Increased insulin-IGF-1 signaling in acne vulgaris activates PI3K-Akt-mTORC1 signaling cascade and plays a key role in the Western-diet induced acne. The mTOR kinase also belongs to the family of PI3K related kinases. Molecular docking studies showed that EGCG binds well to the PI3K domain active site, agreeing with the findings that EGCG competes for ATP binding. Additionally, Van Aller et al., 2011 provided evidence that EGCG is an ATP-competitive inhibitor of both PI3K and mTOR. Im et al., 2012 provided experimental evidence that EGCG treatment of insulin growth factor (IGF-1) stimulated SZ95 sebocytes decreased mTOR phosphorylation and thus mTORC1 activity. The green tea-derived plant sterols have shown a therapeutic role in the treatment of acne vulgaris. Recent evidence suggests that there is increased phosphoinositide 3-kinase-Akt-mammalian target of rapamycin complex 1 (PI3K-Akt-mTORC1) signaling in the skin of patients with acne vulgaris and that increased PI3K-Akt-mTORC1 signaling induces sebum production. acnes) and (d) inflammation around pilosebaceous follicles. Acne may be caused by multiple mechanisms including (a) increased sebum production by the sebaceous glands (b) altered keratinization within pilosebaceous follicles (c) proliferation of bacteria Propionibacterium acnes (P. Acne is not a life threatening condition but it can leave permanent scaring on the face and cause physical and psychological morbidities. Sebum secretion is associated with hormonal activity in the human body and excess sebum production is implicated in the development of skin disorders, such as acne vulgaris. Lipids are produced by other glands in the body but the two most specific lipids to sebaceous glands are squalene and wax esters. Sebaceous glands are found throughout the human body, especially on the face and scalp, and they produce sebum-a mixture of lipids. ( a) (+)-Catechin (C) ( b) (−)-Epicatechin (EC) ( c) (−)-Epicatechin gallate (ECG) ( d) (−)-Epigallocatechin (EGC) ( e) (−)-Epigallocatechin gallate (EGCG). Ĭhemical structures of major tea polyphenols. EGCG is the most abundant catechin and has been shown to have beneficial health effects on skin. Catechins are divided into catechin (C), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin-3-gallate (EGCG) ( Figure 1 and Figure 2). Components of green tea beverage measured as weight percentage of extract solids include 30%–42% catechins, 5%–10% flavonols, and 2%–4% other flavonoids. Green tea is produced from fresh leaves in such a way that prevents oxidation of polyphenolic components (mainly catechins), oolong tea polyphenols are partially oxidized, while polyphenols in black tea undergo a high degree of oxidation. Camellia sinensis is the plant that gives rise to a variety of teas depending on specific processing of the plant. Tea is the second most consumed beverage worldwide and an important source of plant polyphenols in the human diet. They possess anti-inflammatory and anti-carcinogenic properties and may aid in the prevention of cardiovascular disease, as well as protect skin from ultraviolet radiation (UVR). Polyphenols are antioxidants and play a role in preventing oxidative damage caused by the reactive oxygen species (ROS). After ingestion, polyphenols are absorbed in the intestinal epithelium and have been shown to reach systemic circulation. Polyphenols are naturally occurring compounds found in plants and common foods such as nuts, fruits, vegetables, chocolate, wine, and tea. Research studies of high quality and with large sample sizes are needed to assess the efficacy of tea polyphenols in topical and oral prevention of acne vulgaris and lipid synthesis by the sebaceous glands. Overall, there is some evidence that tea polyphenols in topical formulation may be beneficial in reducing sebum secretion and in treatment of acne. Tea polyphenol sources included green tea (six studies) and tea, type not specified (two studies). None of the studies evaluated both topical and systemic tea polyphenols. Seven studies evaluated topical tea polyphenols one study examined systemic tea polyphenols. Two studies evaluated tea polyphenol effects on sebum production six studies examined tea polyphenol effects on acne vulgaris. Of the 59 studies found, eight met the inclusion criteria. The PubMed database was searched for studies on tea polyphenols, sebum secretion, and acne vulgaris. This review examines the evidence for use of topically and orally ingested tea polyphenols against sebum production and for acne treatment and prevention. Recent studies suggest that tea polyphenols may be used for reducing sebum production in the skin and for treatment of acne vulgaris. Polyphenols have antimicrobial, anti-inflammatory, and antineoplastic properties. Polyphenols are antioxidant molecules found in many foods including nuts, fruits, vegetables, chocolate, wine, and tea.
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