Assessment of the photo-degradation of UV-filters and radical-induced peroxidation in cosmetic sunscreen formulations.
Photo-instability of common UV-filters is a well documented phenomenon. This study develops a method for concomitant measurement of photostability and photo-induced ROS generation in cosmetic formulations. Oil-in-water formulations containing three common UV filters (OMC, BMDBM, EHT), individually or combined, were further supplemented with phosphatidylcholine and exposed to UVA. All filters show spectral decrease after UVA exposure. OMC and EHT do not induce significant lipid-peroxidation (as measured by TBARS production) while BMDBM does. In the latter case, this is reduced when BMDBM is combined with OMC but not with EHT. Neither OMC nor EHT stabilize BMDBM with respect to loss of absorbance. ROS-generation assessed via TBARS formation was supported by EPR experiments. The UV-induced changes in UV-filter performance, as monitored in the model formulations and in commercial sunscreens, demonstrate that this is a simple and effective method for stability assessment of sunscreen filters under conditions of use.
Damiani
Elisabetta
E
Dipartimento di Biochimica, Biologia e Genetica, Università Politecnica delle Marche, I-60131 Ancona, Italy. e.damiani@univpm.it
Astolfi
Paola
P
Giesinger
Jochen
J
Ehlis
Thomas
T
Herzog
Bernd
B
Greci
Lucedio
L
Baschong
Werner
W
D019411:Clinical Laboratory Techniques; D003358:Cosmetics / Q000032:analysis / Q000528:radiation effects; D004355:Drug Stability; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects*; D017382:Reactive Oxygen Species / Q000032:analysis / Q000528:radiation effects*; D013473:Sunscreening Agents / Q000032:analysis / Q000528:radiation effects*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014466:Ultraviolet Rays
D003358:Cosmetics; D005609:Free Radicals; D017382:Reactive Oxygen Species; D013473:Sunscreening Agents; D017392:Thiobarbituric Acid Reactive Substances