The invention provides novel compounds of general formula I wherein R.sup.1, R.sup.2 and R.sup.3 are independently hydrogen, OR.sup.4, C.sub.1-C.sub.6 alkyl or C.sub.2-C.sub.6 alkenyl, R.sup.4 is hydrogen, C.sub.1-C.sub.6 alkyl or C.sub.2-C.sub.6 alkenyl, --N-(AA) represents the residue of an amino acid or of a peptide which is bonded over the N-terminus of the amino acid or the peptide and the peptide is composed of 2 to 6, that means 2, 3, 4, 5 or 6, amino acids, wherein the C-terminus of the amino acid or the peptide is optionally esterified with a C.sub.1-C.sub.16 hydrocarbon moiety and n is an integer of 1 to 5. The compounds are in particular useful for cosmetic applications.