Semax: Identity, Origin and Research Status

What Semax is

Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, about 813.9 Da. It joins residues 4 to 7 of adrenocorticotropic hormone (ACTH) to a C-terminal Pro-Gly-Pro tripeptide, and the literature describes it as an analogue of ACTH(4-10). It was developed in Russia. It is not ACTH, and the catalogue item is a laboratory reagent.

Nomenclature and synonyms

•Semax names the peptide. MEHFPGP is the same sequence in one-letter code. "Semax UK" is a search phrase for the same material, not a different compound.
•N-acetyl Semax is a separate molecule. Chemistry work on both forms found that acetylating the amino terminus changes how the peptide coordinates copper(II) and zinc(II) (Magrì and colleagues, 2016), so the two are not alternate names.
•Nasal-spray listings describe other products. The catalogue item is a single-compound lyophilised vial.

Structure and classification

Feature	Detail
Sequence	Met-Glu-His-Phe-Pro-Gly-Pro
Length	Seven residues
Parent	ACTH, residues 4 to 7
C-terminal extension	Pro-Gly-Pro
Class	Synthetic peptide analogue

The Pro-Gly-Pro tripeptide has also been studied on its own, and in one rat study it did not reproduce what Semax did (Dmitrieva and colleagues, 2009). In rat brain membranes, Semax was broken down stepwise by dipeptidyl aminopeptidases, first to the pentapeptide HFPGP and then to Pro-Gly-Pro (Dolotov and colleagues, 2004).

Supplied form

Lyophilised powder in a single-compound vial, listed on the Semax 10mg product page.

Development and regulatory status

Semax came out of Russian research institutes, and Russian authors describe it as a preparation used in clinical practice there (Stavchansky and colleagues, 2010). We are not aware of a UK or European marketing authorisation for it. Use in clinical practice in another country does not extend to the UK, to this catalogue material or to any use in people, and nothing on this page implies a UK licence or availability for human use.

The catalogue item is a laboratory reagent, supplied for non-clinical in-vitro research only.

What the evidence establishes

The full review, with each finding labelled by its model, is on Semax research: evidence base and its limits. In outline:

In vitro and animal findings

The preclinical record is binding and breakdown work in rat brain membranes, copper and zinc chemistry, and a set of rat studies of neurotrophin gene expression, learning tests and induced brain injury. Most of it comes from one research programme in Moscow. Rat findings establish behaviour in that species only.

Human data

A small number of human studies exist: two clinical series in patients, published in Russian, and one placebo-controlled brain-imaging study in 52 healthy volunteers. We found no large randomised, double-blind trial among the records reviewed. The human work does not support presenting rat findings as demonstrated outcomes in people.

What Semax is often confused with

Name	What it is	Relationship to Semax
ACTH(4-10)	A native fragment of the hormone	Semax is an analogue, not the fragment itself
ACTH(1-39)	The full pituitary hormone	A much larger molecule, and a different compound
N-acetyl Semax	Semax with an acetylated amino terminus	A separate molecule with different metal coordination
Pro-Gly-Pro	The C-terminal tripeptide on its own	A fragment that behaved differently from Semax in a rat study
Selank	A heptapeptide built on tuftsin	A different parent molecule, compared on [Semax and Selank](/blog/semax-vs-selank)

•"Nootropic." In retail copy this is a marketing label. It is not a pharmacological class and does not describe a demonstrated outcome.
•"Semax and Selank" as one product. They share a Pro-Gly-Pro extension and a country of origin. They are separate materials with separate parent sequences, and the Selank identity page covers the other one.

Analytical documentation

A batch certificate reports the identity and measured purity of the batch tested. The product record lists batch 100239 with an HPLC purity of 99.533%, and the report is published in the COA library. A certificate says nothing about biological effect and does not extend to other batches.

The guides to reading a peptide COA and understanding HPLC purity explain what those figures can and cannot show. The nootropic category and the Semax buying guide cover the catalogue side.

Key references

•Dolotov OV, Zolotarev IuA, Dorokhova EM, et al. The binding of Semax, ACTH 4-10 heptapeptide, to plasma membranes of the rat forebrain basal nuclei and its biodegradation (in Russian). Bioorg Khim. 2004;30(3):241-246. doi:10.1023/b:rubi.0000030127.46845.f0
•Dmitrieva VG, Povarova OV, Skvortsova VI, et al. Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia. Cell Mol Neurobiol. 2009;30(1):71-79. doi:10.1007/s10571-009-9432-0
•Stavchansky VV, Yuzhakov VV, Botsina AYu, et al. The effect of Semax and its C-end peptide PGP on the morphology and proliferative activity of rat brain cells during experimental ischemia: a pilot study. J Mol Neurosci. 2010;45(2):177-185. doi:10.1007/s12031-010-9421-2
•Magrì A, Tabbì G, Giuffrida A, et al. Influence of the N-terminus acetylation of Semax, a synthetic analog of ACTH(4-10), on copper(II) and zinc(II) coordination and biological properties. J Inorg Biochem. 2016;164:59-69. doi:10.1016/j.jinorgbio.2016.08.013

Scope and laboratory-use boundary

Materials sold on this site are supplied solely for non-clinical in-vitro laboratory research. They must not be ingested, injected, inhaled, applied or otherwise administered to a human or animal.

We do not provide dosing, routes of administration, treatment guidance, cosmetic-use guidance or in-vivo protocols. Preparation, storage and handling must follow a validated institutional SOP, the material documentation and an appropriate risk assessment.