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%.

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.

B7-33 is a soluble synthetic single-chain peptide obtained from the larger, naturally occurring protein H2-relaxin (Relaxin), which is considered to induce pleiotropic actions impacting the musculoskeletal system, cardiovascular system, and reproduction.^[1] B7-33 appears to retain the anti-fibrotic properties of Relaxin without enhancing cAMP production, it may also stimulate ERK1/2 phosphorylation and promote matrix metalloproteinase 2 (MMP2) expression and the degradation of extracellular collagen. The Relaxin family of peptides has four endogenous receptors divided into two pairs (RXFP1/2 and RXFP3/4).^[2] The Relaxin receptors appear to be stimulated by cAMP, orexin, corticotropin-releasing factor (CRF), several insulin-like peptides, and GLP-1. The agonists have been observed to exhibit anti-inflammatory, antioxidant, and tissue-repairing characteristics.

Gonadorelin (GnRH) is a decapeptide gonadotropin-releasing hormone agonist.^[1] It appears to work by stimulating the synthesis and release of luteinizing hormone and follicle-stimulating hormone. It is being researched within the context of infertility and reproductive systems, and hypogonadism. It is also studied for its potential as a diagnostic tool to assess pituitary function.

FOXO4-DRI is a synthetic version of FOXO4, containing D amino acids instead of L amino acids. This modification is intended to allow the peptide to retain the functionality of the original protein but with a longer shelf life and lower clearance. Its most prominent function has been suggested to regulate apoptosis in senescent cells.^[1] It has been suggested in scientific studies that senescent cells might exhibit resistance to apoptosis, aka programmed cell death. This resistance has been associated with increased binding of FOXO4 with another protein, p53, which should trigger apoptosis but become inactivated.

Humanin is an endogenously occurring unique peptide encoded by mitochondrial DNA. The peptide may exist in two different forms found in the cell: a 21 amino acid sequence found inside the cell’s mitochondria, and a 24 amino acid sequence found outside the cell’s cytosol. Both forms appear to act as cytoprotective proteins and may protect cells from the process of apoptosis (programmed cell death) by interfering with the operation of the Bcl2-related X protein (Bax).^[1]

Bax is considered a pro-apoptotic protein that promotes apoptosis by disrupting the mitochondrial outer membrane. It is believed to facilitate the release of cytochrome c from mitochondria into the cytosol, which then triggers a cascade of events leading to cell death. By interfering with Bax’s function, Humanin may help support the initiation of this apoptotic pathway. Researchers posit that Humanin may “[support] the translocation of Bax from the cytosol to mitochondria. Conversely, reducing Humanin expression by small interfering RNAs sensitizes cells to Bax and increases Bax translocation to membranes.”

Apart from research into its possible interaction with Bax, Humanin studies suggest the peptide may also bind with other intracellular molecules, such as actinin-4 and phosphoprotein 8, which are both involved in cellular apoptosis. Binding with these proteins is also thought to contribute to Humanin’s cytoprotective potential.^[2] Thus, studies suggest that Humanin may be important for protecting a variety of cells, most notably neurons. In addition, studies also suggest it may have a protective potential for cells in heart tissue, muscle cells, the retina of the eye, and the lining of blood vessels.

Erythropoietin (EPO) is a kidney-derived glycoprotein made of 11 amino acids that has been studied for its potential to promote blood vessel growth and repair, and possible neuroprotection in the case of diabetic neuropathy. ARA-290 is a peptide derived from the beta-helix domain of EPO.^[1] ARA-290 was developed with the intention of stimulating pain-mitigating and neuroprotective activity of EPO, though without promoting blood cell formation. ARA-290 has been proposed by researchers to exhibit anti-apoptotic, anti-inflammatory, and anti-permeability characteristics, akin to the endogenous glycoprotein, EPO. The peptide is being evaluated for its potential in neuropathic wound healing, immunomodulation, and within the context of Systemic Lupus Erythematosus (SLE) research.

ACE-031 is a soluble protein comprising the type IIB activin receptor (ACVR2B) and the immunoglobulin G1-Fc (IgG1-Fc), and has been studied for its potential in binding and inactivating myostatin, a protein that hampers muscle cell growth. It has been examined during the course of various research studies involved in muscle-wasting disorders and neuromuscular conditions such as Duchenne Muscular Dystrophy (DMD), as well as certain cancers such as those of the prostate or colorectal regions and lipid storage and bone metabolism.

Thymosin Alpha-1, also known as TA1 or Tα1, is a naturally occurring peptide fragment that was discovered in 1972 and researched for its potential action within the context of studies relating to cystic fibrosis, infection (e.g., tuberculosis, cytomegalovirus), respiratory disorders, chronic hepatitis, and cancer. It is also referred to as Thymalfasin when synthetically developed. Originally, research on Thymosin Alpha-1 centered around its potential role in immune modulation. It is hypothesized that it might increase levels of Major Histocompatibility Complex (MHC) class I molecules and boost cytokine production, key components of the immune system that may enhance immune responses.^[1][2] There is also a possibility that it might improve the activity of natural killer cells, which target virus-infected cells and tumors. Furthermore, it might enhance the expression of specific markers on T cells that are considered critical for their identification and function in the immune system, indicating a significant role in immune regulation. Thymosin Alpha-1 is also thought to possibly increase the presence of high-affinity interleukin-2 receptors on cell surfaces, potentially leading to the vigorous activation and proliferation of T lymphocytes, elements of immune response. There is speculation that it may affect both T-helper and cytotoxic T-cell populations, deemed essential for eliminating infected cells. Additionally, it might prompt the differentiation of thymocytes—precursor cells in the thymus—and peripheral blood lymphocytes into mature immune cells, increase natural killer cell numbers, and promote cytokine-driven inflammatory responses. Research also explores its potential role in enhancing macrophage efficiency—cells that engulf and digest pathogens—and in regulating the activity of alpha thrombin, a protein involved in blood clotting, highlighting its broad potential on immune function.