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Semax Peptide Structure And Origin — Background and Details

By Editorial Desk · published 2026-01-27 · last reviewed 2026-02-24 · Faq

A practical reference on ACTH(4-10): what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.

This page was last updated on 2026-02-24 and is reviewed periodically as new material appears.

Semax Peptide Structure and Origin

Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.

The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.

Semax Background and Molecular Structure

The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.

Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.

Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.

Semax at a glance

PropertyValueNotes
Chemical classSynthetic heptapeptideACTH(4-7) analogue
SequenceMet-Glu-His-Phe-Pro-Gly-ProFree N terminus, unmodified side chains
Molecular weight813.9 DaFree base; salt forms differ
AppearanceWhite to off-white powderLyophilised solid
SolubilityFreely soluble in waterHydrophilic; polar solvents preferred

Background and Development

Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.

Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.

Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.

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Chemical Identity and Research Background

Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.

Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.

Semax Peptide Background and Identity

Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.

Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.

Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.

研发背景与监管地位

Semax 是人工设计的七肽,序列为 Met-Glu-His-Phe-Pro-Gly-Pro,骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性,同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。

当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应,Semax 属于这一路线。鼻内给药是其主要使用方式,俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上,样本规模与终点设置同西方试验惯例存在差异,国际同行对其临床证据的强度看法不一。

Notes from published material

=== Honduras === The National Party of Honduras (party of president-elect Nasry Asfura) expressed its support for the action and advocated for an "orderly, peaceful and constitutional transition" in Venezuela.

=== Gastrointestinal === Its mechanism of action is oxygen radical scavenging, anti-oxidation, and acceleration of gastrointestinal wound healing. ZnC adheres to damaged gastric and intestinal mucosa and releases zinc and carnosine locally, helping repair and stabilize epithelial tissues. It exhibits ROS-quenching activities. It can remain in the stomach without rapid dissociation and adhere specifically to ulcerous lesions, after which L-carnosine and zinc are released to heal the ulcer. It has been shown to stimulate mucus production and to maintain the integrity of the gastric mucosal barrier. It maintains homeostasis of the gastric mucosa by prostaglandin-independent cytoprotective effects due to anti-oxidative membrane stabilizing actions, and it promotes the repair of damaged tissues by wound healing action. ZnC inhibits pro-inflammatory cytokines like TNF-α and IL-1β and reduces oxidative stress markers in tissues.[1] It exerts cytoprotection through regulating heat shock proteins and chemokines, and by stabilizing mast cells. It does so without affecting the secretion of gastric acid. It has a potential to stimulate Hsp70 expression, with overexpression of Hsp70 being found to prevent the development of inflammatory process in the large intestinal mucosa provoked by various damaging factors. It decreases p53, p21 and Bax expression and apoptosis in the intestine after irradiation. It possesses antioxidant, anti-inflammatory, and genomic stability enhancement effects, thereby having potential in preventing gastrointestinal cancer development.

Thus, the two substrates of this enzyme are sn-glycerol 3-phosphate and oxidised nicotinamide adenine dinucleotide phosphate (NADP+). Its products are D-glyceraldehyde 3-phosphate, reduced NADPH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is sn-glycerol-3-phosphate:NADP+ 1-oxidoreductase. Other names in common use include glycerol phosphate (nicotinamide adenine dinucleotide phosphate), dehydrogenase, L-glycerol 3-phosphate:NADP+ oxidoreductase, glycerin-3-phosphate dehydrogenase, NADPH-dependent glycerin-3-phosphate dehydrogenase, and glycerol-3-phosphate 1-dehydrogenase (NADP+).

The deSUMOylation may be arrested by the inhibitory phosphorylation of the Ulp2 SUMO protease by the Polo-like kinase Cdc5. By inhibiting the deSUMOylation of Ulp2, polySUMOylation is then promoted as the new stable state of target proteins, which are often but not always bound to other proteins in order to regulate major changes within the cell. Cdc5 is countered by the Rts1-PP2A phosphatase, which maintains the active state of the Ulp2 SUMO protease by removing the phosphate group added by Cdc5 kinase. The consequence of disrupting the counteracting deSUMOylation is the following: First, the targeted protein becomes polySUMOylated. Second, SUMO Targeted Ubiquitin Ligase, or STUbL, (SLX5 or SLX8 in the case of yeast) may then bind the polySUMOylated target and attach Ubiquitin groups (often polyUbiquitinating the already polySUMOylated protein). Third, segregases such as Cdc48 may then dissociate the SUMOylated and ubiquitinated target from its bound protein. Fourth, while the unbound protein it had been bound to is now free to do what it could not do while bound, the dissociated protein may then be degraded by the canonical Ubiquitin-Proteasome pathway. As studied with budding yeast, in the case of Tof2-Cdc14, Cdc14 release from the nucleolus allows the Mitotic Exit Network to commence, but it is regulated by the binding of Tof2, a protein subject to SUMOylation.

Sources: en.wikipedia.org

Background from the literature

=== Potential pharmaceuticals === Currently there is no widespread use of cysteine proteases as approved and effective anthelmintics but research into the subject is a promising field of study. Plant cysteine proteases isolated from these plants have been found to have high proteolytic activities that are known to digest nematode cuticles, with very low toxicity. Successful results have been reported against nematodes such as Heligmosomoides bakeri, Trichinella spiralis, Nippostrongylus brasiliensis, Trichuris muris, and Ancylostoma ceylanicum; the tapeworm Rodentolepis microstoma, and the porcine acanthocephalan parasite Macracanthorhynchus hirundinaceus. A useful property of cysteine proteases is the resistance to acid digestion, allowing possible oral administration. They provide an alternative mechanism of action to current anthelmintics and the development of resistance is thought to be unlikely because it would require a complete change of structure of the helminth cuticle. In several traditional medicines, the fruits or latex of the papaya, pineapple and fig are widely used for treatment of intestinal worm infections both in humans and livestock.

==== Protein kinase C inhibition ==== The exact mechanism by which endoxifen exerts its therapeutic effects has not been established in bipolar I disorder. However, the efficacy of endoxifen could be mediated through protein kinase C (PKC). The PKC represents a family of enzymes highly enriched in the brain, where it plays a major role in regulating both pre-and post-synaptic aspects of neurotransmission. Excessive activation of PKC results in symptoms related to bipolar disorder. The PKC signaling pathway is a target for the actions of two structurally dissimilar antimanic agents – lithium and valproate. Endoxifen exhibits 4-fold higher potency in inhibiting PKC activity compared to tamoxifen in preclinical studies and is not dependent on the isozyme cytochrome P450 2D6 (CYP2D6) for action on the target tissues.

Terminally ill patients in Oregon who have requested physician-assisted suicide have received lethal doses of barbiturates. The protocol has been highly effective in producing a so-called painless death, but the time required to cause death can be prolonged. Some patients have taken days to die, and a few patients have actually survived the process and have regained consciousness up to three days after taking the lethal dose. In a California legal proceeding addressing the issue of the lethal-injection cocktail being "cruel and unusual," state authorities said that the time to death following a single injection of a barbiturate could be as much as 45 minutes. Barbiturate overdoses typically cause death by depression of the respiratory center, but the effect is variable. Some patients may have complete cessation of respiratory drive, whereas others may only have depression of respiratory function. In addition, cardiac activity can last for a long time after cessation of respiration. Since death is pronounced after asystole, and given that the expectation is for a rapid death in lethal injection, multiple drugs are required, specifically potassium chloride to stop the heart. In fact, in the case of Clarence Ray Allen, a second dose of potassium chloride was needed to achieve this.

However, it must not be confused with the traditional Asturian cider as it is a sparkling cider more in the way of French ciders. It is a factory produced cider, sweet and very foamy, much like lambrusco, different from the more artisan and traditional cider productions. Recently, new apple tree plantations have been started in grounds belonging to the old coal mines, once important in Asturias.

GABA is primarily synthesized from glutamate via the enzyme glutamate decarboxylase (GAD) with pyridoxal phosphate (the active form of vitamin B6) as a cofactor. This process converts glutamate (the principal excitatory neurotransmitter) into GABA (the principal inhibitory neurotransmitter). GABA can also be synthesized from putrescine by diamine oxidase and aldehyde dehydrogenase. Historically it was thought that exogenous GABA did not penetrate the blood–brain barrier, but more current research describes the notion as being unclear pending further research.

Sources: en.wikipedia.org

Frequently asked questions

What is Semax chemically?

It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.

How does it relate to ACTH?

It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.

Does it occur naturally?

No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.

What is the amino acid sequence of Semax?

The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.

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