Peptides are not only the building blocks of proteins, and nearly all living tissues, they also are an important category of ingredients in today’s skin care products. A peptide is comprised of two or more amino acids in varying sequences, with new commercially available peptides consistently evolving. Peptides can be used to address a myriad of conditions, and they work in different ways to improve the health and appearance of skin.
As neurotransmitters, neuromodulators and hormones, peptides are responsible for the regulation of biochemical processes in complex organisms. Such processes include cell-to-cell communication and the control of vital functions like metabolism, immune response, digestion, respiration, sensitivity to pain, reproduction, behavior and electrolyte levels. Since peptides possess potent pharmacological properties, they are of enormous medicinal interest.
Creating synthetic peptides to perform specific and targeted actions within the skin is an intricate process. The receptors with which the peptides interact in skin are like “locks,” and the peptides that can instigate positive changes are the “keys.” As such, finding the properly shaped “key” is the goal.
Development begins in a naturally occurring peptide with the characteristics to impart a desired change. A synthetic version of that structure is created, and the peptide’s positive actions are amplified while potential negative effects are minimized. Finally, these molecules are fine-tuned to be more resistant to breaking down and cause fewer side effects.
This is an arduous process. Oftentimes, thousands of molecules do not initially work in the way they are intended until their structures are finalized. In the end, the perfected molecule will provide the desired positive benefits with little to no negative effects. However, this process takes years and can be cost-prohibitive. Further, few skin care companies have the staff or resources to accomplish this chemistry work on their own.
For these reasons, when raw material manufacturers land on a peptide with proven efficacy, its use becomes widespread in skin care formulations.
Of the widely studied and available peptides, three main categories are commonly used in skin care: neurotransmitter-affecting peptides, carrier peptides and signal peptides.
This type of peptide works by impeding neurotransmissions that cause muscle contractions. For example, acetyl hexapeptide-8a inhibits the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) complex. This ingredient has been marketed for more than a decade. Used twice a day at 10%, it can reduce wrinkle depth by 30% in 30 days. Acetyl hexapeptide-8 primarily acts by relaxing the facial muscles that lead to repeated facial expression wrinkling, including crow’s feet, laugh lines and frown lines.
Another neurotransmitter-affecting peptide is dipeptide diaminobutyroyl benzylamide diacetate, which is an antagonist of the muscular nicotinic acetylcholine membrane’s receptor (mnAChR). It also blocks the muscle contractions that lead to facial expression wrinkling. Preliminary studies indicated a twice daily application reduced the appearance of wrinkle depth by 52% in 28 days. More double-blinded studies are needed to substantiate this ingredient’s efficacy, but clinical outcomes are dramatic.
This type of peptide carries trace elements such as copper or magnesium into the skin. These elements have implications in wound healing, and increasing collagen and other matrix proteins. Copper peptide (GHK-Cu) is one example of this type. It is naturally occurring and used in skin care for a variety of anti-aging benefits.
Signal peptides initiate specific responses within the skin. A multitude of signal peptides are used in skin care, with scientific research supporting efficacy of a select group. Described here are some signal peptides supported by scientific research.
sH-Oligopeptide-1. Commonly referred to as epidermal growth factor, its multi-amino acid chain structure specifically interacts with growth factor receptors to stimulate epithelial cell division.
Palmityol pentapeptide-4.b Five amino acids in this peptide allow it to increase the synthesis of collagens I and IV, and fibronectin. Some companies refer to this peptide by its amino acid sequence, Pal-KTTKS.
Palmitoyl tripeptide-38. A newer generation peptide, this amino acid chain has the demonstrated ability to increase the production of six highly important dermal and epidermal components, as well as an important protein.
1. Collagen I is the most abundant form of collagen in the human body (90% of collagen), present in scar tissue due to healing and repair activities.
2. Collagen III is often called “the collagen of youth.” It is produced by young fibroblasts and during the early phases of wound healing.
3. Collagen IV forms the basis of cell membranes and works closely with laminin-5, anchoring keratinocytes.
4. Fibronectin is involved in many processes, including tissue repair and cell migration/adhesion. It is found in the extracellular matrix (ECM) and also acts as an anchor, adhering cells to collagen and binding various components within the ECM.
5. Hyaluronic acid is a key component of the ECM. It is necessary for proper dermal functioning such as water retention in the tissue. It also regulates activities related to cell proliferation and migration, in the case of wound healing, in the dermis and basal layers, at the dermal-epidermal junction.
7. Laminin-5 is a key component of the ECM, involved in the healing of injured epidermal cells. It also plays a role in the migration and anchoring of keratinocytes.
8. Heat Shock Protein 47 (HSP47) acts like a project manager, making sure the synthesis of the six major components of the ECM described above work at their highest potential.
Myristoyl nonapeptide-3. This peptide up-regulates the genes associated with the bioactivity of retinol in low concentrations, in human cell cultures. It has been shown to increase cell turnover and promote collagen I production without the irritation often accompanying retinol application. It can be used in products where retinol may be too sensitizing, such as eye area products. It can also be used in conjunction with retinol to increase and support its efficacy without additional irritation. The retinol-like benefits are important for a variety of skin conditions including aging, acne, skin discoloration and even for improving an overall dull complexion.
Myristoyl pentapeptide-8 and myristoyl hexapeptide-4. These growth factor mimetics stimulate collagen deposition and increase matrix remodeling and cell replication. With these other synthesized growth factor mimetics, the actual structure and actions are clearly identifiable, increasing safety.
Palmitoyl tetrapeptide-7. Consisting of three amino acids, this tetrapeptide has demonstrated improvements in skin firmness and elasticity, as well as decreases in inflammation.
Palmitoyl tripeptide-5. This tripeptide strengthens the skin by supporting collagen deposition.
Dipeptide-2. Consisting of two amino acids, this peptide is thought to improve lymphatic circulation to more effectively remove toxins from the skin.
Palmitoyl oligopeptide and palmitoyl tetrapeptide-7.c This peptide blend has been shown to activate the synthesis of the skin’s ECM, providing visible anti-wrinkle activity.
Palmitoyl oligopeptide. Consisting of multiple amino acids, this peptide has been known to stimulate collagen production and glycosaminoglycan synthesis—hyaluronic acid in particular.
The Future of Peptides
The majority of peptides used in skin care provide anti-aging benefits, although research into anti-inflammatory and antibacterial peptides could provide solutions for acne and sensitive skin conditions like rosacea and dermatitis. While these naturally occurring peptides are active in the human body, they have both positive and negative actions, so more research is needed to fine-tune useful peptide molecules to treat these conditions.
The truly exciting direction where peptide technologies may be headed is in the creation of novel molecules designed to create specific positive changes in the skin without the potential for negative or unwanted side effects. For example, one goal in the fight against skin aging is to stimulate the growth of healthy cells, to replenish volume lost through the aging process. The challenge in this is to stimulate only healthy cell proliferation. Stimulating unhealthy cell growth, at its worst, could lead to tumor development. To safely identify and use this molecule, long and exhaustive scientific processes must be undertaken, along with detailed testing and validation.
Having access to unique and targeted peptides will bring a sea change in anti-aging science and potentially the treatment of a wide variety of other conditions. This effort is in its infancy, but could provide exciting new ways to suppress—and perhaps reverse—the aging process. Even prior to these potential developments, though, the peptides currently available are excellent additions to any cosmeceutical product and good choices for anti-aging regimens.
a Acetyl hexapeptide-8 can be found in Argireline, a peptide made by Lipotec.
b Palmityol pentapeptide-4 can be found in Matrixyl, a peptide blend made by Sederma.
c Palmitoyl oligopeptide and palmitoyl tetrapeptide-7 can be found in Matrixyl 3000, a peptide blend made by Sederma.