Given the role in actinic damage played by free
radicals generated through exposure to solar radiation,
one way to enhance the protective efficacy of sunscreens
is to add ingredients with antioxidant properties. This
strategy was used in an innovative formulation that
combined the UV-B absorber octyl-methoxycinnamate
and the antioxidant piperidine nitroxide (Tempol).15
This novel sunscreen absorbed photons from both
UV-B and UV-A radiation, trapped free radicals, and
reduced lipid peroxidation. In another study excellent
photoprotective results were obtained when avobenzone
and diethylamino hydroxybenzoyl hexyl benzoate, two
UV-A absorbers, were added.16
The combination of
octyl-methoxycinnamate and piperidine nitroxide with
diethylamino hydroxybenzoyl hexyl benzoate produced a broad spectrum, photostable sunscreen that also
attenuated the damage caused by the free radicals
generated by UV radiation. The use of such substances in
multiactive photoprotective formulations will allow the
number of ingredients to be reduced while maintaining
or even increasing overall effectiveness.16