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Research / Selank peptide review
Reference review

Selank peptide: structure, mechanism and published research

Null Bio Lab Research Desk · Last reviewed October 18, 2026 · Research use only

Scope. This article summarises published laboratory literature for readers working with Selank as a research reagent. It gives no dosing, administration or usage guidance, and nothing here is a statement about any use in humans or animals. Selank is not an authorised medicine in the EU or US.
Key facts
  • Sequence: Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP)
  • Design: tuftsin (TKPR) + C-terminal Pro-Gly-Pro (PGP)
  • Monoisotopic mass: 751.43 Da; [M+H]+ ≈ 752.44 (average mass 751.9)
  • Main research areas: enkephalin-degrading enzymes, GABAergic gene expression, immune-related genes
  • Status: not an authorised medicine in the EU or US (to our knowledge)

What Selank is

Selank is a synthetic heptapeptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro. The literature describes it as a stabilised analogue of tuftsin, a naturally occurring tetrapeptide (Thr-Lys-Pro-Arg) linked to immune function, extended with the same Pro-Gly-Pro tail found in Semax.12

Tuftsin and the design logic

Tuftsin on its own is short-lived in biological fluids. Adding PGP is the strategy the developers used to slow enzymatic breakdown, and the resulting molecule was then characterised in behavioural, biochemical and gene-expression experiments.2 Because the parent peptide sits between the immune and nervous systems, Selank papers frequently report on both.

Enkephalin-degrading enzymes

Enkephalins are short endogenous opioid peptides cleared quickly by peptidases. An in-vitro study reported that Selank inhibits enkephalin-degrading enzymes in plasma and proposed this as a possible mechanism behind its behavioural effects in rodent stress models.3 A companion report found that both Semax and Selank inhibit enkephalin-degrading enzymes from human serum.4 The idea is that preserving endogenous peptides, instead of binding a classical receptor directly, could explain part of the profile.

GABAergic gene expression

GABA is the main inhibitory neurotransmitter in the central nervous system. A study of Selank administration reported effects on the expression of some genes involved in GABAergic neurotransmission.5 A later in-vitro study in IMR-32 human neuroblastoma cells compared Selank with GABA itself and with olanzapine, reporting that all three altered expression of genes involved in GABAergic neurotransmission.6 These are transcriptional findings and do not show direct action at the GABA-A receptor.

Immune genes and BDNF

A mouse study reported effects on inflammation-related gene expression in spleen.7 In a rat model of ethanol-induced memory impairment, another study connected Selank to BDNF content in hippocampus and prefrontal cortex,8 the same neurotrophin target studied for Semax (see the Semax review), though in separate experimental systems. A review from the group that developed the compound collects these findings.1

Limits of the evidence

  • The enkephalinase result is biochemical, in vitro; the authors present it as a possible mechanism, not a proven one.3
  • The GABA-pathway results are gene-expression findings from rodent and cell-line work.
  • Most studies come from a small number of related laboratories, and the review literature from the originating group is not independent confirmation.
  • No single receptor target is firmly established.

Regulatory status

To our knowledge Selank is registered as a medicine in Russia and is not an authorised medicine in the EU or the United States. Confirm current status with the relevant regulator. Null Bio Lab does not currently list Selank in its catalog; this page is reference material. To compare it with Semax, see Semax vs Selank; for batch verification, see the COA guide.

Frequently asked questions

What is the Selank amino acid sequence?

Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP), a heptapeptide with a monoisotopic mass of 751.43 Da.

What is the relationship between Selank and tuftsin?

Selank is a stabilised analogue of tuftsin (Thr-Lys-Pro-Arg), extended at the C-terminus with Pro-Gly-Pro.

Is Selank the same as Semax?

No. They share the Pro-Gly-Pro tail but derive from different parent peptides (tuftsin vs an ACTH fragment) and have different published research profiles. See Semax vs Selank.

Is Selank approved by the FDA or EMA?

To our knowledge it is not an authorised medicine in the EU or US. Confirm current status with the regulator.

How is Selank identified on a COA?

By its measured mass: [M+H]+ near 752.44, and often a doubly charged ion near 376.7, since the sequence contains lysine and arginine.

References

  1. Vyunova TV, Andreeva L, Shevchenko K, Myasoedov N. Peptide-based anxiolytics: the molecular aspects of heptapeptide Selank biological activity. Protein and Peptide Letters. 2018. doi:10.2174/0929866525666180925144642. PMID 30255741.
  2. Kozlovskaya MM, Kozlovskii II, Val'dman EA, Seredenin SB. Selank and short peptides of the tuftsin family in the regulation of adaptive behavior in stress. Neuroscience and Behavioral Physiology. 2003. doi:10.1023/a:1025988519919. PMID 14969422.
  3. Zozulya AA, Kost NV, Sokolov OY, et al. The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Bulletin of Experimental Biology and Medicine. 2001. doi:10.1023/a:1017979514274. PMID 11550013.
  4. Kost NV, Sokolov OIu, Gabaeva MV, et al. Semax and selank inhibit the enkephalin-degrading enzymes from human serum. Bioorganicheskaia Khimiia. 2001. doi:10.1023/a:1011373002885. PMID 11443939.
  5. Volkova A, Shadrina M, Kolomin T, et al. Selank administration affects the expression of some genes involved in GABAergic neurotransmission. Frontiers in Pharmacology. 2016;7:31. doi:10.3389/fphar.2016.00031. PMID 26924987.
  6. Filatova E, Kasian A, Kolomin T, et al. GABA, Selank, and olanzapine affect the expression of genes involved in GABAergic neurotransmission in IMR-32 cells. Frontiers in Pharmacology. 2017;8:89. doi:10.3389/fphar.2017.00089. PMID 28293190.
  7. Kolomin T, Shadrina M, Andreeva L, et al. Expression of inflammation-related genes in mouse spleen under tuftsin analog Selank. Regulatory Peptides. 2011. doi:10.1016/j.regpep.2011.05.001. PMID 21609736.
  8. Kolik LG, Nadorova AV, Antipova TA, et al. Selank, peptide analogue of tuftsin, protects against ethanol-induced memory impairment by regulating of BDNF content in the hippocampus and prefrontal cortex in rats. Bulletin of Experimental Biology and Medicine. 2019. doi:10.1007/s10517-019-04588-9. PMID 31625062.

Related reading

For newly published papers on this and other peptides, see the live feed on the Research Desk.