Use of a compound of formula R 1 -W m -X n -AA 1 -AA 2 -AA 3 -AA 4 -AA 5 -AA 6 -(AA 7) a -(AA 8) b -Y p -Z q -R 2, its stereoisomers and/or its cosmetically or pharmaceutically acceptable salts, wherein: AA 1 is Glu; AA 2 is Glu; AA 3 is Met; AA 4 is Gin; AA 5 is Arg; AA 6 is Arg; AA 7 is selected from the group consisting of Ala, Ser, Gly, Thr, Pro, Glu, Lys and Val; AA 8 is selected from the group consisting of Asp, Glu, Asn and Gin; and 0, 1 or 2 of AA 1, AA 2, AA 3, AA 4, AA 5 and AA 6 are replaced providing that: when AA 1 is replaced, it is replaced by an amino acid selected from the group formed by Asp, Gln and Asn; when AA 2 is replaced, it is replaced by an amino acid selected from the group formed by Asp and Gin; when AA 3 is replaced, it is replaced by an amino acid selected from the group formed by Leu and lie; when AA 4 is replaced, it is replaced by an amino acid selected from the group formed by Glu, Asn and Asp; when AA 5 is replaced, it is replaced by Lys; and when AA 6 is replaced, it is replaced by an amino acid selected from the group formed by Lys and His; a is 1 and b is 0 or 1; W, X, Y and Z are each independently an amino acid; m, n, p and q are each independently 0 or 1; m+n+p+q is less than or equal to 2; R 1 is selected from the group consisting of H, a polymer derived from polyethylene glycol, a non-cyclic aliphatic group, alicyclyl, heterocyclyl, heteroarylalkyl, aryl, aralkyl and R 5 -CO-, wherein R 5 is selected from the group consisting of H, a non-cyclic aliphatic group, alicyclyl, aryl, aralkyl, heterocyclyl and heteroarylalkyl; R 2 is selected from the group consisting of -NR 3 R 4, -OR 3, -SR 3, wherein R 3 and R 4 are independently selected from a group consisting of H, a polymer derived from polyethylene glycol, a non-cyclic aliphatic group, alicyclyl, heterocyclyl, heteroarylalkyl, aryl and aralkyl; and R 1 and R 2 are not amino acids, in the cosmetic, non-therapeutic treatment and/or care of the skin, hair, nails and/or mucous membranes, wherein said cosmetic, non-therapeutic treatment and/or care is the maintenance and/or improvement of the physical barrier function of the skin and the immunological barrier function of the skin. AA 1 is Glu; AA 2 is Glu; AA 3 is Met; AA 4 is Gin; AA 5 is Arg; AA 6 is Arg; AA 7 is selected from the group consisting of Ala, Ser, Gly, Thr, Pro, Glu, Lys and Val; AA 8 is selected from the group consisting of Asp, Glu, Asn and Gin; and 0, 1 or 2 of AA 1, AA 2, AA 3, AA 4, AA 5 and AA 6 are replaced providing that: when AA 1 is replaced, it is replaced by an amino acid selected from the group formed by Asp, Gln and Asn; when AA 2 is replaced, it is replaced by an amino acid selected from the group formed by Asp and Gin; when AA 3 is replaced, it is replaced by an amino acid selected from the group formed by Leu and lie; when AA 4 is replaced, it is replaced by an amino acid selected from the group formed by Glu, Asn and Asp; when AA 5 is replaced, it is replaced by Lys; and when AA 6 is replaced, it is replaced by an amino acid selected from the group formed by Lys and His; when AA 1 is replaced, it is replaced by an amino acid selected from the group formed by Asp, Gln and Asn; when AA 2 is replaced, it is replaced by an amino acid selected from the group formed by Asp and Gin; when AA 3 is replaced, it is replaced by an amino acid selected from the group formed by Leu and lie; when AA 4 is replaced, it is replaced by an amino acid selected from the group formed by Glu, Asn and Asp; when AA 5 is replaced, it is replaced by Lys; and when AA 6 is replaced, it is replaced by an amino acid selected from the group formed by Lys and His; a is 1 and b is 0 or 1; W, X, Y and Z are each independently an amino acid; m, n, p and q are each independently 0 or 1; m+n+p+q is less than or equal to 2; R 1 is selected from the group consisting of H, a polymer derived from polyethylene glycol, a non-cyclic aliphatic group, alicyclyl, heterocyclyl, heteroarylalkyl, aryl, aralkyl and R 5 -CO-, wherein R 5 is selected from the group consisting of H, a non-cyclic aliphatic group, alicyclyl, aryl, aralkyl, heterocyclyl and heteroarylalkyl; R 2 is selected from the group consisting of -NR 3 R 4, -OR 3, -SR 3, wherein R 3 and R 4 are independently selected from a group consisting of H, a polymer derived from polyethylene glycol, a non-cyclic aliphatic group, alicyclyl, heterocyclyl, heteroarylalkyl, aryl and aralkyl; and R 1 and R 2 are not amino acids,