Semax and Selank Research

Semax and Selank: two heads, one tail

Семакс · Селанк

Semax and Selank are short lab-made peptides from Moscow research institutes. Each takes a four-amino-acid piece of a natural molecule and adds the same three-amino-acid tail, Pro-Gly-Pro.1,2,3

Semax + Pro-Gly-Pro

The Key

Every amino acid on this page is one flat shape, wherever it appears. Red marks the shared Pro-Gly-Pro tail, so the proline inside Selank's own head stays black.

  • MetMethionine
  • GluGlutamate
  • HisHistidine
  • PhePhenylalanine
  • ThrThreonine
  • LysLysine
  • ProProline
  • ArgArginine
  • GlyGlycine
  • Pro-Gly-ProThe shared tail
PeptideSequenceFormulaMassRegistry
SemaxACTH(4–7) + Pro-Gly-ProMet-Glu-His-Phe-Pro-Gly-ProC37H51N9O10S813.9 g/molPubChem CID 9811102CAS 80714-61-0
SelankTuftsin + Pro-Gly-ProThr-Lys-Pro-Arg-Pro-Gly-ProC33H57N11O9751.9 g/molPubChem CID 11765600CAS 129954-34-3

Identity: 1,4,5

Two Heads

Semax starts from ACTH, a 39-amino-acid hormone made by the pituitary, a pea-sized gland at the base of the brain. ACTH tells the adrenal glands, which sit on the kidneys, to release stress hormones.6 It keeps only amino acids 4 to 7, Met-Glu-His-Phe. Russian papers often call Semax an analogue of the longer fragment ACTH(4–10).2,7

Amino acids 4 to 7 of ACTH, lifted out and given the Pro-Gly-Pro tail.

Selank starts from tuftsin, Thr-Lys-Pro-Arg, a four-amino-acid peptide found in blood and first isolated at Tufts University in 1970.8 Tuftsin is released from IgG, the most common antibody in blood, by two specific enzymes that cut it from the Fc stem, the base of the antibody's Y shape, and an enzyme on white blood cells then trims it down to three amino acids.9

Tuftsin, from the Fc stem of an IgG antibody, given the same tail.

One Tail

Pro-Gly-Pro belongs to a family of short proline- and glycine-rich peptides called glyprolines. Ashmarin's group at Moscow State University argued that peptides carrying them hold up relatively well in the body, and proposed joining them to the body's own signalling peptides to make "chimeric", or hybrid, ones. Semax and Selank are built that way.10

Schematic, not data: the head comes apart and the tail is what remains.

Stable is relative. In rats, Semax tagged with tritium, a radioactive marker that lets it be traced, reached the brain within two minutes, and 80% of the label found there was still intact Semax. It then broke down quickly, and Pro-Gly-Pro was the main fragment found.11 The tail isn't inert on its own. In rats after a stroke induced in the lab, Pro-Gly-Pro by itself also switched on genes for nerve growth factors and their receptors. But it did so in uninjured rats as well, while Semax's effect was largely confined to the injured brain, which suggests the head is what directs the response to injury. The study measured gene activity only, not whether brain damage or recovery changed.7

In the Lab

Almost all of the lab work comes from Moscow groups, chiefly the Institute of Molecular Genetics of the Russian Academy of Sciences.2,3,12 These are animal and test-tube findings.

Semax

BDNF and TrkB, rat hippocampus

One application raised BDNF, a growth factor that helps nerve cells survive and form connections, up to 1.4-fold, and the activation of its receptor, TrkB, 1.6-fold. The genes for both became 3 and 2 times more active.2

Growth-factor genes

Semax changed the activity of genes for neurotrophins, the family of nerve growth factors BDNF belongs to. After a stroke induced in the lab, it raised the genes for BDNF, NGF (another nerve growth factor) and their receptors within 3 to 24 hours.7,13

Genome-wide

Studies that scan thousands of genes at once, in rats after an induced stroke, found shifts in genes tied to the immune system and to blood vessels.14,15

Selank

GABA genes, rat cortex

GABA is the brain's main calming signal. Of 84 genes involved in nerve signalling, 45 changed within an hour of Selank and 22 after three, and the changes tracked those seen after giving GABA itself.12

GABA binding

In tests on brain-cell membranes, Selank made GABA bind more readily. It acted as a positive allosteric modulator, something that turns up a receptor's response from a separate site, apparently not the same site as diazepam (Valium), though the two may partly overlap. The authors present it as one possible mechanism.3

IL-6, human blood cells

IL-6 is an immune signalling protein involved in inflammation. In lab dishes, Selank switched off the IL-6 gene in blood cells from people with depression but not from healthy volunteers, while the amount of IL-6 in the dish rose. The picture is mixed.16

Both: enkephalin-degrading enzymes, human serum

Enkephalins are the body's own opioid-like peptides, which help dampen pain and stress. In blood serum, Semax and Selank slowed the enzymes that break them down, halving the enzymes' activity at 10 and 20 micromolar respectively. Their five-amino-acid fragments did too; shorter pieces didn't.1

In People

Both peptides have been given to patients in Russia. These are the published studies we could verify, with what their abstracts (the published summaries) report. We found none that compared against a placebo, an inactive look-alike that shows how much change would happen anyway.

5published patient studies reviewed 0placebo-controlled trials found 0studies found outside Russia

Semax

Acute stroke, 1997

30 patients had Semax added to intensive care and were compared with 80 patients with similar strokes on standard care. Recovery of nerve function was reported as faster, especially movement. The abstract doesn't say whether patients were assigned to groups by chance, or whether the assessors knew who received Semax.17

Reduced brain blood flow, 2005

187 patients with chronic cerebrovascular insufficiency, long-term reduced blood flow to the brain. The authors report improvement, fewer strokes and transient ischaemic attacks (brief, stroke-like episodes), and few side effects. The design isn't described in the abstract.18

Stroke rehabilitation, 2018

110 patients followed for five months, in early and late rehabilitation groups with and without Semax. BDNF in the blood rose with Semax, and scores for everyday tasks such as dressing and eating improved faster. No placebo group is described.19

Selank

Anxiety, 2008

62 patients with generalized anxiety disorder (persistent, hard-to-control worry) or neurasthenia (long-lasting fatigue and weakness): 30 received Selank and 32 medazepam, a Valium-family anti-anxiety drug. The anti-anxiety effect was similar in both groups, and Selank was also reported to lift fatigue. There was no placebo group.20

Cytokines, 2008

In patients with anxiety disorders given Selank for 14 days, the balance between two families of immune signalling proteins in the blood, called Th1 and Th2 cytokines, shifted.16

The human record is small, Russian-led and mostly compares against standard care or another drug, not placebo. We found no independent trial from outside Russia.

The Research So Far

1970Tuftsin is isolated at Tufts University.8
1987Tuftsin is described as released from the Fc fragment of IgG and trimmed by a white-cell enzyme.9
1997The first Semax study in acute stroke is published.17
2001Semax and Selank both slow enkephalin-degrading enzymes in human serum.1
2005A review of stable glyproline peptides; a 187-patient Semax study.10,18
2006Semax raises BDNF and TrkB in rats; its breakdown leaves Pro-Gly-Pro.2,11
2008Selank is compared with medazepam in 62 patients.20
2010Semax and Pro-Gly-Pro switch on growth-factor genes after experimental stroke.7
2016Selank shifts GABA-related genes in rat cortex.12
2018Selank modulates GABA binding; a 110-patient Semax rehabilitation study.3,19
2020A study of gene activity across the whole genome after Semax, in rats with an induced stroke.15

Where They Stand

Russia

The trials were run there, and the Semax researchers describe it as used in acute stroke care.7

Health Canada

Health Canada's Drug Product Database lists no Semax or Selank product.21

Sport

Neither is named on WADA's 2026 Prohibited List. The list also covers unnamed substances that are unapproved or similar in structure or effect, so not being named isn't a ruling either way.22

Reading a Semax or Selank COA

What a batch report for a seven-amino-acid peptide should show.

Identity

Mass spectrometry, which weighs the molecule, should match about 813.9 g/mol for Semax or 751.9 g/mol for Selank. Reports often give the monoisotopic mass instead, the exact mass using the most common form of each atom: about 813.35 and 751.43. The two are easy to tell apart.4,5

Sequence

Both end in Pro-Gly-Pro, so the mass of the whole peptide, not a fragment, is what confirms which one it is.1

Purity and content

HPLC shows what share of the peptide signal is the intended sequence. Peptide content says how much of the powder is peptide rather than salt and water.

Endotoxin

The LAL test measures bacterial endotoxin, which can skew cell-based experiments.

Batch Reports You Can Verify

Every batch independently lab-tested: identity, purity and LAL endotoxin. Batch-linked COAs you can verify directly with the testing lab.

Browse the COA libraryHow to read a COA

Common Semax and Selank Questions

What are Semax and Selank?

Two lab-made seven-amino-acid peptides from Moscow research institutes. Semax is Met-Glu-His-Phe-Pro-Gly-Pro and Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro.1

What do they have in common?

The last three amino acids, Pro-Gly-Pro, a glyproline added for stability. Their first four come from different natural molecules.10

Is Semax a form of ACTH?

It contains amino acids 4 to 7 of ACTH, plus Pro-Gly-Pro. Its developers call it an analogue of ACTH(4–10).2,6

Where does tuftsin come from?

It's released from the Fc stem of IgG antibodies by two enzymes, and was first isolated in 1970.8,9

How quickly does Semax break down?

Quickly. In rats, intact Semax reached the brain within two minutes, then broke down, leaving Pro-Gly-Pro as the main fragment.11

Have they been tested in people?

Yes, in Russia: Semax in stroke and reduced brain blood flow, Selank in anxiety disorders, compared with standard care or medazepam. We found no placebo-controlled trial and none from outside Russia.17,19,20

Are they approved in Canada?

No. Health Canada's Drug Product Database lists no Semax or Selank product.21

Are they banned in sport?

Neither is named on WADA's 2026 Prohibited List, but the list also covers unnamed unapproved and similar substances, so that isn't a ruling either way.22

Abbreviations and Terms

ACTH

Adrenocorticotropic hormone, a 39-amino-acid pituitary hormone that signals the adrenal glands.

Tuftsin

Thr-Lys-Pro-Arg, a four-amino-acid peptide released from IgG antibodies that stimulates certain white blood cells.

IgG and Fc

IgG is the most common antibody in blood; Fc is the stem of its Y shape.

Glyprolines

Short peptides rich in proline and glycine, such as Pro-Gly-Pro.

BDNF and TrkB

Brain-derived neurotrophic factor, a nerve growth factor, and its receptor.

GABA and allosteric modulation

GABA is the brain's main calming signal. An allosteric modulator changes how a receptor responds by binding somewhere other than the main site.

Enkephalins

The body's own short opioid peptides, broken down by serum enzymes.

IL-6 and Th1/Th2

IL-6 is a signalling protein of the immune system; Th1 and Th2 describe two broad patterns of immune response.

Medazepam

A benzodiazepine, the Valium family of anti-anxiety drugs, used as the comparison in the 2008 Selank study.

HPLC and LAL

HPLC separates a sample to measure purity. The LAL test detects bacterial endotoxin.

References

  1. Kost NV et al. (2001). [Semax and selank inhibit the enkephalin-degrading enzymes from human serum]. Bioorganicheskaia Khimiia 27:180–183. PubMed 11443939
  2. Dolotov OV et al. (2006). Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Research 1117:54–60. PubMed 16996037
  3. Vyunova TV et al. (2018). Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity. Protein & Peptide Letters 25:914–923. PubMed 30255741
  4. PubChem. ACTH (4-7), Pro-Gly-Pro- (Semax), CID 9811102. pubchem.ncbi.nlm.nih.gov
  5. PubChem. Selank, CID 11765600. pubchem.ncbi.nlm.nih.gov
  6. UniProt. P01189, Pro-opiomelanocortin (POMC), including the 39-amino-acid corticotropin (ACTH) chain. uniprot.org
  7. Dmitrieva VG et al. (2010). Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia. Cellular and Molecular Neurobiology 30:71–79. PubMed 19633950
  8. Najjar VA, Nishioka K (1970). "Tuftsin": a natural phagocytosis stimulating peptide. Nature 228:672–673. PubMed 4097539
  9. Mathé G (1987). Do tuftsin and bestatin constitute a biopharmacological immunoregulatory system? Cancer Detection and Prevention Supplement 1:445–455. PubMed 3319151
  10. Ashmarin IP et al. (2005). Natural and hybrid ("chimeric") stable regulatory glyproline peptides. Pathophysiology 11:179–185. PubMed 15837162
  11. Shevchenko KV et al. (2006). [Kinetics of Semax penetration into the brain and blood of rats after its intranasal administration]. Bioorganicheskaia Khimiia 32:64–70. PubMed 16523722
  12. Volkova A et al. (2016). Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission. Frontiers in Pharmacology 7:31. PubMed 26924987
  13. Agapova TY et al. (2007). Neurotrophin gene expression in rat brain under the action of Semax, an analogue of ACTH 4-10. Neuroscience Letters 417:201–205. PubMed 17353092
  14. Medvedeva EV et al. (2014). The peptide semax affects the expression of genes related to the immune and vascular systems in rat brain focal ischemia: genome-wide transcriptional analysis. BMC Genomics 15:228. PubMed 24661604
  15. Filippenkov IB et al. (2020). Novel Insights into the Protective Properties of ACTH(4-7)PGP (Semax) Peptide at the Transcriptome Level Following Cerebral Ischaemia-Reperfusion in Rats. Genes 11:681. PubMed 32580520
  16. Uchakina ON et al. (2008). [Immunomodulatory effects of selank in patients with anxiety-asthenic disorders]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 108:71–75. PubMed 18577961
  17. Gusev EI et al. (1997). [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 97:26–34. PubMed 11517472
  18. Gusev EI, Skvortsova VI, Chukanova EI (2005). [Semax in prevention of disease progress and development of exacerbations in patients with cerebrovascular insufficiency]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 105:35–40. PubMed 15792140
  19. Gusev EI et al. (2018). [The efficacy of semax in the tretament of patients at different stages of ischemic stroke]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 118:61–68. PubMed 29798983
  20. Zozulia AA et al. (2008). [Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 108:38–48. PubMed 18454096
  21. Health Canada, Drug Product Database. Searches for Semax and Selank returned no products, checked October 2026. health-products.canada.ca
  22. World Anti-Doping Agency. The 2026 Prohibited List (in force from January 1, 2026), sections S0 and S2, checked October 2026. wada-ama.org

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