AOD-9604 is a synthetic peptide copied from a short tail-end piece of human growth hormone, not the whole hormone. The published account describes researchers taking the fat-affecting stretch near growth hormone's C-terminus, residues 176 to 191, and rebuilding it as a standalone molecule with one extra amino acid attached. It advanced into human testing as an investigational anti-obesity candidate but never earned FDA approval, and in the United States it is sold as a Research Use Only compound.
AOD-9604 is a 17-residue synthetic peptide reproducing the 176-191 C-terminal fragment of human growth hormone plus an added N-terminal tyrosine, developed by Metabolic Pharmaceuticals as an investigational anti-obesity agent that never reached FDA approval.
Growth hormone is a single chain of 191 amino acids, and AOD-9604 copies only the last sixteen of them, residues 176 through 191 at the C-terminal tail. Structure-activity work dissected the hormone piece by piece to find which regions carried which jobs, and this window was the one that held the fat-affecting activity. The core of the peptide is a faithful copy of that natural sequence, not a redesigned or mutated version.
AOD-9604 corresponds to residues 176 through 191 of human growth hormone, the final sixteen amino acids of the 191-residue chain, reproduced faithfully from the natural C-terminal sequence.
The tyrosine at the front of AOD-9604 is not part of the natural growth hormone sequence; it is a deliberate seventeenth residue added by the people who built the peptide. Its main documented purpose is analytical: the phenolic side chain gives a clean site for radioiodination, so a radioactive iodine label could be attached to track where the molecule went and how it behaved in laboratory and animal studies. Sitting outside the functional 176-191 window, it does that work without disturbing the fat-metabolizing core.
The N-terminal tyrosine is a non-natural seventeenth residue added chiefly to provide a radioiodination site for tracking the molecule, with a secondary role in stabilizing the short peptide, positioned outside the 176-191 window so it does not affect the fragment's lipolytic activity.
AOD-9604 came out of Metabolic Pharmaceuticals, an Australian biotechnology company that advanced it as a candidate anti-obesity therapeutic. The intended use was weight reduction: the record describes a molecule meant to promote the breakdown of stored fat and blunt the conversion of dietary energy into new fat, treating obesity as a metabolic problem. The whole design, a fragment plus a stabilizing residue rather than a full hormone, followed from that single-purpose intent.
AOD-9604 was developed by Metabolic Pharmaceuticals, an Australian biotechnology company, as an investigational anti-obesity candidate intended to reduce body weight by stimulating fat breakdown and inhibiting fat formation without the glucose and growth effects of intact growth hormone.
The point of the fragment was to keep one of growth hormone's jobs and leave the rest behind. Full-length growth hormone binds the growth hormone receptor and sets off a broad cascade: it drives the liver to release IGF-1, pushes tissue and skeletal growth, and shifts glucose handling in ways that can raise blood sugar. The 176-191 fragment lacks the receptor-binding domains behind that cascade, so as characterized it acts on fat metabolism alone.
| Property | Full-length growth hormone | AOD-9604 (176-191 fragment) |
|---|---|---|
| Receptor binding | Binds the growth hormone receptor | Lacks the receptor-binding domains |
| IGF-1 release | Stimulates hepatic IGF-1 | No accompanying IGF-1 rise |
| Tissue/skeletal growth | Drives growth signaling | Not associated with growth signaling |
| Glucose handling | Can raise blood sugar | Characterized without the glucose-raising effect |
| Fat metabolism | One effect among many | The single retained action |
Full-length growth hormone binds its receptor to trigger IGF-1 release, tissue growth, and altered glucose handling, whereas the AOD-9604 fragment lacks those receptor-binding domains and, as characterized, retains only the lipolytic effect on fat tissue without the IGF-1, growth, or glucose consequences.
AOD-9604 is a short peptide of seventeen amino acid residues: the sixteen of the natural 176-191 fragment plus the single added tyrosine. At that size its molecular weight lands in the low-1800s daltons, squarely in the small-peptide range rather than among full proteins. It is classed as a peptide fragment analog of human growth hormone, a chain that mirrors a defined subsequence of a larger natural protein.
AOD-9604 is a seventeen-residue synthetic peptide, the sixteen-residue growth hormone 176-191 fragment plus one added tyrosine, with a molecular weight in the low-1800s daltons, classed as a peptide fragment analog of human growth hormone.
The fat-metabolizing activity of growth hormone was traced to its C-terminal region, specifically the residue 176-191 stretch that became AOD-9604. Investigators reached that by carving the hormone into fragments and testing which pieces held which effects, a mapping that separated the fat function from the receptor-binding regions elsewhere in the chain. Because that determinant sits at the tail end and does not overlap the growth-signaling domains, it could be lifted out as a standalone peptide.
Growth hormone's lipolytic activity was localized to its C-terminal region around residues 176-191, a determinant that does not overlap the receptor-binding growth domains and so could be reproduced as the standalone AOD-9604 peptide.
The name is a purpose tag plus a serial number. AOD stands for Anti-Obesity Drug, signaling straight away what the molecule was built to do, while 9604 is an internal development or catalog code from the research program rather than anything chemically meaningful. That two-part convention, a descriptive prefix plus an alphanumeric code, is typical of pre-market drug candidates before any generic or trade name is assigned.
In AOD-9604, "AOD" stands for Anti-Obesity Drug and "9604" is an internal development code, together forming a purpose-plus-serial designation typical of a pre-market drug candidate.
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