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Methylparaben potentiates UV-induced damage of skin keratinocytes

Osamu Handa1, Satoshi Kokura, Satoko Adachi

  • 1Department of Biomedical Safety Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.

Toxicology
|August 30, 2006
PubMed

Insights

Methylparaben (MP), a common cosmetic preservative, may harm skin cells when exposed to sunlight. Studies show MP combined with UVB radiation increases cell death and oxidative stress in human keratinocytes.

Area of Science:

  • Dermatology
  • Cosmetic Science
  • Toxicology

Background:

  • Methylparaben (MP) is widely used as a preservative in cosmetic products.
  • Its safety has been generally accepted, but potential interactions with environmental factors are less understood.

Purpose of the Study:

  • To investigate the combined effects of methylparaben (MP) and ultraviolet-B (UVB) exposure on human skin keratinocytes.
  • To assess the safety of MP in cosmetic products under sunlight conditions.

Main Methods:

  • HaCaT keratinocytes were cultured with MP, exposed to UVB radiation (15 or 30 mJ/cm(2)), and analyzed for viability, cell death, oxidative stress, nitric oxide (NO) production, lipid peroxidation, and transcription factor activation (NF-κB, AP-1).
  • Assays included MTT, fluorescent microscopy, flow cytometry, fluorescent probes, and electro-mobility gel-shift assay.

Main Results:

  • MP alone or low-dose UVB alone had minimal effects on keratinocyte viability and related stress markers.
  • Combined exposure to MP and UVB significantly increased cell death, oxidative stress, NO production, lipid peroxidation, and activation of NF-κB and AP-1.
  • These effects were observed at practical MP concentrations (0.003%).

Conclusions:

  • Methylparaben, considered safe in cosmetics, may pose risks to human skin when exposed to sunlight.
  • The combination of MP and UVB radiation induces significant cellular damage and oxidative stress in skin keratinocytes.
  • Further research is warranted to evaluate the long-term implications of MP use in sun-exposed cosmetic applications.

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