Abstract

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.