Semax UK — ACTH(4-10) Analogue Research Guide
Also known as ACTH(4-10) Pro-Gly-Pro analogue
Semax is a synthetic heptapeptide analogue developed in Russia from ACTH(4-10), a short fragment of adrenocorticotropic hormone. It is the most heavily researched compound in the nootropic peptide family and the reference point every other peptide in that group — Selank, Adamax, PE-22-28 — is compared against.
This guide covers the structure and why the Pro-Gly-Pro modification matters, the BDNF and neuroprotection research context, how Semax differs from Selank and Adamax, UK legal status in 2026.
For in vitro research use only — not for human or animal consumption. Not a licensed medicine in the UK. Nothing on this page is medical advice.
What is Semax?
ACTH(4-10) is a seven-residue fragment of adrenocorticotropic hormone. On its own it is broken down within minutes and carries hormonal activity that makes it unsuitable for neurological research. Semax attaches a Pro-Gly-Pro tail to the C-terminus, which strips out the hormonal effect and dramatically slows enzymatic degradation.
- Parent structure: ACTH(4-10), a natural melanocortin fragment
- Modification: added Pro-Gly-Pro tail for protease resistance
- Class: regulatory / nootropic research peptide
- Typical supply: 10mg lyophilised vial
That stability is the whole point of the molecule — it is what turned a transient hormone fragment into something with a long enough half-life to study.
BDNF and the neurotrophic research context
The bulk of the published Semax literature centres on BDNF — brain-derived neurotrophic factor — and its receptor TrkB. BDNF is one of the main proteins involved in neuronal survival and synaptic plasticity, and preclinical work reports changes in BDNF expression following Semax administration in animal models.
Alongside that, the Russian literature includes work in ischaemic and hypoxic models, plus studies looking at attention and memory endpoints in animals. Much of this research is published in Russian-language journals and has not been replicated in large Western trials, which is an important limitation to state plainly.
None of this constitutes evidence of a human outcome, and Semax is not for human use.
Semax vs Selank vs Adamax
These three are constantly confused because they came out of the same research programme and are sold alongside each other. They are not variants of one another.
- Semax — ACTH(4-10) derived. Studied around BDNF expression, neuroprotection and cognitive endpoints. Largest dataset of the three.
- Selank — tuftsin derived. Studied around GABAergic signalling and anxiolytic endpoints. Different parent molecule entirely.
- Adamax — Semax backbone with an adamantane modification. Very little independent published research; discussed largely by association.
Read the Adamax UK guide for the full breakdown of how the adamantane modification changes the molecule.
UK legal status and purity verification
Semax is legal to buy and possess in the UK for laboratory research purposes. It is not a licensed medicine here, is not prescribed on the NHS, and is supplied strictly for in vitro research use only.
Our batches are independently HPLC and mass-spec tested. The batch number printed on the vial matches a published document on our Certificates of Analysis page, so purity can be verified before the vial is opened.
Buying Semax in the UK
- UK-held stock — Same-day Royal Mail Tracked 24 dispatch on orders by 1pm, Monday to Friday.
- Royal Mail tracked with photo confirmation on every parcel.
- Independent HPLC and mass-spec testing with a batch-matched Certificate of Analysis.
- Discreet plain packaging and normal UK card checkout — no crypto required.
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View full shopFrequently asked questions
What is Semax?
Semax is a synthetic peptide based on ACTH(4-10), a seven-residue fragment of adrenocorticotropic hormone, stabilised with an added Pro-Gly-Pro tail. The modification removes the hormonal activity of the parent fragment while making the molecule far more resistant to enzymatic breakdown, which is why it is the most-studied peptide in the nootropic research family.
What is the difference between Semax and Selank?
Both come from the Russian regulatory peptide programme, but they have different parents. Semax derives from ACTH(4-10) and is studied in relation to BDNF expression and neuroprotection. Selank derives from tuftsin and is studied around GABAergic and anxiolytic signalling. They are frequently discussed as a pair because the research contexts are complementary rather than overlapping.
How does Semax compare to Adamax?
Adamax shares the same short peptide backbone with an adamantane group added to change stability and lipophilicity. Semax has a substantially larger published dataset; Adamax is mostly discussed by association with its parent structure and has very little independent peer-reviewed research behind it.
Is Semax legal in the UK?
Semax is legal to buy and possess in the UK for laboratory research purposes. It is not a licensed medicine in the UK, is not prescribed on the NHS, and is supplied strictly for in vitro research use only — not for human or animal consumption.
Do you supply a Certificate of Analysis for Semax?
Yes. Our batches are independently HPLC and mass-spec tested and the batch number on the vial matches a published Certificate of Analysis, so purity can be verified before use.
Disclaimer: All products sold by Peptides UK 4U are for laboratory and research purposes only. They are not intended for human or animal consumption, diagnosis, treatment or prevention of any disease.