The peptides have the general following formula: X-Pro*-Pro*-Xaa-Y in which: —Xaa is selected from Leucine (Leu, L), Arginine (Arg, R), Lysine (Lys, K), Alanine (Ala, A), Serine (Ser, S), and Aspartic acid (Asp, D)； —At the N terminal end of the peptide, X is selected from H, —CO—R1 and —SO2—R1； —At the C terminal end of the peptide, Y is selected from OH, OR1, NH2, NHR1 and NR1R2； —R1 and R2 are, independently from each other, selected from an alkyle, aryle, aralkyle, alkylaryl, alkoxy and aryloxy group, that can be linear, branched, cyclic, poly-cyclic, non-saturated, hydroxylated, carbonylated, phosphorylated and/or sulfured, and which skeletum can comprise an heteroatom, in particular an O, S and/or N atom； —Pro* correspond to a Proline, an analogue or derivative thereof； —if X is H then Y is selected from OR1, NH2, NHR1 and NR1R2, and if Y is OH then X is —CO— or —SO2—R1； and the peptide hypoxanthine-Pro-Pro-Arg being excluded. The invention provides the use of the peptides of above formula I to stimulate the synthesis of the molecules constituting the dermal extracellular matrix, including collagen I and IV and elastin. A cosmetic treatment according to the invention includes anti-aging, anti-wrinkles, improving mechanical properties of the skin, firmness/tone/elasticity/suppleness/flexibility, increasing density and volume of the skin, restructuring effect, fighting stretch marks, improving skin barrier and/or skin hydration.
