Influence of complexation with cyclodextrins on photo-induced free radical production by the common sunscreen agents octyl-dimethylaminobenzoate and octyl-methoxycinnamate

Pharmazie. 2006 Jan;61(1):41-5.


The influence of complexation with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) or beta-cyclodextrin (beta-CD) on the photo-induced production of free radicals by the sunscreen agents octyl-dimethylaminobenzoate (ODAB), oxybenzone (OB) and octyl-methoxycinnamate (OMC) was investigated. The formation of radical species during irradiation was detected by spin-trapping electron paramagnetic resonance (EPR) spectroscopy. 2,2,6,6-tetramethylpiperidine-1-oxyl, nitroxide radical (TEMPO) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) were used a spin-traps. Following the 4-h illumination with simulated sunlight, OB did not generate radicals. On the other hand, photoexcitation of solutions containing ODAB or OMC produced a marked decrease (>40%) of the TEMPO signal intensity, demonstrating the formation of carbon-centred radicals. In addition, the results obtained on irradiation of ODAB solutions containing DMPO as spin-trap indicated the generation of oxygen-centred radicals. Complexation of ODAB with HP-beta-CD and OMC with beta-CD markedly inhibited (>64%) the formation of free radicals generated by the sunscreens on exposure to simulated sunlight. Therefore, inclusion of ODAB and OMC into the cyclodextrin cavities minimizes their photosensitising potential.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography, High Pressure Liquid
  • Cinnamates / chemical synthesis*
  • Cinnamates / pharmacology
  • Cyclic N-Oxides
  • Cyclodextrins / chemistry*
  • Electron Spin Resonance Spectroscopy
  • Free Radicals / chemistry*
  • Free Radicals / radiation effects
  • Light
  • Magnetic Resonance Spectroscopy
  • Photochemistry
  • Spectrophotometry, Ultraviolet
  • Sunscreening Agents / chemistry*
  • Sunscreening Agents / radiation effects
  • p-Dimethylaminoazobenzene / analogs & derivatives*
  • p-Dimethylaminoazobenzene / chemical synthesis
  • p-Dimethylaminoazobenzene / pharmacology


  • Cinnamates
  • Cyclic N-Oxides
  • Cyclodextrins
  • Free Radicals
  • Sunscreening Agents
  • octyl-dimethylaminobenzoate
  • octylmethoxycinnamate
  • 5,5-dimethyl-1-pyrroline-1-oxide
  • p-Dimethylaminoazobenzene