α-Lipoic acid inhibit the decrease of collagen deposition in ultravioled B-irradiated cultured normal human skin fibroblasts cell culture

Abstract

Repeated ultraviolet B (UVB) irradiation on human skin has been considered to be responsible in premature aging
process because UVB has been proved to inhibit collagen deposition and accelerates collagen degradation. Clinical
studies showed that topical usage of 5% α-lipoic acid (ALA) improved the clinical appearance of photoaged skin.
However, the effect of ALA on collagen deposition and degradation in UVB-irradiated normal human skin fibroblasts
culture has not been reported. The aim of the study was to investigate the effect of ALA on collagen deposition and
degradation in UVB-irradiated cultured normal human skin fibroblasts. Culture of normal human skin fibroblasts were
treated with 0, 125, 250, 500 μM ALA diluted in complete Dulbecco’s Modified Eagle’s Medium (DMEM) and
irradiated with 300 mJ/cm2 UVB. The mean collagen deposition and degradation’s level were measured by Sirius
red assay and read with spectrophotometer at λ 550 nm. Mean difference of collagen deposition as expressed by
optical density (OD) between normal human skin fibroblasts cell after UVB irradiation and without UVB irradiation
was analyzed by Wilcoxon signed-ranks test and Friedman test, while mean difference collagen degradation was
analyzed by one way analysis of variance (ANOVA) and paired t test with 95% confidence level (p<0.05). The
results showed that ALA 125 μM inhibited the decrease of collagen deposition significantly (p<0.05), though higher
concentrations did not. However, ALA did not inhibit collagen degradation increment (p>0.05). In conclusion, ALA
inhibited the decrease of collagen deposition, but did not inhibit collagen degradation in UVB-irradiated normal
human skin fibroblasts culture.
Key words: α-lipoic acid - collagen - human skin - fibroblasts – UVB - irradiation