Abstract

Tea is one of the most widely consumed beverages worldwide, and is available in various forms. Green tea is richer in antioxidants compared to other forms of tea. Tea is composed of polyphenols, caffeine, minerals, and trace amounts of vitamins, amino acids, and carbohydrates. The composition of the tea varies depending on the fermentation process employed to produce it. The phytochemicals present in green tea are known to stimulate the central nervous system and maintain overall health in humans. Skin aging is a complex process mediated by intrinsic factors such as senescence, along with extrinsic damage induced by external factors such as chronic exposure to ultraviolet (UV) irradiation—A process known as photoaging—Which can lead to erythema, edema, sunburn, hyperplasia, premature aging, and the development of non-melanoma and melanoma skin cancers. UV can cause skin damage either directly, through absorption of energy by biomolecules, or indirectly, by increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Green tea phytochemicals are a potent source of exogenous antioxidant candidates that could nullify excess endogenous ROS and RNS inside the body, and thereby diminish the impact of photoaging. Several 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. The precise mechanism behind the anti-photoaging effect of green tea has not been explored yet. Studies using the worm model have suggested that green tea mediated lifespan extension depends on the DAF-16 pathway. Apart from this, green tea has been reported to have stress resistance and neuroprotective properties. Its ROS scavenging activity makes it a potent stress mediator, as it can also regulate the stress induced by metal ions. It is known that tea polyphenols can induce the expression of different antioxidant enzymes and hinder the DNA oxidative damage. Growing evidence suggests that green tea can also be used as a potential agent to mediate neurodegenerative diseases, including Alzheimer’s disease. EGCG, an abundant catechin in tea, was found to suppress the neurotoxicity induced by Aβ as it activates glycogen synthase kinase-3β (GSK-3β), along with inhibiting c-Abl/FE65—the cytoplasmic nonreceptor tyrosine kinase which is involved in the development of the nervous system and in nuclear translocation. Additionally, green tea polyphenols induce autophagy, thereby revitalizing the overall health of the organism consuming it. Green tea was able to activate autophagy in HL-60 xenographs by increasing the activity of PI3 kinase and BECLIN-1. This manuscript describes the reported anti-photoaging, stress resistance, and neuroprotective and autophagy properties of one of the most widely known functional foods—green tea.

Highlights

  • Tea is one of the most widely consumed beverages worldwide, and is the second-most consumed drink after water [1]

  • epigallocatechin gallate (EGCG), an abundant catechin in tea, was found to suppress the neurotoxicity induced by Aβ as it activates glycogen synthase kinase-3β (GSK-3β), along with inhibiting c-Abl/FE65—the cytoplasmic nonreceptor tyrosine kinase which is involved in the development of the nervous system and in nuclear translocation

  • This study suggests that an optimum concentration of green tea extract (3%) can protect the skin from UV radiation-induced damage [93]

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Summary

Introduction

Tea is one of the most widely consumed beverages worldwide, and is the second-most consumed drink after water [1]. ROS may accumulate inside the body from external sources like smoking, and exposure to harmful pesticides and some other pollutants [31] These ROS molecules induce oxidative stress, which can have an impact on many biological processes including apoptosis and autophagy, as they can harm different biomolecules and organelles and lead to an inflammatory response in the host. ROS promote peroxidation of the lipids in the cell membranes, along with altering the structure and function of different enzymes and promoting carbohydrate oxidation [18] Inside the brain, this could lead to neurological, age-associated diseases like Parkinson’s disease (PD) and Alzheimer’s disease (AD) [35,36]. Humans consume various compounds with antioxidant properties in their diet, like vitamin C, tocopherols, carotenoids, and flavonoids These may have structural and functional variations, but their combined action helps to reduce the level of ROS [20]. Similar results have been reported for vitamin E (3200 mg/day) and ascorbic acid (4 g/day) [47]

Photoaging
Antiphotoaging Properties of Green Tea
Stress Resistance Properties of Green Tea
Neuroprotective Properties of Green Tea
Results
Autophagy Properties of Green Tea
42 Korean females
Conclusions
Full Text
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