Semax complete guide

Semax is a synthetic heptapeptide with the sequence MEHFPGP, originally synthesized in the 1980s at the Institute of Molecular Genetics of the Russian Academy of Sciences (IMG RAS) — the same institute that produced its sister compound Selank. Semax corresponds to the ACTH(4–7) fragment of adrenocorticotropic hormone with a C-terminal Pro-Gly-Pro (PGP) extension added for proteolytic stability. The published corpus around Semax is dominated by cognitive-enhancement, BDNF and NGF expression, neuroprotection, and cerebral-ischemia research literature, making it the most-cited cognitive-research compound in the Russian neuropeptide research lineage.

This guide is a mechanism-focused deep-dive: where Semax came from, how the ACTH(4–7) fragment combined with a PGP stabilization tail produces a research neuropeptide, what the published BDNF / NGF and cerebral-ischemia research actually documents, and how it sits relative to Selank within the broader Russian neuropeptide research programme. Everything is research-frame language. No protocol guidance. No clinical recommendations.

Quick reference — Semax identifiers

Property	Semax
Class	Synthetic heptapeptide ACTH(4–7) analog
Peptide sequence	MEHFPGP (Met-Glu-His-Phe-Pro-Gly-Pro)
Molecular formula	C37H51N9O10S
Molecular weight	813.93 g/mol
CAS	80714-61-0
Origin	Synthetic analog of the ACTH(4–10) fragment, truncated to ACTH(4–7) and modified at the C-terminal with a Pro-Gly-Pro extension for proteolytic stability — the same modification rationale as Selank
Plasma half-life	Extended versus the parent ACTH fragment via PGP-stabilization (the unmodified ACTH(4–7) is rapidly cleaved by aminopeptidases)
Vial strengths (TogoPeptide)	5 mg lyophilized; also part of the Cognitive Stack

Origin and structure — ACTH-derived heptapeptide

The parent compound adrenocorticotropic hormone (ACTH) is a 39-amino-acid pituitary hormone whose primary endocrine role is stimulation of cortisol release from the adrenal cortex. Decades of peptide-chemistry research established that ACTH contains an internal short fragment, ACTH(4–10) (sequence MEHFRWG), that retains some of the parent hormone’s neurotropic activity — effects on attention, learning and adaptive behaviour in research models — without driving the steroid-axis effects of the full hormone. ACTH(4–10) became a starting point for Russian peptide-design work in the 1980s.

Semax was designed at the Institute of Molecular Genetics, Russian Academy of Sciences (IMG RAS), to address the pharmacokinetic limitations of the native ACTH fragment. The strategy was to truncate ACTH(4–10) further to ACTH(4–7) (Met-Glu-His-Phe, MEHF) and to extend the C-terminal with a Pro-Gly-Pro (PGP) tripeptide tag. The resulting heptapeptide MEHFPGP retains the ACTH(4–7) pharmacophore at the N-terminal but is markedly more resistant to enzymatic degradation. The PGP fragment itself is a known glioprotective tripeptide that contributes its own pharmacological footprint to the resulting molecule [4].

Semax emerged from the same Russian research lineage that produced its sister compound Selank — a heptapeptide derived from the immunopeptide tuftsin with an analogous PGP-extension stabilization strategy. Both compounds reflect the same design philosophy: take a short endogenous regulator with known neurotropic properties, append a PGP tag for enzymatic stability, characterise the resulting heptapeptide as a research neuropeptide. The two compounds differ in their parent peptide and in their downstream research line — Selank’s parent is an immunopeptide and its largest corpus is anxiolytic; Semax’s parent is a neuropeptide hormone and its largest corpus is cognitive and neuroprotective.

Mechanism — multi-system neurotropic peptide

Semax’s research footprint spans neurotrophic, melanocortin-receptor, monoaminergic, enkephalinergic, and anti-ischemic literature. The mechanism is not single-pathway; published research documents Semax acting on several converging systems simultaneously, with the BDNF / NGF neurotrophic axis being the dominant published mechanism.

BDNF and NGF expression

The dominant mechanism in the Semax research corpus is upregulation of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) expression in research-animal brain regions. Published research using rodent designs has documented Semax-induced increases in BDNF and NGF mRNA and protein in hippocampus, frontal cortex, basal forebrain and other neurotrophic-sensitive regions [6]. This neurotrophic-system upregulation is the molecular basis for the cognitive-enhancement and neuroprotection framing of the published Semax corpus — BDNF and NGF are master regulators of synaptic plasticity, hippocampal-dependent learning, and neuronal survival in cerebral-ischemia paradigms.

Melanocortin receptor activity

Semax retains some affinity for the melanocortin receptor family (MC3R, MC4R, MC5R) inherited from its ACTH parent peptide. The truncated ACTH(4–7) sequence has a different signaling profile from the full ACTH hormone — the steroid-axis activity at MC2R is absent — but published research documents melanocortin-system contributions to the Semax pharmacological footprint, including effects on attention, arousal and energy-balance research endpoints in research-animal designs.

Serotonergic and dopaminergic modulation

A secondary mechanism layer documented in the published Semax corpus is modulation of biogenic-amine metabolism — including serotonin (5-HT) turnover, dopamine pathways and norepinephrine signaling in research-animal brain tissue [2]. Published work documents Semax-induced changes in monoamine metabolism in attention and stress-paradigm research designs, providing a mechanism layer that complements the primary BDNF / NGF axis.

Enkephalinase inhibition

Like its sister compound Selank, Semax inhibits enkephalin-degrading enzymes (enkephalinases) in research models, prolonging the signaling lifetime of endogenous enkephalins. This mechanism contributes to the broader neuroprotective phenotype documented in the published Semax corpus and overlaps with the endogenous-opioid neuropeptide research line that connects both Russian heptapeptides to the opioid-system literature.

Anti-ischemic and neuroprotective effects

Distinct from Selank, Semax has a substantial published research line in cerebral-ischemia models. Rodent stroke designs — middle cerebral artery occlusion (MCAO) and global-ischemia paradigms — have documented Semax-induced reductions in infarct volume, preservation of post-ischemic cognitive endpoints, and biochemical markers consistent with reduced oxidative stress and neuroinflammation in research-animal models [5]. Russian clinical research has investigated Semax in stroke contexts under the Russian regulatory framework — that material is part of the published peer-reviewed corpus but is research literature distinct from the Western FDA / EMA pathway.

Cognitive-enhancement research literature

The largest published Semax research line is cognitive enhancement. Rodent-model research using the standard cognitive-research test battery — Morris water-maze, passive-avoidance, conditioned-response and operant-task paradigms — has documented Semax-induced changes in memory-consolidation, learning-acquisition and attention endpoints across multiple research groups [3]. Published research has also examined processing-speed and selective-attention research designs in research-animal models, with Semax-induced changes consistent with the BDNF / NGF mechanism layer.

Mechanistically, the cognitive-research line tracks Semax’s neurotrophic effects in hippocampus and cortex — published research documents the cognitive-paradigm changes alongside BDNF and NGF mRNA and protein increases in the same brain regions. This places Semax as the cognitive-research counterpart within the Russian-origin neuropeptide pair, where Selank’s research corpus is dominated by anxiolytic / GABAergic literature and Semax’s corpus is dominated by cognitive / neurotrophic literature.

Cerebral-ischemia and neuroprotection research

Semax has a distinct published research line in cerebral-ischemia and neuroprotection that has no parallel in the Selank corpus. Russian rodent-model research using middle-cerebral-artery occlusion (MCAO) and global-ischemia paradigms has documented Semax-induced reductions in infarct volume, attenuation of post-ischemic neurological deficit scores and improvements in post-ischemic cognitive-paradigm performance in research-animal designs.

Russian clinical research has investigated Semax in stroke and cerebrovascular-event contexts under the Russian regulatory framework, which differs from the Western drug-approval pathway. The compound has been studied in research populations with neurological-recovery endpoints [1]. This research is part of the published peer-reviewed corpus — but its regulatory framing is distinct from the FDA / EMA pathway and the published material referenced here is research literature, not therapeutic recommendation.

Semax vs Selank — sister neuropeptides comparison

Semax and Selank are the two most-cited compounds from the Russian Institute of Molecular Genetics neuropeptide research programme. They share the design philosophy (short endogenous regulator + PGP-extension for stability) but derive from different parent peptides and have meaningfully different research profiles. For the deeper Selank-side mechanism, see the Selank complete guide.

Aspect	Semax	Selank
Parent peptide	ACTH(4–7) (MEHF — adrenocorticotropic hormone fragment)	Tuftsin (TKPR — IgG Fc immunopeptide)
Sequence	MEHFPGP	TKPRPGP
Primary mechanism	BDNF / NGF upregulation + cognitive-research line	GABA-system modulation + multi-system anxiolytic
Best-characterised research line	Cognitive enhancement, neurotrophic, ischemic neuroprotection	Anxiolytic, GABAergic, immune-modulation
Origin institute	Institute of Molecular Genetics, Russian Academy of Sciences (IMG RAS) — both compounds from the same Russian neuropeptide research programme, both built on the same C-terminal PGP stabilization design technique.

Administration routes in research

Published Semax research has used both intranasal and parenteral administration routes. The intranasal route is the historical standard in the Russian research-protocol lineage and is the route most commonly referenced in the published Semax corpus — particularly in cognitive-enhancement and cerebral-ischemia research designs. The heptapeptide crosses the nasal mucosa and reaches central nervous-system tissue without first-pass metabolism. Parenteral routes have also been used in published research designs, particularly in mechanism-of-action studies where dose-precision is the priority over route-realism.

The choice of route in research design has implications for the published mechanism endpoints — intranasal-administration research documents central-nervous-system effects (BDNF / NGF expression, cognitive paradigms, post-ischemic recovery) while parenteral-administration research documents the broader systemic profile including biogenic-amine metabolism and melanocortin-system endpoints.

Storage and handling

Semax ships as lyophilized powder. Standard research-handling literature documents:

• Lyophilized state: sealed at −20°C, protected from light. Stable for the manufacturer-stated window (typically 24+ months).
• Diluent: bacteriostatic water (0.9% benzyl alcohol) is the standard reconstitution diluent for research-grade peptide handling.
• Reconstituted state: refrigerate at 2–8°C. Use within ~28 days under refrigeration.
• Avoid freeze-thaw cycles after reconstitution — repeated freezing and thawing degrades peptide integrity.
• Light protection: store the reconstituted vial in an opaque or amber container, away from prolonged light exposure.

Each TogoPeptide Semax shipment includes a per-batch Certificate of Analysis with HPLC purity (target ≥98%), mass-spectrometry identity confirmation, lot number, manufacture date, analysis date. See how to read a COA or reconstitution methodology for the methodology details.

Cross-research lines and pairings

• Cognitive Stack — Selank + Semax + DSIP: the curated three-compound research stack pairs Semax’s BDNF / NGF cognitive-research mechanism with Selank’s anxiolytic-research corpus and DSIP’s sleep-architecture research line. The most common combined-peptide design in the cognitive neuropeptide research literature.
• Selank + Semax pairing: the canonical Russian-neuropeptide combined-research design. The two sister compounds are commonly paired because the mechanisms are complementary — BDNF / NGF / cognitive plus GABA-system / anxiolytic — with both compounds sharing the same intranasal-administration research lineage and the same PGP-stabilization design philosophy.
• Vial strength: Semax ships at 5 mg per vial. Reconstitution math is documented in the reconstitution calculator.

Closing

Semax is a Russian-origin synthetic heptapeptide derived from the ACTH(4–7) fragment of adrenocorticotropic hormone, stabilized via a C-terminal PGP extension at the Institute of Molecular Genetics, Russian Academy of Sciences. The mechanism converges on BDNF and NGF expression, melanocortin-receptor activity, monoamine modulation, enkephalinase inhibition and anti-ischemic neuroprotection — producing a multi-system neurotropic peptide whose published cognitive-enhancement and cerebral-ischemia research corpus is the largest in the Russian neuropeptide research lineage.

This guide documents what published peer-reviewed research has investigated. It is mechanism context for laboratory researchers, not therapeutic recommendation, not protocol guidance, not a basis for self-administration of any kind.

Source Semax for laboratory research:

• Semax product page — full identifiers, 5 mg vial, per-batch COA
• Cognitive Stack — curated three-compound research stack (Selank + Semax + DSIP)
• Cognitive research compounds — full category listing

For methodology and laboratory-handling questions, contact our research-supply team at info@togopeptide.com.