To obtain an isoleucine-containing composition that can improve stability thereof, particularly the stability at a temperature near the body by admixing a specific compound to medicines, cosmetics, food products and the like.
An isoleucine (or its anhydride) and an amine responding to the compound to be prepared are subjected to condensation reaction using a peptide synthesis reagent, then the free amino groups are acylated, when necessary, and purified, when necessary, to prepare the objective isoleucine derivative of formula I [R1 is H, (subjected) benzyloxycarbonyl; R2 is a 8-22C including cyclic structures) straight or branched chain alkyl, alkenyl; n is 1-8]. typically N-(benzyloxycarbonyl)isoleucinestearylamide of formula II. This compound is admixed to cosmetics, medicines and the like, particularly of high content of oily component. The amount of the compound of formula I is preferably 0.1-100 pts.wt. per 1 pt.wt. of the oily component.
HIRATSUKA KAORI
SHIRAI HIROYOSHI
IYANAGI KOICHI
