Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP). It was developed in Russia and is built from the ACTH(4-7) fragment of adrenocorticotropic hormone, with a Pro-Gly-Pro tail added to the C-terminus. That tail does two things: it slows enzymatic breakdown, and it appears to carry pharmacological activity of its own. Despite the ACTH parentage, Semax is reported to lack hormonal activity, meaning it does not drive cortisol release through the usual ACTH pathway (PubChem CID 9811102).
Its CAS number is 80714-61-0, and the molecular formula is C37H51N9O10S.
What the research suggests it does
The most consistently reported mechanism is an effect on neurotrophins. In rats, a single intranasal dose of Semax (50 µg/kg) raised brain-derived neurotrophic factor (BDNF) protein in the hippocampus and increased trkB receptor phosphorylation, alongside larger jumps in BDNF and trkB mRNA. This was reported by Dolotov and colleagues, who measured a roughly 1.4-fold rise in BDNF protein and a 1.6-fold rise in trkB phosphorylation within hours (Dolotov et al., *Brain Research*, 2006, via ScienceDirect). A companion paper in the Journal of Neurochemistry found that Semax binds specifically in the rat basal forebrain and raised BDNF protein there within about three hours of intranasal dosing (Dolotov et al., *J Neurochem*, 2006, Wiley).
The Pro-Gly-Pro portion is not just a stabilizer. Work in a rat cerebral ischemia model found that both Semax and PGP alone increased transcription of neurotrophin genes and their receptors after the ischemic insult (Semax and Pro-Gly-Pro neurotrophin study, *PMC11498467*). A separate proteomic study in a rat ischemia-reperfusion model reported a protective protein-expression signature consistent with reduced ischemic damage (ACTH(4-7)PGP rat ischemia study, *PMC8226508*).
The clinical picture
Here is the honest limitation: almost all human data come from Russia and post-Soviet countries, and the trials are generally small and not blinded to Western standards. In a 110-patient study, Gusev, Martynov and colleagues gave stroke patients Semax intranasally (6,000 µg/day in two 10-day courses) and reported higher plasma BDNF, faster recovery, and better Barthel index and motor scores than controls (Gusev et al., *Zh Nevrol Psikhiatr*, 2018, PMID 29798983). Semax is registered in Russia for stroke and other cerebral conditions and sits on the country's list of essential medicines.
It is not approved by the FDA, EMA, or Health Canada. There are no large randomized controlled trials published outside the Russian-language literature, so the strength of the human evidence remains hard to judge from independent sources.
Semax is not a banned substance under the WADA prohibited list as a named entry, but athletes should not read that as clearance; peptide products carry contamination and mislabeling risk regardless of listing.
Quality and what buyers can verify
Material sold as Semax is research-use-only and is not approved for human consumption. Because it is a peptide synthesized by many suppliers, what is in a vial is not guaranteed to match the label. The facts a buyer can actually check are identity and purity from a third-party certificate of analysis (typically HPLC for purity, mass spectrometry for identity), and whether independent raters have tested a given vendor's product. peptideone aggregates those public test results and vendor signals rather than running its own assays.
Nothing here is medical or dosing advice. The doses cited above are from published studies and are reported for context, not as guidance.