Influence of complexation with cyclodextrins on photo-induced free radical production by the common sunscreen agents octyl-dimethylaminobenzoate and octyl-methoxycinnamate.
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.
Molinari
A
A
Dipartimento di Chimica, Università di Ferrara, Ferrara, Italy.
Tursilli
R
R
Casolari
A
A
Maldotti
A
A
Scalia
S
S
D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000138:chemical synthesis* / Q000494:pharmacology; D003497:Cyclic N-Oxides; D003505:Cyclodextrins / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet; D013473:Sunscreening Agents / Q000737:chemistry* / Q000528:radiation effects; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology
D002934:Cinnamates; D003497:Cyclic N-Oxides; D003505:Cyclodextrins; D005609:Free Radicals; D013473:Sunscreening Agents; C508310:octyl-dimethylaminobenzoate; C118580:octylmethoxycinnamate; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D004124:p-Dimethylaminoazobenzene; C003959:TEMPO