N-Acetyl Semax Amidate: What Research Shows
N-Acetyl Semax Amidate is a terminally modified form of Semax, a synthetic heptapeptide studied for cognition and neuroprotection. Catalogs often shorten the name to NASA. The core sequence stays the same. An acetyl group on the N-terminus and an amide on the C-terminus are added to slow enzymatic breakdown. The clinical record belongs almost entirely to unmodified Semax. This page is research information only, not a protocol for human use.
Where the sequence comes from
Semax was developed at the Institute of Molecular Genetics in Moscow as an analog of ACTH(4-10), not as a copy of that fragment. ACTH(4-10) is Met-Glu-His-Phe-Arg-Trp-Gly. Semax keeps the Met-Glu-His-Phe start and replaces the rest with Pro-Gly-Pro, giving Met-Glu-His-Phe-Pro-Gly-Pro. That tail resists cleavage better than the native ACTH ending. Unlike full-length ACTH, Semax does not drive adrenal steroid release. Researchers study it for attention, memory, and recovery after ischemic injury.
N-Acetyl Semax Amidate is the same heptapeptide written as Ac-Met-Glu-His-Phe-Pro-Gly-Pro-NH2. The Semax protocol page lists the parent peptide at about 813 daltons, water soluble, stored lyophilized near -20 C. The two caps shift the mass slightly. They are the only reason NASA is catalogued as its own material.
What the two caps are supposed to do
Short peptides in solution are trimmed from the ends. Aminopeptidases remove residues from the N-terminus. Carboxypeptidases work from the C-terminus. N-acetylation blocks the first route. C-terminal amidation blocks the second. Chemists use both caps when they want a longer intact window after mixing. The Pro-Gly-Pro tail already helped Semax. NASA adds a second layer of end protection.
That is standard peptide chemistry, not proof that NASA is stronger or safer. Head-to-head trials of half-life, BDNF response, or cognitive scores for N-Acetyl Semax Amidate versus Semax are not in the mainstream literature. Treating NASA as a proven upgrade overstates the record.
| Feature | Semax | N-Acetyl Semax Amidate |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Same core, N-acetyl and C-amide |
| Main evidence | Rodent studies and Russian clinical reports | Chemical rationale, little direct clinical data |
| Common research form | Intranasal solution (0.1% and 1% in Russian product literature) | Lyophilized powder for laboratory reconstitution |
| Regulatory status | Not FDA-approved. Local clinical use in Russia | Research compound only. No FDA approval |
The comparison is descriptive. It is not a dosing chart and it is not a recommendation to administer either compound.
What studies on Semax actually report
Almost every biological claim attached to NASA is borrowed from the parent peptide. Those findings are real, and they have limits.
- BDNF and NGF. Rodent work reports higher brain-derived neurotrophic factor and nerve growth factor expression in the hippocampus after Semax exposure. That is why cognitive researchers follow it. A rat neurotrophin change is not proof of the same change from a modified analog.
- Monoamines and melanocortin signaling. Preclinical papers describe shifts in dopamine and serotonin turnover, and discuss Semax as a melanocortin-pathway ligand with interest in MC4 and MC5 receptors. It does not copy ACTH's effect on cortisol.
- Ischemic injury. Russian clinical series in acute stroke used intranasal Semax as an adjunct and reported changes in neurological scores. Those trials used registered Semax solutions, not NASA powder, and they are not large independent Western trials.
- Broader gene expression. Transcript studies also describe effects on immune and vascular genes. Semax does not look like a single-target compound, and the map is incomplete.
Handling a lyophilized research vial
NASA is usually supplied as a dry powder. Concentration depends on the stated milligrams in the vial and the diluent volume. Use the reconstitution calculator and the steps in how to reconstitute peptides before writing a protocol. Semax is water soluble. Bacteriostatic water is the usual diluent for injectable research preparations. Sterile saline is the usual diluent for an intranasal solution of the parent peptide.
Keep lyophilized vials cold, dry, and out of light. After reconstitution, refrigerate and use the solution within a short research window. Repeated freeze-thaw cycles damage most peptides of this size. The protocols index collects the same handling pattern for other research sequences.
How it differs from Selank
Selank is the other Russian heptapeptide that sits next to Semax in research catalogs. It is a tuftsin analog, not an ACTH fragment. Its literature leans toward anxiety models and GABAergic tone. Semax literature leans toward neurotrophins, monoamines, and ischemia. They are not substitutes. Research-reported Selank figures are on the Selank peptide dose page, with notes on the Selank protocol.
What is not established
There is no robust long-term safety database for N-Acetyl Semax Amidate. Drug interactions, pregnancy, and outcomes in psychiatric or neurological illness are unknown. Intranasal Semax reports mention nasal irritation most often. Restlessness or shorter sleep is sometimes described with late-day exposure. Those notes come from Semax experience and informal logs, not from a controlled NASA safety program.
Purity is a separate variable. Short custom peptides vary in HPLC purity and residual solvents. An unexpected result can come from impurities rather than the sequence. Prefer lots with a current certificate of analysis, and compare tested vendors on the supplier list.
Terminal caps should slow exopeptidases. That does not mean NASA has been shown to reproduce Semax findings at a known exposure. Cite Semax papers as Semax papers, and describe NASA as a modified research analog with a plausible stability rationale.