title: Effect of 635 nm light-emitting diode irradiation on intracellular superoxide anion scavenging independent of the cellular enzymatic antioxidant system.
abstract: OBJECTIVE
  The aim of this study was to examine the reactive oxygen species (ROS) that are dissipated by 635 nm irradiation, and the effect of 635 nm irradiation on ROS scavenging system.
  
  
  BACKGROUND
  Intracellular ROS are produced in the form of superoxide anion by either nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or xanthine oxidase in response to a number of stimuli. Low-level light irradiation decreases the intracellular ROS level and has been used in clinical situations for reducing the level of oxidative stress.
  
  
  METHODS
  Human epithelial cells were exposed to exogenous and endogenous oxidizing agents that promote the generation of harmful ROS. These were then irradiated with 635 nm LED light, 5 mW/cm(2) for 1 h, 18 J/cm(2) or by 470 nm LED light, also 5 mW/cm(2) for 1 h, 18 J/cm(2) on a 9 cm cell culture dish. After irradiation, the MTT reduction method and malondialdehyde (MDA) colorimetric assay were performed in xanthine/xanthine oxidase (XXO)- or hydrogen peroxide (H(2)O(2))-treated HaCaT cells. The superoxide anion was detected by an electron spin resonance (ESR) spectrometer using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin trap and H(2)O(2) was assayed by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCF-DA).
  
  
  RESULTS
  Irradiation at 635 nm enhanced cell viability in the XXO-treated HaCaT cells. Also, irradiation had a much lesser effect on cell viability in the HaCaT cells treated with exogenous H(2)O(2) as compared with that in cells treated with N-acetyl-L-cysteine. The level of the superoxide anion increased in response to XXO treatment, and then decreased after 635 nm irradiation. Irradiation with 635 nm led to a decrease in superoxide anion and lipid peroxidation levels in the presence or absence of diethyldithiocarbamate.
  
  
  CONCLUSIONS
  These results highlight the potential role of 635 nm irradiation in protection against oxidative stress by scavenging superoxide anions. Also, a pathway that is independent of the activities of intracellular enzymatic ROS scavengers, such as superoxide dismutase, glutathione peroxidase and catalase might be involved in its mechanism of action.
authors: Department of Oral Pathology, School of Dentistry, Dental Science Research Institute, Chonnam National University, Bug-Gu, Gwangju, Korea.
authors: WonBong
authors: W
authors: Lim
authors: JiSun
authors: J
authors: Kim
authors: ChaeGwang
authors: C
authors: Lim
authors: SangWoo
authors: S
authors: Kim
authors: SangMi
authors: S
authors: Jeon
authors: Sandeep
authors: S
authors: Karna
authors: MinSung
authors: M
authors: Cho
authors: HongRan
authors: H
authors: Choi
authors: OkJoon
authors: O
authors: Kim
mesh_terms: D000111:Acetylcysteine / Q000378:metabolism; D000704:Analysis of Variance; D002461:Cell Line, Transformed; D002470:Cell Survival; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015603:Keratinocytes / Q000201:enzymology* / Q000528:radiation effects*; D008027:Light; D015227:Lipid Peroxidation; D009243:NAD / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D019097:Spin Trapping; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D009243:NAD; D013481:Superoxides; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D000111:Acetylcysteine