Peptides — short polymers formed by linking amino acids. When such an amino acid chain is small, the molecule is called a peptide. When it is larger, it is called a polypeptide. Proteins are polypeptide molecules. While proteins cannot penetrate the skin, smaller peptides can be absorbed. The ability to link different numbers of amino acids, thereby forming different peptides and polypeptides, gives these ingredients a variety of beneficial properties when incorporated into cosmetic products. These benefits range from increased skin elasticity and smoothness to improvements in the appearance of wrinkles, a reduction of inflammation, and tissue repair. There are also claims that peptides can activate regenerative skin functions, increase collagen, and synthesize other epidermal components. For cosmetic application, natural peptides are derived from cotton, rice, wheat, casein, and whey. They have various applications in hair and skin care formulations based on their molecular weight distributions, amino acid content, solubility, and odor profiles. Peptides can be natural or synthetic.
Some examples of popular peptides:
Palmitoyl Oligopeptide (Matrixyl™ 3000)
Palmitoyl Tetrapeptide-7
Palmitoyl Tripeptide-38 (Matrixyl™ Synthe’6)
Palmitoyl Tripeptide-5
Acetyl Hexapeptide-8 (Argireline, peptide K8)