Views: 9 Author: Site Editor Publish Time: 2020-08-12 Origin: Site
The main component of green tea polyphenols is EGCG (that is, epigallocatechin gallate). EGCG has been proven to have multiple health benefits. Its properties range from antioxidants to anti-inflammatory. It has multiple effects such as beneficial to cardiovascular health, cancer prevention, reducing the risk of cognitive dysfunction, improving diabetes, and helping weight loss.
1. EGCG can prevent skin cancer and reduce UV damage
EGCG has anti-ultraviolet properties and may play a preventive role in the development of skin cancer. According to reports, EGCG treatment can reduce collagen synthesis and fibroblast collagenase secretion in mice (treatment after 24 hours). Because the typical representative of ultraviolet-induced intracellular damage is to affect the level of collagen synthesis and collagenase secretion.
In addition, by measuring ultraviolet B-induced erythema in guinea pigs, the damage induced by ultraviolet B was quantified. EGCG has been reported to significantly reduce erythema within 24 hours after irradiation.
Another study also analyzed the effect of EGCG on epidermal Langerhans cells (LCs) and described the decrease in cell numbers under UV irradiation. Histological tests showed that compared with the control group, the skin LCs damage of participants treated with EGCG was reduced by 58%. The dose-dependent effect of green tea polyphenols was tested with different concentrations (1-10%). At a concentration of 2.5% or higher, it exhibits adequate protection.
These results are consistent with a recent study to detect UV-induced DNA oxidative damage by measuring CD1a+ cell depletion and UV-induced anti-8-hydroxy-2-deoxyguanosine (8-OHdG) production. 8‐OHdG is related to UV-induced nucleic acid modification.
Compared with non-irradiated skin, the skin exposed to UV rays treated with green tea has a 35% reduction in CD1a+ cells. The vehicle-treated skin was reduced by 57% after irradiation, similar to untreated skin.
The level of 8-OHdG in the exposed skin after applying green tea extract was not significantly different from that in unirradiated skin. But the skin treated with the vehicle showed higher levels of 8-OHdG.
In addition, EGCG has been reported to reduce UV-induced H2O2 and NO production in the dermis and epidermis, and inhibit the infiltration of CD11b+ cells (CD11b+ is a marker on the surface of macrophages and neutrophils), which is an indicator of oxidative stress. EGCG can also inhibit the production of epidermal lipid peroxidation (LPO) and positively affect the level of other antioxidants (GSH).
A similar study involving mice of the same type provided additional information about the extent to which EGCG induced apoptosis in tumor and non-tumor areas irradiated by UVB. After 20 weeks of UV-B irradiation, the mice received EGCG treatment once a day, 5 days a week, for a total of 18 weeks. This treatment resulted in increased apoptosis in 72% of non-malignant tumors and increased apoptosis in 56% of squamous cell carcinoma cells, but had no effect on proliferative or non-tumor areas.