Is Semax approved in the UK?

No. It is registered as a prescription medicine in the Russian Federation but holds no MHRA, EMA or FDA authorisation, and is supplied for laboratory research only.

Is Semax related to ACTH?

It incorporates a short fragment of the ACTH sequence, but the Pro-Gly-Pro extension removes the adrenal-stimulating activity that defines ACTH pharmacologically.

How large is the Semax literature?

Around 231 indexed PubMed records. The mechanistic work is largely rodent; the clinical work is largely Russian-language.

Semax (ACTH Fragment Peptide)

What Is Semax? A Complete Research Overview

JMWritten & reviewed by Jack Muncaster · Founder, UK PeptidesLast reviewed 2026-08-234 cited sources

Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It combines a four-residue fragment of ACTH with a Pro-Gly-Pro extension that confers stability and removes the parent hormone's adrenal-stimulating activity.

Key facts

Sequence: H-Met-Glu-His-Phe-Pro-Gly-Pro-OH
Single-letter: MEHFPGP
Length: 7 residues (heptapeptide)
Molecular weight: 813.9 Da
Molecular formula: C37H51N9O10S
CAS number: 80714-61-0
PubChem CID: 9811102
Origin: Institute of Molecular Genetics, RAS
Western approval: None — not MHRA, EMA or FDA approved

Where it comes from

Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. Its design starts from adrenocorticotropic hormone, a 39-residue pituitary hormone, and takes a short N-terminal-region fragment of it. The peptide has been registered as a prescription medicine in the Russian Federation since the 1990s, and is not approved by any Western regulator.

The Pro-Gly-Pro extension does two jobs

This is the design feature that defines the molecule. Appending Pro-Gly-Pro to the ACTH fragment sharply increases resistance to enzymatic degradation, because proline-rich sequences are poor substrates for most peptidases. It also removes the steroidogenic activity of the parent hormone — Semax does not stimulate adrenal steroid production, which is what separates it pharmacologically from ACTH itself.

Research material referenced

Semax 10mg — third-party HPLC tested

View — £24.99

Reported mechanism

The published work centres on neurotrophins. Semax has been reported to upregulate expression of brain-derived neurotrophic factor and nerve growth factor, with downstream signalling through their TrkB and TrkA receptors. Additional reported activity includes modulation of dopaminergic and serotonergic transmission and interaction with the endogenous opioid system. Most of this is rodent work.

The evidence base, described honestly

PubMed indexes roughly 231 records. The mechanistic literature includes work in Brain Research, BMC Genomics and the Journal of Molecular Neuroscience, and is largely conducted in rats. The clinical literature is substantially published in Russian-language journals, principally the Korsakov Journal of Neurology and Psychiatry, and much of it predates current trial-reporting standards. That is a description of where the evidence sits, not a dismissal of it.

Regulatory position

Registration in the Russian Federation is a fact about a decision made by a national regulator. It confers nothing outside that jurisdiction. Semax holds no marketing authorisation from the MHRA, EMA or FDA, cannot be prescribed or dispensed in the UK, and is supplied here for laboratory research only.

Extended research context

The Semax (ACTH Fragment Peptide) deep dive

Deep dive: what the Pro-Gly-Pro extension actually accomplishes

Semax is built from a four-residue fragment of ACTH with Pro-Gly-Pro appended, and that appendix does two separate jobs at once. Proline is the only proteinogenic amino acid whose side chain bonds back to its own backbone nitrogen, forming a ring that removes the amide hydrogen and locks rotation. Proteolytic enzymes generally need an extended, rotatable backbone at their active site, so bonds near proline are poor substrates for most of them — which is why proline-rich motifs recur throughout stabilised peptide design. The second job is subtractive: Pro-Gly-Pro occupies the positions where ACTH carries Arg-Trp-Gly, and those are the residues contributing to the parent hormone's adrenal-stimulating activity. One substitution therefore buys protease resistance and removes an unwanted pharmacology, which is unusually economical design.

Deep dive: the naming point worth getting right

Semax is near-universally described as an ACTH(4-10) analogue, and peer-reviewed paper titles use that phrase. Structurally it is not quite that. ACTH residues 4 to 10 are Met-Glu-His-Phe-Arg-Trp-Gly; Semax is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues match and the last three are wholly different — replacement rather than modification. PubChem, indexing by structure rather than design lineage, records it as ACTH(4-7) plus Pro-Gly-Pro. Neither name is wrong, but the loose one obscures the fact that the substituted segment is precisely the functionally consequential part.

Deep dive: reading an unevenly distributed evidence base

Semax's roughly 231 indexed records split along an unusual line. Mechanistic work — BDNF and trkB expression in rat hippocampus, transcriptomics in focal cerebral ischaemia, neurotrophin dynamics across brain regions — appears in international journals in English and can be assessed directly. Clinical work is concentrated in Russian-language publications, principally the Korsakov Journal of Neurology and Psychiatry, indexed by translated title and often without accessible English full text, much of it predating current standards for pre-registration and reporting. The honest position is that this is evidence which is difficult to verify independently, which is a different thing from evidence that is absent, and a different thing again from evidence that is established.

Research applications

▸Neurotrophin expression research (BDNF, NGF, TrkB, TrkA)
▸Neuroprotection and cerebral ischaemia models
▸Study of proline-stabilised peptide design
▸Comparative work on ACTH fragments without steroidogenic activity
▸Transcriptomic profiling in rodent brain models

Handling checklist

✓Store lyophilised material cold, dry and protected from light
✓Expect methionine oxidation as the degradation route (+16 Da; only one Met, so not +32)
✓No reducing agent needed — the sequence contains no cysteine
✓Introduce diluent gently against the vial wall; swirl rather than shake
✓Aliquot to avoid repeated freeze-thaw cycles
✓Check whether a certificate reports net peptide content or gross salt weight

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Describing Semax as ACTH(4-10) without qualification

Fix: It shares only residues 4-7; Pro-Gly-Pro replaces Arg-Trp-Gly, and that replacement is the design's whole point.

✗ Treating Russian registration as equivalent to MHRA approval

Fix: Authorisations are jurisdictional and do not transfer. Semax has never been assessed by the MHRA, EMA or FDA.

✗ Reading a BDNF expression change as a demonstrated outcome

Fix: The studies measured gene and protein expression in rats. Expression is upstream of function and upstream again of any clinical claim.

✗ Assuming a named receptor exists

Fix: No primary receptor has been definitively established; the literature characterises downstream effects more confidently than the initiating event.

✗ Expecting ACTH-like adrenal effects

Fix: Semax does not stimulate adrenal steroidogenesis — the responsible residues were substituted out.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Frequently asked questions

Is Semax approved in the UK?: No. It is registered as a prescription medicine in the Russian Federation but holds no MHRA, EMA or FDA authorisation, and is supplied for laboratory research only.
Is Semax related to ACTH?: It incorporates a short fragment of the ACTH sequence, but the Pro-Gly-Pro extension removes the adrenal-stimulating activity that defines ACTH pharmacologically.
How large is the Semax literature?: Around 231 indexed PubMed records. The mechanistic work is largely rodent; the clinical work is largely Russian-language.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

Written and reviewed by

Jack Muncaster · Founder, UK Peptides

Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.

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