| abstract |
SUMMARY OF THE INVENTION The present invention relates to a compound of formula Ia and Ib, a physiologically compatible salt of a compound of formula Ia and Ib, and a stereoisomer of a compound of formula Ia and Ib, wherein R 1 , R 2 , R 3 , R 4 and n comprise one or more compounds having the meaning of claim 1 and b) one or more substances selected from enzymes, vitamins and vitamin derivatives. It relates to cosmetic preparations. A feature of this compound is that the enzymes, vitamins and vitamin derivatives contained in the cosmetic preparation are stabilized and protected against denaturation. |