Peptides are linear chains composed of amino acids. When we are speaking of shorter chains (up to 50-100 amino acids) we call them peptides. Bigger chains (could be up to several thousand amino acids) are called proteins. So peptides are “smaller cousins” of proteins.
There are many peptides naturally present in the body and they typically perform signaling and/or hormonal function. Examples are insulin, endorphin, oxytocin, angiotensin…
Peptides in skin care:
Natural turnover of skin proteins involves degradation of old collagen, elastin and other proteins and synthesis of new molecules. Skin contains enzymes that degrade – cut into smaller pieces – those big proteins. Small molecules that result from cutting the big one, let’s say collagen, are actually peptides (shorter protein chains, “smaller cousins” of proteins) which are called matrikines. Those matrikines are able to react with specific receptors on dermal cells and trigger production of new collagen (or other proteins).
To summarize: skin proteins are naturally degraded by enzymes, and the products of such degradation are peptides called matrikines, which in turn trigger synthesis of new proteins, to replace degraded ones. This process obviously gets slower and less efficient as we age, which contributes to visible signs of aging.
Peptides used in skin care mimic those matrikines, so when applied they trigger synthesis of new collagen, elastin and other skin proteins, hence their anti-aging effect (they build the dermis, epidermis, and lead to increased volume and smoothing of wrinkles.
Some cosmetic peptides might have a different mode of action, here are the classifications of the most used:
- Signaling peptides – stimulate receptors and consequently biochemical reactions for synthesis of dermal and epidermal components (so called filler-like peptides) – these are the peptides explained above
- Carrier peptides (delivery systems)
- Neuropeptides that help relax wrinkles (like Argireline in ExLinea) (so called botox-like peptide)
- Enzyme-inhibiting enzymes that improve under-eye bags, circles (like Eyeseryl or Eyeliss) or hyperpigmentation
When we talk about peptides in skin care, most of the times we talk about signaling peptides (filler like).
Besides ingredients which are called “peptides”, growth factors (epidermal growth factor, fibroblast growth factors etc) chemically also belong to the peptide group. They are signaling to trigger cellular replication, that way they increase thickness of epidermis (epidermal growth factor) and dermis (fibroblast growth factor).