Mechano-Growth Factor (MGF) is an alternative name for the Insulin-like Growth Factor-1Eb (IGF-1Eb), an isoform of IGF-1. It has been studied for its potential in remodeling muscles, cellular survival, and cellular proliferation.^[1] New studies on this specific isoform highlight its potential for activating satellite cells in skeletal muscle, suggesting that this particular isoform may also activate satellite cells in skeletal muscle, protect neurons, and help overcome muscle mass loss.^[2] The principal function of MGF is its possible efficacy in reparating severe muscle wear and tear. Further, its concentration appears to correspond with skeletal muscle growth and differentiation found in rodent models.

Modified GRF (1-29), or Mod GRF (1-29), is a synthetic peptide analog of growth hormone-releasing hormone (GHRH). It was first developed in the 1980s when studies indicated that the first 29 amino acids of GHRH may possess all of the biological roles associated with the full-length 44 residue protein.^[1] The initially designed peptide, known as GRF (1-29), is the shortest segment of GHRH, and appears to possess all the properties of the full-length hormone. A truncated synthetic form of GHRH known as Sermorelin, or GRF 1-29, also has 29 amino acids. Modified GRF (1-29) undergoes alteration to include four substituted amino groups in its chain.^[2] The intention behind these amino modifications is to protect the peptide from both oxidation and degradation during manufacture. The modification also appears to increase the binding affinity to GHRH receptors. Modified GRF (1-29) is also known as Mod GRF, or Tetra-substituted GRF (1-29). The latter name clarifies that the modified peptide differs from GRF (1-29) as a result of changes in four of its amino acids. Modified GRF (1-29) is structurally identical to CJC-1295 without DAC.

Modified GRF (1-29), or Mod GRF (1-29), is a synthetic peptide that is a modified fragment of the endogenously occurring growth hormone-releasing hormone (GHRH). It was first developed in the 1980s when studies indicated that the first 29 amino acids of GHRH may possess all of the biological potential associated with the full-length 44 GHRH molecule.^[1]

This discovery led to the development of a truncated version called GRF (1-29), also referred to as Sermorelin by researchers. Mod GRF (1-29) introduces specific modifications to support the peptide’s stability and efficacy. Four amino acids in the sequence are substituted at positions 2, 8, 15, and 27.^[2] Here is what some researchers believe about these modifications:
– Position 2: The amino acid alanine is replaced with its mirror image, D-alanine. This substitution aims to increase resistance to enzymatic degradation, thereby improving the peptide’s stability.
– Position 8: Asparagine is substituted with lysine, an amino acid with a positively charged side chain. This change may support the peptide’s binding affinity to GHRH receptors, potentially increasing its biological activity.
– Position 15: Histidine is replaced with D-phenylalanine, another D-amino acid. This modification is intended to protect the peptide from further enzymatic breakdown.
– Position 27: Cysteine is substituted with N-methylglycine, also referred to as sarcosine. This alteration may extend the peptide’s half-life by mitigating enzymatic cleavage.

These modifications collectively aim to produce a peptide with increased stability, a longer half-life, and better-supported interaction with GHRH receptors compared to the original GRF (1-29). Modified GRF (1-29) is structurally identical to CJC-1295 without DAC. The DAC in CJC-1295 serves to modify its pharmacokinetic properties.

MOTS-c (mitochondrial open-reading-frame of the 12S rRNA-c) is a 16 amino acid peptide classified as a Mitochondrial-Derived Peptide (MDP), aka “mitochondrial hormone” or “mitokine.” Recent research indicates that MOTS-c is a bioactive peptide closely associated with mitochondrial communication and energy regulation. Initially, researchers hypothesized that it might be most active in the mitochondria, however recent studies suggest otherwise, that MOTS-c may operate via the bloodstream, exhibiting a potentially systemic action.

It is important to note that MOTS-c is a newly identified MDP. Its primary roles are under investigation, but studies include MOTS-c peptide’s influence in cell function and longevity, muscle contractile force, metabolic function and weight regulation.

Nonapeptide-1, also termed Melanostatine-5, is a peptide that may prevent the activation of pigment-producing cells in the skin called melanocytes. It appears to be one of the most potent inhibitors of a receptor found in these pigment-producing cells, called the melanocortin-1 receptor (MC1R). Researchers have explored a peptide library containing 31,360 structurally different compounds, and it appears that the most potent inhibitor identified was Met-Pro-D-Phe-Arg-D-Trp-Phe-Lys-Pro-Val-NH₂, aka Nonapeptide-1.^[1] Structural analysis has revealed that specific amino acids, such as D-Trp at position 5 and Phe at position 6, are considered crucial for their antagonistic potential. The presence of D-Phe at position 3 further underscores such potential. Research on animal models suggests that Nonapeptide-1 may inhibit the synthesis of melanin, bringing it to the forefront of research on conditions impacting skin pigmentation, such as melasma. Studies in animal models posit that Nonapeptide-1 may reduce the synthesis of melanin and potentially decrease pigmentation on a considerable scale.

Oxytocin is a small peptide comprising only nine amino acids, naturally produced in the hypothalamus and secreted by the posterior pituitary gland cells. It has also been isolated from placenta, ovaries, testes, adrenal glands, thymus, retina, and pancreas tissues. The active hormone is obtained by proteolytic cleavage of a larger precursor protein. It is no longer considered merely a neurohypophyseal hormone as its actions are considered to be far-reaching and include interaction with additional peptides. Oxytocin appears to be a protein with two independent natural functions. First, it appears to act as a neuropeptide produced by the hypothalamus to regulate bonding, reproduction, and birth. Oxytocin appears to be bloodborne and secreted by the placenta of pregnant animals to influence birth, milk production, and bonding with their young. Small amounts of the protein produced from testes may promote mating behavior and pair bonding.