The short version of hGH fragment fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-25 and is reviewed periodically as new material appears.
Identity and purity are commonly checked with reversed-phase high-performance liquid chromatography and mass spectrometry. RP-HPLC separates the peptide from related impurities and can estimate purity by peak area. Mass spectrometry confirms molecular mass and helps detect sequence variants or truncations. Some laboratories use amino acid analysis or peptide mapping for additional characterization. No single method proves biological activity; these techniques establish chemical identity and purity only. They also require suitable reference standards for confident comparison.
Commercial AOD-9604 may vary in purity, counterion content, and residual moisture. Certificates of analysis often report HPLC purity, mass confirmation, and appearance, but testing methods differ between suppliers. Independent verification is sometimes used because labeled content may not match actual peptide amount. Stability under different pH and temperature conditions is not fully standardized across studies. Researchers generally treat lyophilized material as the reference form for weighing and reconstitution. Moisture content can affect accurate mass measurement.
AOD-9604 is a synthetic peptide whose sequence matches the C-terminal fragment of human growth hormone, specifically residues 176 through 191. This region differs from the full hormone in its receptor interactions. The peptide is not a growth hormone secretagogue and does not bind the growth hormone receptor in the same manner. Researchers have examined it for effects on lipid metabolism, but its exact pharmacological profile remains an active area of study.
Development of AOD-9604 began in the 1990s as scientists sought to isolate metabolic effects of growth hormone without its growth-promoting actions. Early laboratory work focused on fat cells and animal models. Several human trials followed, examining changes in body composition and fat mass. Results have been mixed, and the peptide has not progressed to widespread clinical approval. Interest continues in research settings, particularly regarding its mechanism and potential metabolic targets.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized form; may appear as cake |
| Solubility class | Water-soluble | Often reconstituted in aqueous buffer |
| Typical storage temperature | −20 °C or below | Protect from light and moisture |
| Typical analytical method | RP-HPLC and mass spectrometry | Used for purity and identity |
| Common synonyms | AOD-9604; AOD9604; hGH fragment 176-191 | Research name and fragment description |
Proposed mechanisms for AOD-9604 focus on fat cells. Laboratory studies suggest the peptide can increase lipolysis, the breakdown of stored fat, and reduce lipogenesis, the formation of new fat. Unlike full human growth hormone, it does not appear to stimulate substantial IGF-1 production in the studies reported so far. Some evidence points to beta-adrenergic signaling, but the precise receptor targets and downstream pathways remain unresolved. The fragment is not thought to act through the classical growth hormone receptor.
Clinical development of AOD-9604 included trials in people with obesity. Reports from early-phase and mid-phase studies described modest or inconsistent changes in body weight. A phase IIb program did not meet its primary endpoint, and the compound was not approved for medical use. Differences in formulation, delivery route, and participant characteristics may explain some of the variation. Later investigations explored whether the peptide might have effects in other tissues, including cartilage.
Regulatory treatment of AOD-9604 is shaped by its classification as a peptide hormone. The World Anti-Doping Agency lists it as a prohibited substance, and many national anti-doping organizations adopt that list. It does not hold approval as a prescription medicine in the United States, the European Union, or other major markets. Products sold online are frequently labeled for research use only and may not undergo independent quality testing. Import and possession rules differ by country, so legal status depends on local law.
Laboratory studies have reported that AOD9604 can increase lipolysis and reduce lipid accumulation in fat cells. The precise molecular target remains uncertain, and the compound does not appear to activate the growth hormone receptor in the same way as full-length hGH. Proposed mechanisms include effects on beta-adrenergic signaling and enzymes involved in fatty acid synthesis, but these pathways are not firmly established. Because most evidence comes from cell and animal models, whether the same effects occur in humans is an open question.
Clinical development of AOD9604 included trials in people with obesity, but the results did not lead to approval as a prescription medicine in major markets. Interest later shifted to research settings and to unapproved products marketed for body composition. Regulatory agencies have questioned whether the peptide qualifies as a dietary ingredient, and some have issued warnings about its presence in supplements. Long-term human safety data are limited, and questions about efficacy, dosing, and target populations remain unresolved.
AOD-9604 is listed as a prohibited substance in sport by the World Anti-Doping Agency. It falls under the peptide hormones, growth factors, related substances, and mimetics class on the prohibited list. Anti-doping organizations treat its presence in an athlete's sample as an adverse finding unless a therapeutic use exemption applies. The prohibition reflects concerns about performance enhancement in competitive settings and the difficulty of distinguishing exogenous peptide use from endogenous hormone fragments.
Detection of AOD-9604 in biological samples relies on analytical techniques capable of distinguishing a small synthetic peptide from related endogenous sequences. Liquid chromatography coupled with tandem mass spectrometry is commonly used for confirmatory analysis. Sample preparation may involve immunoaffinity enrichment or solid-phase extraction to concentrate the peptide. Because the molecule is small and may be present at low concentrations, assay sensitivity and specificity are ongoing analytical challenges. Laboratories also validate methods against reference materials when available.
Regulatory interest in AOD-9604 increased after high-profile anti-doping cases involving peptide products. In some cases, the substance was supplied under alternative names or in compounded preparations, complicating traceability. Sports tribunals and anti-doping panels have discussed whether the peptide was explicitly banned at the time of use, leading to clarifications by the World Anti-Doping Agency. For consumers and researchers, the legal status can vary by jurisdiction, and products marketed as research chemicals may lack independent quality verification.
=== Mechanism of action === Fabry disease is a genetic disorder caused by various mutations of the enzyme α-GalA, which is responsible for breaking down the sphingolipid globotriaosylceramide (Gb3), among other glycolipids and glycoproteins. Some of these mutations result in misfolding of α-GalA, which subsequently fails protein quality control in the endoplasmic reticulum and is decomposed. Lack of functional α-GalA leads to accumulation of Gb3 in blood vessels and other tissues, with a wide range of symptoms including kidney, heart, and skin problems. Migalastat is a potent, orally available inhibitor of α-GalA (IC50: 4 μM). When binding to faulty α-GalA, it shifts the folding behaviour towards the proper conformation, resulting in a functional enzyme provided the mutation is amenable. Molecules with this type of mechanism are called pharmacological chaperones. When the enzyme reaches its destination, the lysosome, migalastat dissociates because of the low pH and the relative abundance of Gb3 and other substrates, leaving α-GalA free to fulfill its function. Depending on the mutation, the EC50 is between 0.8 μM and over 1 mM in cellular models.
Growing evidence indicates that complete androgen receptor (AR) dysfunction disrupts systemic metabolic homeostasis and neither external nor endogenous estrogen can normalize it. AR absence is related to decrease in mature neutrophils in mice, but there is no evidence that human CAIS individuals have impaired neutrophil function. The proteome related to inflammation is predominantly inhibited in CAIS. Upregulation of IFN-β and IL-6 are reported in the blood of CAIS individuals. Leukocytes of CAIS individuals exhibit relative resistance to DNA damaging.
=== Legal === This technique is also used for detection of illicit drugs in various samples. The most common method of drug detection has been an immunoassay. This method is much more convenient. However, convenience comes at the cost of specificity and coverage of a wide range of drugs, therefore, HPLC has been used as well as an alternative method. As HPLC is a method of determining (and possibly increasing) purity, using HPLC alone in evaluating concentrations of drugs was somewhat insufficient. Therefore, HPLC in this context is often performed in conjunction with mass spectrometry. Using liquid chromatography-mass spectrometry (LC-MS) instead of gas chromatography-mass spectrometry (GC-MS) circumvents the necessity for derivitizing with acetylating or alkylation agents, which can be a burdensome extra step. LC-MS has been used to detect a variety of agents like doping agents, drug metabolites, glucuronide conjugates, amphetamines, opioids, cocaine, BZDs, ketamine, LSD, cannabis, and pesticides. Performing HPLC in conjunction with mass spectrometry reduces the absolute need for standardizing HPLC experimental runs.
Sources: en.wikipedia.org
== Multi-junction == The increased demand for faster and easy-to-use protein separation tools has accelerated the evolution of IEF towards in-solution separations. In this context, a multi-junction IEF system was developed to perform fast and gel-free IEF separations. The multi-junction IEF system utilizes a series of vessels with a capillary passing through each vessel. Part of the capillary in each vessel is replaced by a semipermeable membrane. The vessels contain buffer solutions with different pH values, so that a pH gradient is effectively established inside the capillary. The buffer solution in each vessel has an electrical contact with a voltage divider connected to a high-voltage power supply, which establishes an electrical field along the capillary. When a sample (a mixture of peptides or proteins) is injected in the capillary, the presence of the electrical field and the pH gradient separates these molecules according to their isoelectric points. The multi-junction IEF system has been used to separate tryptic peptide mixtures for two-dimensional proteomics and blood plasma proteins from Alzheimer's disease patients for biomarker discovery.
=== pH-metric === The pH-metric set of techniques determine lipophilicity pH profiles directly from a single acid-base titration in a two-phase water–organic-solvent system. Hence, a single experiment can be used to measure the logarithms of the partition coefficient (log P) giving the distribution of molecules that are primarily neutral in charge, as well as the distribution coefficient (log D) of all forms of the molecule over a pH range, e.g., between 2 and 12. The method does, however, require the separate determination of the pKa value(s) of the substance.
The MEROPS online database for peptidases and their inhibitors: I04.953 Archived 2019-10-16 at the Wayback Machine Angiotensins at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human AGT genome location and AGT gene details page in the UCSC Genome Browser. Overview of all the structural information available in the PDB for UniProt: P01019 (Angiotensin) at the PDBe-KB.
Sources: en.wikipedia.org
Lyophilized powder is commonly stored at −20 °C or below, protected from light and moisture. Reconstituted solutions are typically kept refrigerated and used within a limited period.
Reversed-phase HPLC and mass spectrometry are standard checks. They confirm peptide purity and molecular mass, but they do not by themselves demonstrate biological activity.
Synthesis, purification, and handling conditions can differ, leading to variations in purity and salt content. Certificates of analysis help, but independent testing is often needed for verification.
AOD-9604 is a synthetic peptide fragment of human growth hormone, corresponding to amino acids 176-191. It is studied for potential effects on fat metabolism, but it is not approved as a drug in most countries. Its exact mechanism remains under investigation.