Semax

Semax Research Peptide: Comprehensive Laboratory Guide

For professional laboratory research only. Not for human or veterinary use. Not for food, supplement, cosmetic, household, diagnostic, or therapeutic use.

Overview

Semax research peptide is a synthetic linear heptapeptide with the amino-acid sequence Met-Glu-His-Phe-Pro-Gly-Pro, abbreviated MEHFPGP. Its N-terminal Met-Glu-His-Phe segment corresponds to residues 4-7 of adrenocorticotropic hormone (ACTH), and its C-terminal Pro-Gly-Pro sequence is a glyproline segment. PubChem records the free peptide as CID 9811102, with the neutral molecular formula C₃₇H₅₁N₉O₁₀S and an average molecular mass of 813.9 g/mol.^[1]

Older publications often call Semax an “ACTH(4-10) analogue,” while the literal Semax sequence contains ACTH residues 4-7 followed by a replacement Pro-Gly-Pro segment. The historical name describes the design lineage, not seven unchanged ACTH residues. This distinction matters in sequence confirmation, database searching, and mechanistic interpretation. Semax is not full-length ACTH, and the cited research does not establish that the catalog peptide reproduces ACTH endocrine activity or acts through a single confirmed melanocortin receptor.

Published work spans peptide chemistry, proteolysis, neurotrophin expression, monoamine measurements, transcriptomics, protein-expression profiling, artificial-membrane systems, animal behavioral models, and older human studies. Most mechanistic evidence comes from rodents or in vitro systems. The literature supports well-defined laboratory questions but does not establish a universal molecular target, a predictable human effect, or suitability for self-use. Experimental outcome depends on the chemical form, lot attributes, matrix, intact-peptide exposure, tissue or cell model, time point, analytical method, and controls.

Molecular identity and physicochemical profile

The free peptide and acetate must not share one unqualified formula, mass, or CAS row. PubChem records the acetate as a separate multicomponent substance containing the MEHFPGP parent and acetic acid.^[2] FDA’s 2026 chemistry review also noted inconsistent identity information in historical nomination packages, including CoAs labeled as acetate while listing free-peptide identifiers.^[12] This is a practical warning for research procurement: sequence, salt form, water, counterion, net peptide content, and analytical reference basis must agree within the lot documentation.

Semax includes a methionine thioether, a histidine imidazole, an acidic glutamate side chain, an aromatic phenylalanine, and two proline residues. Those features influence ionization, retention, surface adsorption, fragmentation, oxidation susceptibility, and metal interactions. Methionine oxidation is a plausible stability-indicating target, not a fixed degradation rate. Histidine can complicate metal-containing matrices. Multiple acidic and basic sites make observed charge states and retention sensitive to pH and mobile-phase composition. Method suitability must therefore be established under the laboratory’s actual conditions.

Evidence map and mechanistic research themes

1. Neurotrophin and TrkB-associated signaling

The best-known Semax mechanism hypothesis concerns brain-derived neurotrophic factor (BDNF) and its receptor TrkB. A rat hippocampus study reported time-dependent changes in Bdnf and TrkB transcripts, BDNF protein, and TrkB phosphorylation after Semax exposure.^[3] A second study measured NGF and BDNF transcripts across hippocampus, frontal cortex, and retina and found that direction and timing differed by tissue and sampling interval.^[4] Together, these results support research into neurotrophin regulation, but not the simplified statement that Semax uniformly “boosts BDNF.”

Transcript abundance, total protein, processed neurotrophin forms, and receptor phosphorylation are different endpoints. A rigorous replication should prespecify brain region or cell model, distinguish proBDNF from mature BDNF when feasible, validate antibodies, measure TrkB activation with appropriate phosphatase controls, and include multiple time points. Causality requires more than correlation: a selective perturbation of BDNF-TrkB signaling should alter the downstream phenotype if that pathway is necessary. Behavioral readouts also need blinded scoring and controls for locomotion, sensory function, stress, and motivation.

2. Neurotrophin transcription in focal-ischemia models

Semax and the Pro-Gly-Pro fragment have been compared in rat permanent middle-cerebral-artery-occlusion models. One study reported changes in Bdnf, Ngf, Nt-3, and Trk-family transcripts that varied across early and later sampling points, with overlapping but nonidentical patterns for Semax and PGP.^[5] This provides a useful framework for fragment-aware experiments: the C-terminal tripeptide may contribute to some transcriptional observations, while the intact heptapeptide may produce additional effects.

These are injury-model transcription data, not evidence that the peptide treats stroke or restores human tissue. Occlusion severity, infarct location, anesthesia, surgical variability, sham procedures, tissue dissection, and the interval after injury can dominate expression profiles. Appropriate controls include sham plus vehicle, injury plus vehicle, intact Semax, PGP, and where justified a sequence control. Histology, perfusion, neurological scoring, and molecular endpoints should be analyzed without allowing one correlated result to stand in for another.

3. Immune and vascular transcriptome responses

Genome-wide analysis of rat cortex after focal ischemia reported that Semax-associated differentially expressed genes were enriched for immune and vascular processes, including chemokine, immunoglobulin, endothelial, and cell-migration categories.^[6] A later transcriptome comparison of Semax and PGP again identified immune-response, cytokine, stress-response, ribosomal, and neurotransmission-related patterns.^[7] These datasets show broad system-level responses in a defined injury model; they do not establish direct interaction with any one immune receptor or a general anti-inflammatory effect.

Bulk tissue contains neurons, glia, endothelial cells, infiltrating immune cells, and blood-derived material. A change in bulk RNA may reflect cell-composition shifts rather than regulation within a fixed population. Stronger studies combine cell-type measurements with RNA sequencing, correct for multiple testing, publish analysis code, and confirm selected targets by an orthogonal method. Endotoxin testing of the test article is important because trace contamination can produce immune-transcript signatures that mimic a peptide effect.

4. Protein-level stress, inflammatory, and recovery markers

A rat ischemia-reperfusion study examined MMP-9, c-Fos, JNK, phosphorylated JNK, CREB, and phosphorylated CREB after Semax exposure. The authors reported region-specific differences consistent with altered inflammatory, cell-death, and recovery-associated signaling under their model conditions.^[8] Protein-level measurements complement transcriptomics, but they remain a targeted panel selected from many possible pathways.

Phosphorylation must be normalized to total protein and validated within the linear range. Tissue regions should be sampled consistently, and ischemic damage should be quantified independently. MMP-9 abundance is not equivalent to gelatinase activity; JNK or CREB phosphorylation is not sufficient to infer cell fate or functional recovery. Gelatin zymography, pathway-specific perturbations, immunohistochemistry, and prespecified tissue viability measures can help distinguish mechanism from association. Results should be described as model-specific signaling changes, not therapeutic proof.

5. Monoamine-system interactions

Rodent microdialysis and tissue studies have investigated dopamine, serotonin, and their metabolites. Semax alone did not uniformly raise dopamine in one striatal experiment, while serotonin-metabolite measures changed and the peptide amplified an amphetamine-associated dopamine and locomotor response.^[9] This pattern argues against marketing Semax as a simple dopamine enhancer. It instead supports carefully controlled research on context-dependent interactions among peptide exposure, monoamine turnover, and pharmacological challenge.

Extracellular transmitter concentration reflects release, reuptake, metabolism, probe recovery, and tissue damage. A sound design measures parent transmitters and major metabolites, calibrates microdialysis recovery, controls circadian and handling effects, and separates basal from challenge conditions. Drug-interaction arms need the challenge agent alone, peptide alone, and combination groups. FDA’s nonclinical review noted the amphetamine interaction as a safety and abuse-potential concern rather than evidence of a desirable performance effect.^[12]

6. Proteolysis, fragments, and glyproline biology

Short regulatory peptides can generate fragments that persist differently from the parent. Tritium-labeling work identified HFPGP and PGP among major Semax biodegradation products in a nerve-cell preparation, while the same analytical program studied glyproline-peptide degradation in plasma and tissues.^[10] Parent disappearance therefore cannot be inferred from nominal incubation time, and a late biological endpoint may reflect the intact heptapeptide, fragments, altered peptidase activity, or several of these simultaneously.

Fragment-aware experiments should use a stability-indicating LC-MS method, multiple collection times, and recovery studies in both buffer and biological matrix. Where feasible, intact Semax, HFPGP, and PGP should be tested as separate identity-confirmed arms. Isotope-label placement matters because a labeled fragment can remain detectable after the parent is gone. These data do not establish a human half-life, bioavailability, or blood-brain-barrier penetration, and they should not be used to invent a dosing schedule.

7. Metal, amyloid, and artificial-membrane systems

An in vitro study evaluated Semax in copper-containing amyloid-beta aggregation and artificial-membrane models using spectrofluorometry, calorimetry, and a cell-viability assay. The authors reported changes in copper-associated aggregation behavior under their test conditions.^[11] The histidine and methionine residues make metal-dependent chemistry an analytically plausible research topic, but this model does not establish activity in a living brain or support a claim about preventing or treating neurodegenerative disease.

Aggregation assays are sensitive to peptide batch, metal stoichiometry, buffer, surfaces, agitation, fluorescent-dye interference, and amyloid preparation. Orthogonal readouts such as light scattering, electron microscopy, size-exclusion chromatography, mass spectrometry, and metal-speciation analysis are needed. Include Semax-only, amyloid-only, copper-only, vehicle, and interference controls. A viability readout downstream of an aggregation mixture should be interpreted only after excluding direct assay interference and differences in delivered aggregate burden.

Appropriate nonclinical research applications

Within a qualified laboratory and after a task-specific risk assessment, the Semax research peptide may support the following analytical and nonclinical programs:

• Identity and method development: establish LC-UV, LC-MS, high-resolution MS, tandem-MS, amino-acid analysis, and chromatographic methods for MEHFPGP and expected related substances.
• Neurotrophin-pathway studies: examine time- and region-dependent BDNF, NGF, TrkB, and downstream signaling with transcript, protein, processing, and functional endpoints kept distinct.
• Fragment-aware peptide research: quantify intact parent, HFPGP, PGP, and other degradants across the actual matrix and experimental interval.
• Transcriptomic experiments: investigate cell- or tissue-specific immune, vascular, stress, and neurotransmission signatures with multiple-testing control and orthogonal validation.
• Protein-signaling panels: study selected kinase, transcription-factor, protease, or cell-stress markers without treating a targeted panel as complete pathway proof.
• Neurochemical model comparisons: measure dopamine, serotonin, metabolites, and pharmacological interactions with separate basal and challenge conditions.
• Artificial-membrane and aggregation assays: test metal-dependent binding or aggregation hypotheses with robust physical controls and orthogonal measurement.
• Stability and compatibility programs: evaluate methionine oxidation, hydrolysis, adsorption, freeze-thaw sensitivity, container compatibility, and matrix recovery using stability-indicating analytics.

These are research themes, not validated protocols, indications, or performance claims. Related catalog materials can support orthogonal comparisons: Selank research peptide is a different tuftsin-derived heptapeptide; DSIP research peptide, Pinealon neuropeptide research, the Cerebrolysin peptide mixture, VIP peptide signaling, and Epithalon tetrapeptide research have distinct compositions and evidence bases. Catalog proximity does not establish a shared receptor or interchangeability.

Experimental design and assay controls

1. Confirm chemical identity. Record the sequence, free-peptide or salt designation, lot, CoA version, net-content basis, storage history, and opening date. Do not combine free-base and acetate identifiers.
2. Measure parent exposure. Establish intact MEHFPGP recovery and fragment formation over the actual experiment. Nominal concentration does not prove persistence in the matrix.
3. Use a concentration-time matrix. Select in vitro ranges from solubility, analytical recovery, assay interference, and viability data generated in the relevant system.
4. Include matched controls. Use untreated, vehicle, process-blank, and where informative PGP, HFPGP, scrambled-sequence, or related-peptide arms. A related peptide is not automatically a negative control.
5. Build orthogonal pathway evidence. Pair mRNA with protein and activity; pair BDNF abundance with processing and TrkB signaling; pair phosphorylation with total protein and functional perturbation.
6. Control model variability. For tissue work, prespecify region, injury severity, sampling interval, randomization, blinding, exclusions, and normalization. For culture, report cell source, passage, medium, and density.
7. Test analytical artifacts. Evaluate plate and tube adsorption, carryover, matrix suppression, oxidation during handling, peptide aggregation, fluorescent-probe interference, and recovery after filtration.
8. Predefine statistics. State primary outcomes, biological versus technical replicates, multiplicity correction, sample-size rationale, and data-exclusion rules before collection.
9. Report evidence boundaries. A rodent transcript, protein, or behavioral association does not establish a human molecular target, safety profile, or clinical effect.

Broader metabolic or stress-response comparisons may include Humanin mitochondrial-derived peptide, the SS-31 mitochondrial peptide, MOTS-c metabolic signaling research, NAD+ metabolism research, or the chemically distinct AICAR metabolism probe. These links aid navigation only. They do not imply co-use, compatibility, synergy, or a recommended combination. Multi-compound studies require single-material arms, a prespecified interaction model, and analytical confirmation that components remain stable together.

Analytical identity and quality control

Quality assessment for the Semax research peptide should answer separate questions: Is the MEHFPGP sequence present? Are major related substances resolved? What amount of the declared peptide is present? What chemical form was measured? Does the material remain suitable throughout the analytical workflow? A single HPLC area percentage cannot answer all of them. A fit-for-purpose lot package may include:

• Identity by mass spectrometry: high-resolution or otherwise qualified MS matched to the declared free peptide or salt, with theoretical and observed ions, charge states, adducts, tolerance, and traceable raw data.
• Sequence confirmation: tandem-MS fragments, amino-acid analysis, or another orthogonal method adequate to distinguish MEHFPGP from truncations, sequence variants, and terminally modified analogues.
• Chromatographic purity: a stability-indicating HPLC or UPLC method with stated column, mobile phases, gradient, detection mode, integration rules, reporting threshold, and system suitability.
• Peptide content: quantitative amino-acid analysis, calibrated reference-standard HPLC, qNMR, or a justified mass-balance approach. Report assay separately from area purity and gross fill mass.
• Water and counterions: water measurement where relevant and direct or mass-balance assessment of acetate or another declared counterion. These components affect molar calculations.
• Oxidation and related substances: resolution and identification of methionine-oxidized material, truncations, deletion sequences, epimers, synthesis reagents, and process-specific impurities as appropriate.
• Model-specific compatibility: endotoxin, bioburden, or cell-culture compatibility testing only when required by the intended assay. Such results do not establish sterility or suitability for administration.

Positive-ion mass spectra may contain several charge states and adducts because the sequence has multiple ionizable sites. A nominal intact-mass match cannot by itself establish residue order, stereochemistry, terminal state, or purity. Conversely, a clean UV chromatogram cannot establish chemical identity. Tandem MS, chromatographic separation, and an orthogonal content method provide a stronger assignment. Any reference standard should have its own traceability, water, counterion, and assay documentation.

Stability-indicating method development should challenge the sample only as needed to demonstrate specificity and should monitor the parent plus meaningful degradants. Methionine oxidation, peptide-bond hydrolysis, adsorption, and aggregation are plausible targets, but their rates must be measured for the actual matrix. Include preparation replicates, blanks, carryover checks, spike recovery, dilution linearity, and system-suitability samples. Lot release values must come from the matching CoA rather than generic website language.

Handling, stability, and documentation

Handle the Semax research peptide with trained personnel, suitable personal protective equipment, engineering controls, and an institution-approved chemical hygiene plan. Review the current safety data sheet and lot documents before opening the material. Avoid inhalation of dry material, unintended skin or eye contact, environmental release, and contamination of shared work areas. Segregate research material from food, medicines, personal products, and clinical supplies.

No universal storage or solution-stability claim should be inferred from the peptide name. Follow conditions stated for the specific lot. Laboratories can establish internal stability by testing the actual container, temperature, light, humidity, matrix, pH, concentration, and handling schedule. Monitor intact MEHFPGP, oxidized species, fragments, and visible or subvisible particles with appropriate methods. Freeze-thaw behavior, low-concentration adsorption, and compatibility with glass, polymer, filters, and plates require empirical verification.

Solution preparation for analytical or in vitro work should follow an approved laboratory SOP. Record solvent identity and grade, pH, ionic strength, concentration basis, mixing history, hold time, and container. This page intentionally provides no human or animal dosing, administration, or reconstitution procedure. Gross mass, peptide assay, counterion-corrected content, and molar amount should remain separate in calculations.

For reproducibility, retain the lot CoA, raw chromatograms, mass spectra, receipt record, chain of custody, storage history, preparation worksheet, instrument sequence, and deviations. Report the exact lot in publications and internal records. The site’s research-use terms explain the general intended-use boundary, but only the matching lot certificate can support a batch-specific identity, purity, content, or release claim.

Evidence and regulatory boundary

The Semax literature is dominated by rodent studies and publications from a relatively narrow research network. Older human reports indexed in PubMed include small Russian-language controlled or comparative studies in neurological settings, but they do not constitute a modern, large, independently replicated, multicenter, placebo-controlled efficacy and safety program.^[13] Their design, reporting detail, geographic concentration, and limited accessible safety data prevent generalization to this catalog material.

FDA’s 2026 scientific evaluation of Semax free base and Semax acetate identified chemistry inconsistencies, limited human pharmacokinetic information, insufficiently characterized safety data, potential immunogenicity concerns from aggregation and peptide-related impurities, and insufficient evidence of effectiveness for the nominated uses. The review also highlighted possible bleeding concerns from antithrombotic findings and the rodent amphetamine interaction as issues requiring caution.^[12] A July 2026 advisory committee considered Semax-related bulk substances, but advisory discussion is not approval. The current federal 503A bulks list does not include Semax; the regulation also states that inclusion of a substance would not by itself establish safety, effectiveness, or FDA endorsement.^[14]

A PubChem CID, CAS number, or FDA UNII identifies a substance; it is not evidence that a particular lot is approved, sterile, clinically effective, or suitable for administration. A branded Semax medicinal product has a registration history in some jurisdictions, but product-specific status does not transfer to Hanpro’s research material or to other countries. This catalog product is not an FDA-approved drug product and is not represented as a food, supplement, cosmetic, or veterinary product.

Human or animal use, self-experimentation, diagnosis, treatment, prevention, cognitive enhancement, athletic or occupational performance enhancement, and personal dosing are outside the intended use. Published stroke, stress, cognition, neurodegeneration, pain, or other model findings describe research contexts only. Nothing on this page is medical advice or a clinical protocol.

Related research materials and internal navigation

Semax and Selank are sometimes grouped together because both are synthetic heptapeptides with a C-terminal Pro-Gly-Pro segment. Their N-terminal sequences differ: Semax begins with the ACTH(4-7)-derived MEHF segment, while Selank begins with the tuftsin sequence TKPR. Shared length or a PGP tail does not establish shared targets, potency, stability, or functional equivalence.

Other linked products span distinct peptide and nonpeptide research categories. Each requires its own identity map, controls, analytical method, and evidence appraisal. Internal links are provided for catalog navigation and do not constitute a bundle, protocol, recommendation, or claim of synergy.

Frequently asked questions

What is the Semax research peptide?

Semax is a synthetic linear heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP). PubChem records the free peptide as C₃₇H₅₁N₉O₁₀S, average molecular mass 813.9 g/mol, CAS 80714-61-0, and CID 9811102.^[1] Salt, water, solvent, and net peptide content must be confirmed from lot-specific documentation.

Is Semax the same as ACTH(4-10)?

No. The first four Semax residues correspond to ACTH(4-7), and the remaining three are Pro-Gly-Pro rather than the native ACTH residues that follow. “ACTH(4-10) analogue” is a historical design label used in many papers. It should not be read as sequence identity, full ACTH activity, or proof of action at a specific melanocortin receptor.

Does Semax directly activate BDNF or TrkB?

The cited rat studies reported time- and region-dependent changes in BDNF-related transcripts, BDNF protein, and TrkB phosphorylation.^[3][4] They do not establish direct binding to BDNF or TrkB, a uniform increase across models, or a human effect. Direct mechanism requires receptor-level and pathway-perturbation evidence.

Why should PGP and other fragments be measured?

Biodegradation work identified HFPGP and PGP among major products under studied conditions.^[10] A late endpoint may therefore reflect intact Semax, fragments, or both. A stability-indicating LC-MS time course helps determine actual exposure and prevents a fragment response from being assigned automatically to MEHFPGP.

Are Semax free peptide and Semax acetate interchangeable?

No. They share the MEHFPGP active moiety but have different complete composition, formula, mass, and identifiers. FDA has documented inconsistencies in submitted Semax CoA information, which makes lot-level identity especially important.^[12] Use the chemical form and content basis stated and analytically supported for the actual lot.

What purity, content, or shelf life does this page guarantee?

No generic value is asserted. Chromatographic area purity, peptide assay, water, counterion, gross fill mass, net content, physical form, release date, shelf life, and availability are lot- or variant-specific. Consult the live selection and matching CoA. HPLC area alone is not equivalent to identity, net content, sterility, or assay suitability.

Is this material intended to diagnose, treat, or prevent a condition?

No. It is supplied solely for controlled laboratory research and analytical use. It is not for human or veterinary use, self-experimentation, food, supplements, cosmetics, diagnosis, treatment, prevention, or performance enhancement. Published model findings and database identifiers do not change that boundary.

References

1. PubChem. ACTH(4-7), Pro-Gly-Pro- (Semax), CID 9811102. Free-peptide sequence, formula, mass, and identifiers.
2. PubChem. Semax acetate, CID 155977617. Distinct acetate composition, formula, mass, and identifiers.
3. Dolotov OV, et al. Semax regulates BDNF and TrkB expression in the rat hippocampus. Brain Res. 2006;1117(1):54-60. PMID: 16996037.
4. Shadrina M, et al. Temporal dynamics of NGF and BDNF gene expression in rat hippocampus, frontal cortex, and retina under Semax action. J Mol Neurosci. 2010;41(1):30-35. PMID: 19662538.
5. Dmitrieva VG, et al. Semax and Pro-Gly-Pro activate neurotrophin and receptor-gene transcription after cerebral ischemia. Cell Mol Neurobiol. 2010;30(1):71-79. PMID: 19633950.
6. Medvedeva EV, et al. Semax affects immune- and vascular-system gene expression in rat focal ischemia: genome-wide analysis. BMC Genomics. 2014;15:228. PMID: 24661604.
7. Medvedeva EV, et al. Semax regulates immune-response genes during ischemic brain injury in rats. Mol Genet Genomics. 2017;292(3):635-653. PMID: 28255762.
8. Dmitrieva VG, et al. Brain protein-expression profile in a rat cerebral ischemia-reperfusion model after ACTH(4-7)PGP (Semax). Int J Mol Sci. 2021;22. PMID: 34201112.
9. Eremin KO, et al. Semax modulates dopaminergic and serotonergic brain systems in rodents. Neurochem Res. 2005;30(12):1493-1500. PMID: 16362768.
10. Zolotarev YA, et al. Evenly tritium-labeled peptides and their in vivo and in vitro biodegradation. Bioorg Khim. 2006;32(2):183-191. PMID: 16637290.
11. Migliorini C, et al. Semax affects copper-induced amyloid-beta aggregation and amyloid formation in artificial-membrane models. Int J Mol Sci. 2022;23. PMID: 35080861.
12. U.S. Food and Drug Administration. Semax-related bulk drug substances: PCAC scientific evaluation. Chemistry, pharmacology, safety, and evidence review, 2026.
13. Gusev EI, et al. Semax in the acute period of hemispheric ischemic stroke: a clinical and electrophysiological study. Zh Nevrol Psikhiatr Im S S Korsakova. 1997;97(6):26-34. PMID: 11517472.
14. Electronic Code of Federal Regulations. 21 CFR § 216.23: Bulk drug substances that can be used to compound drug products under section 503A. Current federal list and regulatory limits on the meaning of inclusion.

Research-use-only notice: This page summarizes chemical identity, analytical considerations, and published research to support qualified laboratory planning. It does not provide medical advice or instructions for administration. The product is not intended for human or animal consumption, clinical use, diagnosis, treatment, prevention, cognitive enhancement, or performance enhancement.