PURPOSE: To obtain the subject external agent for skin excellent in the treatment of pigmentation caused by the spots, freckles, sun-burn, etc., stability and safety by compounding a phenylalaninol derivative or a tyrosinol derivative as an effective component.
CONSTITUTION: A phenylalaninol derivative or a tyrosinol derivative of formula I (R1 is H or OH; R2 and R3 are H or alkyl; R4 is H, alkanoyl or benzoyl), e.g. L-tyrosinol is, as an effective component, compounded in an amount of 0.01-50wt.%, preferably 0.1-20wt.%, based on the total composition. The composition is formulated as a cosmetic in a form of lotion, milky lotion, cream, ointment, stick, solution, pack, jell, etc. A compound of formula I is obtained by suspending a phenylalanin derivative or a tyrosin derivative of formula II in alcohol, adding thionyl chloride dropwise under heating and stirring to lead to the ester, adding benzoyl chloride or an alkanoyl chloride dropwise to lead to a compound of formula III and finally subjecting this compound to reduction.
KITAYAMA TAKASHI
NISHIZAWA YOSHINORI
KIMURA MITSUTOSHI
YADA YUKIHIRO
IMOKAWA GENJI
