AOD9604

Chemical identity

AOD9604 is a sixteen-residue analogue of the C-terminal region of human growth hormone, spanning residues 176–191 with an additional tyrosine at the N-terminus. The tyrosine is not decorative — it was added to provide a radioiodination site during the original characterisation work, and it stayed in the sequence that entered later studies.

The single disulfide bridge between Cys7 and Cys14 constrains the peptide into a loop. Reduction of that bridge changes the molecule's conformation and, in the published work, its activity — which makes the disulfide a specification point rather than a footnote. Any batch stored in solution with a reducing agent present should be treated as a different reagent.

Mechanism in research models

The interest in AOD9604 rests on a dissociation reported in the 1990s at Monash University: in rodent adipose tissue the C-terminal fragment reproduced the lipolytic and antilipogenic effects of the intact hormone while showing no measurable effect on IGF-1 output, insulin sensitivity or cell proliferation in the same models.

No receptor has been definitively assigned. Work in mouse adipocytes has implicated β3-adrenergic signalling in the observed lipolysis, but the effect persists in β3-knockout preparations, so the pathway remains open. Investigators designing binding assays should not assume a growth hormone receptor interaction — the fragment does not engage it at the concentrations used in the metabolic work.

What the literature establishes

The rodent metabolic findings replicate reasonably well across laboratories. The human data do not extend them: a phase IIb obesity trial reported no statistically significant weight difference against placebo at twelve weeks, and development for that indication stopped.

A second literature exists around cartilage and disc research, where the fragment has been examined in combination with other agents. Those studies are small, mostly in vitro, and should not be read as establishing an effect in isolation.

The practical summary for a research plan: strong preclinical adipocyte data, a failed clinical endpoint, and an unresolved mechanism. That combination makes AOD9604 useful as a tool compound for adipocyte work and poor as a positive control for anything else.

Handling, reconstitution and storage

Supplied lyophilised. Peptides of this class are typically held sealed at −20 °C and protected from light, but the validated condition and shelf life for your material are the ones stated on its lot documentation. Allow the vial to reach room temperature before opening — cold glass condenses atmospheric moisture, and water is the main enemy of a lyophilised peptide.

Reconstitute with bacteriostatic or sterile water directed down the vial wall rather than onto the cake. Do not vortex; the disulfide-constrained loop is vulnerable to shear and to the air–liquid interface generated by vigorous mixing. Swirl until dissolved.

Reconstituted material should be aliquoted immediately into single-use volumes and held at −20 °C or below. Repeated freeze–thaw cycling is the single most common cause of the potency loss reported informally in peptide work, and it is entirely avoidable.

Analytical documentation

Every batch should arrive with RP-HPLC purity, an ESI-MS or MALDI-TOF spectrum with the observed mass, and a water-content figure. For AOD9604 specifically, ask whether the disulfide is confirmed — a mass spectrum alone will not distinguish the cyclic peptide from its reduced linear form at the resolution most suppliers report.

Peptide content (the fraction of vial mass that is peptide rather than counter-ion and residual water) is routinely 70–85% for TFA-salt material. If your calculations assume the label weight is all peptide, they are wrong by roughly a quarter before the experiment begins.

References and authoritative sources

Chemical identity, regulatory status and anti-doping classification should be confirmed against primary sources rather than against this page. The records below are the ones to check first.

1. PubChem compound record (US National Library of Medicine)
2. PubMed indexed literature
3. ClinicalTrials.gov registered studies

These are database and regulatory sources. Citations to specific primary papers are being added to this page as part of ongoing scientific review; until they appear, treat the mechanism and literature sections above as a summary to verify rather than a citation of record.