Green tea extracts have a protective effect on photoaging and photoimmunosuppression. - GreenMedInfo Summary
Protective effects of green tea extracts on photoaging and photommunosuppression.
Skin Res Technol. 2009 Aug;15(3):338-45. PMID: 19624431
OBJECTIVES: This study aimed to investigate whether the sunscreen-containing 2-5% green tea extracts (GTEs) protect ultraviolet irradiation (UVR)-induced photoaging and photoimmunosuppression. MATERIALS AND METHODS: Twenty volunteers were exposed to repetitive solar-simulated UVR (ssUVR) on the upper back at a dosage of 1.5 minimal erythema doses (MED) per day for four consecutive days. Thirty minutes before each UVR and 6, 24, and 48 h after the last UV exposure, the products containing vehicle, and 2-5% GTEs were applied onto five sites on the dorsal skin, respectively. The skin biopsies were obtained 72 h after the last UVR. The thickness of the stratum corneum and epidermis was measured under the microscope and the expression of cytokeratins (CK)-5/6, CK16, metalloproteinases (MMP)-2, MMP-9, and the CD1a(+) Langerhans cells (LCs) were determined using immunohistochemistry. RESULTS: Our results showed that UVR substantially induced cutaneous erythema, thickening of the epidermis, overexpression of CK5/6, CK16, MMP-2, MMP-9, and depletion of CD1a(+) LCs. The sunscreens containing different concentrations of GTEs conferred significant protection against the photoaging and photoimmunology-related biological events. Interestingly, the protective effects were not parallel to the concentrations of GTEs, with 2% and 3% GTEs showing the most efficacious photoprotection. CONCLUSIONS: GTEs-containing sunscreens have potential photoprotective effects on UVR-induced photoaging and photoimmunosuppression.