Effects of polyphenols on skin damage due to ultraviolet A rays: an experimental study on rats

Ultraviolet (UV) radiation causes many acute and chronic conditions such as oedema of the skin, sunburn, immunosuppression, photo-ageing and skin cancer. The use of antioxidants has become of paramount importance in prevention of the damage caused by ultraviolet radiation. Epigallocatechin-3-gallate (EGCG), one of the main components of green tea, has been reported to have anti-inflammatory, antioxidant and anticarcinogenic properties.

The aim of this experimental study was to investigate to what extent EGCG prevented acute skin damage caused by UVA.

The sample contained 2% EGCG, which was prepared in hydrophilic ointment (USP XXIV) as the vehicle. Twenty-four 12-week-old Wistar albino rats are included in the study and divided into four groups, each containing six rats. Group I was formed to be the control group, which was not applied any topical medication or exposed to UV radiation. Group II was formed to observe acute effects of UVA on the skin, Group III was formed to observe effectiveness of topical EGCG on the skin applied 30 min after exposure to UVA, and Group IV was formed to observe topical EGCG applied 30 min before exposure to UVA. All groups were examined for sunburn cells, leucocyte infiltration, dermo-epidermal activity, collagen changes and elastic fibre pathologies on 24 and 72 h. Statistical analysis was performed using spss 11.5, and chi-squared test was used for the evaluation of parameters.

Group IV showed a statistically significant decrease in sunburn cells and dermo-epidermal activation compared with Group II. Group II showed significant increase in all parameters compared with Group I, showing the effects of UV exposure alone, and no difference was detected in Group II and III.

These results show a protective effect of EGCG when applied topically before UVA exposure. No benefit was detected when EGCG was applied after UV exposure.