The 5 Most-Studied Cognitive Peptides in Preclinical Research
The following compounds are the primary subjects of nootropic peptide research in 2025, selected for volume of published literature and specificity of cognitive mechanism.
1. Semax — ACTH Analogue, BDNF Upregulator (AXON Line)
Semax is a synthetic heptapeptide analogue of ACTH(4-7) developed at the Institute of Molecular Genetics in Moscow. It is the most studied nootropic peptide for BDNF (brain-derived neurotrophic factor) upregulation. Preclinical studies show Semax increases BDNF and NGF expression in the hippocampus and cortex, with demonstrated neuroprotective effects in ischemia, stroke, and stress models. It is approved as a nasal spray in Russia for stroke rehabilitation and cognitive disorders. CAS: 80714-61-0 · M.W.: 813.96 g/mol · Available in 5 mg vials.
2. Selank — Anxiolytic Heptapeptide (AXON Line)
Selank is a synthetic analogue of the immunomodulatory peptide tuftsin (Thr-Lys-Pro-Arg-Pro-Gly-Pro), developed by the Institute of Molecular Genetics in collaboration with the Institute of Pharmacology. It is the most studied anxiolytic peptide in Russian neuropharmacology. Preclinical research shows modulation of GABA-A receptors, reduced anxiety-like behavior in elevated plus-maze tests, and anti-stress effects via enkephalin regulation. It is approved as a nasal spray in Russia for anxiety disorders. CAS: 129954-34-3 · Available in 5 mg vials.
3. Dihexa — HGF/MET Agonist (AXON Line)
Dihexa (N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) is an angiotensin IV analogue developed at Washington State University. It is an HGF/MET agonist studied for hippocampal synaptogenesis. Dihexa is reported to be approximately 10 million times more potent than BDNF at promoting new synaptic connections in rodent brain slice preparations. Preclinical studies show cognitive improvement in aged and scopolamine-treated rats. CAS: 1401708-83-5 · Available in 50 mg vials.
4. DSIP — Delta Sleep Inducing Peptide (AXON Line)
DSIP is a nonapeptide first isolated from rabbit cerebral venous blood during slow-wave sleep. It is studied for modulation of sleep architecture, circadian rhythm regulation, and stress-axis normalization. Research shows DSIP reduces ACTH and cortisol in stress models, modulates delta-wave sleep patterns, and has antioxidant properties. Sleep quality is directly linked to cognitive consolidation and neurological health, making DSIP relevant in both sleep and cognitive research. CAS: 62568-57-4 · Available in 5 mg vials.
5. 5-Amino-1MQ — Metabolic / Cognitive Crossover (AXON Line)
5-Amino-1-methylquinolinium (5-Amino-1MQ) is a small-molecule NNMT (nicotinamide N-methyltransferase) inhibitor studied for metabolic regulation and NAD+ pathway modulation. Emerging research links NNMT inhibition to improved mitochondrial function in neurons, reduced neuroinflammation, and enhanced synaptic energy availability — positioning 5-Amino-1MQ at the intersection of metabolic and cognitive research. CAS: 1369441-93-7 · Available in 50 mg vials.
Comparison Table: Cognitive Peptides at a Glance
| Peptide | Primary Mechanism | Key Research Effect | Cognitive Profile | Format |
|---|---|---|---|---|
| Semax | BDNF / NGF upregulation | Neuroprotection, memory | Stimulatory / nootropic | 5 mg vial |
| Selank | GABA-A / enkephalin | Anxiolytic, anti-stress | Calming / anxiolytic | 5 mg vial |
| Dihexa | HGF/MET agonism | Synaptogenesis, memory | Potent / neurogenic | 50 mg vial |
| DSIP | Sleep / cortisol modulation | Delta sleep, stress reduction | Sleep / recovery | 5 mg vial |
| 5-Amino-1MQ | NNMT inhibition / NAD+ | Mitochondrial / neuroenergy | Metabolic crossover | 50 mg vial |
Frequently Asked Questions
What is the difference between Semax and Selank?
Semax has a more stimulatory cognitive profile — it upregulates BDNF and NGF in the hippocampus and is studied for memory, focus, and neuroprotection. Selank is primarily anxiolytic — it modulates GABA-A receptor activity and is studied for anxiety reduction, stress response normalization, and emotional regulation. Both are used in Russian clinical practice as nasal sprays.
How does Dihexa compare to BDNF?
Dihexa is reported to be approximately 10 million times more potent than BDNF at promoting synaptogenesis in hippocampal slice models. Unlike BDNF, which has poor blood-brain barrier penetration and a short half-life, Dihexa is orally bioavailable and has demonstrated cognitive improvement in aged rodents in published Washington State University research.
Are nootropic peptides legal to buy for research?
Nootropic research peptides including Semax, Selank, and Dihexa are legal to purchase for legitimate in vitro and preclinical research in most jurisdictions. They are not controlled substances in the US or EU. Rainbow Peptide sells them exclusively For Research Use Only to qualified researchers.
Summary
The 5 most studied cognitive enhancement peptides in 2025 are Semax, Selank, Dihexa, DSIP, and 5-Amino-1MQ. Each operates through a distinct neurological mechanism — from BDNF upregulation and GABAergic modulation to HGF/MET-driven synaptogenesis. All are available from Rainbow Peptide in research-grade formulations with ≥98% purity HPLC verification and Certificate of Analysis. For Research Use Only.
Browse AXON Line Peptides →