Complementary effects of antioxidants and sunscreens in reducing UV-induced skin damage as demonstrated by skin biomarker expression.

ABSTRACT

BACKGROUND: UV-exposure of the skin causes oxidative stress, leading to inflammatory reactions and premature skin aging. Sunscreens protect by absorbing or reflecting UV on the skin surface. Antioxidants provide protection by quenching UV-induced reactive oxygen species inside skin. OBJECTIVE: To evaluate the complementary photoprotective benefits of formulas containing either an antioxidant complex of Cassia alata leaf extract or a combination of the antioxidant complex and sunscreens on normal healthy volunteers using biomarkers of skin damage. METHODS: Each formula and a placebo control were applied separately to selected areas on the lower back of 10 individuals for 4 consecutive days. On Day 4, the control and three test sites were exposed to 5 x MED (minimal erythemal dose) of solar-simulated UV-irradiation (UVR). On Day 5, 4-mm punch biopsies were collected from the four exposed sites and a control site (untreated, unexposed) for immunohistochemistry. RESULTS: Exposure to 5 x MED demonstrated significant damage as assessed by thymine dimer formation, MMP-9 and p53 protein expression on untreated exposed skin. The formula containing sunscreens + the antioxidant complex was the most protective, followed by the formula with the antioxidant alone. CONCLUSION: The study demonstrated that a combination of antioxidants and sunscreens complement each other, resulting in superior photoprotection.