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Research use only
· 6 min read
Before ghrelin had a name, before anyone knew the receptor existed, Cyril Bowers had already built a synthetic peptide that could bind it. GHRP-6 (growth-hormone-releasing hexapeptide-6, CAS 87616-84-0) is the prototypical small-peptide growth-hormone secretagogue and a synthetic agonist at the GHS-R1a receptor that was later de-orphanised when ghrelin was discovered in 1999. The compound was characterised before its own receptor had an official name, which is a neat inversion of the usual order. Kovalabs supplies it strictly as a research reagent; everything below describes what published studies have investigated, not any human use, dose, route, schedule or outcome.
| Compound | GHRP-6 (growth-hormone-releasing hexapeptide-6) |
|---|---|
| Synonyms | His-D-Trp-Ala-Trp-D-Phe-Lys-NH2; Hexapeptide-2; SK&F-110679; GH-releasing hexapeptide 6 |
| Class / mechanism | Synthetic hexapeptide growth-hormone secretagogue; agonist at the growth-hormone-secretagogue receptor (GHS-R1a / ghrelin receptor) |
| Molecular formula | C46H56N12O6 |
| Molecular weight | 873.0 g/mol (some vendor sources report 872.97 g/mol for the free peptide; salt forms differ) |
| CAS number | 87616-84-0 |
| PubChem CID | 9919153 (CAS-anchored, authoritative record) |
GHRP-6 is the synthetic hexapeptide H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2: six residues, C-terminally amidated, with D-configuration at positions two (tryptophan) and five (phenylalanine). PubChem indexes it under CID 9919153, the CAS-anchored record that carries CAS number 87616-84-0, the full stereochemical synonym set, molecular formula C46H56N12O6 and molecular weight 873.0 g/mol. The isomeric SMILES on that record confirms both D-stereocentres and the C-terminal amide. These identifiers were adversarially cross-checked against the authoritative PubChem record.
Here is the trap. PubChem also holds CID 4345065, which surfaces whenever a plain name search returns GHRP-6. It carries the same His-Trp-Ala-Trp-Phe-Lys backbone, the same formula C46H56N12O6 and the same mass 873.0 g/mol - but no stereochemical descriptors and no CAS linkage. The two records are mutually consistent on formula, mass and sequence; they differ only on stereochemical completeness. Cite CID 4345065 and you have referenced a different chemical entity from the defined compound. The authoritative citation throughout this page is CID 9919153. One further caution: the connectivity record's free-text synonym table surfaces a mislabelled GHRP-2 string. GHRP-2 is a separate compound with a different sequence and formula; that synonym entry is not evidence of equivalence. The molecular weight of 873.0 g/mol is for the free peptide; salt forms such as the acetate carry a different mass that should be stated separately where a salt is supplied. Purity and identity ship documented on every batch through the certificate of analysis.
| Identifier | Value | Source record |
|---|---|---|
| Sequence | H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (six residues, C-terminally amidated, D-Trp and D-Phe) | PubChem CID 9919153 |
| Molecular formula | C46H56N12O6 | PubChem CID 9919153 |
| Molecular weight | 873.0 g/mol | PubChem CID 9919153 |
| CAS number | 87616-84-0 | PubChem CID 9919153 |
| PubChem CID (authoritative) | 9919153 (CAS-anchored, stereochemically complete) | NCBI PubChem |
| PubChem CID (connectivity record) | 4345065 (same molecule, no stereo descriptors) | NCBI PubChem |
| Receptor target | Growth-hormone-secretagogue receptor (GHS-R1a / ghrelin receptor) | Bowers 1998, PMID 9893708 |
GHRP-6 acts at the growth-hormone-secretagogue receptor (GHS-R1a), a class-A G-protein-coupled receptor. Bowers (Cellular and Molecular Life Sciences, 1998) reviews the growth-hormone-releasing peptide class and positions GHRP-6 as a synthetic agonist within the ligand series, with a binding site described as distinct from that of growth-hormone-releasing hormone (GHRH). It is in this receptor-pharmacology sense - agonist at GHS-R / ghrelin receptor - that GHRP-6 is grouped on this site, by molecular target rather than by any indication. See the GHRP-6 product page and the wider GH-axis research peptides catalogue.
At the intracellular level, the signal-transduction pathway the receptor engages was the subject of an in-vitro study by Lei et al. (Journal of Molecular Endocrinology, 1995). Working in cultured human pituitary somatotroph cells, the study used phosphatidylinositol (PI) turnover - a phospholipase-C / inositol-phosphate second-messenger readout - as its pre-specified endpoint. That names the pathway the work set out to interrogate; no effect or magnitude is asserted here.
GHRP-6 sits within a family of GHS-R-directed peptidic ligands. A neuroendocrinology review (Camanni et al., Frontiers in Neuroendocrinology, 1998) catalogues these peptides and their analogues, describing structure-activity relationships across the family at the receptor level. It is a narrative pharmacology review cited here for receptor-level ligand-class context only; no human outcome, dose recommendation or effect is imported from it.
Structural-biology context comes from solution-conformation work on the same receptor system. Silva Elipe et al. (Biopolymers, 2001) carried out a 1H-NMR solution-structure analysis of the endogenous GHS-R ligand and a set of six truncated analogues, with solution conformation and structural descriptors as the endpoints. This characterises the conformational behaviour of small-peptide ligands at the receptor GHRP-6 targets; no pharmacological effect is asserted.
The receptor toolset around GHRP-6 includes a pharmacological counterpart: [D-Lys3]-GHRP-6, a peptidic antagonist used to probe the GHS-R axis, and a chemically and mechanistically distinct entity from GHRP-6 itself. Shahryar et al. (Arquivos Brasileiros de Endocrinologia e Metabologia, 2014) describe a controlled in-vivo Wistar-rat study using that antagonist, with serum hormonal and biochemical parameters as the pre-specified endpoints. This is documented to map the receptor-pharmacology toolset; the antagonist is a separate molecule, the endpoints are disease-relevant, and no result, effect, magnitude or clinical interpretation is asserted.
The GHRP-6 literature spans receptor pharmacology, intracellular signalling, structural biology and investigational provocation paradigms. Each item below is described strictly by what the study set out to investigate - design and endpoint name only:
Several of these sources are narrative reviews (PMID 9893708, 9465289), cited only for receptor-pharmacology and ligand-class context, never as evidence of any effect.
The notes below are general physicochemical-stability and storage information for laboratory work only. They are not dosing, administration or use instructions, and nothing here describes a preparation for use in humans or animals.
GHRP-6 is typically supplied as a lyophilised solid, commonly as the acetate salt. The sealed lyophilised peptide should be held desiccated and protected from light; long-term storage at -20 C or lower is standard practice for peptides of this class. As a histidine-, tryptophan- and phenylalanine-containing peptide it is susceptible to oxidation and light degradation, so minimise freeze-thaw cycles and limit exposure time at working temperature.
For laboratory reconstitution, the general bench procedure uses an appropriate laboratory solvent - typically aqueous with a low percentage of acetic acid as a co-solvent where solubility is limiting - after which the solution is kept refrigerated and used within a defined working window for analysis. This is a dissolution step for bench use, not a preparation method for any use in humans or animals. The full procedure and dilution calculator live on the reconstitution guide.
Peptide identifiers are easy to state and easy to get wrong. A vial bearing the name GHRP-6 is not the same as a vial that has been confirmed as GHRP-6. Every Kovalabs batch ships with a certificate of analysis, so the mass and purity of the material in hand can be checked against the documented identifiers (formula C46H56N12O6, CAS 87616-84-0) rather than taken on trust. A mechanistically related compound in the same GH-axis catalogue is the GHS-R agonist ipamorelin; the full axis sits at GH-axis research peptides.
Tier one is solid: the chemistry is pinned down. GHRP-6 is a defined hexapeptide (H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, C46H56N12O6, CAS 87616-84-0) anchored to PubChem CID 9919153, and its molecular target is well characterised as the GHS-R1a receptor later de-orphanised by ghrelin. Tier two is the mechanism work: in-vitro signalling in cultured somatotroph cells (phosphatidylinositol turnover), animal studies of a related antagonist, and solution-structure analysis of GHS-R ligands. These describe pathways and conformations, not outcomes; a cell in a dish is not a person. Tier three is the weakest: human evidence is essentially absent, with the one human-context entry being a provocation-paradigm study design from which no result is drawn. It is not a licensed medicine, and it has not been shown to produce defined outcomes in humans. Curiosity is warranted; certainty is not.
GHRP-6 is supplied by Kovalabs for laboratory and in-vitro research only. It is not a medicine, not a supplement, and not for human or veterinary use, and nothing on this page describes a dose, a route, a schedule or an outcome. No medicinal, therapeutic, efficacy or human-outcome claim is made or implied anywhere here. Every study above is described by design and endpoint name only, with an explicit no-effect-asserted guard on the disease-relevant endpoints (the somatotroph-axis provocation endpoint of PMID 8887178 and the serum hormonal and biochemical endpoints of the animal study PMID 24863092). GHRP-6 has not been evaluated by the MHRA or any comparable regulator for safety or efficacy in humans or animals. Every batch is third-party tested with a certificate of analysis. See the full research disclaimer at research disclaimer for terms.
No. GHRP-6 has not been approved as a medicine by the MHRA or any comparable regulator. Kovalabs supplies it strictly as a research reagent for laboratory use, not for human or veterinary use, and makes no medicinal, therapeutic or efficacy claim.
Published reviews characterise GHRP-6 as a synthetic agonist at the growth-hormone-secretagogue receptor (GHS-R1a), the receptor later de-orphanised by ghrelin, with a binding site described as distinct from that of growth-hormone-releasing hormone (Bowers, 1998). It is grouped by this molecular target rather than by any indication.
GHRP-6 is the hexapeptide H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 with molecular formula C46H56N12O6 and a molecular weight of 873.0 g/mol (some vendor sources quote 872.97 g/mol for the free peptide). Its CAS number is 87616-84-0 and its authoritative PubChem record is CID 9919153.
No. GHRP-6 (the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) and GHRP-2 are distinct compounds with different sequences and formulae. PubChem's connectivity record for GHRP-6 (CID 4345065) contains a mislabelled GHRP-2 string in its free-text synonyms; the CAS-anchored record CID 9919153 is authoritative and the two peptides should not be conflated.
The cited literature spans receptor pharmacology and ligand-class reviews (PMID 9893708, 9465289), an in-vitro signalling study with phosphatidylinositol turnover as its endpoint (PMID 7772238), a 1H-NMR solution-structure analysis of related GHS-R ligands (PMID 11745115), and provocation- and antagonist-paradigm study designs (PMID 8887178, 24863092). Each is described by design and endpoint name only, with no result or effect asserted.
As bench handling of a research reagent only. The lyophilised peptide is held desiccated, protected from light and stored at -20 C or lower, with freeze-thaw cycles minimised because of its oxidation-prone histidine, tryptophan and phenylalanine residues. Reconstitution is a dissolution step in an appropriate laboratory solvent (aqueous with low-percentage acetic acid as a co-solvent if needed), after which the solution is used within a defined working window for analysis; see the reconstitution guide. None of this is a preparation method for use in humans or animals.