Double-Blinded, Placebo-Controlled Trial of Green Tea Extracts in the Clinical and Histologic Appearance of Photoaging Skin
ABSTRACT Green tea extracts have gained popularity as ingredients in topical skin care preparations to treat aging skin. Green tea polyphenolic compounds have significant antioxidant and anti-inflammatory activities, and studies suggest that these extracts help mediate ultraviolet radiation damage.
To evaluate the effects of a combination regimen of topical and oral green tea supplementation on the clinical and histologic characteristics of photoaging.
Forty women with moderate photoaging were randomized to either a combination regimen of 10% green tea cream and 300 mg twice-daily green tea oral supplementation or a placebo regimen for 8 weeks.
No significant differences in clinical grading were found between the green tea-treated and placebo groups, other than higher subjective scores of irritation in the green tea-treated group. Histologic grading of skin biopsies did show significant improvement in the elastic tissue content of treated specimens (p<.05).
Participants treated with a combination regimen of topical and oral green tea showed histologic improvement in elastic tissue content. Green tea polyphenols have been postulated to protect human skin from the cutaneous signs of photoaging, but clinically significant changes could not be detected. Longer supplementation may be required for clinically observable improvements.
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ABSTRACT: The compound (-)-epigallocatechin-3-gallate (EGCG) is the major catechin found in green tea [Camellia sinensis L. Ktze. (Theaceae)]. This polyphenolic compound and several related catechins are believed to be responsible for the health benefits associated with the consumption of green tea. The potential health benefits ascribed to green tea and EGCG include antioxidant effects, cancer chemoprevention, improving cardiovascular health, enhancing weight loss, protecting the skin from the damage caused by ionizing radiation, and others. The compound EGCG has been shown to regulate dozens of disease-specific molecular targets. Many of these molecular targets are only affected by concentrations of EGCG that are far above the levels achieved by either drinking green tea or consuming moderate doses of green tea extract-based dietary supplements. In spite of this, well-designed double-blinded controlled clinical studies have recently demonstrated the efficacy of green tea extracts and purified EGCG products in patients. Therefore, this review highlights results from what the authors believe to be some of the most clinically significant recent studies and describes current developments in the stereoselective total synthesis of EGCG.Phytochemistry 10/2006; 67(17):1849-55. DOI:10.1016/j.phytochem.2006.06.020 · 3.35 Impact Factor
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ABSTRACT: Ultraviolet (UV) exposure and menopause are known as the inducers of damage to the skin structure. The combination of these two factors accelerates the skin aging process. In this study, we aimed to evaluate the influence of UV and ovariectomy (OVX) on the permeation of drugs through the skin. The role of tight junctions (TJs) and adherens junctions (AJs) in the cutaneous absorption of extremely lipophilic permeants and macromolecules was explored. The OVX nude mouse underwent bilateral ovary removal. Both UVA and UVB were employed to irradiate the skin. The physiological and biochemical changes of the skin structure were examined with focus on transepidermal water loss (TEWL), skin color, immunohistochemistry, and mRNA levels of proteins. UVB and OVX increased TEWL, resulting in stratum corneum (SC) integrity disruption and dehydration. A hyperproliferative epidermis was produced by UVB. UVA caused a pale skin color tone due to keratinocyte apoptosis in the epidermis. E-cadherin and β-catenin showed a significant loss by both UVA and UVB. OVX downregulated the expression of filaggrin and involucrin. A further reduction was observed when UV and OVX were combined. The in vitro cutaneous absorption demonstrated that UV increased the skin permeation of tretinoin by about twofold. However, skin accumulation and flux of estradiol were not modified by photoaging. OVX basically revealed a negligible effect on altering the permeation of small permeants. OVX increased tretinoin uptake by the appendages from 1.36 to 3.52 μg/cm(2). A synergistic effect on tretinoin follicular uptake enhancement was observed for combined UV and OVX. However, the intervention of OVX to photoaged skin resulted in less macromolecule (dextran, molecular weight = 4 kDa) accumulation in the skin reservoir because of retarded partitioning into dry skin. The in vivo percutaneous absorption of lipophilic dye examined by confocal microscopy had indicated that the SC was still important to controlling topical delivery, although the role of epidermal junctions could not be simply ignored.Journal of the American Aging Association 04/2015; 37(2):9757. DOI:10.1007/s11357-015-9757-1 · 3.45 Impact Factor
- Green Tea: Varieties, Production and Health Benefits, Edited by Wenbiao Wu, 01/2013: chapter 6. Antidiabetic Propertiew of Green Tea Catechins: pages 109-124; NOVA Publishers., ISBN: 978-1-62257-562-6