In vitro photostability and photoprotection studies of a novel 'multi-active' UV-absorber.
This paper reports on the synthesis and properties of a new UV-absorber (OC-NO) based on the most popular UV filter worldwide, ethylhexyl methoxycinnamate (OMC) in which the methoxy group has been replaced with a pyrrolidine nitroxide bearing antioxidant activity. This sunscreen active has therefore both UV-absorbing and antioxidant properties which could ideally address both the UV-B and UV-A skin photo-damage. For broad-spectrum coverage, the combinations of OC-NO with two commonly used UV-A absorbers (BMDBM and DHHB) were also studied. The results obtained reveal that OC-NO: (a) is as photostable as OMC after UV-A exposure; (b) acts as free radical scavenger as demonstrated by EPR and chemical studies; (c) reduces UV-A and UV-A+BMDBM induced lipid peroxidation in liposomes and cells, measured as reduced TBARS levels and increased C11-BODIPY red fluorescence, respectively; (d) has comparable antioxidant activity to that of vitamin E and BHT commonly used in skin care formulations; (e) is non-cytotoxic to human skin fibroblasts as assessed with the MTT assay when exposed to increasing doses of UV-A; and (f) OC-NO+DHHB is a promising, photostable broad spectrum UV-filter combination that concomitantly reduces UV-induced free radical damage. These results suggest that nitroxide/antioxidant-based UV-absorbers may pave the way for the utilization of 'multi-active' ingredients in sunscreens thereby reducing the number of ingredients in these formulations.
Venditti
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Istituto di Biochimica, Università Politecnica delle Marche, I-60131 Ancona, Italy.
Spadoni
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Tiano
L
L
Astolfi
P
P
Greci
L
L
Littarru
G P
GP
Damiani
E
E
D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D002934:Cinnamates / Q000737:chemistry* / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000737:chemistry*; D005347:Fibroblasts / Q000187:drug effects; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000494:pharmacology; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D011835:Radiation Protection / Q000379:methods*; D013471:Sunburn / Q000517:prevention & control; D013473:Sunscreening Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
D000975:Antioxidants; D002934:Cinnamates; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D013473:Sunscreening Agents; C516303:ethylhexyl methoxycinnamate