Chemical identity
| Designation | Selank |
|---|---|
| CAS number | 129954-34-3 |
| Molecular formula | C33H57N11O9 |
| Molecular weight | 751.9 g/mol |
| Amino-acid sequence | TKPRPGP (tuftsin + Pro-Gly-Pro) |
| Cartridge strength | 20 mg per cartridge |
| Concentration | 6.67 mg/ml |
| Presentation | Pre-mixed solution, sealed 3 ml cartridge |
| Storage | 2–8 °C, protect from light, do not freeze |
Identifiers verified against PubChem in both directions — name to compound record, then each CAS number back again — and, where the sequence is of standard residues, cross-checked by recomputing the molecular weight from the sequence. No purity, HPLC or certificate-of-analysis figure is stated, because no supplier data supports one.
What Selank is
Selank is a synthetic heptapeptide consisting of the tetrapeptide tuftsin with a proline-glycine-proline sequence attached at the carboxyl end. Tuftsin itself is a four-residue peptide — threonine, lysine, proline, arginine — that occurs as a fragment released from the heavy chain of immunoglobulin G, and it was originally characterised for its effects on phagocytic cells.
The construction is the same pattern as Semax: a short natural fragment chosen for its properties, plus a proline-rich tail that makes the resulting molecule far harder for peptidases to cut. A bare tetrapeptide has a very short life in any biological preparation; the extension is what makes the sequence workable as a research compound at all.
Selank was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, the same institution behind Semax, and has been used clinically there. As with Semax, that is sometimes loosely described as approval — and as with Semax, it confers no UK status. Selank holds no UK marketing authorisation and no licensed UK medicine contains it.
An immune-derived sequence, studied in the brain
The interesting feature of Selank is the mismatch between where its parent sequence comes from and what it is studied for. Tuftsin is an immunological peptide, released from an antibody, characterised for its action on macrophages and neutrophils. Selank, built directly on it, is studied predominantly in relation to the nervous system.
That is not as odd as it first appears — the boundary between immune and neural signalling is thoroughly blurred, and peptides acting across it are common — but it does mean the literature on Selank spans two fields that use different models and different readouts. A researcher approaching the compound from an immunology background and one approaching it from neuroscience will find largely non-overlapping bodies of work, and both are about the same molecule.
One consequence worth flagging: because the parent peptide has a well-characterised immunological role, an in-vitro observation in a mixed or immune-competent preparation may have more than one plausible route. Experiments intended to address a neural question in such a system need a design that can distinguish them, which is a real constraint rather than a formality.
What is studied in vitro
Neurotransmitter systems are the largest strand of published work. The GABAergic and serotonergic systems recur, with binding and functional assays in neuronal preparations, and receptor expression measured after treatment. Selank has also been reported to inhibit the degradation of enkephalins by peptidases, which is a mechanistically specific claim and is assayed directly by tracking substrate breakdown in the presence and absence of the compound.
Gene expression work in neuronal and glial cultures forms a second strand, generally asking which transcriptional programmes shift after treatment rather than testing a single named target. Immunological assays in leucocyte preparations constitute a third, following from the tuftsin parentage.
Stability work comparing the heptapeptide with bare tuftsin in the presence of peptidase preparations demonstrates what the Pro-Gly-Pro tail achieves — the same experiment that substantiates the design of Semax.
How it is supplied
Peptide Global supplies it as the Selank Pen 20 mg: 20 mg pre-mixed in a sealed 3 ml cartridge at 6.67 mg/ml, in a dial-dosing pen device, with no reconstitution step. The fill matches the Semax Pen 20 mg exactly, which is convenient given how often the two are studied together — see Semax versus Selank.
Storage is 2–8 °C, protected from light and not frozen, for as long as the cartridge is held. See storage and handling.
Common questions
What is Selank?
A synthetic heptapeptide made of the tetrapeptide tuftsin — a fragment released from the heavy chain of immunoglobulin G — with a proline-glycine-proline sequence attached at the carboxyl end. The tail makes an otherwise very short-lived peptide resistant to enzymatic cleavage.
What is tuftsin?
A four-residue peptide, threonine-lysine-proline-arginine, occurring as a fragment of immunoglobulin G's heavy chain. It was originally characterised for its effects on phagocytic cells such as macrophages and neutrophils, which is why Selank's parentage is immunological even though most work on Selank is neurological.
How is Selank different from Semax?
Their parent sequences are unrelated. Selank is built on tuftsin, an immune-derived tetrapeptide; Semax is built on a fragment of ACTH. Both are Russian-developed heptapeptides carrying the same stabilising proline-rich tail, which is why they are constantly paired, but they are not variants of one another.
Is Selank legal in the UK?
Selank holds no UK marketing authorisation and no licensed UK medicine contains it. It was developed in Russia and has been used clinically there, which confers no UK status. Material supplied for in-vitro laboratory research sits outside the medicines framework rather than being prohibited by it, and institutional policy is often the stricter test. Nothing here is legal advice.
What strength is the Selank Pen?
20 mg in a 3 ml cartridge, giving 6.67 mg/ml — the same fill and concentration as the Semax pen.
Products described in this guide
Supplied for laboratory research use only. UK delivery is free on every order, tracked as standard.
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