Semax Peptide: What It Is, How It Works and What the Research Shows

Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, an analog of the ACTH(4-10) fragment developed in Russia. Its first four residues come from ACTH(4-7), and a Pro-Gly-Pro tail adds metabolic stability. Rodent research studies its effects on BDNF signaling in the brain. For laboratory research use only.

What is Semax?

Semax is a synthetic seven-amino-acid peptide, Met-Glu-His-Phe-Pro-Gly-Pro, built on a fragment of the hormone ACTH. It was developed by Russian researchers, and much of the published work on it still comes from Moscow labs. That’s a big part of why it’s less familiar in the West.

You’ll see it called a Semax peptide, an ACTH(4-10) analog, or by its structural shorthand, ACTH(4-7)PGP. They’re all the same molecule.

	At a glance
Sequence	Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP)
Class	Heptapeptide; ACTH(4-10) analog
Structure	ACTH(4-7) fragment plus a Pro-Gly-Pro tail
Molecular formula	C37H51N9O10S
Molecular weight	About 813.9 g/mol
Modified form	N-Acetyl Semax Amidate, 855.0 g/mol
Main research areas	BDNF signaling, rat stroke models, metal binding
Regulatory status	Not approved by the FDA for any use

How Semax is built

ACTH is a long pituitary hormone, but researchers were interested in one tiny piece of it. Semax keeps four amino acids from ACTH, Met-Glu-His-Phe, a stretch that also matches part of another hormone called alpha-MSH (Sudarkina et al., 2021).

On its own, a fragment that short gets broken down fast. So the designers added a Pro-Gly-Pro tail to the end, which gives the molecule more metabolic stability (Sudarkina et al., 2021).

Think of it as a short message sealed in a sturdier envelope. The message comes from ACTH; the envelope is what lets it last long enough to study.

What does Semax do in research?

In rat studies, Semax raised levels of BDNF, a growth factor for neurons, and activated its receptor, trkB. That’s the finding that made it famous, and most of the research since has built on it.

BDNF and trkB signaling

BDNF, short for brain-derived neurotrophic factor, is a protein that helps neurons grow, survive and form new connections. It works by switching on a receptor called trkB, so researchers usually measure both.

A 2006 rat study looked at the hippocampus, a brain region tied to learning. After Semax, BDNF protein there rose 1.4-fold and trkB activation rose 1.6-fold, while the gene activity behind them jumped even more: 3-fold for one form of BDNF and 2-fold for trkB (Dolotov et al., 2006).

Their behavior changed, too. The rats got better at a conditioned avoidance task, a standard lab test where animals learn to avoid a signal paired with something unpleasant (Dolotov et al., 2006).

A companion study from the same year showed Semax binding specifically in the rat basal forebrain and raising BDNF protein there as well (Dolotov et al., 2006, J Neurochem). Two brain regions, one consistent signal.

BDNF-focused work isn’t unique to Semax. The Pinealon peptide is another short peptide studied in neuronal research, and pinealon vs semax compares the two side by side.

Stroke models in rats

Stroke research is the second big thread, done in rats with a temporarily blocked brain artery. Earlier genome-wide work in that model found Semax turning down inflammatory genes and turning up genes tied to nerve signaling (Sudarkina et al., 2021).

A 2021 study checked whether the proteins followed the genes. In the cortex next to the injured area, Semax lowered MMP-9, an enzyme that breaks down the tissue scaffolding around cells, at both the gene and the protein level (Sudarkina et al., 2021).

That’s an animal model result, and a specific one. It tells researchers where to look next, not what happens outside a rat.

How Semax studies measure their effects

Semax papers tend to measure things at three levels, and it helps to know which one you’re reading about. The first is gene activity, usually measured with real-time RT-PCR or genome-wide RNA sequencing, which shows which genes switch on or off.

Protein comes second. Researchers in the 2006 hippocampus study measured BDNF protein and trkB activation directly, and the 2021 stroke study used immunodetection to check whether protein levels followed the gene changes (Dolotov et al., 2006; Sudarkina et al., 2021).

Behavior is the third level, like the conditioned avoidance task. Each level answers a different question, and a change at one doesn’t guarantee a change at the next.

The copper connection

Here’s a detail most Semax articles skip. Italian chemists found that Semax grips copper(II) ions in an albumin-like way, and that it reduced copper-induced toxicity in cells (Tabbì et al., 2015).

If that sounds familiar, it should. Researchers made the same albumin comparison decades earlier for the GHK-Cu peptide, which is also built around a histidine that holds copper.

What is Semax used for in research?

In the lab, Semax is used to study BDNF signaling, protection of brain tissue in stroke models, and how small hormone-derived peptides can be redesigned for stability. Four lines of work stand out:

• Neurotrophin signaling. How BDNF and trkB respond in rat brain tissue.
• Ischemia models. Gene and protein changes in rats after a temporarily blocked brain artery.
• Metal binding. How the peptide holds copper and zinc, and what that does to cells.
• Peptide design. How a short ACTH fragment behaves once it’s stabilized.

For the full paper list, the Semax study index collects the published papers, and the broader cognitive and neuroprotection research hub maps related compounds.

What is N-Acetyl Semax Amidate?

N-Acetyl Semax Amidate is a modified form of Semax with an acetyl group capping one end and an amide group capping the other. PubChem lists it as Ac-MEHFPGP-NH2, with the formula C39H54N10O10S and a molecular weight of 855.0 g/mol (PubChem).

Those caps aren’t just cosmetic. The same Italian group studied how acetylating Semax’s starting end changes the way it binds copper and zinc (Magrì et al., 2016).

One caution matters here. Every BDNF and stroke-model study above used standard Semax, so their findings don’t automatically carry over to the modified version.

Semax vs Selank

Semax and Selank are both Russian-developed seven-amino-acid peptides ending in Pro-Gly-Pro, but they’re built on different parent molecules. Semax starts from a fragment of ACTH; Selank starts from tuftsin, a short fragment of an antibody protein (Volkova et al., 2016).

	Semax	Selank
Sequence	Met-Glu-His-Phe-Pro-Gly-Pro	Thr-Lys-Pro-Arg-Pro-Gly-Pro
Parent molecule	ACTH(4-7) fragment	Tuftsin, from the immunoglobulin G heavy chain
Shared tail	Pro-Gly-Pro, for metabolic stability	Pro-Gly-Pro, for metabolic stability
Main research focus	BDNF signaling; rat stroke models	Genes tied to GABA signaling
Where it was developed	Moscow research institutes	Institute of Molecular Genetics, Moscow

In rats, Selank changed the activity of several genes linked to GABA signaling in the frontal cortex within hours (Volkova et al., 2016). Same stabilizing tail, different starting message.

For the full comparison, see semax vs selank. Spartan also carries Selank for laboratory research.

Reading a Semax study critically

With a research record this concentrated, a few questions will tell you a lot about any single paper.

• Which form was tested? Standard Semax and N-Acetyl Semax Amidate aren’t interchangeable. Check the sequence in the methods.
• What was the model? Rat hippocampus, a rat stroke model and a human-derived cell line are three different systems, and results in one don’t transfer automatically.
• When was it measured? The Selank gene study looked at 1 and 3 hours; the stroke protein study looked at 24 hours. Timing changes what you see.
• Genes, protein or behavior? A shift in gene activity is a lead. It becomes stronger evidence when protein or behavior moves with it.
• Who ran it? Independent replication from outside the originating labs counts for more than another study from the same group.

Where the Semax evidence is limited

Semax has a real research record, and it has limits. Nearly all of it comes from rats and cell cultures.

It’s also concentrated. Much of the work traces to a small network of Moscow institutes, including the Institute of Molecular Genetics, which is typical for a compound developed there but means independent replication counts for more.

And results don’t always generalize. When the same Moscow group tested Selank in a human-derived cell line, Selank on its own changed none of the GABA-related genes they measured (Filatova et al., 2017). The model matters as much as the molecule.

Is Semax FDA approved?

No. Semax isn’t approved by the FDA for any use, and research-grade Semax is sold for laboratory work only.

The Moscow group behind much of the stroke-model research describes it as a peptide used clinically for ischemic stroke (Sudarkina et al., 2021). That status doesn’t extend to the US.

Storage and handling

Research-grade Semax comes as a lyophilized powder. Keep sealed vials cold, dry and out of the light, and follow the storage conditions on the batch’s certificate of analysis.

Once material is in solution, follow your institution’s handling protocols. Log the batch number and dates for every vial so results can be traced back to the exact material.

Buying Semax for research: what to check

Before buying, confirm what the supplier documents. It doesn’t take long, and three checks cover most of it.

• Identity. Mass spectrometry should match the expected mass for Semax, which also separates it from N-Acetyl Semax Amidate.
• Purity. HPLC testing reports what share of the sample is the target peptide.
• Batch match. The certificate of analysis should carry a batch or lot number that matches your vial.

You can review Spartan’s peptide certificates of analysis before you buy Semax. Researchers comparing several neuronal peptides can also look at the Semax, Pinealon and NAD+ research stack.

When you’re ready to source material, you’ll find Semax for sale on the product page in 30 mg research vials.

Semax research summary

Semax takes a four-amino-acid piece of ACTH and gives it a stabilizing tail. In rats, it raised BDNF and activated trkB, and in stroke models it shifted inflammatory genes and lowered MMP-9 near the injury.

It also binds copper, has a modified cousin in N-Acetyl Semax Amidate, and shares its tail with Selank. Read the studies for what they are: a focused, mostly rodent research record from a small group of labs.

Frequently asked questions

What is Semax?

Semax is a synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro, built from an ACTH(4-7) fragment plus a stabilizing Pro-Gly-Pro tail. It’s studied in rodent research on BDNF signaling and is sold for laboratory research use only.

What does Semax do?

In rat studies, Semax raised BDNF protein and trkB activation in the hippocampus and basal forebrain. In rat stroke models it shifted inflammatory gene activity and lowered MMP-9 near the injury. These are preclinical findings.

What is Semax used for?

In laboratory research, Semax is used to study BDNF signaling, gene and protein changes in rat ischemia models, metal binding, and the design of stabilized hormone-derived peptides.

What is N-Acetyl Semax Amidate?

It’s a modified form of Semax with an acetylated N-terminus and an amidated C-terminus, listed in PubChem at 855.0 g/mol. The studies on standard Semax don’t automatically apply to it.

What’s the difference between Semax and Selank?

Both are seven-amino-acid peptides ending in Pro-Gly-Pro. Semax is built on an ACTH fragment and is studied mainly for BDNF signaling; Selank is built on tuftsin and is studied mainly for GABA-related gene activity.

Is Semax FDA approved?

No. Semax isn’t approved by the FDA for any use. Research-grade Semax is sold for laboratory research only.

Where was Semax developed?

Semax was developed in Russia, and much of its published research comes from Moscow institutes, including the Institute of Molecular Genetics.

How should Semax be stored for research?

Keep lyophilized vials sealed, cold, dry and away from light, following the storage conditions on the batch’s certificate of analysis.

What should a Semax certificate of analysis show?

Identity confirmation by mass spectrometry, purity by HPLC, and a batch or lot number that matches the vial.

Research use disclaimer. All content published by Spartan Peptides is for educational and research purposes only. It is not medical advice and is not a recommendation for human use. Products sold on this site are research compounds intended for laboratory and in vitro applications only.