Everything below concerns anti-doping. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-21. Numbers and descriptions here follow the published literature rather than marketing material.
Detection and characterization of AOD-9604 in research and anti-doping settings typically rely on mass spectrometry coupled with liquid chromatography. These methods can identify the peptide by its mass and fragmentation pattern. Immunoassays may also be used in some screening contexts, but they can cross-react with related peptides. Because the molecule is small and may be present at low concentrations, sample preparation and method validation are important. Confirmatory analysis usually requires comparison with a certified reference standard.
In laboratory settings, AOD-9604 is commonly supplied as a lyophilized powder and stored cold to limit degradation. Reconstituted solutions are typically kept refrigerated or frozen, depending on the buffer and concentration, and protected from repeated freeze-thaw cycles. Stability can be influenced by pH, temperature, and the presence of proteases. Purity is usually assessed by high-performance liquid chromatography and mass spectrometry. These practices support reproducibility, but they do not imply safety or efficacy for any human use.
Regulatory status: AOD-9604 is not approved as a therapeutic drug in the United States, European Union, or other major markets. It is listed by the World Anti-Doping Agency as a prohibited substance in sport, specifically under growth hormone fragments. Many jurisdictions restrict its sale for human consumption. Products marketed online may not meet pharmaceutical quality standards. The legal status varies by country and often depends on whether the material is presented as a research chemical, supplement, or drug.
Research interest in AOD-9604 often focuses on whether it can influence lipid metabolism without the growth-promoting or glucose-related effects of full-length hGH. This question remains unresolved, and findings depend on model, dose, and measurement method. Some reviews treat the peptide as a historical obesity candidate rather than an active therapeutic. Others cite it in discussions of peptide fragments, metabolic signaling, and performance-enhancing substances. Clear conclusions are limited by the small number of rigorous, independent human studies.
AOD-9604 has been investigated primarily as a potential treatment for obesity and related metabolic conditions. Early laboratory work examined its effects on fat cells, and later studies moved into animal models and human clinical trials. Some trials reportedly reached Phase II, but the program did not lead to an approved medicine. Published summaries often note that weight-loss results were modest or inconsistent. The full trial data are not all publicly available in detail.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Not approved as a medicine | Status varies by country; prohibited in sport. |
| Common storage temperature | 2–8 °C for lyophilized powder | Protect from light and moisture; follow supplier instructions. |
| Typical analytical method | LC-MS/MS | Used for identification and quantification in biological samples. |
| Purity assessment | HPLC and mass spectrometry | Reverse-phase HPLC is common for peptide purity. |
| Common synonyms | AOD9604; hGH 176-191 fragment | Naming conventions differ across studies. |
Research on AOD-9604 also examines how the peptide is measured in biological samples. Analytical methods may include liquid chromatography coupled with mass spectrometry, immunoassays, or both. Detection can be challenging because the peptide is small and may be present at low concentrations. Published methods vary in sensitivity and specificity, so comparative interpretation requires attention to validation details. The presence of related hGH fragments can complicate identification in some matrices.
AOD-9604 has been investigated mainly in the context of body fat and metabolic endpoints. Some early animal and small human studies reported changes in fat mass or lipid markers, but findings were not uniform. Larger, well-controlled trials that would establish efficacy are lacking in the public literature. As a result, claims about weight loss or metabolic benefit remain investigational rather than established. The distinction between a research finding and a proven clinical outcome is central to discussing this peptide.
A central uncertainty is whether observed metabolic changes translate into meaningful clinical benefits. Study designs vary in dose, duration, and participant characteristics, making comparisons difficult. Independent replication is limited, and the field lacks consensus on optimal endpoints or treatment duration. Ongoing or future studies may clarify mechanism and effect size, but current evidence does not establish a clear therapeutic role. Researchers often call for larger, longer, and better-controlled trials, while questions remain about which patient groups might respond.
Proposed mechanism focuses on lipolysis, the breakdown of stored triglycerides into free fatty acids and glycerol. AOD-9604 is thought to act on adipose tissue without stimulating appetite or affecting blood sugar in the same way as growth hormone. Laboratory studies report increased fat oxidation in some models. The precise receptor interactions and signaling pathways remain incompletely characterized. Researchers have proposed that the peptide may influence fat mobilization through pathways distinct from the full hormone.
Research has examined whether the peptide affects fat mass independently of growth hormone's other actions. Early animal studies suggested reductions in body fat, but species differences and small sample sizes limit interpretation. Human studies have generally been short and have not consistently shown large effects. Some trials measured body composition, lipid profiles, and safety parameters, but the overall picture is one of suggestive yet inconclusive metabolic activity. Findings vary across study populations and protocols.
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.
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.
Quality varies among research-grade suppliers, so certificates of analysis and independent testing are important for verification. A typical certificate reports purity by HPLC, identity by mass spectrometry, appearance, and sometimes residual solvents or water content. AOD9604 is often sold as a research chemical not intended for human consumption, and labels can be inaccurate. Common misconceptions include treating the peptide as a form of growth hormone, assuming supplement status, or expecting approved-drug quality from unregulated products.
AOD9604 is commonly supplied as a white to off-white lyophilized powder. The powder is typically stored at -20 °C or below, protected from light and moisture, because peptides can degrade through oxidation, hydrolysis, or aggregation. If it is reconstituted for laboratory use, an appropriate aqueous buffer or solvent is chosen, and the solution is kept cold and handled to avoid repeated freeze-thaw cycles. These practices support stability but do not imply suitability for human use.
Identity and purity are usually assessed with reversed-phase high-performance liquid chromatography and mass spectrometry. Reversed-phase HPLC separates the peptide from related impurities and can estimate purity by ultraviolet absorbance, while mass spectrometry confirms the molecular mass and detects modifications. Peptide mapping, amino acid analysis, and disulfide mapping may be used when the sequence or disulfide arrangement must be verified. Because AOD9604 contains cysteine residues, oxidation and disulfide isomers are possible quality concerns in synthetic batches.
The presence of autoantibodies against citrullinated proteins in rheumatoid arthritis patients was first described in the mid-1970s when the biochemical basis of antibody reactivity against keratin and filaggrin was investigated. Subsequent studies demonstrated that autoantibodies from RA patients react with a series of different citrullinated antigens, including fibrinogen, deiminated Epstein–Barr virus nuclear antigen 1 and vimentin, which is a member of the intermediate filament family of proteins. Several assays for detecting ACPAs were developed in the following years, employing mutated citrullinated Vimentin (MCV-assay), filaggrin-derived peptides (CCP-assay) and viral citrullinated peptides (VCP-assay). A 2006 clinical study showed that anti viral citrullinated peptide (VCP) antibodies of the IgG and IgA isotypes represent a discriminating specific marker of rheumatoid arthritis from other chronic arthritides and disease controls, suggesting an independent production of each isotype. In 2010, ACPA testing has become substantial part of The 2010 ACR-EULAR classification criteria for rheumatoid arthritis.
Unk is sometimes used instead of Xaa, but is less standard. Ter or * (from termination) is used in notation for mutations in proteins when a stop codon occurs. It corresponds to no amino acid at all. In addition, many nonstandard amino acids have a specific code. For example, several peptide drugs, such as Bortezomib and MG132, are artificially synthesized and retain their protecting groups, which have specific codes. Bortezomib is Pyz–Phe–boroLeu, and MG132 is Z–Leu–Leu–Leu–al. To aid in the analysis of protein structure, photo-reactive amino acid analogs are available. These include photoleucine (pLeu) and photomethionine (pMet).
Another common example is the reaction of a primary amine or secondary amine with a carboxylic acid or with a carboxylic acid derivative to form an amide. This reaction is widely used, especially in the synthesis of peptides. On the simple addition of an amine to a carboxylic acid, a salt of the organic acid and base is obtained. To overcome this, the carboxylic acid first needs to be "activated". This is usually done by converting the acid into a more reactive derivative (i.e. anhydride, acid halide) or by using a coupling agent. In some cases, high temperatures (>200 °C) can overcome salt formation by driving off water, without the need for "activation" of the carboxyl group. The downside to this simple reaction is that the compounds may decompose at these elevated temperatures. The carboxylic acid derivatives can be esters, anhydrides, acid halides or any other activated species. The choice of activated carboxyl group or coupling agent can be very important in peptide synthesis, as using the wrong one can lead to racemization.
5-HEDH is an NADPH dehydrogenase oxidoreductase enzyme. It transfers a hydrogen cation (or hydron) H+ from 5(S)-hydroxy (i.e. 5(S)-OH) residues of its fatty acid targets to nicotinamide adenine dinucleotide phosphate+ (NADP+) to form 5-oxo (i.e. 5-O=) counterparts of its targets plus reduced NADP+, i.e. NADPH. The reaction (where R indicates a long chain [14 or more carbons] fatty acid) is: NADP+ + 5(S)-hydroxy fatty acid (i.e. 5(S)-OH-R) ⇌ {\displaystyle \rightleftharpoons } NADPH + H+ + oxo fatty acid (i.e. 5-O=R) The reaction appears to follow a ping-pong mechanism. It is fully reversible, readily converting 5-oxo targets to their corresponding 5(S)-hydroxy counterparts. The direction of this reaction is dependent on the level of NADP+ relative to that of NADPH: The immediate metabolic precursor to 5(S)-HETE, 5(S)-hydroperoxy-6S,8Z,11Z,14Z-eicosatetraenoic acid 5(S)-HpETE, can be converted to 5-oxo-ETE in a non-enzymatic dehydration reaction or chemical lipid peroxidation reactions. The physiological occurrence and relevancy of these reaction pathways has not been ascertained.
In the US, Aducanumab is indicated for the treatment of Alzheimer's disease. In July 2021, the US Food and Drug Administration (FDA) limited the indication to people with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials. Aducanumab is a monoclonal IgG1 antibody that binds to the amyloid beta protein at amino acids 3–7, which is posited to result in slowing the progression of Alzheimer's disease. The mechanism is based on the amyloid hypothesis, which posits that amyloid proteins cause Alzheimer's disease, hence removing amyloid should slow the progression of the disease. How the antibody accesses the plaques is under active research. One mechanism suggests the plaques are exposed to the lumen of blood vessels and the antibody accesses the plaques from the lumen side. This assumes the plaque formed as a result of a leaky blood brain barrier and may also explain why there is hemorrhage after the plaques are removed. The most common serious adverse reactions reported are:
Sources: en.wikipedia.org
Diamphotoxin is a toxin produced by larvae and pupae of the beetle genus Diamphidia. Diamphotoxin is a hemolytic, cardiotoxic, and highly labile single-chain polypeptide bound to a protein that protects it from deactivation. Diamphotoxin increases the permeability of cell membranes of red blood cells. Although this does not affect the normal flow of ions between cells, it allows all small ions to pass through cell membranes easily, which fatally disrupts the cells' ion levels. Although diamphotoxin has no neurotoxic effect, its hemolytic effect is lethal, and may reduce hemoglobin levels by as much as 75%. The San people of Southern Africa use diamphotoxin as an arrow poison for hunting game. The toxin paralyses muscles gradually. Large mammals hunted in this way die slowly from a small injection of the poison. Several leaf beetles species of genus Leptinotarsa produce a similar toxin, leptinotarsin. Palytoxin Arrow poison
At low concentrations of TNP-ATP (≤1 μM), fluorescent intensity is proportional to the concentration of TNP added. However, at concentrations exceeding 1 μM, inner filter effects cause this relationship to no longer be linear. To correct this, researchers must determine the ratio of the predicted theoretical fluorescence intensity (assuming linearity) to the observed fluorescence intensity and then apply this correction factor. However, in most cases, researchers will try to keep the concentration of TNP to lower than 1 μM. To determine binding affinities, TNP-ATP is added to a solution and then titrated with protein. This produces a saturation curve from which the binding affinity can be determined. The number of binding sites may also be determined through this saturation curve by looking to see if there are sudden changes in slope. One can also titrate a fixed amount of protein with increasing additions of TNP-ATP to obtain a saturation curve. To do so, however, may get complicated due to the inner filter effects that will need to be corrected for. To determine dissociation constants, TNP-ATP can be competed off of a protein with ATP. The value of the dissociation constant Kd for a single-site binding can then be obtained by applying the Langmuir equation for a curve fit:
Recycling chromatography is mode practiced in both HPLC and CCC. In recycling chromatography, the target compounds are reintroduced into the column after they elute. Each pass through the column increases the number of theoretical plates the compounds experience and enhances chromatographic resolution. Direct recycling must be done with an isocratic solvent system. With this mode, the eluant can be selectively re-chromatographed on the same or a different column in order to facilitate the separation. This process of selective recycling has been termed a "heart-cut" and is especially effective in purifying selected target compounds with some sacrificial loss of recovery. The process of re-separating selected fractions from one chromatography experiment with another chromatographic method has long been practiced by scientists. Recycling and sequential chromatography is a streamlined version of this process. In CCC, the separation characteristics of the column may be modified simply by changing the composition of the biphasic solvent system.
ADAMTS7 was identified as a protease that binds and cleaves COMP in a yeast two-hybrid screen using the epidermal growth factor (EGF) domain of COMP as the bait. However, this initial finding has been contested; a 2025 study demonstrated that purified ADAMTS7 does not exhibit proteolytic cleavage activity toward purified COMP. Furthermore, three independent unbiased N-terminal amine isotopic labeling of substrates (N-TAILS) proteomic studies identified a number of candidate substrates for ADAMTS7 but did not identify COMP as a potential substrate. Consequently, there is as yet no scientific consensus on the physiological function of ADAMTS7. Tissue inhibitor of metalloproteinases 4 (TIMP-4) appears to be the physiological inhibitor of ADAMTS7.
A particular challenge in analysing AlphaFold models is distinguishing genuine topology from structural prediction artefacts. A high confidence score does not by itself guarantee that a predicted chain crossing is correct, and incorrect modelling of termini or flexible regions may change the calculated topology. AlphaKnot 2.0 therefore provides several measures intended to help evaluate a predicted knot, including the pLDDT values of the complete chain and knot core, the confidence near the boundaries of the knot core, and detection of unusually close contacts between Cα atoms. Users can also compare AlphaFold predictions with independently generated ESMFold models for shorter proteins. Because automated analysis at the scale of the AlphaFold database cannot be manually verified structure by structure, AlphaKnot 2.0 introduced a user annotation system. Database entries can be assessed by users as a knot, artifact, or unsure, allowing potentially incorrect predictions to be flagged for further consideration.
Sources: en.wikipedia.org
No major regulatory agency has approved AOD-9604 as a medicine. It is treated as an experimental peptide in research settings. Some countries restrict its sale or import.
The World Anti-Doping Agency classifies growth hormone fragments, including AOD-9604, as prohibited substances. The classification reflects concern about potential performance-enhancing use. Athletes are subject to testing for such peptides.
Detection typically uses liquid chromatography combined with mass spectrometry. These methods separate the peptide and identify it by mass. Immunoassays may screen samples but require confirmation by a more specific technique.
No major medicines regulator appears to have approved AOD-9604 for human therapeutic use. It has been studied in clinical trials, but those programs did not result in a marketed drug.