Compound monograph
Pralmorelin (GHRP-2)
Pralmorelin is a synthetic hexapeptide growth hormone secretagogue acting at the ghrelin receptor, containing three D-configured residues and a naphthylalanine substitution.
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Identity & nomenclature
Pralmorelin is a synthetic hexapeptide growth hormone secretagogue acting at the ghrelin receptor, containing three D-configured residues and a naphthylalanine substitution.
GHRP-2 is not GHRP-6; they are different hexapeptides. And GHRP does not denote a GHRH-receptor ligand — the similar names refer to GH secretion, not a shared receptor. A generic 'Nal' field loses both the 2-naphthyl substitution and the D configuration, either of which changes the molecule.
Declared aliases and development codes: GHRP-2, Growth hormone-releasing peptide-2, KP-102.
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Molecular properties
| Molecular formula | C45H55N9O6 |
|---|---|
| Molecular mass | 817.99 Da |
| CAS Registry Number | 158861-67-7 |
| PubChem CID | 6918245 |
| UNII | E6S6E1F19M |
| Three-letter sequence | D-Ala–D-2-Nal–Ala–Trp–D-Phe–Lys–NH2 |
No one-letter string is published here. Position 2 is 3-(naphthalen-2-yl)-D-alanine, a single nonstandard residue; written as ordinary letters it would denote different amino acids. Three of six residues are D-configured and the stereochemistry is identity-defining, not annotation.
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Structural characteristics
Pituitary work distinguishes its direct action from GHRH-mediated responses, and it appears in CD36 binding competition experiments alongside hexarelin. The CD36 observation is a binding result in the systems tested; it does not establish that every pralmorelin response is CD36-mediated.
- D-2-naphthylalanine at position 2
- D-Ala1
- D-Phe5
Terminal features: Free N-terminus, C-terminal amide at Lys6.
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Molecular targets & mechanisms
Growth hormone secretagogue receptor
GHS-R1a · Ghrelin receptor · GHSR
A G-protein-coupled receptor distinct from the GHRH receptor. Antagonist profiling reported that ipamorelin releases growth hormone through a GHRP-like receptor rather than through the GHRH receptor, establishing the two pathways as separate.
CD36 scavenger receptor
CD36 · FAT · SR-B2
A multifunctional scavenger receptor, distinct from the growth hormone secretagogue receptor, reported as a binding target for certain synthetic secretagogue peptides. It is recorded separately here precisely because collapsing it into the ghrelin-receptor mechanism would erase the finding that these compounds are not pharmacologically interchangeable.
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Analytical considerations
An intact-mass match distinguishes neither D from L residues nor 1-naphthyl from 2-naphthyl positional isomers — both are identical in elemental composition. Those require chiral amino-acid analysis with authentic standards, or NMR. A growth-hormone secretion assay cannot establish which GHRP is present; the comparative LC-MS work is the reference that actually separates them.
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Verified bibliography
- Effect of GHRH and GHRP-2 treatment in vitro on GH secretion and levels of GH, pituitary transcription factor-1, GHRH-receptor, GH-secretagogue-receptor and somatostatin receptor mRNAs in ovine pituitary cells.current
Yan M, Hernandez M, Xu R, Chen C
European journal of endocrinology · 2004-02 · Journal Article
- Identification of the growth hormone-releasing peptide binding site in CD36: a photoaffinity cross-linking study.current
Demers A, McNicoll N, Febbraio M, Servant M, Marleau S, Silverstein R, Ong H
The Biochemical journal · 2004-09-01 · Journal Article
- Determination of growth hormone releasing peptides (GHRP) and their major metabolites in human urine for doping controls by means of liquid chromatography mass spectrometry.current
Thomas A, Höppner S, Geyer H, Schänzer W, Petrou M, Kwiatkowska D, Pokrywka A, Thevis M
Analytical and bioanalytical chemistry · 2011-02-06 · Journal Article
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Methodology & citation verification
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