Selank and Semax: Two Peptides Derived From Endogenous Sequences
Selank and Semax are frequently grouped together because they share a development lineage and a common design strategy, not because they act on the same target. Both are synthetic extensions of naturally occurring peptide fragments.
The shared design strategy
Both compounds append a C-terminal Pro-Gly-Pro tripeptide to a biologically derived parent sequence. That extension is the deliberate part of the design: proline-rich termini resist exopeptidase cleavage, and adding Pro-Gly-Pro substantially slows degradation of an otherwise short-lived fragment. The same strategy appears across several peptides developed by the same research programme.
Selank
Selank is built on tuftsin, a tetrapeptide (Thr-Lys-Pro-Arg) that occurs as a fragment of the immunoglobulin G heavy chain. Tuftsin itself has a long literature in phagocyte biology dating to the 1970s. Selank is tuftsin extended with Pro-Gly-Pro, giving a heptapeptide. Literature: PubMed and tuftsin.
Semax
Semax derives from ACTH(4-10), a fragment of adrenocorticotropic hormone that lacks the steroidogenic activity of the full hormone — the portion of ACTH responsible for adrenal stimulation is not present in the fragment. Semax is ACTH(4-7) extended with Pro-Gly-Pro. Because the melanocortin core motif is partially retained, its relationship to melanocortin receptor pharmacology is worth considering alongside the melanocortin receptor subtypes. Literature: PubMed.
Evidence considerations
As with several compounds developed within the same research tradition, much of the primary literature is Russian-language and incompletely indexed internationally, and independent replication outside the originating groups is limited. Mechanistic proposals in the published work vary considerably between papers. A researcher should treat mechanism as an open question rather than settled, and design experiments that test rather than assume it.
Handling notes
Both peptides are short, highly soluble in water and contain no cysteine, so disulfide scrambling is not a concern. Semax contains methionine and tryptophan, both oxidation-prone; Selank contains neither, and is correspondingly more forgiving in storage. For Semax, minimising headspace oxygen and light exposure is worthwhile.
Products: Selank 5mg, Selank 10mg, Semax 10mg, listed under neuropeptides.
ExoLabz supplies compounds for laboratory research use only. Nothing on this page is medical advice or a suggestion of human or veterinary use. Certificates of analysis for each compound are published on this site.
