The influence of complexation with hydroxypropyl-b-cyclodextrin (HP-b-CD) or b-cyclodextrin (b-CD) on the photo-induced production of free radicals by the sunscreen agents octyl-dimethylaminobenzoate (ODAB), oxybenzone (OB) and octyl-methocycinnamate (OMC) was investigated. The formation of radical species during irradiation was detected by spin trapping electron paramagnetic resonance spectroscopy. 2,2,6,6-tetramethylpiperidine-1-oxyl, nitroxide radical (TEMPO) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) were used as spin traps. Following the 4h illumination with simulated sunlight, OB didi 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-centered 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-b-CD and OMC with b-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 photosensitizing potential.
Influence of complexation with cyclodextrins on photo-induced free radical production by the common sunscreen agents octyl-dimethylaminobenzoate and octyl-methoxycinnamate
MOLINARI, Alessandra;TURSILLI, Rosanna;CASOLARI, Alberto;MALDOTTI, Andrea;SCALIA, Santo
2006
Abstract
The influence of complexation with hydroxypropyl-b-cyclodextrin (HP-b-CD) or b-cyclodextrin (b-CD) on the photo-induced production of free radicals by the sunscreen agents octyl-dimethylaminobenzoate (ODAB), oxybenzone (OB) and octyl-methocycinnamate (OMC) was investigated. The formation of radical species during irradiation was detected by spin trapping electron paramagnetic resonance spectroscopy. 2,2,6,6-tetramethylpiperidine-1-oxyl, nitroxide radical (TEMPO) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) were used as spin traps. Following the 4h illumination with simulated sunlight, OB didi 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-centered 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-b-CD and OMC with b-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 photosensitizing potential.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
