Methylparaben potentiates UV-induced damage of skin keratinocytes

Toxicology. 2006 Oct 3;227(1-2):62-72. doi: 10.1016/j.tox.2006.07.018. Epub 2006 Jul 28.


For many years, methylparaben (MP) has been used as a preservative in cosmetics. In this study, we investigated the effects of ultraviolet-B (UVB) exposure on MP-treated human skin keratinocytes. HaCaT keratinocyte was cultured in MP-containing medium for 24h, exposed to UVB (15 or 30 mJ/cm(2)) and further cultured for another 24h. Subsequent cellular viability was quantified by MTT-based assay and cell death was qualified by fluorescent microscopy and flow cytometry. Oxidative stress, nitric oxide (NO) production and cellular lipid peroxidation were measured using fluorescent probes. In addition, activation of nuclear factor kappa B and activator protein-1 was assessed by electro-mobility gel-shift assay. Practical concentrations of MP (0.003%) had a little or no effect on cellular viability, oxidative stress, NO production, lipid peroxidation and activation of nuclear transcription factors in HaCaT keratinocytes. Low-dose UVB also had little or no effect on these parameters in HaCaT keratinocytes. However, UVB exposure significantly increased cell death, oxidative stress, NO production, lipid peroxidation and activation of transcription factors in MP-treated HaCaT keratinocytes. These results indicate that MP, which has been considered a safe preservative in cosmetics, may have harmful effects on human skin when exposed to sunlight.

MeSH terms

  • Apoptosis* / drug effects
  • Apoptosis* / radiation effects
  • Cell Survival / drug effects
  • Cell Survival / radiation effects
  • Cells, Cultured
  • Electron Spin Resonance Spectroscopy
  • Electrophoretic Mobility Shift Assay
  • Flow Cytometry
  • Humans
  • Keratinocytes* / drug effects
  • Keratinocytes* / pathology
  • Keratinocytes* / radiation effects
  • Lipid Peroxidation / drug effects
  • Lipid Peroxidation / radiation effects
  • Nitric Oxide / metabolism
  • Parabens / toxicity*
  • Preservatives, Pharmaceutical / toxicity*
  • Reactive Oxygen Species / metabolism
  • Skin* / drug effects
  • Skin* / pathology
  • Skin* / radiation effects
  • Ultraviolet Rays / adverse effects*


  • Parabens
  • Preservatives, Pharmaceutical
  • Reactive Oxygen Species
  • Nitric Oxide
  • methylparaben