The invention concerns a cosmetic composition comprising as an active substance a cosmetically effective amount of at least one mu-conotoxin peptide It further concerns a composition wherein the mu-conotoxin peptide is Argninine, lysine polypeptide, CAS Number: 937286-43-6, Molecular formula C92,H139,N35,028,S6 acetate salt (molar mass 2376 g/mol.). It also concerns the use of a composition according to the invention, to improve the mechanical properties of the skin, tonicity and/or firmness and/or elasticity of the skin.
