Semax: The Modified Heptapeptide for Neuroprotection and Nootropic Induction
Semax is a synthetic peptide known in Russian neurology for its neuroprotective, nootropic, and neurotrophic properties.40
Structural Parameters of Semax
| Property | Value and Specification | References |
|---|---|---|
| CAS Number | 80714-61-0 | 38 |
| Molecular Formula | C37H51N9O10S | 38 |
| Molecular Weight | 813.92 g/mol | 38 |
| Sequence | Met-Glu-His-Phe-Pro-Gly- Pro (ACTH4-7-PGP) | 40 |
| Isoelectric Point | ~5.2 | 42 |
Origin, History, and Research Stage
Semax was developed in the 1980s by the Institute of Molecular Genetics of the Russian Academy of Sciences, led by researcher Igor Ashmarin . The design aimed to retain the cognitive benefits of adrenocorticotropic hormone (ACTH) fragments without inducing peripheral steroidal or adrenal side effects.44 Semax was registered with the Russian Ministry of Health in 1994 for ischemic stroke, traumatic brain injury, and cognitive disorders.44 In 2011 and 2019, it was included on the Russian List of Vital & Essential Drugs.45 In Western markets, it is not FDA-approved and remains classified as a research chemical, although it is prescribed through 503A compounding pharmacies for cognitive enhancement.44
Mechanism of Action and Pharmacokinetics
Semax is a synthetic heptapeptide derived from the ACTH4-7 fragment (Met-Glu-His-Phe), stabilized by a C-terminal tripeptide sequence (Pro-Gly-Pro or PGP).40 This addition protects the peptide from immediate degradation by blood peptidases, extending its half-life and enabling intranasal absorption.44 Semax binds to melanocortin receptors (primarily MC4R) and upregulates the expression of Brain-Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF) in the hippocampus and cortex.44 Animal models show a 1.4-fold increase in BDNF protein and enhanced phosphorylation of tyrosine kinase B (TrkB) receptors within 3 hours.44 During ischemic events, Semax downregulates the apoptotic marker pJNK and matrix metalloproteinase-9 (MMP-9), while upregulating the survival transcription factor pCREB, mitigating cell death in the ischemic penumbra.39 It also sequesters copper divalently to reduce amyloid-beta (Ab1-42) aggregation.47
Scientific and Clinical Effects
In clinical trials, intranasal Semax (6,000 mcg/day) improved motor recovery and daily living scores (Barthel Index) in patients recovering from acute ischemic stroke.44 Electrophysiological trials confirm that Semax induces changes in EEG mapping, indicating increased default mode network (DMN) connectivity.44 This connectivity supports memory consolidation, attention accuracy under stress, and sustained mental focus.44
