What Is Semax? ACTH-Derived Peptide, BDNF Upregulation, and Research Uses

Semax is a synthetic heptapeptide developed from work on adrenocorticotropic hormone (ACTH) fragments, and it's one of the most heavily studied nootropic-category research peptides to come out of Russian neuropeptide research. This article covers what the literature reports on its origin, structure, and best-characterized mechanism — brain-derived neurotrophic factor (BDNF) upregulation. For a head-to-head against a related Russian research peptide with a very different profile, see Semax vs Selank.

ACTH(4-10) Origin

Semax has the sequence Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment of adrenocorticotropic hormone, with a Pro-Gly-Pro tail added to slow enzymatic breakdown and extend stability. Despite the ACTH lineage, the ACTH(4-10) portion has essentially no affinity for the melanocortin-2 receptor — the receptor that drives cortisol release — so in research models Semax does not trigger the hormonal cascade associated with its parent molecule. Its studied activity is neurotrophic, not endocrine.

BDNF and TrkB Upregulation

The best-characterized finding in the Semax literature is its effect on brain-derived neurotrophic factor (BDNF) signaling. In a frequently cited rat study, a single intranasal application of Semax produced roughly a 1.4-fold increase in BDNF protein, a 1.6-fold increase in TrkB receptor phosphorylation, and approximately a 3-fold increase in BDNF mRNA in the hippocampus (Dolotov et al., 2006). The hippocampal BDNF/TrkB system is one of the best-established molecular pathways underlying learning and memory in animal models, which is why this finding anchors most of the downstream research interest in the compound.

Later work extended this into ischemia research: Semax and its Pro-Gly-Pro metabolite have been reported to activate transcription of neurotrophins and their receptors following cerebral ischemia in animal models, a line of research distinct from — but consistent with — the original cognition-focused BDNF findings.

Dopaminergic Signaling

Alongside the BDNF data, Semax has been studied for effects on dopaminergic signaling in animal models, which is part of why it's grouped with focus- and attention-oriented research compounds rather than purely memory-oriented ones. The mechanistic overlap between neurotrophic and dopaminergic effects is an active area of ongoing preclinical study rather than a fully resolved picture.

Regulatory Status and Evidence Base

Semax has been registered as a pharmaceutical product in Russia, which is part of why the research literature on it is unusually deep for a compound that remains unapproved in the United States and most other jurisdictions. That regulatory history in one country doesn't change its status here: it is not FDA-approved, and it is sold in our catalog strictly as a research chemical.

Supply and Storage

Research-grade Semax is supplied as a lyophilized powder. Purity should be verified by HPLC with sequence identity confirmed by mass spectrometry — see peptide purity standards for how that figure is calculated. Once reconstituted, refrigerate at 2–8°C and use within the window specified on the COA; see how to reconstitute research peptides for technique.

Research Use Only

Semax is sold and discussed here strictly for laboratory and preclinical research, not for human or animal consumption. Every lot we ship is third-party HPLC tested and lot-tracked — confirm any lot on our verification page.