Synthesis and application of a novel sunscreen-antioxidant.
Background information on the inefficacy of sunscreens to provide free radical protection in skin, despite their usefulness in preventing sunburn/erythema, prompted us to synthesize a compound which would display in the same molecule both UV-absorbing and antioxidant capacities. For this purpose, the UVB absorber, 2-ethylhexyl-4-methoxycinnamate (OMC) was combined with the piperidine nitroxide TEMPOL, which has antioxidant properties. The spectral properties of the new nitroxide-based sunscreen (MC-NO) as well as its efficacy to prevent photo-oxidative damage to lipids induced by UVA, natural sunlight and 4-tert-butyl-4-methoxydibenzoylmethane (BMDBM), a photo-unstable sunscreen which generates free radicals upon UV radiation, was studied. The results obtained demonstrate that MC-NO: (a) absorbs in the UVB region even after UVA irradiation; (b) acts as free radical scavenger as demonstrated by EPR experiments; (c) strongly reduces both UVA-, sunlight- and BMDBM-induced lipid peroxidation in liposomes, measured as reduced TBARS levels; and (d) has comparable antioxidant activity to that of commonly used vitamin E and BHT in skin care formulations. These results suggest that the use of the novel sunscreen-antioxidant or of other nitroxide-based sunscreens in formulations aimed at reducing photoinduced skin damage may be envisaged.
Damiani
Elisabetta
E
Istituto di Biochimica, Università Politecnica delle Marche, Ancona, Italy. e.damiani@univpm.it
Astolfi
Paola
P
Cionna
Laura
L
Ippoliti
Francesca
F
Greci
Lucedio
L
D000975:Antioxidants / Q000138:chemical synthesis / Q000494:pharmacology*; D002934:Cinnamates / Q000138:chemical synthesis / Q000494:pharmacology*; D003497:Cyclic N-Oxides / Q000138:chemical synthesis / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008081:Liposomes; D010084:Oxidation-Reduction / Q000187:drug effects; D013113:Spin Labels / Q000138:chemical synthesis; D013473:Sunscreening Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014466:Ultraviolet Rays
D000975:Antioxidants; D002934:Cinnamates; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D008081:Liposomes; D013113:Spin Labels; D013473:Sunscreening Agents; D017392:Thiobarbituric Acid Reactive Substances; C118580:octylmethoxycinnamate; C001803:tempol