What Is Sermorelin?
By the Zen Well Labs Research Team · Last reviewed October 2026 · For laboratory research reference only
Short answer: Sermorelin is the synthetic C-terminal amide of the first 29 amino acids of human growth hormone–releasing hormone — written GHRH(1-29)-NH2 or GRF 1-29 amide. Its sequence is Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2 (one-letter YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2), molecular formula C149H246N44O42S, average molecular weight ≈3357.9 Da and CAS number 86168-78-7 (PubChem CID 16132413; FDA UNII 89243S03TE). It is the unmodified GHRH(1-29) amide, chemically distinct from tetrasubstituted Mod GRF 1-29 / “CJC-1295 no DAC,” from DAC-bearing CJC-1295, from tesamorelin and from the ghrelin-receptor agonist ipamorelin. Zen Well Labs sells Sermorelin (10 mg) as a laboratory reagent for in-vitro research only. It is not a currently marketed FDA-approved drug product and is not for human or veterinary use.
Sermorelin at a glance
| Common names | Sermorelin, GHRH(1-29)-NH2, GRF 1-29 amide, hGHRH(1-29)NH2 |
|---|---|
| Type | Synthetic linear peptide, 29 residues, C-terminally amidated |
| Sequence (one-letter) | YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2 |
| Sequence (three-letter) | Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2 |
| Molecular formula | C149H246N44O42S |
| Molecular weight (average) | ≈3357.9 Da |
| Monoisotopic mass | ≈3355.82 Da |
| CAS number | 86168-78-7 (primary PubChem synonym; alternate registry numbers also appear) |
| PubChem CID | 16132413 |
| FDA UNII | 89243S03TE |
| Receptor class (literature) | GHRH receptor agonist (native 1–29 fragment) |
| Contains Met (oxidation watch) | Yes (Met27) |
| Typical supplied form | Lyophilized powder (Zen Well Labs: 10 mg vial) |
| US regulatory note | Historical finished-product brand Geref (sermorelin acetate) was discontinued; Zen Well Labs material is a research reagent, not that product |
Where does sermorelin come from?
Human growth hormone–releasing hormone (GHRH, also called GRF or somatoliberin) is a 44-residue hypothalamic peptide. Guillemin, Brazeau and colleagues (Science, 1982) isolated growth hormone–releasing factor from a human pancreatic tumour and characterised the peptide that launched the modern GHRH field. The N-terminal 29 residues, as a C-terminal amide, retain the core receptor-active fragment used in much subsequent laboratory and pharmaceutical chemistry. That fragment — GHRH(1-29)-NH2 — is the defined structure of sermorelin.
Commercial research vials are made by solid-phase peptide synthesis of that amidated 29-mer. Identity should be confirmed by mass spectrometry against ≈3357.9 Da (average) / ≈3355.82 Da (monoisotopic) and by chromatographic purity, not by trade name alone. PubChem lists the compound under CID 16132413 (title “Sermorelin”) with formula C149H246N44O42S.
Sequence and chemical identity
One-letter code (C-terminal amide): YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2.
Three-letter code: Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2.
Bench notes:
- Position 2 is L-Ala (not D-Ala). D-Ala2 is a hallmark of Modified GRF 1-29, not of sermorelin.
- Position 8 is Asn (not Gln). Gln8 is another Mod GRF substitution.
- Position 15 is Gly (not Ala).
- Position 27 is Met (not Leu). Met27 makes sermorelin oxidation-prone (+16 Da methionine sulfoxide on MS of aged or poorly stored material). Mod GRF replaces this with Leu27.
- The C-terminus is amidated (Arg-NH2). A free-acid 29-mer is a different chemical entity.
CAS 86168-78-7 is the primary registry synonym on the PubChem record. Another RN (114466-38-5) also appears on that record; prefer the CAS and observed mass printed on the batch COA when writing a methods section. Salt forms (for example acetate) change the formula weight of the supplied solid without changing the peptide’s MS mass.
Sermorelin versus CJC-1295, Mod GRF 1-29, tesamorelin and ipamorelin
Catalogues often group these names. They are not interchangeable reagents.
| Feature | Sermorelin (GHRH 1–29 amide) | Mod GRF 1-29 (“CJC-1295 no DAC”) | CJC-1295 with DAC | Tesamorelin | Ipamorelin |
|---|---|---|---|---|---|
| Backbone | Native GHRH(1-29)-NH2 | Tetrasubstituted GHRH(1-29)-NH2 | Same tetrasubstituted core + DAC linker | Distinct GHRH(1-44)–related construct | Short GHSR-1a agonist |
| Approx. average mass | ≈3358 Da | ≈3368 Da | ≈3647 Da | ≈5136 Da | ≈712 Da |
| Key sequence markers | Ala2, Asn8, Gly15, Met27 | D-Ala2, Gln8, Ala15, Leu27 | As Mod GRF + maleimidopropionyl-Lys | Much larger; not the 29-mer | Different peptide class |
| CAS (typical) | 86168-78-7 | 863288-34-0 | 446262-90-4 | 218949-48-5 | (see Ipamorelin page) |
| Pathway | GHRH receptor | GHRH receptor | GHRH receptor | GHRH receptor | Ghrelin / GHSR-1a |
Practical MS rule of thumb:
- ≈3358 Da with sulfur (Met) → sermorelin / native GRF 1-29 amide.
- ≈3368 Da without the native Met27 pattern → usually Mod GRF 1-29.
- ≈3647 Da → CJC-1295 with DAC.
- ≈5136 Da → tesamorelin-scale material, not sermorelin.
- ≈712 Da → ipamorelin, a different receptor class entirely.
See our CJC-1295 reference page for the DAC vs Mod GRF split, and ipamorelin for the GHSR pathway.
What has the published research looked at?
Themes that appear repeatedly in cell, pituitary and animal-model GHRH literature include:
- Isolation and fragment definition. Guillemin et al. (Science, 1982) reported isolation and characterisation of growth hormone–releasing factor and established the foundation for later GHRH(1-29) work.
- GHRH-receptor pharmacology of the 1–29 amide. Sermorelin is used in laboratory systems as the native-sequence short fragment that activates the GHRH receptor on somatotroph models — distinct from ghrelin-mimetic secretagogues.
- Analogue comparison. Later medicinal-chemistry programmes (including tetrasubstituted Mod GRF and albumin-binding DAC constructs) are best read as derivatives of, not synonyms for, the native 1–29 amide. Mass and sequence markers above keep them straight.
These are mechanistic and preclinical research themes. They do not show that research-grade sermorelin from any catalogue has a health effect in people, and they do not make a research vial equivalent to any finished pharmaceutical.
Regulatory status
Historical finished product. Sermorelin acetate was previously marketed in the United States under the brand Geref as FDA-approved finished pharmaceutical products. Those products were later discontinued. In 2013, FDA published a Federal Register determination that the Geref products were not withdrawn from sale for reasons of safety or effectiveness (78 FR 14095, 4 March 2013). That determination is about the discontinued finished drug products and the pathway for abbreviated applications referring to them. It is not an authorisation to use research-chemical sermorelin in humans.
Zen Well Labs material. Zen Well Labs Sermorelin is a lyophilized laboratory reagent for in-vitro research. It is not Geref, is not a currently marketed FDA-approved drug product, and is not for human or veterinary use. Historical approval or discontinuance of a finished brand does not transfer to catalogue research vials.
What is missing
- Equivalence to discontinued brands. There is no basis to treat a research-chemical vial as Geref or as any ANDA product.
- Name confusion with Mod GRF / CJC labels. A label that says only “GHRH” or “CJC” without mass and sequence is unresolved until the COA is checked.
- Transfer from models. Pituitary-cell and animal-model findings depend on the preparation and endpoint. They do not transfer automatically to human use, and Zen Well Labs material is not sold for that purpose.
Storage and stability in the laboratory
Store sermorelin as sealed lyophilized powder: keep vials closed, dry and protected from light, at −20 °C for long-term storage. Short periods at 2–8 °C are generally tolerated for sealed dry material. Let a cold vial reach room temperature before opening so moisture does not condense on the powder, and reseal promptly. Because of Met27, limit unnecessary air exposure of opened vials and re-check MS if a +16 Da species appears later. Record the batch number and date of first opening. See our guide to lyophilized peptide storage and stability for the general principles.
How are identity and purity verified?
Reversed-phase HPLC reports purity as percent peak area. Mass spectrometry confirms identity: the observed mass should be consistent with ≈3357.9 Da (average) or ≈3355.82 Da (monoisotopic) for the free peptide amide, allowing for the adducts your instrument reports. A Certificate of Analysis should report both results and a batch number, and ideally CAS 86168-78-7.
Because sermorelin (≈3358 Da) and Mod GRF 1-29 (≈3368 Da) sit only about 10 Da apart, low-resolution MS plus sequence awareness matters: look for Met27 vs Leu27 and the substitution pattern, not only a rounded “~3360 Da” label. Our explainer on how to read a peptide COA covers the fields; HPLC vs mass spec for peptide identity explains why purity percentage alone is not identity.
Catalogue and methods hygiene
When sermorelin appears in a purchasing cart or a methods section:
- Write GHRH(1-29)-NH2 or the full sequence, not only a shop nickname.
- Record CAS 86168-78-7, PubChem CID 16132413, and the observed MS mass (~3358 Da).
- If the supplier’s label says “CJC-1295,” “Mod GRF,” or “GHRH” without a mass, treat identity as unresolved until the COA settles native vs tetrasubstituted vs DAC forms.
- Keep ipamorelin on a separate item master — same “GH-axis research” aisle in catalogues, different receptor and different mass.
Zen Well Labs supplies Sermorelin as a 10 mg lyophilized research vial for in-vitro laboratory research under your institution’s protocols.
Frequently asked questions
What is the amino acid sequence of sermorelin?
Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2 (YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2). It is GHRH(1-29) as a C-terminal amide.
What is the molecular weight and CAS number of sermorelin?
About 3357.9 Da (formula C149H246N44O42S), CAS 86168-78-7, PubChem CID 16132413, UNII 89243S03TE. Salt forms have higher formula weights.
Is sermorelin the same as CJC-1295 or Mod GRF 1-29?
No. Sermorelin is the native GHRH(1-29) amide. Mod GRF 1-29 (“CJC-1295 no DAC”) carries four substitutions (D-Ala2, Gln8, Ala15, Leu27) and a slightly different mass. CJC-1295 with DAC adds an albumin-binding linker (~3647 Da). See What is CJC-1295?.
Is sermorelin the same as ipamorelin or tesamorelin?
No. Ipamorelin is a short GHSR-1a (ghrelin-receptor) agonist (~712 Da), not a GHRH(1-29) fragment — see What is ipamorelin?. Tesamorelin is a larger GHRH-related pharmaceutical construct (~5136 Da), not the 29-mer sermorelin sequence.
Is Zen Well Labs Sermorelin the same as Geref?
No. Geref was a finished pharmaceutical brand of sermorelin acetate that was discontinued. Zen Well Labs Sermorelin is a research reagent for in-vitro use only.
What is Zen Well Labs Sermorelin 10 mg intended for?
In-vitro laboratory research only. It is not for human or veterinary use.
References
- Guillemin R, Brazeau P, Bohlen P, Esch F, Ling N, Wehrenberg WB. Growth hormone-releasing factor from a human pancreatic tumor that caused acromegaly. Science. 1982;218(4572):585–587. doi:10.1126/science.6812220.
- PubChem Compound Summary, CID 16132413 (Sermorelin). National Center for Biotechnology Information.
- PubChem Compound Summary, CID 16137828 (Tesamorelin). National Center for Biotechnology Information.
- NCATS Inxight Drugs / UNII 89243S03TE (SERMORELIN).
- U.S. Food and Drug Administration. Determination That GEREF (Sermorelin Acetate) Injection… Were Not Withdrawn From Sale for Reasons of Safety or Effectiveness. Federal Register. 2013;78(42):14095–14096 (4 March 2013). https://www.federalregister.gov/documents/2013/03/04/2013-04827
Related
- What is CJC-1295?
- What is Ipamorelin?
- What is Epithalon?
- What is MOTS-c?
- How to read a peptide COA
- HPLC vs mass spec for peptide identity
- Lyophilized peptide storage and stability
Research use only. All products sold by Zen Well Labs are intended strictly for in-vitro laboratory research. They are not drugs, foods, cosmetics or dietary supplements, are not approved by the FDA for any use, and are not for human or veterinary use. Nothing on this page is medical advice, and nothing here describes or recommends administration to humans or animals.
