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Semax ACTH Research: Russian Origins | Midwest Peptide

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Semax ACTH Origins: Russian Neuropeptide Research Program

Semax · Published April 9, 2026 · Updated May 18, 2026 · 9 min read

Quick Answer

Semax ACTH origins research covers natural ACTH(4-10) fragments, the Russian peptide research program, and the structural design that produced Semax. This article examines the historical development, fragment-active design, and ACTH-derived behavioral activity underlying Semax research applications. For research use only, not for human consumption.

Semax ACTH Origins: Russian Neuropeptide Research Program

Research Use Only. All products are strictly for research use only (RUO). Not for human consumption. Products on this site are not intended to diagnose, treat, cure, or prevent any disease. These statements have not been evaluated by the FDA. By purchasing, you agree that you are a qualified researcher and that products will be used solely for in-vitro research purposes.

What Is ACTH?
ACTH(4-10) and ACTH(4-7) in Research
ACTH Fragment Limitations as Research Tools
The Russian Peptide Research Program
Semax Structural Design
ACTH and the Melanocortin Family
Semax in the Synthetic Peptide Landscape
Open Research Questions
Conclusion
Related Research Articles
Explore Related Products
Frequently Asked Questions
Glossary

Semax ACTH research provides the historical and biochemical foundation for understanding Semax as a research tool. Semax is structurally derived from a fragment of adrenocorticotropic hormone (ACTH), specifically the ACTH(4-7) sequence, extended with a Pro-Gly-Pro tripeptide tail to create a synthetic heptapeptide research compound. As the historical and structural background component of the Semax research cluster, this article reviews the published literature on ACTH biology, the cognitive effects of ACTH fragments, the Russian peptide research program that produced Semax, and the structural relationship between ACTH and Semax.

Frequently Asked Questions

What is Semax in research contexts?

Semax is a synthetic heptapeptide derived from the ACTH(4-10) fragment with extended stability via a C-terminal Pro-Gly-Pro tail. It is studied in preclinical models for cognitive endpoints, BDNF and NGF expression, and neuroprotection in cerebral ischemia.

How was Semax developed from ACTH?

Semax was developed at the V.V. Zakusov Research Institute by extending the ACTH(4-10) fragment (Met-Glu-His-Phe-Pro-Gly-Pro variant) with a Pro-Gly-Pro tail. The C-terminal extension enhanced metabolic stability while preserving the parent fragment's neurotropic activity.

Why was ACTH(4-10) selected as the Semax template?

ACTH(4-10) had documented neurotrophic and behavioral effects without the corticosteroid-stimulating effects of full-length ACTH. Selecting this fragment allowed isolation of the neuropeptide effects of interest while avoiding the systemic endocrine activity of the parent hormone.

Is Semax approved for human use?

No. Semax is not approved by the FDA for any human therapeutic use. It is supplied strictly for in-vitro and preclinical research purposes by qualified investigators.

Glossary

Key terms used in this article.

ACTH(4-10): The 4-10 amino acid fragment of adrenocorticotropic hormone, the natural sequence from which Semax is derived.
BDNF: Brain-derived neurotrophic factor, a key neurotrophin supporting neuronal survival, synaptic plasticity, and learning.
NGF: Nerve growth factor, the prototypical neurotrophin essential for peripheral and central neuronal survival and growth.
Intranasal Delivery: Administration through the nasal mucosa, used for peptides like Semax to bypass first-pass metabolism and access the CNS.
Heptapeptide: A peptide consisting of seven amino acid residues; Semax has the sequence Met-Glu-His-Phe-Pro-Gly-Pro.
Pro-Gly-Pro Tail: A three-amino-acid C-terminal extension on Selank and Semax that confers stability against carboxypeptidase degradation.

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What Is ACTH?

Adrenocorticotropic hormone (ACTH) is a 39 amino acid peptide hormone produced by the anterior pituitary gland. It is the primary regulator of cortisol production by the adrenal cortex in research models, acting on the melanocortin 2 receptor (MC2R) in adrenal tissue to stimulate the production and release of glucocorticoid hormones. The ACTH-cortisol axis is a fundamental component of the hypothalamic-pituitary-adrenal (HPA) stress response system characterized in research literature.

ACTH is produced from a precursor protein called proopiomelanocortin (POMC), which also gives rise to several other biologically active peptides including alpha-melanocyte stimulating hormone (alpha-MSH), beta-endorphin, and other POMC-derived peptides. The processing of POMC produces a family of related peptides with different biological activities, all sharing common structural features and sometimes overlapping receptor binding profiles.

Beyond its endocrine effects on cortisol production, ACTH and its fragments have been characterized as having effects on the central nervous system that are distinct from the adrenal effects of intact ACTH. These central effects are mediated by fragments rather than by the full ACTH molecule, providing the basis for research on smaller ACTH-derived peptides as research tools for cognitive and behavioral studies.

ACTH(4-10) and ACTH(4-7) in Research

Research in the 1970s and 1980s identified ACTH(4-10) as a fragment of ACTH with cognitive and behavioral effects in animal research models. ACTH(4-10) is the seven amino acid sequence from positions 4 through 10 of the full ACTH molecule, with the sequence Met-Glu-His-Phe-Arg-Trp-Gly. This fragment was characterized as having effects on learning, memory, and various other behavioral endpoints in rodent research models, distinct from the adrenal cortisol-stimulating effects of intact ACTH.

Subsequent research narrowed the active region of ACTH(4-10) to the ACTH(4-7) tetrapeptide (Met-Glu-His-Phe), which retains many of the cognitive effects of the longer fragment in research models. This reduction to the minimum active sequence was an important finding for the development of synthetic peptide research tools, since it identified the smallest peptide unit that retained the desired biological activity.

The cognitive effects of ACTH(4-10) and ACTH(4-7) in research models include enhanced learning in various paradigms, improved memory retention, and effects on behavioral endpoints related to attention and information processing. These findings provided the experimental foundation for the development of stable synthetic analogs that could be used as research tools without the rapid degradation that limits the natural fragments.

ACTH Fragment Limitations as Research Tools

Despite their cognitive activity, natural ACTH fragments have significant limitations as research tools. The most important limitation is short half life in research models, due to rapid enzymatic cleavage by aminopeptidases and other proteases that degrade small peptides in plasma and tissue fluids. The N-terminal methionine residue of ACTH(4-7) and ACTH(4-10) makes these fragments vulnerable to aminopeptidase activity, which removes amino acids from the N-terminal end of peptides.

The rapid clearance of natural ACTH fragments limits their utility for research applications that require sustained effects or precise control over the timing of peptide exposure. Studies of these fragments in research models typically require either continuous infusion or very frequent administration, both of which add operational complexity and may produce variability in receptor activation across the experiment.

These limitations motivated the development of more stable ACTH(4-7) analogs that could be used as research tools without the rapid degradation. The Russian peptide research program addressed this challenge by developing Semax, which extends the ACTH(4-7) sequence with a Pro-Gly-Pro tripeptide stabilizing tail to provide protection against enzymatic degradation while preserving the active sequence.

The Russian Peptide Research Program

Semax was developed at the V.V. Zakusov Institute of Pharmacology in Moscow, Russia, as part of a broader Russian peptide research program. The institute has produced multiple synthetic neuropeptide research tools over several decades, including both Semax (the ACTH(4-7) derived heptapeptide discussed here) and Selank (the tuftsin derived heptapeptide studied in our Selank research cluster).

The Russian peptide research program developed somewhat in parallel with Western peptide research but with different research priorities and different specific compounds. Several synthetic peptides developed in this program have become reference compounds in international research literature. The program's design strategy of using Pro-Gly-Pro stabilizing tails was applied to multiple peptides, including both Semax and Selank, providing a consistent approach to creating stable research tools from natural peptide fragments.

The institute had significant expertise in both basic peptide chemistry and applied research on peptide effects in animal models, which enabled the systematic development and characterization of Semax and other synthetic peptides. The accumulated research output from this program represents one of the more substantial contributions to international synthetic neuropeptide research.

Semax Structural Design

Semax's structural design addresses the stability limitations of natural ACTH(4-7) while preserving its active sequence. The molecule consists of seven amino acids: the four amino acids of ACTH(4-7) (Met-Glu-His-Phe) followed by a Pro-Gly-Pro tripeptide tail. The added tripeptide tail provides protection against aminopeptidase cleavage and other enzymatic degradation pathways that affect natural ACTH fragments.

The Pro-Gly-Pro stabilizing tail is the same design feature used in Selank, the other major Russian neuropeptide developed at the same institute. This shared design strategy reflects the recognition that proline residues confer resistance to many proteolytic enzymes and that the Pro-Gly-Pro arrangement specifically provides robust stability for small peptide research tools. The result is a peptide with significantly extended half life relative to natural ACTH(4-7) while retaining the biological activity associated with the ACTH-derived sequence.

The seven amino acid length of Semax places it in the heptapeptide category, which is a common length for synthetic neuropeptide research tools developed in the Russian research program. The structural design represents one of the more successful applications of the Pro-Gly-Pro stabilization approach.

ACTH and the Melanocortin Family

ACTH is part of the broader melanocortin family of peptides, which also includes alpha-MSH, beta-MSH, and other POMC-derived peptides. The melanocortin family acts on a family of related receptors (MC1R through MC5R) that mediate diverse biological effects in research models. MC2R is the specific receptor for ACTH on adrenal cells, while the other melanocortin receptors bind alpha-MSH and other family members with various selectivity profiles.

Understanding the melanocortin family provides context for Semax research, since the ACTH(4-7) sequence in Semax is within the melanocortin family and shares some structural features with other family members. However, the cognitive effects of ACTH(4-7) and Semax in research models are mediated by mechanisms distinct from the classical melanocortin receptor signaling that characterizes the broader family. The specific molecular targets of ACTH(4-7)-mediated cognitive effects are still being characterized in research.

Semax in the Synthetic Peptide Landscape

Semax is part of a broader category of synthetic research peptides developed to overcome the stability limitations of natural peptide ligands. Other examples in this category include stabilized GHRH analogs (such as tesamorelin and CJC-1295), stabilized GLP-1 receptor agonists (such as long-acting GLP-1 SM), Selank (the tuftsin derived heptapeptide), and various other synthetic peptides designed with specific stability modifications for research use.

The general approach of stabilizing natural peptide sequences through amino acid substitutions, N-terminal modifications, or stabilizing tail sequences has produced many useful research tools. Semax represents a successful example of this approach applied to a small ACTH-derived fragment, providing a stable analog that retains the cognitive activity of the natural ACTH(4-7) sequence while being more practical for research applications.

For more on the broader pharmacological profile of Semax, see our companion articles on Semax BDNF and NGF research and Semax cognitive research.

Open Research Questions

Several open research questions remain in the ACTH origins and Semax history literature. These include how the specific molecular receptor for ACTH(4-7) and Semax cognitive effects is identified and characterized in modern research, how the stability advantages of Semax translate quantitatively to functional improvements over natural ACTH fragments in research models, and how the Pro-Gly-Pro stabilization strategy affects tissue distribution and cellular uptake of Semax. Each of these is a legitimate research opportunity for investigators studying ACTH-derived peptides.

Conclusion

Semax ACTH research provides the historical and biochemical foundation for understanding Semax as a research tool. The relationship between Semax and natural ACTH fragments, the development of Semax in the Russian peptide research program, and the structural design that confers improved stability all combine to position Semax as a useful research tool for studies of ACTH-related cognitive biology. For investigators using Semax 10mg as a research tool, the historical and structural literature provides essential context for understanding the molecule.

For more on the full Semax research cluster, see the pillar overview article and the supporting articles on each major topic.

Semax is supplied by Midwest Peptide for research use only and is not intended for human administration.

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Semax ACTH Origins: Russian Neuropeptide Research Program