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Identity And Research Context — Reference Sheet

By Editorial Desk · published 2025-09-24 · last reviewed 2025-11-04 · Guide

If you have been reading about hGH fragment and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.

Updated 2025-11-04. Numbers and descriptions here follow the published literature rather than marketing material.

Identity and Research Context

AOD-9604 is a synthetic peptide that corresponds to a short section of human growth hormone. It is commonly identified as hGH fragment 176-191 because its sequence matches residues at the C-terminal end of the hormone. The molecule contains sixteen amino acids and is made by solid-phase peptide synthesis. Researchers study it for metabolic effects rather than for the growth-promoting actions associated with full human growth hormone. Its small size distinguishes it from the complete 191-amino-acid hormone.

Several names appear in scientific and commercial settings. AOD9604 and AOD-9604 are development codes used interchangeably, while hGH fragment 176-191 describes the same region. The peptide includes a disulfide bond between two cysteine residues, which helps shape its three-dimensional structure. Different suppliers may provide acetate or other salt forms, and purity can vary. These differences matter because analytical tests and biological assays can respond to the specific form being studied.

Early interest in AOD-9604 centered on whether a fragment of human growth hormone could influence fat metabolism without the broader effects of the full hormone. Cell and animal studies reported changes in fat storage and breakdown. Human trials followed, but the results were not strong enough to secure regulatory approval. The compound remains available for laboratory research, and its clinical potential is still described as uncertain. Studies continue to examine its activity and safety profile.

Mechanism and Regulatory Status

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.

Aod-9604 at a glance

PropertyValueNotes
Common nameAOD-9604Development code used in scientific literature.
Chemical classSynthetic peptideFragment of human growth hormone.
Amino acid length16 residuesMatches hGH region 176-191.
AppearanceWhite to off-white powderTypical lyophilized peptide solid.
SolubilitySoluble in waterDissolves in aqueous media; exact behavior depends on salt form.

Identity And Research Background

AOD-9604 drew attention in the 1990s and 2000s as a potential anti-obesity agent. Early work explored both injectable and oral routes, which is unusual for a peptide of this size. Animal studies reported changes in fat metabolism without the growth-promoting or insulin-like effects associated with full-length growth hormone. Subsequent human trials produced mixed or modest results, and the compound did not obtain regulatory approval for weight management in major markets. It remains known mainly through research literature, sports anti-doping listings, and non-approved supplement advertising.

AOD-9604 is prohibited in sport by the World Anti-Doping Agency under the peptide hormone class. Its presence in a sample can be detected through mass spectrometry-based methods, although the exact assay depends on the laboratory. In research settings, material is often supplied as a lyophilized powder for reconstitution. Buyers and researchers should note that products labeled AOD-9604 may vary in purity and actual peptide content. Analytical certificates and independent testing are common ways to verify identity, but no global harmonized standard exists for all commercial lots.

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Handling And Analytical Properties

AOD-9604 is typically supplied as a lyophilized white to off-white powder. In this form, it is relatively stable when kept cool, dry, and protected from light. Common storage recommendations place it at −20 °C or below for long-term retention. Reconstituted solutions are less stable and are often kept at 2–8 °C for short periods. Freeze-thaw cycles should be minimized because they can promote aggregation or loss of peptide content. Vials are usually sealed under inert gas to reduce oxidation.

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.

Further detail

Anne Ferguson (26 July 1941 – 21 December 1998) was a Scottish physician, clinical researcher and expert in inflammatory bowel disease. She was considered one of the most distinguished gastroenterologists in Britain. Anne Glen was born in Glasgow in 1941. Her parents were Monica and John Glen. She was educated at Notre Dame High School and the University of Glasgow, graduating with a first class honours BSc in physiology in 1961, followed in 1964 with a MB ChB with honours. She won the Brunton Medal for the most distinguished graduate in medicine at the university.

In many organisms including Xenopus and Drosophila, the midblastula transition usually occurs after a particular number of cell divisions for a given species, and is defined by the ending of the synchronous cell division cycles of the early blastula development, and the lengthening of the cell cycles by the addition of the G1 and G2 phases. Prior to this transition, cleavage occurs with only the synthesis and mitosis phases of the cell cycle. The addition of the two growth phases into the cell cycle allows for the cells to increase in size, as up to this point the blastomeres undergo reductive divisions in which the overall size of the embryo does not increase, but more cells are created. This transition begins the growth in size of the organism. The mid-blastula transition is also characterized by a marked increase in transcription of new, non-maternal mRNA transcribed from the genome of the organism. Large amounts of the maternal mRNA are destroyed at this point, either by proteins such as SMAUG in Drosophila or by microRNA. These two processes shift the control of the embryo from the maternal mRNA to the nuclei.

In May 1952, Raymond Gosling, a graduate student working under the supervision of Rosalind Franklin, took an X-ray diffraction image, labeled as "Photo 51", at high hydration levels of DNA. This photo was given to Watson and Crick by Maurice Wilkins and was critical to their obtaining the correct structure of DNA. Franklin told Crick and Watson that the backbones had to be on the outside. Before then, Linus Pauling, and Watson and Crick, had erroneous models with the chains inside and the bases pointing outwards. Franklin's identification of the space group for DNA crystals proved her correct. In February 1953, Linus Pauling and Robert Corey proposed a model for nucleic acids containing three intertwined chains, with the phosphates near the axis, and the bases on the outside. Watson and Crick completed their model, which is now accepted as the first correct model of the double helix of DNA. On 28 February 1953 Crick interrupted patrons' lunchtime at The Eagle pub in Cambridge, England to announce that he and Watson had "discovered the secret of life".

Sources: en.wikipedia.org

Supporting material

A microbial electrolysis cell (MEC) is a technology related to Microbial fuel cells (MFC). Whilst MFCs produce an electric current from the microbial decomposition of organic compounds, MECs partially reverse the process to generate hydrogen or methane from organic material by applying an electric current. The electric current would ideally be produced by a renewable source of power. The hydrogen or methane produced can be used to produce electricity by means of an additional PEM fuel cell or internal combustion engine.

The first generation uses linking technologies that conjugate drugs non-selectively to cysteine or lysine residues in the antibody, resulting in a heterogeneous mixture. This approach leads to suboptimal safety and efficacy and complicates optimization of the biological, physical and pharmacological properties. Site-specific incorporation of unnatural amino acids generates a site for controlled and stable attachment. This enables the production of homogeneous ADCs with the antibody precisely linked to the drug and controlled ratios of antibody to drug, allowing the selection of a best-in-class ADC. An Escherichia coli-based open cell-free synthesis (OCFS) allows the synthesis of proteins containing site-specifically incorporated non-natural amino acids and has been optimized for predictable high-yield protein synthesis and folding. The absence of a cell wall allows the addition of non-natural factors to the system to manipulate transcription, translation and folding to provide precise protein expression modulation.

The use of additional manipulation tools may be needed to organize 3D co-cultures into a configuration similar enough to native tissue architecture. Endothelial cells (PEC), smooth muscle cells (SMC), fibroblasts (PF), and epithelial cells (EpiC) cultured through magnetic levitation can be sequentially layered in a drag-and-drop manner to create bronchioles that maintain phenotype and induce extracellular matrix formation. Below is a list of cell types (primary and cell lines) that have been successfully cultured by the magnetic levitation method.

Adalimumab, sold under the brand name Humira and others, is a disease-modifying antirheumatic drug and monoclonal antibody used to treat rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn's disease, ulcerative colitis, plaque psoriasis, hidradenitis suppurativa, and uveitis. It is administered by subcutaneous injection (injection under the skin). It works by inactivating tumor necrosis factor (TNF). Common side effects include upper respiratory tract infections, pain at the site of injection, rash, and headache. Other side effects may include serious infections, cancer, anaphylaxis, reactivation of hepatitis B, new onset or exacerbation of demyelinating diseases (such as multiple sclerosis), heart failure, liver failure, and aplastic anemia. Use during pregnancy is not recommended, but some sources show use during breastfeeding may be safe. Adalimumab was approved for medical use in the United States in 2002. It is on the World Health Organization's List of Essential Medicines. It is available as a biosimilar medication. In 2023, it was the 244th most commonly prescribed medication in the United States, with more than 3 million prescriptions.

Sources: en.wikipedia.org

Supporting material

Secretases are enzymes that "snip" pieces off a longer protein that is embedded in the cell membrane. Among other roles in the cell, secretases act on the amyloid-beta precursor protein (APP) to cleave the protein into three fragments. Sequential cleavage by beta-secretase 1 (BACE) and gamma-secretase (γ-secretase) produces the amyloid-beta peptide fragment that aggregates into clumps called amyloid plaques in the brains affected by Alzheimer's disease. If alpha-secretase (α-secretase) acts on APP first instead of BACE, no amyloid beta is formed because α-secretase recognizes a target protein sequence closer to the cell surface than BACE. The non-pathogenic middle fragment formed by an α/γ cleavage sequence is called P3. The structure of the three secretases varies widely.

The molecular weight of c7orf26 is 50 kilodaltons. The isoelectric point is 7.61. The protein sequence is uniquely rich for leucine at 15.8% of its composition, this may indicate a leucine-zipper. Further analysis from PSORT indicates that a leucine-zipper region is found at amino acid 318 and lasts until position 340 (22 amino acids long). There are no extremes with regards to acidity and alkalinity. c7orf26 has a positive charge cluster from amino acid 245 – 275 and does not have any negative, or mixed charge clusters. An even distribution of amino acids compose c7orf26. The percent composition of each amino acid is fairly consistent throughout the orthologs of the protein. The most distant ortholog displays the most variance in amino acid composition. There is a higher percent composition of tyrosine, histidine and leucine and a lower composition of valine and alanine.

Motilin is a 22-amino acid polypeptide hormone in the motilin family that, in humans, is encoded by the MLN gene. Motilin is secreted by endocrine Mo cells (also referred to as M cells, which are not the same as the M cells, or microfold cells, found in Peyer's patches) that are numerous in crypts of the small intestine, especially in the duodenum and jejunum. It is released into the general circulation in humans at about 100-min intervals during the inter-digestive state and is the most important factor in controlling the inter-digestive migrating contractions; and it also stimulates endogenous release of the endocrine pancreas. Based on amino acid sequence, motilin is unrelated to other hormones. Because of its ability to stimulate gastric activity, it was named "motilin." Apart from in humans, the motilin receptor has been identified in the gastrointestinal tracts of pigs, rats, cows, and cats, and in the central nervous system of rabbits.

Sources: en.wikipedia.org

Frequently asked questions

What is AOD-9604?

AOD-9604 is a synthetic peptide fragment of human growth hormone. It corresponds to the C-terminal region known as hGH 176-191 and is studied for metabolic effects. It is not an approved therapeutic drug.

Is AOD-9604 the same as human growth hormone?

No. It contains only a small portion of the human growth hormone sequence. The full hormone has 191 amino acids and many additional actions that the fragment does not share.

Why is it called hGH fragment 176-191?

The name refers to the amino acid positions in the human growth hormone chain. The fragment spans residues 176 through 191 at the C-terminal end. This naming convention helps distinguish it from full-length hGH.

Is AOD-9604 approved for weight loss?

No. Major drug regulators have not approved AOD-9604 for weight loss or any other therapeutic indication. It remains an investigational compound studied in research settings.

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