Semax Peptide: the ACTH-fragment heptapeptide
Semax peptide is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro): the ACTH(4-7) fragment of adrenocorticotropic hormone with a Pro-Gly-Pro tail for stability, often described as an ACTH(4-10) analog. Developed in Russia, it is studied mainly in rat models of cerebral ischemia, where it altered neurotrophin and immune-gene expression, and in stress and cognition models. Human evidence is limited to Russian clinical reports. Researchers looking to buy semax for laboratory work can find ≥98% purity, HPLC-tested vials here — research use only.
Specifications
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro (7 amino acids) |
|---|---|
| Origin | ACTH(4-7) fragment with C-terminal Pro-Gly-Pro |
| CAS number | 80714-61-0 |
| Purity | ≥98% (HPLC) |
| Form | Lyophilised powder |
| Evidence basis | Mostly rat ischemia and stress models; Russian clinical reports |
What is semax?
Semax is a synthetic peptide built from ACTH(4-7) — Met-Glu-His-Phe, a short piece of adrenocorticotropic hormone — extended with Pro-Gly-Pro to slow enzymatic breakdown. It is often called an ACTH(4-10) analog because it was designed from that neuroactive region of the hormone. In laboratory models the fragment does not show the corticosteroid-releasing activity of full ACTH.
Like selank, it carries the Pro-Gly-Pro extension, and the two peptides are often compared in Russian-developed peptide research.
Neurotrophin research: BDNF and NGF
The most-cited Semax finding concerns neurotrophins. In rats, Semax changed the time course of BDNF and NGF gene expression in the hippocampus, frontal cortex and retina (Shadrina et al., 2010). This measures gene expression in rodent tissue; it does not show a cognitive effect in people.
Cerebral ischemia models
Most recent Semax papers use rat models of brain ischemia. Transcriptome studies after ischemia–reperfusion reported that Semax shifted the expression of immune-response and inflammation-related genes (Medvedeva et al., 2017; Filippenkov et al., 2020), and a proteomic study reported a protein-expression profile consistent with a protective effect (Sudarkina et al., 2021).
A Russian clinical report describes Semax in patients at different stages of ischemic stroke (Gusev et al., 2018). It is not a large, blinded, placebo-controlled trial of the kind used for FDA approval.
Stress and behaviour models
In male rats exposed to chronic unpredictable stress, Semax showed antidepressant-like and antistress effects in behavioural tests; the study compared it with melanotan II, another ACTH-related analog (Inozemtseva et al., 2024).
What has not been established
There is no large Western randomised controlled trial of Semax, and most mechanistic evidence comes from a small number of Russian research groups using rodent models. Gene-expression changes in rat brain tissue are signals for further research, not evidence of effects in humans.
Semax vs Selank
Semax derives from an ACTH fragment and is studied mainly in ischemia, cognitive and stress models; selank derives from the immune peptide tuftsin and is studied mainly in anxiety-related models. Both share the Pro-Gly-Pro tail. See the Semax vs Selank comparison for the side-by-side breakdown.
Handling in the lab
Store lyophilised semax sealed, cold and protected from light and moisture. After reconstitution with bacteriostatic water, refrigerate the solution and avoid repeated freeze–thaw cycles. Record lot numbers and match each vial to its certificate of analysis.
Frequently asked questions
What is semax peptide?
A synthetic seven-amino-acid peptide (Met-Glu-His-Phe-Pro-Gly-Pro) built from the ACTH(4-7) fragment plus a Pro-Gly-Pro tail, studied in ischemia, cognitive and stress research models.
Is semax ACTH(4-10) or ACTH(4-7)?
Its sequence is ACTH(4-7) followed by Pro-Gly-Pro. It is often labelled an ACTH(4-10) analog because it was designed from that region of the hormone.
Does semax have hormonal activity?
The ACTH fragment it is built from does not show the corticosteroid-releasing activity of full ACTH in laboratory models.
Does semax affect BDNF?
In rats, Semax altered BDNF and NGF gene expression in the hippocampus, frontal cortex and retina. That is a rodent gene-expression finding, not proof of a human effect.
What is semax studied for?
Mainly rat models of cerebral ischemia, plus stress and behaviour models. Russian clinical reports describe its use after ischemic stroke.
Is there clinical research on semax?
Russian clinical reports exist, including in ischemic stroke patients. There are no large Western blinded, placebo-controlled trials.
What is the difference between semax and selank?
Semax is an ACTH-fragment heptapeptide studied in ischemia, cognitive and stress models; selank is a tuftsin-derived heptapeptide studied in anxiety models.
Is semax an approved drug?
Not in the United States. It is registered in Russia but has no FDA approval and is sold here strictly for laboratory research.
What hasn't been established about semax?
Large Western controlled trials and broad independent replication. Most mechanism data come from rodent tissue.
Where can I buy semax peptide for research?
PeptidesDirect sells semax in 25mg vials for laboratory research only. Orders placed before 1:00 PM Central on business days ship the same day. See our research peptides guide research peptides guide for how to compare suppliers and read test documents.
Product pages: Semax 25mg · Selank
How should semax be stored?
Keep lyophilised semax cold, dry and away from light; refrigerate reconstituted solutions and avoid repeated freeze–thaw cycles.
Is this product for human use?
No. PeptidesDirect sells this compound for laboratory research only. It is not a drug, food or cosmetic and is not for human or veterinary use. This page summarises published research and is not dosing or medical guidance.
Shop the compounds covered in these FAQs: Semax 25mg · Selank
References
- Shadrina M, et al. Comparison of the temporary dynamics of NGF and BDNF gene expression in rat hippocampus, frontal cortex, and retina under Semax action. J Mol Neurosci. 2010. PubMed 19662538
- Medvedeva EV, et al. Semax, an analog of ACTH(4-7), regulates expression of immune response genes during ischemic brain injury in rats. Mol Genet Genomics. 2017. PubMed 28255762
- Filippenkov IB, et al. Novel insights into the protective properties of ACTH(4-7)PGP (Semax) peptide at the transcriptome level following cerebral ischaemia-reperfusion in rats. Genes (Basel). 2020. PubMed 32580520
- Sudarkina OY, et al. Brain protein expression profile confirms the protective effect of the ACTH(4-7)PGP peptide (Semax) in a rat model of cerebral ischemia-reperfusion. Int J Mol Sci. 2021. PubMed 34201112
- Gusev EI, et al. The efficacy of semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 2018. PubMed 29798983
- Inozemtseva LS, et al. Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress. Eur J Pharmacol. 2024. PubMed 39442746
Research compounds
Related guides
- Semax Peptide Research and BDNF Evidence
- Semax vs Selank
- Selank research guide
- Research peptides guide
- Reconstitution guide
- Storage guide
Research Use Only. Not for human or veterinary use. Not dosing or medical guidance.
