Dr. Thomas Herrling
Messung von UV-induzierten freien Radikalen in der
menschlichen Haut
Privatinstitut
Galenus GmbH, Berlin
UVA generated free radicals in human skin were measured by ESR (Electron Spin Resonance) spectroscopy and imaging. The short life time of the generated free radicals and reactive oxygen species like •OH-; and L• demands the application of spin traps (nitroxide spin labels) for scavenging and accumulating to get a sufficient signal to Noise ratio.
The ESR spectroscopy and imaging measurements have shown that the free radicals in skin are mainly generated by UVA. Using ESR measurements the protective effect of UVA-filters and antioxidants in the skin could be distinctly detected.
The used microwave frequencies of 9.5 GHz (λ=3 cm) and
3 GHz (λ= 9.5 cm) enable an undisturbed investigation of the whole skin
up to the lower dermis in contrast to optical detection methods with λ=350
– 600 nm.
The ESR is a valuable method for the evaluation of the UVA protection capacity
of sunscreen products.
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