This is a working overview of synthetic peptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-30. Anything still debated is marked as such rather than presented as settled.
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 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.
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.
AOD-9604 is a synthetic peptide modeled on the C-terminal region of human growth hormone. It is often described as hGH fragment 176-191. Research interest arose because it was designed to isolate possible effects on fat metabolism from other actions of growth hormone. It is not a full growth hormone molecule. Its development history includes early laboratory and animal studies followed by human trials. The peptide has been examined in laboratory, animal, and limited human studies.
The compound has been studied as a potential treatment for obesity and related metabolic conditions. Published trials have examined changes in body weight, fat mass, and safety markers over limited durations. Results have been mixed or modest, and no large-scale outcome trials are established. Regulatory agencies in several countries have not approved it as a therapeutic drug. Some commercial products have been marketed outside regulated pharmaceutical channels, which raises questions about quality and claims.
In the scientific literature, AOD-9604 appears in reviews of growth hormone fragments and in discussions of peptide-based metabolic research. Some sources distinguish it from growth hormone itself, while others group it with compounds marketed for weight management. The evidence base is small compared with approved obesity medications. Questions about long-term efficacy and clinical relevance remain open, and independent replication of key findings is limited. Most published reports are early-stage and exploratory.
The Cambridge University undergraduate newspaper also ran its own short article on the discovery on Saturday, May 30, 1953. Bragg's original announcement at a Solvay Conference on proteins in Belgium on April 8, 1953, went unreported by the press. In 1962 Watson, Crick, and Maurice Wilkins jointly received the Nobel Prize in Physiology or Medicine for their determination of the structure of DNA.
The initial product from the hydrolysis reaction is de-watered and further processed by dry cracking at 500 °C. The "SlurryCarb" process operated by EnerTech uses similar technology to decarboxylate wet solid biowaste, which can then be physically dewatered and used as a solid fuel called E-Fuel. The plant at Rialto is said to be able to process 683 tons of waste per day.
=== Research tool === Due to its high proteolytic specificity, thrombin is a valuable biochemical tool. The thrombin cleavage site (Leu-Val-Pro-Arg-Gly-Ser) is commonly included in linker regions of recombinant fusion protein constructs. Following purification of the fusion protein, thrombin can be used to selectively cleave between the arginine and glycine residues of the cleavage site, effectively removing the purification tag from the protein of interest with a high degree of specificity.
Sources: en.wikipedia.org
== Role in treatment of disease == A 1996 study by McPhee et al. suggested that stercobilin and other related pyrrolic pigments — including urobilin, biliverdin, and xanthobilirubic acid — has potential to function as a new class of HIV-1 protease inhibitors when delivered at low micromolar concentrations. These pigments were selected due to a similarity in shape to the successful HIV-1 protease inhibitor Merck L-700,417 (N,N-bis(2-hydroxy-1-indanyl)-2,6-diphenylmethyl-4-hydroxy-1,7-heptandiamide). Further research is suggested to study the pharmacological efficacy of these pigments.
Inhibition of enzymes involved in purine biosynthesis has been exploited as a potential drug target for chemotherapy. Cancer cells require high concentrations of purines to facilitate division and tend to rely on de novo synthesis rather than the nucleotide salvage pathway. Several folate based inhibitors have been developed to inhibit formylation reactions by GAR transformylase and AICAR transformylase. The first GAR transformylase inhibitor Lometrexol [(6R)5,10-dideazatetrahydrofolate] was developed in the 1980s through a collaboration between Eli Lilly and academic laboratories. Although similar in structure to N10-formyl-THF, lometrexol is incapable of carrying out one carbon transfer reactions. Additionally, several GAR based inhibitors of GAR transformylase have also been synthesized. Development of folate based inhibitors have been found to be particularly challenging as the inhibitors also down regulate the enzyme folylpolyglutamate synthase, which adds additional γ-glutamates to monoglutamate folates and antifolates after entering the cell for increased enzyme affinity. This increased affinity can lead to antifolate resistance.
The dyes are immobilized on the column matrix effectively, since usually the dyes link to a monochlorotriazine or dichlorotriazine ring (triazine dye). This type of dyes works especially well on a support matrix with hydroxyl group. The commonly used supporting matrix would be cross-linked agarose (sepharose), sephadex, polyacrylamide, and silica. An example for triazine linkage immobilization is Blue Sepharose, resulting from Cibacron blue FG3-A with monochlorotriazine covalently coupled with OH group of sepharose. This reaction form an ether linkage and also hydrogen chloride. C29H20ClN7O11S3 + C24H38O19 → C53H57N7O30S3 + HCl Cibacron Blue FG3-A + Sepharose → Blue Sepharose + HCl
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.