The use of amino acids, peptides, and proteins in skin care products is not new. One of the earliest moisturizing ingredients that acted like a sponge to retain water on the skin’s surface was hydrolyzed collagen. Collagen was obtained by cooking cowhide and collecting a culture medium rich in collagen fragments for addition to moisturizers. Collagen is made up of about 4000 amino acids, but the fragments produced by heating cowhide are unstable, unpredictable, and undefined. New synthetic chemistry allowed him to create peptide fragments one link at a time from specific amino acids that could become biologically active through receptor-mediated activity. Although this production method is laborious and expensive, it is highly reproducible and produces well-defined peptides. Recently, the price of peptides has dropped, allowing this ingredient to move from the high-end cosmetics market to the mass cosmetics market, and a number of skin care products have been introduced that utilize this technology.
How peptides work
Peptides function based on a lock-and-key model of receptor-mediated activity. Peptides are fragments of larger molecules, such as type I collagen, that are presented on cell membranes and recognized by specific receptor molecules. This initiates certain biological reactions through structural changes in transmembrane structures, triggering a series of events in the biochemistry inside the cell. This cascade leads to the amplification of the signal transmitted by the peptide, which is used in cosmetic formulations in parts per million based on cost.
For peptides to work, they must reach the viable layers of the skin. The skin is very good at protecting against proteins, which are the source of most allergens, such as peanuts and shellfish. Penetration may also be limited depending on the size of the peptide. Penetration of short peptides is enhanced by palmitoylation, which adds free fatty acids such as palmitic acid to the peptides.
Types of peptides available
There are three families of peptides: signal peptides, carrier peptides, and neurotransmitter-inhibiting peptides. The signal peptide is intended to act as a messenger that triggers the synthesis of collagen by fibroblasts. Many of these data are derived from wound healing studies. Carrier peptides are used to deliver ingredients to the skin, but only peptides that deliver copper have been commercialized. Neurotransmitter-inhibiting peptides are thought to inhibit acetylcholine release at the neuromuscular junction.
The most common one on the market
The most widely used peptides are signal peptides, which form the basis of anti-aging claims in many moisturizer formulations.
Neurotransmitter peptides have been developed to mimic the effects of neurotoxins. The most common neurotransmitter peptide is acetyl-glutamyl-glutamyl-methoxyl-glitaminyl-arginyl-arginylamide (argireline), which is said to prevent the release of acetylcholine by destabilizing protein complexes. Pentapeptide-3 is another amino acid sequence, but its sequence is unknown. This peptide is said to act like curare at the postsynaptic membrane. Achieving neurotoxic effects with topical agents is difficult because peptides must penetrate deeply into the skin to reach receptors and remain in place long enough to produce physiological effects.
Dr. Zoe Diana Drellosis a consultant professor of dermatology at Duke University School of Medicine in Durham, North Carolina. Dermatology Times.