Polypeptide and cosmetic composition or pharmaceutical composition and use thereof

A peptide represented by Formula (I), or a stereoisomer thereof, or a mixture of the stereoisomers thereof, or a cosmetically acceptable salt thereof, or a pharmaceutically acceptable salt thereof, characterized in that

• R1—X1—X2—X3—X4—X5—X6—X7—X8—R2 (I)
• in Formula (I),
• X1 is selected from -Val-, -Ser-, -Trp-, -Met-, -Leu-, -Glu-, -Ala-, -Pro-, -Tyr- or -Thr-;
• X2 is selected from -Lys-, -Arg-, -His-, -Met-, -Ala-, -Leu-, -Asn-, -Trp-, -Thr-, -Pro-, -Gly-, -Phe-, -Asp-, -Ser- or -Cys-;
• X3 is selected from -Val-, -Gly-, -Leu-, -Pro-, -Met-, -Ala-, -Gln-, -Asp-, -Phe-, -Ser-, -Cys- or -Lys-;
• X4 is selected from -Gly-, -Leu-, -Pro-, -Ala-, -Phe-, -Val-, -Trp-, -Asn- or -Glu-;
• X5 is selected from -Phe-, -Trp-, -Tyr- or a bond;
• X6 is selected from -Gln-, -Leu-, -Ala-, -Val-, -Phe-, -Arg-, -Tyr-, -Gly- or -Asn-;
• X7 is selected from -Lys-, -Arg-, -His- or a bond;
• X5 is selected from -Trp-, -Ala-, -Asp-, -Lys-, -Gly-, -Tyr-, -Met- or -Arg-;
• R1 is selected from H or R3—CO—, wherein R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl;
• R2 is selected from —NR4R5 or —OR4, wherein each R4 and R5 are independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl;
• the alkyl refers to a saturated aliphatic linear or branched chain alkyl having 1-24 carbon atoms (optionally having 1-16 carbon atoms;
• optionally having 1-14 carbon atoms;
• optionally having 1-12 carbon atoms;
• or optionally having 1, 2, 3, 4, 5, or 6 carbon atoms);
• optionally selected from methyl, ethyl, isopropyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-ethylhexyl, 2-methylbutyl, or 5-methylhexyl;
• the alkenyl refers to a linear or branched chain alkenyl having 2-24 carbon atoms (optionally having 2-16 carbon atoms;
• optionally having 2-14 carbon atoms;
• optionally having 2-12 carbon atoms;
• or optionally having 2, 3, 4, 5, or 6 carbon atoms);
• the alkenyl has one or more carbon-carbon double bonds, optionally has 1, 2, or 3 conjugated or non-conjugated carbon-carbon double bonds;
• the alkenyl is bonded to the rest portions of a molecule through a single bond;
• and is optionally selected from vinyl, oleyl, or linoleyl;
• optionally, the substituent in the “substituted alkyl” or “substituted alkenyl” is selected from C1-C4 alkyl;
• hydroxyl;
• C1-C4 alkoxy;
• amino;
• C1-C4 aminoalkyl;
• C1-C4 carbonyloxy;
• C1-C4 oxycarbonyl;
• halogen (such as fluorine, chlorine, bromine, and iodine);
• cyano;
• nitro;
• azide;
• C1-C4 alkylsulfonyl;
• thiol;
• C1-C4 alkylthio;
• C6-C30 aryloxy such as phenoxy;
• —NRb(C═NRb)NRbRc, wherein Rb and Rc are independently selected from H, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, C3-C10 cycloalkyl, C6-C18 aryl, C7-C17 aralkyl, a heterocyclic group having 3 to 10 members, or an amino protecting group.