Tempol, one of nitroxides, is a novel ultraviolet-A1 radiation protector for human dermal fibroblasts.

BACKGROUND

Nitroxide has been reported to have antioxidant and some photoprotective properties. Exposure of skin to ultraviolet-A1 (UVA1, 340-400 nm) can lead to formation of reactive oxygen species, reduction in collagen, and increased expression of matrix metalloproteinases (MMPs).

OBJECTIVE

The goal of this research was to determine the effects of 4-hydroxy-Tempo (Tempol), one of nitroxides, in the presence of UVA1 on cytotoxicity, superoxide dismutase enzyme (SOD) activity, lipid peroxidation, and expression of collagen I, collagen III and MMP-1, MMP-3 in human dermal fibroblasts in vitro.

METHODS

Fibroblasts were irradiated by a single exposure to UVA1 and at the same time incubated with, or without, Tempol and detected twenty-four hours later. SOD activity and lipid peroxidation, as shown by accumulation malonyldialdehyde (MDA), were detected by biochemical assay. Expressions of collagen I, collagen III (protein levels) and MMP-1, MMP-3 (mRNA level) were detected by ELISA and semi-quantitative reverse transcriptase-PCR separately.

RESULTS

Cell survival curve after UVA1 irradiation showed dose dependent decrement pattern and Tempol, between 0.03 and 8 mM, increased cell viability in a dose-effect manner when the cells were exposed to 20 J/cm(2) UVA1. Fifteen Joule per centimetre square of UVA1 significantly inhibited SOD activity and collagen I, collagen III protein levels, while increased MDA level and stimulated MMP-1 and MMP-3 mRNA expression. Tempol reversed these effects caused by UVA1 in some degree or completely and in proper concentration, the results were statistically significant compared with irradiated group.

CONCLUSIONS

Tempol had photoprotective properties against UVA1 irradiation in vitro. With antioxidant ability, Tempol inhibited extracellular matrix degradation and preserved collagen production in dermis and may be used as an anti-photoaging agent.