Semax Research Profile — Peptide Overview

Semax is a synthetic heptapeptide developed in Russia in the 1980s as part of a research programme investigating stable analogues of the ACTH(4-10) neuropeptide fragment. It has since been studied extensively in preclinical and, in a Russian regulatory context, some clinical research, and is registered in Russia as a pharmaceutical for specific medical indications. Outside that regulatory context it is treated as a research peptide.

What Semax is

Semax is a chemically synthesised heptapeptide (7 amino acids) whose sequence extends the biologically active core of the corticotropin (ACTH) fragment 4-7 with a C-terminal Pro-Gly-Pro tripeptide. The C-terminal PGP extension increases the peptide's resistance to enzymatic degradation, giving it a longer half-life than the parent fragment. The research programme that developed Semax was based at the Institute of Molecular Genetics of the Russian Academy of Sciences.

Molecular information

Sequence: Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP in one-letter code)
Number of residues: 7
Approximate monoisotopic mass: ~813 Da (as the free acid)
Origin: Structural analogue of ACTH(4-7) with a C-terminal Pro-Gly-Pro extension
Physical form: Typically supplied as a white lyophilised powder

The methionine residue at the N-terminus is susceptible to oxidation, which is worth noting during analytical work; oxidised Semax appears at a characteristic +16 Da mass shift in LC-MS.

Areas of published research

Semax has been studied across several research domains, largely in Russian-language and international peer-reviewed literature:

Cognitive research — animal and human studies have investigated its effects on attention, memory-related tasks and cognitive performance under fatigue.
Neuroprotection — preclinical models of cerebral ischaemia and hypoxic injury have examined the peptide's effect on neuronal survival and functional recovery.
Neuropeptide signalling — its role as a stable analogue of ACTH fragments has made it a research tool for probing melanocortin and related signalling pathways in non-endocrine tissues.
Neurotrophic factor expression — studies have examined the peptide's influence on BDNF and other neurotrophic factor expression in animal models.

Research history and current interest

Semax was developed from the 1980s onwards in the context of ACTH-fragment research. It has since accumulated a body of preclinical and clinical literature, predominantly published in Russian medical and neuroscience journals with a smaller international footprint. Its continued academic interest reflects both its use as a chemically stable ACTH-analogue research tool and its regulatory status in specific jurisdictions. Researchers outside Russia should note that Semax is not approved as a medicinal product in most jurisdictions and is treated as a research peptide.

Analytical considerations

For laboratory work with Semax:

Identity by mass spectrometry. The observed monoisotopic mass should match the theoretical ~813 Da to within a small tolerance. Watch for the +16 Da methionine oxidation product, which is a common minor synthesis artefact.
Purity by HPLC. Reversed-phase HPLC at 214 nm is standard. Because the peptide is relatively short and hydrophilic, method conditions should be chosen to give adequate retention and resolution — see what is HPLC peptide testing.
Batch documentation. A batch-specific COA is essential for reproducibility; see how to read a peptide COA.
Storage considerations. Lyophilised Semax should be stored under conditions that minimise methionine oxidation.

Research Professionals Only

Semax: Research Profile