Peptides in Cosmetics: Types, Characteristics, and Application Insights, PART 2
Signal Peptides
These peptides are added to cosmetic products because they can stimulate fibroblasts (cells responsible for skin function and repair) to produce more collagen, elastin, and other proteins in the dermal matrix. Elevating the levels of these structural proteins makes the skin more elastic and firm. An example of a signaling peptide is GHK—it was initially isolated from human plasma in the early 1970s, and its wound-healing properties were first discovered in the mid-80s. Nowadays, this ingredient is synthesized.
Signaling peptides in cosmetics combat skin aging. Currently, several bioactive amino acid sequences are known, typically included in cosmetic formulas. The most popular signaling peptide for cosmetic use is the lysine-threonine-threonine-lysine-serine (KTTKS) sequence found in type I procollagen. It is now marketed as Palmitoyl Pentapeptide-3 or Matrixyl® (Sederma). This pentapeptide has been demonstrated to stimulate feedback-regulated synthesis of new collagen and increase the production of proteins in the extracellular matrix, such as collagen I and II types and fibronectin. KTTKS is usually coupled with palmitic acid to enhance penetration through the epidermis for action on the dermis. It is also considered a synthetic isomer (an isomer is a molecule with a structure identical to another molecule but different atomic components). Matrixyl promotes healing in the deeper layers of the skin, accelerating wound recovery.
The skin consists of collagen, which is the foundation providing support and thickness to the skin. Collagen is a protein composed of long chains of amino acids linked together. Since collagen consists of three polypeptide chains, adding signaling peptides can stimulate the skin to produce additional collagen. More collagen can make the skin more elastic and youthful.
Our body naturally produces collagen, especially actively in youth, but over time, collagen production decreases, causing the skin to appear lifeless, dull, and less smooth. As collagen breaks down with age, it is not adequately replaced. Consequently, youthful, smooth skin gradually becomes thin and wrinkled. Introducing collagen directly into a cosmetic product will not yield significant results since the collagen molecule is too large to penetrate deeply. This is where peptides differ.
In fact, their mechanism of action is based on the cellular functions of fibroblasts. Over time, fibroblast activity diminishes, leading to a slowdown in the synthesis of the protein supporting the skin. This is one of the factors associated with biological aging, resulting in wrinkle formation and loss of elasticity. Peptides introduced externally, with a specific sequence of amino acids, can stimulate fibroblasts. In vitro and in vivo studies have demonstrated the positive effects of cosmeceutical peptides on both chronologically aged and photoaged skin.
Ingredients:
- Matrixyl (Palmitoyl Pentapeptide-4, Palmitoyl Tetrapeptide-3)
- Matrixyl 3000 (Palmitoyl Oligopeptide / Palmitoyl Tetrapeptide-7 / Palmitoyl Hexapeptide)
- Matrixyl synthe’6 (Palmitoyl Tripeptide-38)
- SYN-TC (Palmitoyl Tripeptide-5)
- Syn Tacks (Palmitoyl Dipeptide-6)
Carrier Peptides
These peptides deliver trace elements, such as copper and magnesium, aiding in wound healing and enzymatic processes. It has been proven that these trace elements stimulate procollagen synthesis, improve skin elasticity, and enhance its overall appearance. For example, a copper complex consists of the amino acids glycine, histamine, and lysine and is used in the treatment of diabetic neuropathic ulcers. They are sometimes called “penetrating peptides” or “membrane transduction peptides.”
Ingredients:
- Copper tripeptide (GHK tripeptide, Copper PCA) — transports copper peptides crucial for collagen synthesis. Recommended percentage in cosmetics ranges from 1% to 2.5%.
- Manganese tripeptide-1 — combats photoaging, showing effectiveness in skin recovery after prolonged sun exposure.
Enzyme Inhibitor Peptides
These peptides can reduce the breakdown of collagen and other proteins by interfering with processes that break down these proteins. Peptides derived from rice proteins or soy proteins can inhibit enzymes, especially proteases. They may have some potential for slowing hair growth and reducing pigmentation.
Ingredients:
- Progeline (Trifluoroacetyl tripeptide-2)
- Trylagen (Tripeptide-10, Tripeptide-1)
- Dipeptide-2
- Acetyl Tetrapeptide-5
- Oligopeptide-20
- Soybean peptide
Peptides can be an excellent addition to daily skincare because they help address numerous issues. However, as with all anti-aging ingredients, the best approach is to use them in conjunction with other beneficial components—antioxidants, moisturizing, and restoring ingredients. Such a comprehensive complex of active substances, complemented by sunscreen, can significantly improve the condition of the skin and extend its youthful appearance.