Hexarelin
[CAS 140703-51-1]

Identification

• Classification: Biochemical >> Peptide
• Name: Hexarelin
• Synonyms: L-Histidyl-2-methyl-D-tryptophyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide; Examorelin
• Molecular Formula: C₄₇H₅₈N₁₂O₆
• Molecular Weight: 887.04
• Protein Sequence: HXAWFK
• CAS Registry Number: 140703-51-1
• SMILES: CC1=C(C2=CC=CC=C2N1)C[C@H](C(=O)N[C@@H](C)C(=O)N[C@@H](CC3=CNC4=CC=CC=C43)C(=O)N[C@H](CC5=CC=CC=C5)C(=O)N[C@@H](CCCCN)C(=O)N)NC(=O)[C@H](CC6=CN=CN6)N

Properties

• Solubility: H2O: 1 mg/mL (Expl.)

chemBlink Chemical Story

Hexarelin, also called examorelin, is a synthetic six-residue peptide studied for its ability to stimulate growth hormone release. It is chemically distinct from growth hormone itself, a much larger protein. The short peptide supplies a signal to the endocrine system; the hormone measured after the signal is produced by the body. This distinction is essential to interpreting the early human experiments.

The molecule illustrates how medicinal chemists modify a peptide without making it longer. Hexarelin is related to GHRP-6 but has a methylated D-tryptophan residue in place of D-tryptophan. The D designation refers to configuration, not to whether the residue is natural, active, or safe. A methyl group on the aromatic side chain changes the shape of the chemical surface while leaving the number of peptide bonds unchanged. The C-terminal amide is another part of its identity; a peptide with a free terminal carboxyl group would not be the same substance.

Early human studies examined the rise in circulating growth hormone after a controlled challenge. One question was how the response changed in the presence of other signals that regulate secretion. Such experiments show why a response cannot be understood from the structure of the stimulus alone. Growth hormone is normally released intermittently, and the size of a measured change depends on the state of the endocrine system and the time of sampling. A change over a short observation period establishes a pharmacological response under those conditions, not an enduring clinical effect.

The scientific interest of hexarelin lies in this combination of defined chemistry and a measurable physiological response. Measuring a transient hormone rise does not establish increased strength, altered body composition, or benefit in a disease. Those are separate outcomes requiring their own controlled comparisons. Results for a characterized research material also cannot establish the composition or safety of another preparation with the same label.

References:
1. PubChem. Examorelin, CID 6918297. https://pubchem.ncbi.nlm.nih.gov/compound/Examorelin
2. Human study of modulation of hexarelin activity. https://pubmed.ncbi.nlm.nih.gov/7731498/

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