The protective effects of green tea extracts on solar simulator ultraviolet irradiation induced photodamage

Hong‐Duo Chen

Chinese Journal of Aesthetic Medicine · 2009

Abstract

Objective To investigate the protective effects of green tea extracts on the skin irradiated by solar simulator ultraviolet irradiation(ssUVR).Methods Twenty healthy volunteers were enrolled in this study.Seven sites on the nonexposed back skin were marked for the experiment.Negative control site received neither ssUVR nor test materials, and positive control site received ssUVR but with no test materials.Another 5 sites were applied with base cream or 2% -5%green tea extracts followed by ssUVR at a dosage of 1.5 minimal erythema dose.Pre-and after-irradiation, erythema index(EI)was measured.Skin biopsies were taken after the last ssUVR,and immunohistochemistry was used to detect the epidermal thickness(ET)and the expression of metalloproteinases(MMP)-2,-9.Results On negative control site,the EI difference value,ET,MMP-2 score and MMP-9 score were 8.2,60.4μm,1.8 and 2.1,respectively.On positive control,these index obviously increased to 168.0,105.4μm,2.4 and 2.6,seperately.Whereas on 2%～3%green tea extracts-treated sites,those index increased least comparing to other irradiated sites(P0.05),with the values of 131.5～143.4,79.5～83.1μm,1.8～1.9 and 2.1.Conclusions Green tea extracts in the concentration of 2%～3%were essential for protection against ssUVR-induced photodamage.