Semax and Selank Explained: Neuropeptide Analogs and Their Modified Forms
Semax and Selank are synthetic heptapeptides developed in Russia from natural sequences. This guide explains their origins and what modified versions such as N-acetyl and amidate mean.
Key takeaways
- Semax is a heptapeptide analog of ACTH(4-10); Selank is a heptapeptide analog of tuftsin.
- N-acetylation and C-terminal amidation are chemical modifications intended to change stability.
- These are research compounds and this guide makes no claims about use in people.
Origins
Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It is built from the ACTH(4–10) fragment, Met-Glu-His-Phe-Pro-Gly-Pro, in which the Pro-Gly-Pro tail is added to slow enzymatic breakdown. Selank was developed from tuftsin, a tetrapeptide (Thr-Lys-Pro-Arg) with immune-related activity, by attaching a Pro-Gly-Pro tail as well.
Why modifications are used
Natural peptides are usually broken down quickly by peptidases. Chemical modifications are one way to extend how long a peptide survives in a biological system.
- N-acetylation caps the N-terminus with an acetyl group, which can protect against aminopeptidases.
- C-terminal amidation replaces the terminal carboxyl with an amide, protecting against carboxypeptidases.
Products named N-Acetyl Semax Amidate or NA Semax Amidate combine both modifications. They are different molecules from the unmodified peptides, so they should never be treated as interchangeable when reviewing the literature.
Reading the literature
Much of the research on these compounds comes from Russian groups. Note which molecule, which model and which route of administration a study used, and be cautious about extrapolating. This guide is educational only.
Quality and combinations
Both peptides contain proline-rich sequences, so identity checks by mass spectrometry are important; see how to read a certificate of analysis. Some catalogs offer both together in a blend.