Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide analogue of the N-terminal fragment (4-10) of adrenocorticotropic hormone (ACTH), developed at the Institute of Molecular Genetics, Russian Academy of Sciences . Unlike the parent ACTH hormone, Semax lacks hormonal activity (does not affect corticosteroid production) while retaining potent neurotropic and neuroprotective properties .

The peptide has been successfully used in research models of cerebral ischemia and has demonstrated profound effects on learning, memory formation, and neuronal survival in both rodent and human studies . Its molecular mechanism is associated with increased levels of brain-derived neurotrophic factor (BDNF), a potent modulator of synaptic plasticity and neuronal resilience .

Each vial contains lyophilized powder tested to ≥98% purity by HPLC, with sequence confirmed by mass spectrometry.

Best for: Neuroprotection research, ischemic stroke models, cognitive enhancement studies, BDNF pathway investigations, and neuroinflammatory research.

Key Research Applications

• Ischemic Stroke & Neuroprotection: Semax has demonstrated neuroprotective properties in cerebral ischemia-reperfusion models, suppressing inflammation-related gene expression and activating neurotransmission-related genes . It has been used successfully in research models of severe impairment of cerebral blood circulation .

• Cognitive Enhancement (Nootropic): The peptide exerts profound effects on learning and memory formation in rodents and humans, associated with rapid BDNF protein level increases in brain regions critical for cognition .

• BDNF Pathway Research: Semax applied intranasally (50-250 μg/kg) results in rapid BDNF level increases in the basal forebrain within 3 hours, pointing to specific binding sites in this brain region (KD = 2.4 ± 1.0 nM) .

• Anxiety & Psychomodulation: Research demonstrates anxiolytic and psychomodulatory effects, correcting behavioral disorders and anxiety-depressive states in laboratory models .

• Transcriptome Research: RNA-Seq analysis has revealed that Semax suppresses genes related to inflammatory processes and activates genes related to neurotransmission following cerebral ischemia .

Mechanism of Action

Semax exerts its biological effects through several well-characterized pathways:

BDNF Upregulation (Primary Mechanism): Semax binds specifically to cell membranes in the basal forebrain (KD = 2.4 ± 1.0 nM) in a calcium-dependent, reversible manner. Intranasal application leads to rapid BDNF protein level increases in this region, which is associated with the peptide’s cognitive effects .

Neuroinflammation Suppression: Following cerebral ischemia, Semax suppresses the expression of inflammation-related genes and activates neurotransmission-related genes, compensating for mRNA expression patterns disrupted during ischemia-reperfusion .

Synacton Mechanism: Semax functions through a “synacton” — a complex of bioregulators including its metabolic products (HFPGP and PGP) that act in sequence and interaction, extending the regulatory potential of the parent molecule .

Gene Expression Modulation: RNA-Seq studies have identified differentially expressed genes (DEGs) associated with Semax action under cerebral ischemia conditions. Semax significantly reduces expression distortions caused by ischemia for genes associated with immune and neurosignaling pathways .

Route-Dependent Effects: Research in BALB/c mice demonstrates that Semax exhibits route-specific effects — intraperitoneal administration maximizes anxiolytic efficiency, while intranasal administration favors nootropic outcomes .

Semax vs. Selank: Key Differences

While both are synthetic peptides developed by the Russian Academy of Sciences, Semax and Selank have distinct mechanisms and applications:

Source: Comparative studies demonstrate distinct functional connectivity profiles between Semax and Selank in human fMRI research 

Specifications

Key Research Findings

Reconstitution Guidance

Reconstitute Semax with sterile water or bacteriostatic water (0.9% benzyl alcohol) for research use. For intranasal administration studies, sterile water is commonly used. Direct diluent gently down the inner wall of the vial rather than onto the lyophilized cake. Swirl slowly until fully dissolved — do not shake.

Research Dosing (for reference):

• Rat studies: 50-250 μg/kg (intranasal) for BDNF studies 

• Rat studies: 100 μg/kg (intraperitoneal) for gene expression studies 

• Mouse studies: 0.6 mg/kg/day for behavioral studies 

For best results, aliquot the reconstituted solution into single-use tubes immediately to avoid repeated freeze-thaw cycles.

Storage & Stability

Before Reconstitution: Store the unopened, lyophilized vial at −20°C in a desiccated, light-protected environment. Stable under these conditions for up to 3 years .

After Reconstitution: Store working solutions at 2–8°C for short-term use (up to 7-14 days). For long-term storage, prepare single-use aliquots and store at −80°C for up to 1 year . Avoid repeated freeze-thaw cycles.

Quality Assurance

Every lot of Semax undergoes comprehensive release testing against internal specifications, including:

• HPLC for purity confirmation (≥98%)

• Mass spectrometry for identity verification

• Visual inspection of vial integrity

Each vial is coded with a lot number that links directly to release testing documentation. A lot-specific Certificate of Analysis (COA) is available upon request.

Important Research Notes

ACTH Derivative Without Hormonal Activity: Unlike the parent ACTH hormone, Semax is specifically engineered as a non-hormonal analogue. It retains the neurotropic and neuroprotective properties of ACTH fragments while lacking corticosteroid-stimulating activity .

BDNF as a Key Mediator: The cognitive-enhancing effects of Semax are associated with rapid BDNF upregulation in the basal forebrain — a region critical for learning, memory, and attention. This represents a distinct mechanism from traditional nootropics .

Specific Binding Sites Identified: Research has identified specific, saturable, reversible binding sites for Semax in rat basal forebrain cell membranes, with a KD of approximately 2.4 nM, indicating high-affinity interactions with neuronal targets .

Synacton Model: Semax functions through a “synacton” — a complex of bioregulators including its metabolic products (HFPGP and PGP) that act in sequence. This mechanism considerably extends the regulatory potential of the initial molecule .

Transcriptome-Level Protection: RNA-Seq analysis demonstrates that Semax significantly reduces expression distortions caused by ischemia for genes associated with immune and neurosignaling pathways, providing molecular evidence for its neuroprotective effects .

Related Products from Pyrex Labs

Researchers who order Semax frequently also purchase:

• Selank – Complementary anxiolytic peptide for comparative studies

• Noopept – Synthetic nootropic for cognitive research

• NAD+ – For cellular energy and metabolic research

• MOTS-c – Mitochondrial-derived peptide for metabolic research

• P21 – CDK5 inhibitor peptide for cognitive research

Frequently Asked Questions

What is Semax? Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) analogue of ACTH(4-10). Unlike the parent hormone, it lacks hormonal activity but retains potent neuroprotective and nootropic (cognitive-enhancing) properties .

How does Semax work? Semax binds specifically to sites in the basal forebrain (KD = 2.4 nM), rapidly increasing BDNF protein levels within 3 hours. It also suppresses inflammation-related genes and activates neurotransmission-related genes following cerebral ischemia .

What is the difference between Semax and Selank? Semax is primarily a nootropic (cognitive-enhancing) and neuroprotective agent that works through BDNF upregulation. Selank is primarily an anxiolytic (anxiety-reducing) that works through GABA(A) modulation and enkephalinase inhibition. They have distinct functional connectivity profiles in fMRI studies .

What research has been conducted with Semax? Semax has been studied in models of ischemic stroke, cognitive enhancement, anxiety, and neuroinflammation. RNA-Seq studies have identified Semax-associated genes involved in immune response and neurotransmission pathways .

What is the optimal route of administration in research models? Research demonstrates route-dependent effects: intraperitoneal administration maximizes anxiolytic efficiency, while intranasal administration favors nootropic (cognitive) outcomes. Intranasal administration is also effective for BDNF upregulation .

Is Semax approved for human use? No. This product is for research purposes only and is not FDA-approved for human consumption, medical treatment, or veterinary applications.

Do you provide a Certificate of Analysis? Yes. A lot-specific COA is available upon request for every vial shipped.

Disclaimer

⚠️ FOR RESEARCH PURPOSES ONLY. NOT FOR HUMAN USE.

Not approved by the FDA. Not intended for diagnostic, therapeutic, or medical applications in humans or animals. For in-vitro laboratory research exclusively. Pyrex Labs products are intended solely for scientific investigation and research purposes by qualified professionals.