Quick answer: Semax is a short synthetic peptide built from a fragment of ACTH, a naturally occurring hormone. Published laboratory research has mostly examined whether it changes BDNF, a protein involved in neuron growth and connection, and how it behaves in models of brain injury. The findings are interesting but come from a limited body of preclinical work, and many questions remain open.
What is Semax and where does it come from?
Semax, sometimes written SEMAX or described as an ACTH(4-10) analog, is a chain of seven amino acids: Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues match a stretch of ACTH. The last three, Pro-Gly-Pro, are an addition to that natural fragment.
ACTH is best known as a hormone. Researchers became interested in its smaller fragments because some of them appeared to act on nerve cells without the hormone's usual activity.
How does Semax work? What researchers propose
No single mechanism has been confirmed. Published papers describe several proposed routes:
- Neurotrophin signaling. Changes in BDNF and in TrkB, the receptor BDNF acts on.
- Gene expression. Shifts in genes tied to inflammation, blood vessels and nerve-cell survival in injury models.
- Neurotransmitter systems. Reported effects on dopamine and serotonin pathways in brain tissue.
- Melanocortin receptors. Because of its ACTH origin, interaction with this receptor family has been proposed, though the details are less settled.
What have studies reported about Semax and BDNF?
Several preclinical studies reported higher BDNF levels and changes in TrkB signaling in brain regions such as the hippocampus after exposure to Semax. The hippocampus is a region tied to learning and memory in the research literature.
Other published laboratory work looked at Semax in models of reduced blood flow to the brain. Those studies reported changes in gene activity and in markers of cell survival. Researchers also examined it in learning and memory tasks and in stress-response paradigms.
These are reports of what was measured in those experiments. They do not show what Semax would do outside them.
How strong is the evidence?
Early and narrow, with some depth in a few areas. Much of the published work comes from a small number of research groups, and independent replication is thinner than for many better-known compounds.
| Research area | What was examined | Evidence level |
|---|---|---|
| BDNF and TrkB | Protein and signaling changes in brain tissue | Several preclinical reports; limited independent replication |
| Brain injury models | Gene activity and cell-survival markers | Preclinical; models vary between studies |
| Neurotransmitter systems | Dopamine and serotonin pathway changes | Smaller set of studies |
| Receptor target | Melanocortin receptor interaction | Proposed, not fully mapped |
What is still unknown
The exact receptor target is not settled. It is also unclear which reported effects are direct and which are downstream. Cell studies cannot answer whole-organism questions, and preclinical results often do not carry over to other settings.
What is in the Semax 20mg vial?
Our Semax 20mg is supplied as a lyophilized (freeze-dried) powder, listed at ≥99% research-grade purity. It is synthesized at a WHO/GMP and ISO 9001 certified laboratory in California. For laboratory research use only. For more on the powder format, see Lyophilization Explained.
How is Semax tested?
Three checks matter most: identity by mass spectrometry, purity by HPLC, and the amount of peptide in the vial. Our article on why mass matters more than purity explains why identity should be confirmed first.
Semax has one quality issue worth knowing. It contains methionine, an amino acid that oxidizes easily. An oxidized copy weighs slightly more than the correct peptide and often appears as its own HPLC peak. A good Certificate of Analysis should show the measured mass matching the expected mass for the seven-residue sequence, with no large side peaks. The COA for this product is shown below, and our line-by-line COA guide covers how to read one.
Frequently asked questions
Why does Semax have a Pro-Gly-Pro tail?
Researchers describe the Pro-Gly-Pro ending as a way to make the fragment more resistant to breakdown by enzymes. Studies of its stability are limited, so treat this as a proposed explanation.
Does Semax act like the ACTH hormone?
Published reports say Semax does not share the hormone's main activity. That comes from a limited set of studies, so it is not a settled point.
What does the 20mg on the label mean?
It refers to the amount of peptide in the vial. Purity is a separate figure showing how much of the material is the correct peptide.
Is Semax the same as Selank?
No. They are different seven-amino-acid peptides with different parent molecules. Our Selank 20mg is a separate product.
How long has Semax been studied?
Published research on it goes back several decades. The volume of work is still small next to many other research compounds.
Is Semax sold as a powder or a liquid?
Our Semax ships as a lyophilized powder.
Every lot we sell has a Certificate of Analysis you can read before you order. Questions before you buy? Our team is in Chandler, Arizona: (888) 745-1505 or our contact page.
View Semax | 20mgAll products sold by BioPure Peptides are intended strictly for in-vitro laboratory and research use only. They are not for human or animal consumption. These statements have not been evaluated by the U.S. Food and Drug Administration, and these products are not intended to diagnose, treat, cure, or prevent any disease.