N-Acetyl Semax is posited to be an acetylated form of the Semax peptide. The peptide consists of a 4 amino acid fragment (Met-Glu-His-Phe) from the chain of melanocortin hormones. These include the adrenocorticotropic hormone (ACTH) and a Pro-Gly-Pro fragment. The integration of Pro-Gly-Pro (PGP) into N-Acetyl Semax may potentially enhance the permeability of the peptide through the blood-brain barrier (BBB). This enhancement might occur by increasing the peptide’s lipophilicity, thereby potentially improving passive diffusion or uptake via lipid raft-mediated endocytosis.

This process may hypothetically allow the peptide to bypass the BBB’s tight junctions, which researchers claim are usually highly restrictive. Adding PGP at the C-terminus might also modify the peptide’s interactions with specific BBB transporters or receptors, possibly facilitating receptor-mediated transcytosis. Receptor-mediated transcytosis is a process where substances are transported across cells via specific receptors, and alterations at the C-terminus might influence this pathway.

Researchers have noted that the acetylation of the peptide into N-Acetyl Semax appears to reduce the affinity of other ions, such as Cu++, to its N-terminus.^[1] Acetylation may contribute to an increase in the peptide’s resistance to enzymatic degradation, potentially leading to an extended half-life observed in experimental models. Increased resistance to degradation might mean that the peptide potentially remains active for a longer period, which may enhance its stability.

N-Acetyl Selank is an acetylated form of the Selank peptide. The acetylation of the peptide into N-Acetyl Selank appears to improve its stability. Selank is a synthetic analogue of the natural tetrapeptide Tuftsin. Tuftsin is an immunomodulatory peptide, and N-Acetyl Selank appears to share many of its potential functions. In addition, N-acetyl Selank also appears to exhibit an impact on neurotransmitters, brain signaling, and neuroplasticity.

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.

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.

Pal-GHK, also known as Palmitoyl Tripeptide-1 and Palmitoyl Oligopeptide, is a synthetic peptide developed to function in protein production to support the skin’s extracellular matrix (ECM), and skin pigmentation. Pal-GHK is a synthetic hybrid peptide with one fatty acid and one peptide. “Pal” represents Palmitoyl—the covalent attachment of fatty acid to the end of the structure. “GHK” represents glycine-histidine-lysine—the peptide’s amino acid structure. This sequence is thought to be a small fraction of the large protein collagen, which is one of the main proteins in the extracellular matrix of skin and other tissues. The GHK sequence appears to be present in the “alpha 2(I) chain of type I collagen”, and researchers suggest that such a “tripeptide might be liberated by proteases at the site of a wound” as a signal of injury and thus, may be a powerful stimulant for repair.^[1] Particularly, it may signal and attract fibroblasts—cells responsible for synthesizing collagen, elastin, and other proteins in the skin’s extracellular matrix, bones, and connective tissues. “Pal” represents Palmitoyl—the covalent attachment of fatty acid to the end of the structure. The addition of palmitoyl to the molecule is thought to result in better penetration through skin cells and, more specifically, stratum corneum.