Semax is a synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP), derived from ACTH(4-10) — the fragment of adrenocorticotropic hormone associated with behavioural rather than corticotropic effects. Molecular formula C37H51N9O10S, molecular weight 813.9 g/mol.
A Pro-Gly-Pro extension at the C-terminus confers resistance to enzymatic degradation while removing the hormonal activity of the parent molecule. It was developed in Russia and remains far better documented in Russian-language literature than in Western journals.
Research context
The published work examines Semax in relation to brain-derived neurotrophic factor (BDNF) and nerve growth factor expression, along with effects on monoamine systems. Its research interest lies in the separation achieved between the neurotrophic and endocrine activities of the ACTH sequence — the peptide retains one while discarding the other.
Selank comes from the same research programme and uses the same Pro-Gly-Pro stabilisation strategy, but derives from tuftsin and acts through different pathways. As with several compounds of Russian origin, independent replication outside the original research programme is limited.
For a fuller treatment of the sequence, published models and technical data, see the Semax research guide.
Specification
CAS number 80714-61-0. Supplied as a white lyophilized powder, soluble in water. This batch assayed at 99.76% purity, verified at ILS Lab.
Handling
Reconstitute with bacteriostatic or sterile water and swirl gently to dissolve. The N-terminal methionine is oxidation-prone — minimise air exposure and protect from light more carefully than you would a sequence without it.
Store lyophilized at −20°C protected from light; refrigerate at 2–8°C once reconstituted.
Ships with a batch-specific Certificate of Analysis. Cross-check the batch ID printed on your vial against the CoA before use — see the guide to reading a CoA if you are unfamiliar with the format.
Frequently asked questions about Semax
What does “ACTH(4-10) analogue” mean?
Semax corresponds to residues 4 through 10 of adrenocorticotropic hormone, plus a Pro-Gly-Pro tail. The full ACTH molecule drives cortisol release from the adrenal cortex; this seven-residue fragment does not. The research interest lies exactly in that separation — the fragment retains behavioural and neurotrophic activity associated with the parent sequence while discarding the endocrine function.
Semax or Selank?
Different mechanisms from the same programme. Semax is studied primarily through BDNF and NGF expression — neurotrophic signalling. Selank derives from tuftsin and published work centres on GABAergic and serotonergic pathways. Both carry the same Pro-Gly-Pro stabilisation, which is a shared design principle rather than a shared mode of action.
Is Semax stable in solution?
Reasonably, though the N-terminal methionine deserves attention. Methionine oxidises readily on air exposure to methionine sulfoxide, adding 16 Da and altering the molecule — the same consideration that applies to MOTS-c. Minimise headspace and exposure time, protect from light, and prepare working dilutions fresh where the protocol allows.
What purity should Semax be?
This batch assayed at 99.76% at ILS Lab, batch CR-3XAG-90-2606-80. Given the methionine content, check the mass spectrum on the Certificate of Analysis rather than the purity figure alone — oxidation shows as a +16 Da species that an HPLC percentage may not clearly separate.
Research use only. Not for human or veterinary use, not for use in diagnostic procedures, and not evaluated by the U.S. Food and Drug Administration.
