Selank 10mg

At a glance

Strength

10 mg

Also known as

TP-7, Selanc, Thr-Lys-Pro-Arg-Pro-Gly-Pro

CAS number

129954-34-3

Molecular formula

C33H57N11O9

Molecular weight

751.9 g/mol

Sequence

Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP)

PubChem CID

11765600

What Selank is

Selank is a tuftsin derivative: the tetrapeptide Thr-Lys-Pro-Arg is extended at its C-terminus by Pro-Gly-Pro, giving TKPRPGP ¹. Russian papers describe it as a synthetic analog of tuftsin ². Several of the gene-expression studies cited on this page come from the Institute of Molecular Genetics of the Russian Academy of Sciences in Moscow ³⁴. Proline accounts for three of the seven residues. Every residue has the L configuration, the N-terminus is a free amine and the C-terminus a free acid, and there is no disulfide bond. Semax, a different peptide derived from ACTH, carries the same C-terminal Pro-Gly-Pro tail. Alternative names in PubChem include TP-7 and Selanc, and FDA's compounding records call the acetate salt selank acetate (TP-7).

Chemical identity and salt forms

PubChem CID 11765600 is the free base, C33H57N11O9, average mass 751.9 g/mol, CAS 129954-34-3. With a free N-terminal amine, a lysine and an arginine, Selank carries several positive charges at neutral pH, so suppliers normally isolate it as a salt. PubChem includes TP-7 (diacetate) among its synonyms. For laboratory calculations the counter-ion is not a detail. If a vial is labeled by total powder mass, part of that mass is counter-ion and residual water rather than peptide. Only a stated net peptide content lets a researcher work out how much Selank is actually present. Where a supplier gives no salt form, the material is best regarded as unspecified.

Regulatory status

FDA has not approved Selank, and openFDA's Drugs@FDA data return no record for it. On FDA's list of bulk drug substances that may present significant safety risks in compounding, selank acetate (TP-7) sits in the table of nominations withdrawn after being placed in category 2. The entry says FDA lacks important information on safety issues raised by selank acetate administered to humans. It also raises possible immunogenicity linked to aggregation and peptide-related impurities. Selank is registered as a medicine in Russia, which has no effect on its US status. The Selank supplied by this store is a laboratory research material and is not an approved medicine.

Published research

Laboratory and animal work makes up most of the Selank literature, and much of it appears in Russian journals. A 2001 enzyme study found that Selank inhibited the enkephalin-degrading enzymes of human serum in a concentration-dependent way, with an IC50 of 20 micromolar ¹. The same study reported that its pentapeptide fragment also inhibited these enzymes, while the tri-, tetra- and hexapeptide fragments did not ¹. In IMR-32 human neuroblastoma cells, Selank on its own left the mRNA levels of the GABAergic genes tested unchanged ³. Two expression-profiling studies examined rodent tissue after one administration. One measured 84 neurotransmission-related genes in rat frontal cortex ⁴. The other followed genes for chemokines, cytokines and their receptors in mouse spleen 6 and 24 hours later ². Clinical studies in people are few and small, and most were published in Russian. In 52 healthy volunteers, a resting-state functional MRI study looked at brain connectivity after Selank, Semax or placebo ⁵.

What is not known

The breakdown of Selank is better described than its activity in people. Using peptides evenly labeled with tritium, one group found that blood plasma converts Selank mainly into TKPRP, TKP, RP and GP ⁶. In the mouse spleen work, the dipeptide Gly-Pro given alone changed most of the same genes in the same way as Selank ². Together with the enzyme data on the pentapeptide ¹, this means some fragments are themselves active in these assays. Studies that tracked only the intact heptapeptide are therefore harder to interpret; that is this page's reading, not the authors' claim. Long-term human data do not appear in the PubMed literature reviewed here. FDA says it lacks important human safety information on the acetate salt.

Quality testing

Identity and purity are the two results a Selank certificate has to establish. For identity, PubChem's monoisotopic mass of 751.434 Da for the free base puts the [M+H]+ ion at about m/z 752.44. Because the molecule has three basic sites, doubly charged ions are also worth checking in the spectrum. For purity, the HPLC method must resolve the intact heptapeptide from its own shorter sequences, since TKPRP and TKP are known breakdown products ⁶. Net peptide content, counter-ion and water content, appearance, lot number and analysis date complete a useful certificate. Batch purity is reported only on that batch's certificate.