To obtain a preparation for external use such as for a cosmetic material, capable of effectively suppressing various disorders caused by singlet oxygen in living bodies, e.g. immediate melanism generated by the oxidation of DOPA by allowing to contain a compound having a specific reaction rate constant with a singlet oxygen as an effective component.
This preparation for external use contains a compound having ≥1×106M-1s-1 reaction rate constant with a singlet oxygen as an effective component and preferably a UV absorber (e.g. 4-t-butyl-4'- methoxydibenzoylmethane, etc.). To screen the compound, e.g. is to irradiate laser of a UV ray wave length to a system in which generation of the singlet oxygen is known, measure a minute emission in the near infrared region which is specific to the singlet oxygen, then measure the emission when a compound to be tested is added to the same system and calculate the constant from the reduction of the emission in the near infrared region and, as a concrete example, β-carotene can be used for this purpose.
MASUNAGA TAKUJI
RYU AKIYOSHI
