title: Tea extracts protect normal lymphocytes but not leukemia cells from UV radiation-induced ROS production: An EPR spin trap study.
abstract: OBJECTIVE
  An ex vivo method for detection of free radicals and their neutralization by aqueous tea in human normal lymphocytes and MEC-1 leukemia cells under ultraviolet (UV) irradiation was investigated.
  
  
  METHODS
  This method is based on the electron paramagnetic resonance (EPR) spectroscopy spin-trapping technique. 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide (BMPO) was used as the spin trap. Normal human lymphocytes and leukemia cells were exposed to UVB radiation (290-315 nm) at 47.7 and 159 mJ/cm(2) and to UVA radiation (315-400 nm) at 53.7 J/cm(2).
  
  
  RESULTS
  No significant radical production at 47.7 mJ/cm(2) UVB dose in both cell lines was observed. In normal cells, free radical production was observed at 159 mJ/cm(2) UVB and 53.7 J/cm(2) UVA doses. However, both UV sources did not significantly produce free radicals in leukemia cells. A radical scavenging property of tea extracts (black, green, sage, rosehip) was observed in normal lymphocytes after both UVB and UVA exposure. In leukemia cells, the intensities of EPR signals produced in BMPO with tea extracts were found to be increased substantially after UVA exposure.
  
  
  CONCLUSIONS
  These results showed that UV radiation induced free radical formation in normal human lymphocytes and indicated that tea extracts may be useful as photoprotective agents for them. On the other hand, tea extracts facilitated free radical production in leukemia cells.
authors.affiliation: a Gazi University Faculty of Medicine Biophysics Department , Beşevler, Ankara , Turkey.
authors.forename: Semra
authors.initials: S
authors.lastname: Tepe Çam
authors.affiliation: b Physics Engineering Department, Hacettepe University , Beytepe, Ankara , Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Polat
authors.affiliation: a Gazi University Faculty of Medicine Biophysics Department , Beşevler, Ankara , Turkey.
authors.forename: Meriç Arda
authors.initials: MA
authors.lastname: Esmekaya
authors.affiliation: a Gazi University Faculty of Medicine Biophysics Department , Beşevler, Ankara , Turkey.
authors.forename: Ayşe G
authors.initials: AG
authors.lastname: Canseven
authors.affiliation: a Gazi University Faculty of Medicine Biophysics Department , Beşevler, Ankara , Turkey.
authors.forename: Nesrin
authors.initials: N
authors.lastname: Seyhan
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005260:Female; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D010936:Plant Extracts / Q000008:administration & dosage*; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects; D011837:Radiation-Protective Agents / Q000008:administration & dosage; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013113:Spin Labels; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D010936:Plant Extracts; D011837:Radiation-Protective Agents; D017382:Reactive Oxygen Species; D013113:Spin Labels; D013662:Tea
keywords: EPR spin trap; Lymphocyte; UV; antioxidants; leukemia; radicals; tea extract