Selank

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) developed in Russia as a proteolytically stabilized analog of the endogenous immunopeptide tuftsin, and it is supplied for laboratory research only. It is not approved by the FDA for any use and is not for human or animal consumption.

Specifications

Structure and origin

Tuftsin is a naturally occurring tetrapeptide (Thr-Lys-Pro-Arg) released by enzymatic cleavage from the heavy chain of immunoglobulin G. Selank extends that sequence with a C-terminal Pro-Gly-Pro tripeptide. The extension is the point of the molecule: Pro-Gly-Pro is a glyproline motif associated with resistance to peptidase cleavage, and the design intent described in the primary literature was to slow degradation of the tuftsin core rather than to alter its receptor pharmacology.

The compound was developed jointly by the Institute of Molecular Genetics of the Russian Academy of Sciences and the V. V. Zakusov Research Institute of Pharmacology in the 1990s. That origin shapes the evidence base: the great majority of primary Selank publications come from those two institutes and a small circle of collaborators, and much of it appears in Russian-language journals indexed by PubMed in translation or by title only.

Mechanistic research

Enkephalin-degrading enzymes

Zozulya et al. (2001), writing in Bulletin of Experimental Biology and Medicine, reported that Selank inhibited enkephalin-degrading enzyme activity in human blood serum in vitro. The authors proposed protection of endogenous enkephalins from degradation as a candidate mechanism. This remains an in vitro observation in a cell-free matrix; it has not been shown to be the operative mechanism in an intact organism.

GABAergic gene expression

Volkova et al. (2016) profiled 84 neurotransmission-related transcripts in rat frontal cortex at one and three hours after administration of Selank or GABA, using real-time PCR. They reported significant expression changes in 45 genes at one hour and 22 at three hours, with correlated response patterns between the Selank and GABA groups, and interpreted the result as consistent with allosteric modulation of the GABAergic system. Filatova et al. (2017) extended the same approach to IMR-32 cells, a human neuroblastoma line, comparing Selank against GABA and olanzapine in vitro. Both papers describe transcriptional signatures, not receptor binding; no binding constant for Selank at a GABA_A receptor subunit has been established in the published record.

Neurotrophin expression

Inozemtseva et al. (2008) reported regulation of BDNF expression in rat hippocampus following intranasal administration of Selank in vivo. Kolik et al. (2019) measured BDNF content in the hippocampus and prefrontal cortex of rats in an ethanol-induced memory impairment model and reported changes in that model. Both are rodent studies from Russian institutes; neither has an independent replication in the indexed literature.

Study models at a glance

Human data and its limits

One clinical report accounts for most of the human record. Zozulia et al. (2008) studied 62 patients carrying diagnoses of generalized anxiety disorder or neurasthenia, comparing 30 who received Selank against 32 who received medazepam, with assessment by the Hamilton, Zung and CGI scales alongside measurement of serum enkephalin activity. The paper is in Russian, single-centre, and small.

Set against that, Vanhee et al. (2020), analytical chemists at the Belgian public health institute Sciensano, wrote in Drug Testing and Analysis that Selank and Semax had not, to their knowledge, completed any clinical trials — a statement made while developing an LC-MS/MS screening method after both peptides turned up in seized preparations. The two positions are not strictly contradictory, but the tension is the honest summary: the human evidence is thin, geographically concentrated, and has not been reproduced outside its country of origin. No FDA-recognized efficacy trial exists.

Regulatory status

Selank holds no FDA approval, no New Drug Application, and no legal status as a dietary ingredient in the United States. It is not a compendial substance and there is no USP monograph governing its identity or purity. Material offered for research is therefore governed entirely by the supplier's own analytical documentation. Sale and possession terms are set out in the research use policy.

Handling, storage, and identity verification

Selank is supplied as a lyophilized powder. Standard practice for lyophilized peptides applies: keep vials sealed and desiccated at −20 °C or colder, protect from light, and allow vials to equilibrate to room temperature before opening to avoid condensation drawing moisture into hygroscopic material. Repeated freeze-thaw cycling of solutions is the usual cause of degradation seen in stability work. Further detail is collected in the notes on peptide storage and reconstitution, and concentration arithmetic can be checked with the peptide calculator.

Because no pharmacopoeial standard exists, identity and purity rest on third-party analysis. A defensible package for a peptide of this size includes HPLC purity with the chromatogram attached, and mass spectrometry confirming a molecular ion consistent with 751.9 g/mol. Reported lab testing that omits the raw traces cannot be independently evaluated, whatever the summary figure says.

Frequently asked questions

How should lyophilized Selank be stored?

Sealed, desiccated, and protected from light at −20 °C or colder. Short ambient excursions during shipping are normal for lyophilized peptides; prolonged room-temperature storage is not.

What documentation should accompany a research-grade peptide?

A certificate of analysis naming the lot, an HPLC chromatogram rather than a bare purity percentage, and a mass spectrum whose observed mass matches the theoretical molecular weight. A certificate that cannot be tied to a specific lot number documents nothing.

Is Selank approved by the FDA?

No. It is not approved for any indication in the United States, is not a recognized dietary ingredient, and is offered for laboratory research only. It is not for human or animal consumption.

Why is so much of the Selank literature in Russian?

The compound was developed by Russian state research institutes and the pharmacological and clinical work was published domestically. Many of those journals are PubMed-indexed, so the records are findable, but full texts are often Russian-only and the studies have rarely been replicated elsewhere.

References

1. Zozulya AA, Kost NV, Sokolov OY, et al. (2001). The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Bulletin of Experimental Biology and Medicine.
2. Kozlovskaya MM, Kozlovskii II, Val'dman EA, Seredenin SB (2003). Selank and short peptides of the tuftsin family in the regulation of adaptive behavior in stress. Neuroscience and Behavioral Physiology.
3. Zozulia AA, Neznamov GG, Siuniakov TS, 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.
4. Inozemtseva LS, Karpenko EA, Dolotov OV, et al. (2008). Intranasal administration of the peptide Selank regulates BDNF expression in the rat hippocampus in vivo. Doklady Biological Sciences.
5. Volkova A, Shadrina M, Kolomin T, et al. (2016). Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission. Frontiers in Pharmacology.
6. Filatova E, Kasian A, Kolomin T, et al. (2017). GABA, Selank, and Olanzapine Affect the Expression of Genes Involved in GABAergic Neurotransmission in IMR-32 Cells. Frontiers in Pharmacology.
7. Kolik LG, Nadorova AV, Antipova TA, et al. (2019). 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.
8. Vanhee C, Francotte A, Janvier S, Deconinck E (2020). The occurrence of putative cognitive enhancing research peptides in seized pharmaceutical preparations: An incentive for controlling agencies to prepare for future encounters of the kind. Drug Testing and Analysis.