopreventive and chemotherapeutic effects of C. sinensis (green tea). Catechin in Camellia sinensis has properties that can prevent and treat breast cancer. It has been shown to inhibit proliferation of breast cancer cells and block carcinogenesis. Increased consumption may lower the risk of breast cancer and reduce incidence. In vivo and invitro studies have shown potential breast cancer chemopreventive effect. Studies have demonstrated anti-breast cancer activity via adjustment of cell signaling pathways such as angiogenesis, apoptosis, and transcription factors. However, evidence of low effect and no effect has been observed. More clinical trials are needed to prove anti-breast cancer activity decisively. (57)
• Mast Cell Stabilizing / Anti-Anaphylactic / Green Tea: Study evaluated an aqueous extract of green tea for mast cell stabilizing and anti-anaphylactic activities. Extracts (11, 13, 15 mg/ml) significantly (p<0.05) inhibited compound 48/80-induced rat mesenteric mast cell degranulation in a dose dependent manner. Anti-anaphylactic activity of green tea extract at doses of 400, 500,, 600 mg/kbw, showed significant reduction in mortality of mice subjected to anaphylactic shock by compound C48/80. Ketotifen was used for comparison. Study suggests potential use in the treatment of asthma and allergic rhinitis. (58)
• Antiviral / Review: The mini-review results support the green tea has both antibacterial and antiviral effects. The beneficial effects of green tea are mainly attributed to the presence of polyphenols known as catechins and isomers including (-) - epigallocatechin gallate (EGCG), (-) - epigallocatechin, (-) - epicatechin gallate, (-) -epicatechin, and (+) - catechin. The catechins in green tea have a wide range of antiviral activity against a variety of virus that act by interfering with its replication cycle. (59)
• Anticancer / Bladder Carcinoma: Polyphenolic compounds are mainly responsible for the significant antioxidant properties and anticarcinogenic potential of leaves of C. sinensis. Epidemiological studies showed that regular consumption of tea can be a preventive factor for bladder cancer. Several in vivo and in vitro studies reported that tea and its components may interfere in the cancer cells' signaling, preventing bladder tumor progression. The mechanisms of cancer protection include deregulation of cell cycle, induction of apoptosis while protecting surrounding healthy bladder cells, inhibition of metastasis, etc. (60)
• Neuropharmacological Potential of Various Morphological Parts / Seed and Leaves: Study evaluated the dose-dependent neuropharmacological behavioral potential of C. sinensis seed and leaf extracts on mice using open field, head dip, rearing, cage cross, swimming and traction tests. Both seed and leaf extracts showed significant results at high doses. Leaf extract at high dose showed significant effect in open field and head dip test, while seed at high dose showed significant stimulus on mice CNS in rearing, cage cross, swimming and traction tests. Seeds produced more stimulant effect and less calmness compared to leaf extract. Results suggest tea seed has potential as alternative CNS stimulant agent with more effective stimulant action. (61)
• Anti-Thrombotic Effects / Review: Study reviews the antithrombotic effects of C. sinensis searching five databases. Review showed Camellia sinensis possesses anti-coagulant properties. In vivo and in vitro experiments have showed various plant components have anti-coagulant and antiplatelet aggregation abilities. Regular consumption of tea can reduce the risk of developing heart disease and reducing the risk for thrombosis. (62)
• Anti-Inflammatory / Flowers: Study evaluated the anti-inflammatory effects of hot water extract of tea flowers. Pharmacologic studies showed tea flowers extract (TFE) could effectively inhibit croton oil-induced ear edema and carrageenan-induced paw edema. TFE also protected against Propioni-bacterium acnes plus lipopolysaccharide (LPS)-induced liver inflammation by reversing histologic damage and plasma ALT increase. Also, levels of nitric oxide (NO), TNF-α, and IL-1ß mRNA in mouse liver were markedly suppressed after treatment with TFE in mice with immunological liver inflammation. Results suggest tea flowers have potent anti-inflammatory effects on acute and immunological inflammation in vivo, and may be used as a functional natural food. (63)
• Gold Nanoparticles / Antioxidant / Chemotherapeutic Potential in Acute Myeloid Leukemia / Leaves: Study reports on the synthesis of gold nanoparticles using aqueous extract of C. sinensis leaves. The AuNPs were reported to exert a dietary therapeutic potential compared to Daunorubicin in an animal model of acute myeloid leukemia. DPPH assay revealed similar antioxidant potentials for daunorubicin and AuNPs. The NPs similar to daunorubicin had low cell viability dose-dependently against Human HL-60/vcr, 32D-FLT3-ITD, and Murine C1498 cell lines without cytotoxicity on HUVEC cell line. AuNPs significantly (p≤0.05) increased inflammatory cytokines and lymphocyte, platelet, and RBC parameters and decreased weight and volume of liver and spleen, pro-inflammatory cytokines, total WBC, blast, neutrophil, monocyte, eosinophil, and basophil counts. Results suggest AuNPS can be used as chemotherapeutic drug for the treatment of acute myeloid leukemia in the clinical trial. (64)
• Anti-Adenovirus Activity / Antioxidant / Black Tea: Study evaluated the invitro anti-adenovirus (ADV) activity, antioxidant potential, and total phenolic compounds of black tea hydroalcoholic crude extract. Anti-ADV activity was evaluated on Hep2 cell line using MTT assay. CC50 and IC50 were 165.95 and 6.62 µg/ml, respectively, with selectivity index (SI) of 25.06. The extract inhibited ADV replication in post-adsorption stage. IC50 of DPPH radical was 8.0 µg/mL, compared wi6th BTH IC50 of 25.41 µg/mL. Total phenol and flavonoid contents were 341.8 mg GAE/g and 21.1 mg/g, respectively. Results suggest that with the Si value of 25.05with inhibitory effect on ADV replication, particularly during post-adsorption period, the black tea extract could be considered a potential anti-ADV agent, and its activity attributable to its phenolic contents. (65)
• Anti-Photoaging Activity / Stress Resistance / Neuroprotective / Autophagy: Manuscript describes the reported photoaging, stress resistance, neuroprotective, and autophagy properties of green tea. Skin aging is a complex process mediated by intrinsic factors such as senescence, along with extrinsic factors such as chronic exposure to UV-irradiation causing photoaging, which can lead to erythema, edema, sunburn, hyperplasia, premature aging, development of non-melanoma and melanoma skin cancers. Green tea phytochemicals are a potent source of exogenous antioxidants that can nullify excess endogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS) inside the body and diminish the impact of photoaging. In vivo and in vitro studies suggest that green tea supplementation increases the collagen and elastin fiber content, and suppresses collagen degrading enzyme MMP-3 production in the skin, conferring an anti-wrinkle effect. Green tea mediated lifespan extension depends on the DAF-16 pathway. EGCG, an abundant catechin in tea, suppresses the neurotoxicity induced by Aß as it activates glycogen synthase kinase-3ß (GSK-3ß), along with inhibiting c-Abl/FE65, the cytoplasmic nonreceptor tyrosine kinase involved in the development of the nervous system and nuclear translocation. Green tea polyphenols induced autophagy in HL-60 xenographs by increasing activity of PI1 kinase and BECLIUB-1. (66)
• Drug-Drug Interactions with Green Tea / Review: Review summarizes published in vitro, animal, and clinical studies on the effects of green tea extract and associated catechins on drug-metabolizing enzymes and drug transporters. In vitro studies suggest that GT extract and its main catechin, (-)-epigallocatechin-3-gallate, in varying degrees, inhibit the activity of CYP1A1, CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2D6, and CYP3A4. Animal studies suggest GT extract and/or (-)-epigallo-catechin-3-gallate significantly increase the bioavailability of diltiazem, verapamil, tamoxifen, simvastatin, 5-FU, and nicardipine. Conversely, they reduce the bioavailability of quetiapine, sunitinib, clozapine, and nadolol. Neither GT extract and EGCG inhibit ant any major cytochrome p450 enzyme. In vitro studies have indicated drug transporters are potentially inhibited by GT extract. Review suggests ingestion of GT extract or its associated catechins is not expected to cause clinically significant influences on major cytochrome p450) or uridine 5'-diphospho-glucuronosyltransferase enzyme substrates or drugs serving as substrates of P-glycoprotein. However, caution is advised in the consumption of significant amounts of GT beverages or extract in patients prescribed known substrates of organic anion transporting polypeptide, especially those with a narrow therapeutic index. (67)
• Antioxidant / Anti-Inflammatory / Anti-Tyrosinase / Anti-Hepatotoxic / Fresh Tea Leaves: Fresh tea leaves (FTL) exhibited best shelf life at low temperatures and demonstrated concentration-dependent antioxidant, anti-inflammatory, antihepatotoxic, and anti-tyrosinase effects. FTE at 2000 mg/k/day fir 28 days reversed CCl4-induced oxidative damage in hepatic tissues with 69% lowering of ALT and 90% lowering of malondialdehyde. FTE showed capacity to scavenge free radicals and can protect against oxidative stress induced by CCl4 intoxication. Docking results were consistent with invitro data, indicating anti-tyrosinase potency of principal catechins. (68)
• Anxiolytic / Antidepressant: Study evaluated the ameliorative effects of Ocimum sanctum and Camellia sinensis on stress-induced anxiety and depression on male albino rats using elevated plus maze (EPM), open field test (OFT), forced swim test (FST), and tail suspension test (TST). Restraint stress induced Increased significant reduction in entries and time spent in open arms in EPM. Increased latency and decreased ambulation and rearing were reversed in OFT. There was significantly reduced immobility times of rats in FST and TST. Results suggest anxiolytic and antidepressant activities. (69)
• Green Tea for Patients with Knee Osteoarthritis / Clinical Trial: A randomized open-label active-controlled clinical trial assessed the efficacy and safety of green tea in patients with knee osteoarthritis. Results suggest green tea extract may be considered as an adjunctive treatment for both control of pain and for betterment of knee joint physical functions in adults with osteoarthritis. (70)
• Anti-Obesity / Leaves: Study evaluated the hypothesis that selected herbs/extracts can inhibit the enzymatic activity of LPL in vitro, using methanolic and aqueous extracts of Camellia sinensis leaves. Extracts were examined for in-vitro lipase inhibitory activity at concentration level of 0.5, 1 and 2 g/l. Results of of in-vitro lipase activity showed percentage inhibition of methanolic extract was greater than aqueous extract at all tested concentration levels. The methanol extract at 2 g/l showed maximum inhibition of pancreatic lipase enzyme at 80%, which can be the most effective extract for anti-obesity activity. (71)
• Anticancer in Caco-2 Colorectal Cancer Cell Line / Leaves: Study evaluated a hydroalcoholic extract of C. sinensis young leaves for anticancer effects on two cell lines: Caco-2, colon carcinoma cells, and mouse normal fibroblasts (L929). MTT assays of the extract showed considerable inhibition of growth of Caco-2 cells, significant at 800 µg/ml (p<0.05), with little effect on L929 cells. Levels of aquaporin 5 protein decreased in Caco-2 cell culture following green tea extract treatment. (Aquaporin 5 is a water channel protein that exhibit several properties related to tumor development. The expression of AQP5 protein in intestinal cells is a strong prognostic biomarker for colorectal cancer.) (72)
• Ameliorative Effect Against Contrast Media Induced Acute Kidney Injury / Green Tea: Study evaluated the protective property of green tea on renal toxicity induced by contrast media in rats. The group pretreated with green tea significantly showed reduction in blood creatinine level compared with the contrast media group. Green tea extract is an inexpensive, nontoxic, and effective treatment modality in individuals with risk for acute kidney injury from contrast media. (73)
Availability
- Wild-crafted.
- Extracts, capsules, tinctures, ointments, tea seed oil in the cybermarket. |
