Q: What is the function of peptides in skin care?
Peptides are made up of different numbers of amino acids. A dipeptide consists of 2 amino acids, a tripeptide consists of 3 amino acids, and a tetrapeptide consists of 4 amino acids. Not only is the number of amino acids important, but also the order in which the amino acids are arranged. For example, glycylhistidine is thought to stimulate collagen synthesis in fibroblasts, while glycyl histidine is thought to stimulate lipolysis in adipocytes. However, the function of the peptide in skin care is to transmit a biochemical message from one area of the body to another area of the body, thereby communicating the physiological change.
Q: What are the most commonly used antioxidant peptides?
The two most commonly used antioxidant peptides in skincare are glutathione (Bglutamyl-cysteinyl-glycine) and carnosine (γ-alanyl-l-histidine). Glutathione is a GSH tripeptide. Since the level of glutathione decreases with age, topical application of the antioxidant peptide is believed to possess anti-aging properties, despite limited evidence of topical clinical benefits.
Carnosine is a known scavenger of reactive oxygen species in the cell membrane, and prevents the oxidation of free fatty acids. It can also prevent the formation of advanced skin end products by preventing the non-enzymatic binding of sugars to proteins. Over time, carnosine is broken down into BAlanine and histamine. BAlanine is believed to stimulate the biosynthesis of nucleic acids and collagen. Thus, both the peptide and its degradation metabolites are believed to be biologically active.
Q: What are tissue repair peptides?
The idea that a peptide applied to a wound bed or intact skin can stimulate collagen production is a compelling one. These large, fragmented molecules are known as matrikines. Matrikines recycle the breakdown fragments of larger molecules, such as collagen, to stimulate repair activity. For example, the most widely used matrikine peptide in skin care is the pentapeptide Pal-KTTKS, and it consists of palmitic acid, lysine, threonine, threonine, lysine, and serine, also known as palmitoyl pentapeptide-4. This is the name that will be found in the ingredient disclosure list when using this peptide. This pentapeptide is the shortest type 1 procollagen A fraction capable of stimulating fibroblast collagen synthesis in a Petri dish. It was detected by sequentially incised collagen and placing the fragments on fibroblast cultures to see which cultures produced more collagen.
It can be difficult to understand the true benefit of tissue repair peptides and peptides in general. Because of the expense, peptides are used in parts per million (ppm) concentrations. It is believed that because they modify the biological process, a small amount will produce enough results to see an improvement in appearance. However, pure peptide cannot be applied to the skin in low concentrations. The peptide must be delivered in some type of compound, usually a humectant, to spread the active ingredient over the surface of the skin. This means that it can be difficult to separate the means of hydration from the benefit of the peptide. Vehicle-controlled studies are the best way to determine the additional benefit of a peptide, but they are rarely performed.