Semax and Selank: two heptapeptides explained

Semax is a heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. The first four amino acids are fragment 4–7 of ACTH (adrenocorticotropic hormone); Pro-Gly-Pro is attached to it, which makes the peptide less prone to breakdown by enzymes.

The literature links Semax to the expression of BDNF and its receptor TrkB in the brains of rodents. Unlike ACTH, it is reported to have no effect on the adrenal gland.

Selank is a heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. The first four amino acids form tuftsin, an endogenous peptide of the immune system; here too Pro-Gly-Pro was added for stability.

Studies, largely from Russia, link Selank to the GABAergic system, to the breakdown of enkephalins and to the expression of cytokines.

• Semax: Met-Glu-His-Phe-Pro-Gly-Pro, about 813.9 g/mol, derived from ACTH(4–7).
• Selank: Thr-Lys-Pro-Arg-Pro-Gly-Pro, about 751.9 g/mol, derived from tuftsin.
• Both: seven amino acids, synthetic, with a Pro-Gly-Pro end.
• Research: mainly in rodent models and cell studies, largely published by Russian research groups.

The research comes largely from a small number of groups; independent replication outside Russia is scarce.

• Neurotrophic factors, such as BDNF and the receptor TrkB, in the brains of rodents (Semax).
• The GABA system and the breakdown of enkephalins (Selank).
• Immunomodulation and cytokine expression (Selank, in line with its origin in tuftsin).
• Gene expression in the brains of rodents.

• As powder cool, dry and dark; briefly in the fridge (2–8 °C), longer in the freezer (−20 °C or colder).
• Semax contains methionine, which is prone to oxidation: keep the vial closed and protected from light.
• Dissolve following Dissolving peptides and work out the concentration with the peptide calculator.
• Keep a solution in the fridge and do not freeze it.

BrabantLabs supplies Semax in 5, 10 and 30 mg and Selank in 5 and 10 mg, shipped from the Netherlands. The certificates are on Lab results.

• A certificate per lot with purity (HPLC) and a mass measurement that matches Semax or Selank.
• A lot number on the vial that matches the certificate.
• Mind the name: variants with an extra acetyl group or another modification have a different mass.

What is the difference between Semax and Selank?

Semax derives from a fragment of ACTH, Selank from tuftsin. Both are heptapeptides with a Pro-Gly-Pro end, but with a different sequence and a different research field.

How many amino acids do Semax and Selank have?

Seven each: they are heptapeptides.

Where do Semax and Selank come from?

Both were developed by Russian research institutes, and most of the research comes from there too.

What does Pro-Gly-Pro mean?

It is three amino acids (proline, glycine, proline) at the end of the chain. They make the peptide less prone to breakdown by enzymes.

• View Semax in the shop
• View Selank in the shop