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Green Tea and Skin

Green Tea and Skin ObjectiveTo discuss the current knowledge of polyphenolic compounds present in green tea as anti-inflammatory, antioxidant, and anticarcinogenic in skin.Data SourcesReferences identified from bibliographies of pertinent articles, including our work in related fields.Study Selection and Data ExtractionArticles were selected based on the use of green tea or its polyphenolic constituents for prevention against inflammation and cancer in the skin. Also discussed is the possible use of green tea to treat various inflammatory dermatoses.Data SynthesisThe polyphenolic compounds from green tea were tested against chemical carcinogenesis and photocarcinogenesis in murine skin. These green tea polyphenols were found to afford protection against chemical carcinogenesis as well as photocarcinogenesis in mouse skin. A few experimental studies were conducted in human skin in our laboratory. Analysis of published studies demonstrates that green tea polyphenols have anti-inflammatory and anticarcinogenic properties. These effects appear to correlate with antioxidant properties of green tea polyphenols.ConclusionsThe outcome of the several experimental studies suggests that green tea possess anti-inflammatory and anticarcinogenic potential, which can be exploited against a variety of skin disorders. Although more clinical studies are needed, supplementation of skin care products with green tea may have a profound impact on various skin disorders in the years to come.GREEN TEA, a popular beverage consumed worldwide, contains many polyphenols that have antioxidant activity superior to that of any other naturally occurring antioxidant known. Many laboratory studies conducted in mouse models of chemical carcinogen as well as UV-induced skin cancer have shown that its topical application or oral consumption results in inhibition of tumorigenesis. Studies have also shown that green tea extract also possesses anti-inflammatory activity. These anti-inflammatory and skin cancer preventive effects of green tea were found to be due to its polyphenolic constituents. The major and most preventive constituent in green tea responsible for these biological effects is (−)-epigallocatechin-3-gallate (EGCG). Understanding the molecular mechanisms for these broad effects of green tea is a subject of investigation in many laboratories. Green tea polyphenols (GTPs) have been shown to modulate biochemical pathways important in inflammatory responses, cell proliferation, and responses of tumor promoters. Treatment with EGCG on mouse skin also results in prevention of UV-B–induced immunosuppression and reactive oxygen species generation. The effect of green tea treatment, either topical or consumed orally, on human skin inflammatory responses and cancer is not clear. Based on documented extensive beneficial effects of green tea on mouse skin models, many pharmaceutical and cosmetic companies are supplementing skin care products with green tea extracts.In this review, we focus on agents in green tea and their use in dermatology. As mentioned in the editorial introduction to this article, a wide variety of naturally occurring botanical compounds have been studied for their ability to prevent UV-related skin damage.In initial studies in mouse models, we showed that cutaneous application or oral consumption of a polyphenolic fraction isolated from green tea affords protection against inflammation, chemical carcinogenesis, and photocarcinogenesis.Induction of carcinogenesis in murine and possibly in human skin is a multistage process involving 3 distinct stages: initiation, promotion, and progression.Multistage carcinogenesis requires both initiating and promoting stimuli for the development of cancer. The initiation stageis essentially an irreversible step in which genetic changes occur in gene(s) leading to genetic mutations.The promotion stageleads to the development of visible nonmalignant lesions through epigenetic mechanisms, essentially by alterations in signal transduction pathways,while the progression stageis characterized by the transformation of the preneoplastic cells to a neoplastic cell population as a result of additional genetic alterations.Because oxidants play an important role in many skin functions, including the initiation and promotion stages of multistage skin carcinogenesis, in recent years, the effect of antioxidant compounds present in fruits, vegetables, and beverages humans consume has received considerable attention as a strategy to ameliorate their adverse effects.These antioxidant compounds for the prevention of cancer can be targeted for intervention at the initiation, promotion, or progression stages of multistage carcinogenesis.Studies have shown that dietary or environmental mutagens and carcinogens, including UV light, to which humans are constantly exposed, exert their biological effects at least in part via the generation of reactive oxygen species (ROS) and free radicals. The generation of these ROS and free-radical moieties plays a major role in the induction of cancer, specifically at the promotion stage of carcinogenesis.Dietary intake of naturally occurring antioxidants therefore has been suggested as an important strategy against the toxic effects of these mutagenic and carcinogenic agents.We and others have demonstrated the inhibitory effects of polyphenols from green tea, which is commonly consumed as a beverage worldwide, against inflammation and tumor formation in skin.In this article, we have particularly summarized the available information of laboratory studies on the antioxidant, anti-inflammatory, and anticarcinogenic effects of GTPs mainly in the murine model. Available information on the human skin is also highlighted.GREEN TEATea is manufactured from the leaf and bud of the plant Camellia sinensisand is commercially available mainly in 3 forms: green tea, black tea, and oolong tea.Of the total tea production, about 78% is consumed as black tea mainly in the Western countries and some Asian countries, while about 20% is consumed as green tea mainly in Asian countries, including Japan, China, Korea, and India. About 2% is manufactured in the form of oolong tea, which is mainly produced and consumed in southeastern China.The basic steps of manufacturing the various forms of tea are similar except in the creation of their aroma and in the fermentation process, which is dependent on the oxidation states of different polyphenolic compounds present in tea leaves. The term green tearefers to the product manufactured from the fresh leaves of the tea plant by steaming and drying at elevated temperatures, with care to avoid oxidation and polymerization of the polyphenolic components. "Herbal teas" are not derived from the plant C sinensis, and when the term teais used to describe them, the plant source should be identified.POLYPHENOLS IN GREEN TEAThe polyphenolic composition in green tea is approximately similar to that of fresh leaves, including flavanols, flavonoids, and some phenolic acids. Most of the polyphenols present in the green tea are flavanols, commonly known as catechins. The major catechins found in green tea are (−)-epicatechin (EC), (−)-epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC), and EGCG. Their chemical structures are shown in Figure 1. These polyphenols are antioxidant in nature and have been shown to function as anti-inflammatory and anticarcinogenic agents in various biological systems.Of these 4 major green tea catechin derivatives or polyphenols, EGCG has been shown to be the major component and the most effective chemopreventive agent against cutaneous inflammatory or carcinogenic responses.Chemical structures of major polyphenolic compounds present in green tea.ANTI- http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA Dermatology American Medical Association

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Publisher
American Medical Association
Copyright
Copyright 2000 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.
ISSN
2168-6068
eISSN
2168-6084
DOI
10.1001/archderm.136.8.989
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Abstract

ObjectiveTo discuss the current knowledge of polyphenolic compounds present in green tea as anti-inflammatory, antioxidant, and anticarcinogenic in skin.Data SourcesReferences identified from bibliographies of pertinent articles, including our work in related fields.Study Selection and Data ExtractionArticles were selected based on the use of green tea or its polyphenolic constituents for prevention against inflammation and cancer in the skin. Also discussed is the possible use of green tea to treat various inflammatory dermatoses.Data SynthesisThe polyphenolic compounds from green tea were tested against chemical carcinogenesis and photocarcinogenesis in murine skin. These green tea polyphenols were found to afford protection against chemical carcinogenesis as well as photocarcinogenesis in mouse skin. A few experimental studies were conducted in human skin in our laboratory. Analysis of published studies demonstrates that green tea polyphenols have anti-inflammatory and anticarcinogenic properties. These effects appear to correlate with antioxidant properties of green tea polyphenols.ConclusionsThe outcome of the several experimental studies suggests that green tea possess anti-inflammatory and anticarcinogenic potential, which can be exploited against a variety of skin disorders. Although more clinical studies are needed, supplementation of skin care products with green tea may have a profound impact on various skin disorders in the years to come.GREEN TEA, a popular beverage consumed worldwide, contains many polyphenols that have antioxidant activity superior to that of any other naturally occurring antioxidant known. Many laboratory studies conducted in mouse models of chemical carcinogen as well as UV-induced skin cancer have shown that its topical application or oral consumption results in inhibition of tumorigenesis. Studies have also shown that green tea extract also possesses anti-inflammatory activity. These anti-inflammatory and skin cancer preventive effects of green tea were found to be due to its polyphenolic constituents. The major and most preventive constituent in green tea responsible for these biological effects is (−)-epigallocatechin-3-gallate (EGCG). Understanding the molecular mechanisms for these broad effects of green tea is a subject of investigation in many laboratories. Green tea polyphenols (GTPs) have been shown to modulate biochemical pathways important in inflammatory responses, cell proliferation, and responses of tumor promoters. Treatment with EGCG on mouse skin also results in prevention of UV-B–induced immunosuppression and reactive oxygen species generation. The effect of green tea treatment, either topical or consumed orally, on human skin inflammatory responses and cancer is not clear. Based on documented extensive beneficial effects of green tea on mouse skin models, many pharmaceutical and cosmetic companies are supplementing skin care products with green tea extracts.In this review, we focus on agents in green tea and their use in dermatology. As mentioned in the editorial introduction to this article, a wide variety of naturally occurring botanical compounds have been studied for their ability to prevent UV-related skin damage.In initial studies in mouse models, we showed that cutaneous application or oral consumption of a polyphenolic fraction isolated from green tea affords protection against inflammation, chemical carcinogenesis, and photocarcinogenesis.Induction of carcinogenesis in murine and possibly in human skin is a multistage process involving 3 distinct stages: initiation, promotion, and progression.Multistage carcinogenesis requires both initiating and promoting stimuli for the development of cancer. The initiation stageis essentially an irreversible step in which genetic changes occur in gene(s) leading to genetic mutations.The promotion stageleads to the development of visible nonmalignant lesions through epigenetic mechanisms, essentially by alterations in signal transduction pathways,while the progression stageis characterized by the transformation of the preneoplastic cells to a neoplastic cell population as a result of additional genetic alterations.Because oxidants play an important role in many skin functions, including the initiation and promotion stages of multistage skin carcinogenesis, in recent years, the effect of antioxidant compounds present in fruits, vegetables, and beverages humans consume has received considerable attention as a strategy to ameliorate their adverse effects.These antioxidant compounds for the prevention of cancer can be targeted for intervention at the initiation, promotion, or progression stages of multistage carcinogenesis.Studies have shown that dietary or environmental mutagens and carcinogens, including UV light, to which humans are constantly exposed, exert their biological effects at least in part via the generation of reactive oxygen species (ROS) and free radicals. The generation of these ROS and free-radical moieties plays a major role in the induction of cancer, specifically at the promotion stage of carcinogenesis.Dietary intake of naturally occurring antioxidants therefore has been suggested as an important strategy against the toxic effects of these mutagenic and carcinogenic agents.We and others have demonstrated the inhibitory effects of polyphenols from green tea, which is commonly consumed as a beverage worldwide, against inflammation and tumor formation in skin.In this article, we have particularly summarized the available information of laboratory studies on the antioxidant, anti-inflammatory, and anticarcinogenic effects of GTPs mainly in the murine model. Available information on the human skin is also highlighted.GREEN TEATea is manufactured from the leaf and bud of the plant Camellia sinensisand is commercially available mainly in 3 forms: green tea, black tea, and oolong tea.Of the total tea production, about 78% is consumed as black tea mainly in the Western countries and some Asian countries, while about 20% is consumed as green tea mainly in Asian countries, including Japan, China, Korea, and India. About 2% is manufactured in the form of oolong tea, which is mainly produced and consumed in southeastern China.The basic steps of manufacturing the various forms of tea are similar except in the creation of their aroma and in the fermentation process, which is dependent on the oxidation states of different polyphenolic compounds present in tea leaves. The term green tearefers to the product manufactured from the fresh leaves of the tea plant by steaming and drying at elevated temperatures, with care to avoid oxidation and polymerization of the polyphenolic components. "Herbal teas" are not derived from the plant C sinensis, and when the term teais used to describe them, the plant source should be identified.POLYPHENOLS IN GREEN TEAThe polyphenolic composition in green tea is approximately similar to that of fresh leaves, including flavanols, flavonoids, and some phenolic acids. Most of the polyphenols present in the green tea are flavanols, commonly known as catechins. The major catechins found in green tea are (−)-epicatechin (EC), (−)-epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC), and EGCG. Their chemical structures are shown in Figure 1. These polyphenols are antioxidant in nature and have been shown to function as anti-inflammatory and anticarcinogenic agents in various biological systems.Of these 4 major green tea catechin derivatives or polyphenols, EGCG has been shown to be the major component and the most effective chemopreventive agent against cutaneous inflammatory or carcinogenic responses.Chemical structures of major polyphenolic compounds present in green tea.ANTI-

Journal

JAMA DermatologyAmerican Medical Association

Published: Aug 1, 2000

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