Sourcing Guide

Selank in the US: The Tuftsin Analog From the Russian Literature

A heptapeptide with a real research program published almost entirely in one language, and what that means for reading the evidence

July 16, 2026·Compiled by Eppix Labs

Selank is a heptapeptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, built by extending the immunomodulatory tetrapeptide tuftsin with a Pro-Gly-Pro tail that resists enzymatic degradation. It has a genuine research program behind it, and that program is published almost entirely in Russian-language journals with limited independent replication outside that literature.

That is not a reason to dismiss the compound. It is a reason to be precise about what has and has not been shown, which is what this guide tries to be. Selank is supplied for laboratory research use only.

Chemical Identity

Name: Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro)
Also known as: Selank, TP-7, Tuftsin analog
Molecular formula: C₃₃H₅₇N₁₁O₉
Molecular weight: 751.9 g/mol
CAS number: 129954-34-3
Sequence (1-letter): TKPRPGP
Sequence (3-letter): Thr-Lys-Pro-Arg-Pro-Gly-Pro
Salt forms: Acetate

What selank is

Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro. The first four residues are tuftsin, a naturally occurring immunomodulatory tetrapeptide derived from the Fc region of immunoglobulin G. The appended Pro-Gly-Pro sequence is a stabilizing extension, a design device used across the Russian regulatory-peptide program to slow enzymatic cleavage without altering the pharmacophore.

The proposed mechanism in the published work is indirect: rather than binding a classical receptor, selank is reported to inhibit enkephalin-degrading enzymes, extending the action of endogenous enkephalins.[1] Later work reported effects on GABAergic and monoaminergic gene expression in rat brain.

General Image — Selank lyophilized research material as supplied by Eppix Labs. Labelled and measured content are stated on the certificate below.

Sequence and structure

Seven residues, around 752 Da, proline-rich. The three prolines are structurally significant: proline constrains the backbone and is what gives short regulatory peptides of this family their resistance to exopeptidases. Synthetically it is a simple target, which means a low purity figure on a selank certificate points at a supplier problem rather than at a difficult molecule.

Amino Acid Sequence diagram — Amino-acid sequence of selank, TKPRPGP.

Chemical Structure diagram — Chemical structure of selank, C₃₃H₅₇N₁₁O₉.

What the published research shows

The accessible peer-reviewed record, primarily in Bulletin of Experimental Biology and Medicine:

·Enkephalin-degrading enzymes. Zozulya et al. (2001) reported inhibition of enkephalin-degrading enzyme activity in human blood plasma as a proposed mechanism for the compound's anxiolytic activity in models.[1]
·Behavioural models and enzyme activity. Sokolov et al. (2002) reported effects on behavioral reactions alongside plasma enkephalin-degrading enzyme activity in mice with differing baseline phenotypes.[2]
·Opioid-system involvement. Meshavkin et al. (2006) reported that naloxone blocked a selank effect on apomorphine-induced behaviour, which is consistent with opioid-system involvement in the compound's activity.[3]

The limit of the evidence

Selank has been used clinically in Russia, where it holds a registration that does not transfer to any other jurisdiction. Outside that context there are no published randomized controlled trials meeting the standards Western regulators apply, and there is very little independent replication of the mechanistic work.

the FDA has authorized nothing containing selank. It is not approved for human or veterinary use here, is not a controlled substance, and is supplied as a laboratory research material. A supplier presenting the Russian registration as evidence of approval in the US is describing a different country.

Verifying a selank lot

Identity by mass spectrometry against the expected mass near 752 Da, HPLC purity, and measured content against the labeled amount. Note that a related compound, semax, is often stocked alongside selank and is also a short proline-containing Russian-programme peptide; they are different molecules with different masses, and an identity line is what distinguishes them if a vial is mislabelled upstream.

Every Eppix selank lot is tested by Janoshik Analytical, published before sale and verifiable on the laboratory's own database.

Certificate of analysis for Selank 10mg, batch SEL-CA-26A-01, 99.161% purity, 10.55 mg measured content — Published certificate for the current selank lot, read live from the batch record.

Sourcing in the United States

Domestic fulfillment is by FedEx, typically one to three business days across the United States, free over $200 USD, with card and PayPal checkout and mix-and-match pricing at 5 and 10 vials.

For the general method of reading a certificate, see how to verify a peptide COA.

Available at Eppix Labs

Selank

10mg

Every batch tested by an independent laboratory, with the certificate published before sale.

From $39.99 USDIn stock

Frequently Asked

Tuftsin, a naturally occurring immunomodulatory tetrapeptide from the Fc region of immunoglobulin G, extended with a Pro-Gly-Pro sequence that slows enzymatic degradation.

It holds a registration in Russia. That registration does not extend to the United States or to any other jurisdiction, and the FDA has authorized nothing containing selank.

It may be sold and held as a laboratory research material. It is not approved by the FDA for human or veterinary use, and it is not a controlled substance. This is not legal advice.

Most of it was published in Russian-language journals within a single research program, with limited independent replication elsewhere. That is a reason to read the primary papers carefully rather than to rely on secondary summaries.

Batch number matching the vial, the named testing laboratory with an independent verification path, MS identity against the expected mass near 752 Da, HPLC purity, and measured content against the labeled amount.

Lyophilized: cool, dry, dark, at -20 °C for long-term storage. Reconstituted: refrigerated, used within the window your protocol defines.

References

Zozulya, A.A. et al. (2001). The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Bull Exp Biol Med 131(4):315-317. PMID 11550013
Sokolov, O.Y. et al. (2002). Effects of Selank on behavioral reactions and activities of plasma enkephalin-degrading enzymes in mice with different phenotypes of emotional and stress reactions. Bull Exp Biol Med 133(2):152-154. PMID 12432865
Meshavkin, V.K. et al. (2006). Naloxone-blocked depriming effect of anxiolytic selank on apomorphine-induced behavioral manifestations. Bull Exp Biol Med 142(5):571-573. PMID 17415472

Selank

From $39.99 USD · Janoshik-verified COA

Research Use Only

This article summarizes published preclinical research literature. Compounds referenced are supplied by Eppix Labs strictly as research materials for laboratory investigation within the United States. They are not approved by the FDA for human or veterinary use, and nothing on this page should be interpreted as medical advice or guidance on human or animal administration.