GHK is an endogenous copper peptide that occurs in the tripeptide glycyl-L-histidyl-L-lysine. It has two variants — GHK with or without Cu (Copper). GHK appears to have a strong affinity for copper (II), and it is synthesized from plasma, although it has been isolated in other areas. Endogenous GHK production is considered to decline over time. ^[1]

In cases of injury, GHK may be released from tissue cells. That may be because GHK is present in various proteins that get broken down via hydrolysis during injury. For example, studies suggest that GHK is present in the “alpha 2(I) chain of type I collagen”, which “suggests that the tripeptide might be liberated by proteases at the site of a wound and exert in situ healing.” ^[2] GHK peptide may also be released from the breakdown of another extracellular matrix-binding protein involved in regulating cell shape and proliferation, called SPARC (Secreted Protein, Acidic, and Rich in Cysteine). GHK is found in tissues undergoing remodeling, such as during the process of angiogenesis.^[3]

When GHK is released from the breakdown of proteins like collagen and SPARC, this signaling appears to trigger the fibroblasts to begin synthesizing new collagen and other structural proteins in the skin structure and connective tissues like elastin and glycosaminoglycan. Further, this copper-binding peptide appears to affect genes that control recuperative responses to injury and stress. Its functions appear to include the following: tissue remodeling, anti-inflammatory response, pain perception inhibition, nootropic, anti-cancer action, blood vessel growth, and nerve outgrowth.

SNAP-8, or Synaptosomal-associated protein 8, is a synthetic octapeptide believed to mimic certain functionalities of its larger counterpart, SNAP-25, a protein deemed integral to neurotransmitter release and muscle contraction.^[1] Constructed from eight amino acids, SNAP-8’s structure is designed with specific modifications: an acetylated N-terminus and an amidated C-terminus, culminating in the sequence Ac-Glu-Glu-Met-Gln-Arg-Arg-Ala-Asp-NH2. It is structurally similar to another peptide known as acetyl hexapeptide-3, which also reportedly mimics a fragment of SNAP-25 and inhibits its function, leading to similar anti-wrinkle potential. By adding two amino acids to the chain of acetyl hexapeptide-3, the resultant acetyl octapeptide further enriches the field of research compounds studying cell aging and skin cell rejuvenation.^[2]

The synthesis and manufacturing of SNAP-8 comprises a final freeze-drying step called lyophilization. Generally, the crystalline powder obtained due to freeze-drying is in the form of a polymorphous compound. It may be present in aggregates and show variation in the crystal size. However, this does not appear to lead to any chemical discrepancy in its composition. Extensive experimental studies have supported the homogeneity of this compound. The usual shelf life of SNAP-8 is posited to be at least 12 months, provided the compound is stored in a clean, cool, and dry place. If the compound is intended to be stored longer than a year, the temperature should be maintained at 4 degrees Celsius. This may extend the shelf life to approximately 18 months. Refrigeration of the SNAP-8 may potentially lead to its precipitation; however, this doesn’t appear to change the integrity of the compound.

Pal-AHK, also referred to as Palmitoyl Tripeptide-3, is a tripeptide with a fatty acid attachment. It consists of amino acid sequences (alanine-histidine-lysine) and appears to be attached to a Palmitoyl fatty acid molecule. The fatty-acid component of AHK makes it lipophilic (soluble in fat), which may increase the potential of the peptide for penetration and absorption by epidermal cells in experimental models while maintaining the same mechanisms of action as regular AHK. AHK appears to be a multifunctional copper-binding peptide that has been studied for its potential role in supporting cellular functions related to the kin’s extracellular matrix.

Research indicates that AHK-Cu may increase the proliferation and viability of dermal fibroblasts—the primary cells responsible for producing collagen and other essential proteins in the extracellular matrix (ECM).^[1] Moreover, the peptide appears to possess significant antioxidative potential compared to other tripeptides when investigated via chromatographic evaluations. This appears to be related to its potent metal-chelating properties.

Matrixyl is a lipopeptide that combines fatty acids with amino acids. The peptide is also sometimes referred to as palmitoyl pentapeptide-4 or palmitoyl pentapeptide-3. The palmitoylated sequence of Lys-Thr-Thr-Lys-Ser-OH, which makes up the peptide, is posited to be a signal peptide fragment of the C-terminal propeptide of type I collagen.^[1] Researchers report that “The conjugation with the palmitoyl moiety [may] result in more [impactful] delivery across the skin and better stability to skin proteases.” Overall, this signal peptide is posited to act as a stimulus to fibroblasts and stimulate them into producing extracellular matrix (ECM) proteins such as collagen. Therefore, Matrixyl is considered by researchers to be a matrikine – a messenger peptide capable of regulating cell activities by interacting with their specific receptors.

AHK-Cu is a tripeptide containing a copper atom. It is a short peptide in which the copper atom is attached between the histidine and alanine residues of the alanine-histidine-lysine tripeptide. The copper atom is linked to three nitrogen atoms in this molecule. It is a naturally occurring compound that has been suggested to add support in cell growth and regulation, and cell death, particularly in the case of vascular endothelial cells (the innermost layer of blood vessels). AHK-Cu has also been studied extensively in animal models under laboratory conditions for its suggested impact on collagen synthesis. Researchers posit that the peptide appears to regulate various cellular processes primarily by controlling the production of two compounds: Vascular Endothelial Growth Factor (VEGF) and Transforming Growth Factor beta (TGF-B).^[1] According to the researchers “TGF-beta1 induction of angiogenesis requires a rapid and transient apoptotic effect mediated by VEGF/VEGFR2.” AHK-Cu, by enhancing levels of the Vascular Endothelial Growth Factor, may possibly activate fibroblasts and endothelial cells. Fibroblasts are considered to lead to the production of two complex compounds; elastin and collagen. Endothelial cells are considered responsible for the growth and function of blood vessels that supply nutrition to hair follicles and skin cells. The activation of endothelial cells in association with the fibroblasts may lead to a strengthened skin barrier and increased skin elasticity, as well as potential acceleration in tissue repair. Some laboratory studies done on dermal cells indicate an increase in collagen type 1 production to the extent of as much as 300%.

Syn-AKE is a peptide, also known as tripeptide-3 or dipeptide diaminobutyroyl benzyl amide diacetate. Syn-AKE, a synthetic peptide ingredient, appears to mimic the actions of the Waglerin-1 peptide, which is 21 amino acids in length. Waglerin-1 functions primarily as a muscle relaxant by inhibiting the activity of acetylcholine at the neuromuscular junction, which may potentially result in reduced muscle contractions. Acetylcholine is a neurotransmitter considered essential for muscle movement, and its inhibition at the neuromuscular junction prevents the normal contraction signals from reaching muscles. In the development of Syn-AKE, researchers sought to synthesize a peptide that might potentially mimic this action. Thus, the peptide Syn-AKE was engineered to emulate the mechanism by which Waglerin-1 acts, but in a more selective manner. Researchers suggest Syn-AKE may act to reduce transmission between muscles and nerves, working similarly to botulinum toxin to relax muscles and thus reduce instances of creasing and wrinkle development along epidermal surfaces, as suggested in animal model research. The apparent reduction of this transmission appears to be reversible when triggered by Syn-AKE. Therefore its action is temporary.^[1] According to Pentapharm, “the Syn-AKE invokes its action by blocking the muscle nAChR in a reversible manner by blocking the ion channel. As a result, the Na+ uptake is substantially disturbed, and the muscles remain relaxed.”

Vialox, also known as Pentapeptide-3V, is a peptide with a five amino acid sequence (Gly-Pro-Arg-Pro-Ala). It was originally isolated from endogenously produced snake venom. The peptide appears to replicate temporary muscular paralysis. This result has been observed by researchers in paralytic compounds such as botulinum toxin, which are believed to reduce wrinkle depth. Vialox appears to inhibit nicotinic acetylcholine receptors. This potential may enable curare-like actions at the neuromuscular junction, which might block nervous system electrical impulses from reaching muscles. A block like this may ultimately halt muscle contraction.

This mechanism appears to be analogous to the function of tubocurarine. This function is observed through Vialox’s hypothetical interaction with acetylcholine receptors on the postsynaptic membrane of muscle cells. Tubocurarine, a naturally occurring alkaloid compound, is primarily found in the bark of certain plants. This includes Chondrodendron tomentosum, commonly referred to as “curare.” Experts recognize this compound as a potent neurotoxin. Its mode of action is considered to function as a non-depolarizing neuromuscular blocker. It is hypothesized that this function obstructs the activity of acetylcholine—a neurotransmitter deemed by researchers to be critical for muscle contraction—at the neuromuscular junction, which might inhibit muscle contraction.

Pentapeptide-18 (Leuphasyl) is a modified analog of the naturally occurring pentapeptide leu-enkephalin, which is part of a class of peptides called enkephalins which are believed to directly interact with opioid receptors.^[1] Structurally, Pentapeptide-18 differs from leu-enkephalin by the addition of D-Alanine in place of glycine at its second position. Pentapeptide-18 is thought to penetrate the epidermal barrier and influence cellular processes that affect muscle cell contraction. Studies suggest that it acts by modulating calcium release in neuronal synapses. By interfering with the signals that trigger muscle contraction, Pentapeptide-18 may help to relax muscles, reducing the formation of fine lines and wrinkles across the skin barrier. Additionally, modified versions of Pentapeptide-18 may interact with melanin production pathways, which is a pigment responsible for adding color to tissues and may play a protective role against UV radiation. By potentially influencing melanin synthesis, modified versions of Pentapeptide-18 may offer research value in skin tissue studies.

Syn-Coll, otherwise known as Palmitoyl Tripeptide-5 or Tripeptide-5, is a synthetic peptide that was developed to enhance the production of type I collagen. It appears to repair damages caused by photo-aging, and Syn-Coll has also been suggested to support the regeneration of skin protein production, such as elastin or collagen. Syn-Coll (Palmitoyl Tripeptide-5) is the synthetic equivalent of Thrombospondin 1 (TSP-1). TSP-1 is an extracellular matrix protein and is found in the skin near collagen and elastin. Syn-Coll appears to mimic the functions of TSP-1, possibly aiding in the prevention of collagen degeneration via stimulating the release of TGF- induced by TSP-1.^[1] TGF-β is an essential growth factor potentially significant in preserving skin integrity and facilitating the development of skin structures, mainly through the promotion of collagen synthesis. Additionally, Syn-Coll, a synthetic peptide, has been the subject of extensive research in animal models and laboratory experiments. The findings tentatively indicate that Syn-Coll might enhance collagen production and potentially inhibit its degradation. The inhibition of collagen breakdown by Syn-Coll is possibly due to its ability to suppress the activity of matrix metalloproteinases (MMPs), including MMP1 and MMP3, which are enzymes studied for their role in the degradation of collagen in the skin. The peptide is palmitoylated, to potentially extend its bioavailability in experiments involving different skin tissue models.