HGH Fragment 176-191 is a synthetic peptide modeled on the C-terminal end of human growth hormone (hGH). In the native hormone, residues 176 to 191 read FLRIVQCRSVEGSCGF, with a disulfide bridge betwe...
Certificate of Analysis included with every order.
Technical Specifications
Purity
≥98%
Form
Lyophilized Powder
Storage
-20°C
Molecular Weight
See Certificate of Analysis
Sequence
See Certificate of Analysis
CAS Number
See Certificate of Analysis
About HGH Fragment 176-191
HGH Fragment 176-191 is a synthetic peptide modeled on the C-terminal end of human growth hormone (hGH). In the native hormone, residues 176 to 191 read FLRIVQCRSVEGSCGF, with a disulfide bridge between the two cysteines.[1][3] Pepitiva supplies HGH Fragment 176-191 as a lyophilized powder (2 mg, 5 mg and 10 mg vials, ≥98% purity) for in vitro and preclinical research.
HGH Fragment 176-191 or AOD-9604?
The two names are used for closely related but not identical peptides, and it is worth checking which one a study or a supplier means:
Native hGH 176-191: 16 residues beginning with phenylalanine (FLRIVQCRSVEGSCGF). PubChem lists the formula C78H123N23O22S2, a molecular weight of 1799.1 g/mol and CAS 66004-57-7.[1]
AOD-9604: hGH residues 177 to 191 with an extra tyrosine at the N-terminus (YLRIVQCRSVEGSCGF), formula C78H123N23O23S2, 1815.1 g/mol, CAS 221231-10-3.[2][11]
A 2026 review lists AOD9604 under the label "hGH 176-191", which shows how loosely the two names are used.[9] The exact sequence and mass of each Pepitiva batch are documented in its Certificate of Analysis. See also AOD-9604.
For research use only. Not for human consumption.
Quality & Storage
≥98% purity. Lyophilized Powder. Storage: -20°C. For research purposes only.
Mechanism of Action
Locating a metabolic domain in growth hormone
From the 1970s to the early 2000s, F. M. Ng and colleagues mapped which part of hGH carries its metabolic effects. Their findings with C-terminal fragments include:
Early in vivo work (1978): synthetic hGH 172-191, 176-191, 177-191 and 178-191 produced a short-lived rise in blood glucose and a more sustained rise in plasma insulin in rats, while the shorter 179-191 and 180-191 were inactive. The authors noted that activity required both the right sequence and the right physical configuration.[4]
Fat metabolism (1993 to 1994): hGH 177-191 inhibited lipogenesis in rat adipose tissue with activity identical to the intact hormone, without a significant lipolytic effect in that assay. Chronic treatment of obese mice reduced cumulative weight gain and adipose tissue mass.[5][6]
The tyrosine analogue (2000 to 2001): the disulfide-bonded C-terminal peptide stimulated lipolysis and inhibited lipogenesis in rodent, porcine and human adipose tissue in vitro.[8] In obese mice, the Tyr-extended version (AOD9604) increased fat oxidation and reduced weight gain without causing hyperglycemia, and it did not compete for the hGH receptor or stimulate proliferation of receptor-expressing cells.[7]
Structure
NMR analysis of the cyclic C-terminal peptide showed two type I beta-turns inside the disulfide loop and some structural similarity to the same region in the crystal structure of intact hGH.[8]
Much of the later work used AOD9604 rather than the native phenylalanine-176 sequence, so results from one cannot automatically be transferred to the other.
Research Applications
Other published research
Drug delivery (2022): chitosan nanoparticles loaded with hGH fragment 176-191 plus doxorubicin showed greater anti-proliferative activity against MCF-7 breast cancer cells than nanoparticles loaded with doxorubicin alone.[10]
Analytical detection: a doping-control method detected AOD9604 in urine down to 50 pg/mL and identified a stable serum metabolite, CRSVEGSCG.[11]
Laboratory research applications
Adipocyte assays: lipogenesis, lipolysis (glycerol release) and fat oxidation.
Structure-activity studies: how the C-terminal loop of hGH contributes to its metabolic actions, with full-length hGH as comparator.
Receptor-independence controls: metabolic effects measured in the absence of hGH receptor binding.
Multi-pathway adipose research: alongside AOD-9604, the adipocyte-apoptosis compound CBL-514, the NNMT inhibitor 5-Amino-1MQ and the GHRH analogue Tesamorelin.
HGH Fragment 176-191 is not approved for human or veterinary use; a 2026 review places AOD9604 (hGH 176-191) among the unregulated peptides marketed as research compounds.[9] This product is sold for laboratory research only.
Storage & Handling Guidelines
Proper storage and handling are essential to maintain peptide integrity and ensure reliable research results. All Pepitiva Biolabs peptides are supplied as lyophilized (freeze-dried) powder, which provides excellent long-term stability when stored correctly. Store lyophilized peptides at -20°C for long-term storage or 2-8°C for short-term use. Once reconstituted, peptide solutions should be stored at 2-8°C and used within the timeframe specified in the product documentation. Always use sterile bacteriostatic water for reconstitution and handle peptides in a clean laboratory environment to prevent contamination. Avoid repeated freeze-thaw cycles, as thermal stress can cause peptide degradation and loss of biological activity.
Quality Control & Certification
This product is manufactured under strict quality control protocols and has been verified through comprehensive analytical testing. Each batch undergoes reverse-phase HPLC analysis for purity determination and electrospray ionization mass spectrometry (ESI-MS) for molecular identity confirmation. A detailed Certificate of Analysis (COA) is available for download, documenting purity percentage, molecular weight verification, appearance, and recommended storage conditions. Pepitiva Biolabs maintains batch-level traceability from synthesis through delivery, ensuring complete transparency and quality assurance for your research.
Frequently Asked Questions
What is HGH Fragment 176-191?
A synthetic peptide based on the last 16 amino acids of human growth hormone (residues 176 to 191), a disulfide-bonded loop that early studies linked to the hormone's effects on fat metabolism.
Is HGH Fragment 176-191 the same as AOD-9604?
Not exactly. Native hGH 176-191 starts with phenylalanine (FLRIVQCRSVEGSCGF, 1799.1 g/mol); AOD-9604 is hGH 177-191 with an added tyrosine (YLRIVQCRSVEGSCGF, 1815.1 g/mol). The names are often used interchangeably, so check the Certificate of Analysis. See AOD-9604.
Does the 176-191 peptide bind the growth hormone receptor?
In mouse studies, the tyrosine analogue AOD9604 did not compete for the hGH receptor and did not stimulate proliferation of receptor-expressing cells, unlike intact hGH.
What sizes are available?
HGH Fragment 176-191 is supplied as lyophilized powder in 2 mg, 5 mg and 10 mg vials, at ≥98% purity.
Is HGH Fragment 176-191 approved?
No. It is not approved for human or veterinary use and is sold for laboratory research only.
How should HGH Fragment 176-191 10mg be stored?
Keep the lyophilized powder at −20 °C, protected from light and moisture.
Is this product approved for human use?
No. This product is intended exclusively for in vitro scientific research and laboratory use. It is not approved for human or veterinary use, not intended for diagnostic or therapeutic purposes, and should not be administered to humans or animals under any circumstances.
How do I reconstitute this peptide?
Add sterile bacteriostatic water slowly to the vial, directing the stream against the glass wall rather than directly onto the lyophilized powder. Gently swirl the vial until the powder is fully dissolved — do not shake vigorously. The recommended reconstitution volume depends on your desired concentration. Refer to the product documentation for specific guidance.
Can I get a Certificate of Analysis (COA)?
Yes. A Certificate of Analysis is included with every order and is also available for download from the product page. The COA documents HPLC purity, mass spectrometry identity confirmation, batch number, production date, and storage recommendations.
UniProt. P01241, Somatotropin (GH1), Homo sapiens: 217-residue precursor ending in ...FLRIVQCRSVEGSCGF. Source
Ng FM, Bornstein J. Hyperglycemic action of synthetic C-terminal fragments of human growth hormone. Am J Physiol. 1978;234(5):E521-6. PubMed
Wu Z, Ng FM. Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone. Biochem Mol Biol Int. 1993;30(1):187-96. PubMed
Natera SH, Jiang WJ, Ng FM. Reduction of cumulative body weight gain and adipose tissue mass in obese mice: response to chronic treatment with synthetic hGH 177-191 peptide. Biochem Mol Biol Int. 1994;33(5):1011-21. PubMed
Heffernan MA, Thorburn AW, Fam B, et al. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. Int J Obes Relat Metab Disord. 2001;25(10):1442-9. PubMed
Ogru E, Wilson JC, Heffernan M, et al. The conformational and biological analysis of a cyclic anti-obesity peptide from the C-terminal domain of human growth hormone. J Pept Res. 2000;56(6):388-97. PubMed
Dominikowski A, Rękoś Z, Olejarz M, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475. PubMed
Habibullah MM, Mohan S, Syed NK, et al. Human Growth Hormone Fragment 176-191 Peptide Enhances the Toxicity of Doxorubicin-Loaded Chitosan Nanoparticles Against MCF-7 Breast Cancer Cells. Drug Des Devel Ther. 2022;16:1963-1974. PubMed
Cox HD, Smeal SJ, Hughes CM, et al. Detection and in vitro metabolism of AOD9604. Drug Test Anal. 2015;7(1):31-8. PubMed
Sources are peer-reviewed publications indexed in PubMed and trial registrations on ClinicalTrials.gov. Each citation was checked against its PubMed record.
For research use only. Not for human consumption.
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