Blue light-induced oxidative stress in human corneal epithelial cells: protective effects of ethanol extracts of various medicinal plant mixtures

Invest Ophthalmol Vis Sci. 2014 Jun 12;55(7):4119-27. doi: 10.1167/iovs.13-13441.


Purpose: To investigate the effects of visible light on human corneal epithelial cells and the impact of natural antioxidants on oxidative stress produced by overexposure to light.

Methods: Light-emitting diodes with various wavelengths (410-830 nm) were used to irradiate human corneal epithelial cells, and cell viability was assessed. The production of reactive oxygen species (ROS) was analyzed using 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA). Ethyl alcohol (EtOH) extracts were prepared from mixtures of medicinal plants. After application of the EtOH extracts, the free radical scavenging activity was measured using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The induction of antioxidant enzymes including heme oxygenase-1 (HO-1), peroxiredoxin-1 (Prx-1), catalase (CAT), and superoxide dismutase-2 (SOD-2) by the extracts was evaluated by reverse transcription-polymerase chain reaction and Western blotting. The ability of the extracts to inhibit ROS was also analyzed using DCF-DA.

Results: The viability of corneal epithelial cells was diminished after irradiation of blue light (above 10 J at 410 nm and 50 J at 480 nm). Reactive oxygen species production was induced by irradiation at 410 and 480 nm at doses of 5 J/cm(2) and higher. Ethyl alcohol extracts had potent radical scavenging activity. Application of the extracts not only increased the expression of HO-1, Prx-1, CAT, and SOD-2, but it also attenuated the ROS production induced by blue light in a dose-dependent manner.

Conclusions: Overexposure to blue light (410-480 nm) may have a harmful effect on human corneal epithelial cells compared with other visible light wavelengths. Medicinal plant extracts can have potent protective effects on blue light-induced oxidative stress.

Keywords: corneal epithelial cells; light emitting diode; medicinal plants; oxidative stress; reactive oxygen species; visible light.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Survival / drug effects
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Dose-Response Relationship, Radiation
  • Epithelium, Corneal / drug effects
  • Epithelium, Corneal / metabolism*
  • Epithelium, Corneal / radiation effects
  • Ethanol / pharmacology*
  • Humans
  • Light / adverse effects*
  • Oxidative Stress / drug effects*
  • Oxidative Stress / radiation effects
  • Plant Extracts / pharmacology*
  • Plants, Medicinal*
  • Radiation Injuries / metabolism
  • Radiation Injuries / pathology
  • Radiation Injuries / prevention & control*
  • Reactive Oxygen Species / metabolism
  • Solvents / pharmacology


  • Plant Extracts
  • Reactive Oxygen Species
  • Solvents
  • Ethanol