N-Acetyl Selank

NA-Selank amidate

N-Acetyl Selank (NA-Selank amidate) is a cognitive & mood research compound. Acetylated Selank with better CNS penetration and stability — anxiolytic and nootropic via GABA and BDNF pathways.

How N-Acetyl Selank works

Acetylated Selank with better CNS penetration and stability — anxiolytic and nootropic via GABA and BDNF pathways.

Proposed benefits

Researched for focus, memory, neuroprotection, mood and stress resilience.

Where to get N-Acetyl Selank

N-Acetyl Selank is sold in 2 forms. They are not interchangeable — the dose and the route differ, so pick the one this page describes unless you know why you want another.

The evidence for N-Acetyl Selank

Graded by what exists behind each claim.

✅ Clinically validated

• No trials of the acetylated form specifically. The clinical record belongs to Selank itself — Russian clinical work in generalized anxiety disorder — and this variant is a chemical modification made for stability, not a separately studied drug. See Selank's clinical tier for the underlying evidence and its limits.

📊 Correlative data

• Used intranasally in place of Selank on the reasoning that it survives longer before degradation. Reported experience is described as slightly stronger and longer-lasting, though nobody has compared them head-to-head in any controlled way.

🧪 Theoretical / extrapolated

• Selank with an acetyl group added to the N-terminus, which slows enzymatic breakdown by aminopeptidases.
• The modification changes pharmacokinetics, not pharmacology — the same tuftsin-derived mechanism, the same proposed GABAergic and BDNF effects, delivered over a slightly longer window. Anyone claiming a different effect profile is describing dose, not mechanism.

How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →

What N-Acetyl Selank actually does

This page is not about Selank. It is about the acetyl group, because that is the only thing this compound has that Selank does not. The parent is Thr-Lys-Pro-Arg-Pro-Gly-Pro, printed in exactly those seven residues in the paper that measured what it does to human plasma Zozulya 2001. What is sold here is that heptapeptide with an acetyl group on the N-terminal threonine and — per this site's own alternate name, ‘NA-Selank amidate’ — an amide at the C-terminal proline. Both ends blocked.

The chemistry, computed, because it produces a number a buyer can actually use. The parent is 751.89 Da, formula C33H57N11O9, with a computed net charge of +1.94 at blood pH. Acetylation adds 42.04 Da; C-terminal amidation removes 0.98 Da. So N-acetyl Selank amidate is about 792.9 Da — a 41 Da gap from the parent that any mass spectrometer resolves without effort. The charge barely moves: acetylation deletes a positive N-terminus, amidation deletes a negative C-terminus, and the two cancel to +2.00. But the modified peptide has no isoelectric point in any usable sense: with both termini capped, only the lysine and arginine side chains remain ionizable, so it is permanently cationic at every pH the body reaches. The parent can be neutralized at pH 11.65. This one cannot be neutralized at all.

Now the question the modification actually raises, which is not the one vendors answer. N-terminal acetylation exists to block aminopeptidases, which chew peptides from the amino end. Two published facts about the parent say that is the wrong flank to defend. First, the parent is trimmed from the other end: in rats the intact heptapeptide is present in plasma for 7–10 minutes and its main pharmacologically active metabolite is tuftsin, the Thr-Lys-Pro-Arg tetrapeptide left behind when Pro-Gly-Pro is removed Boiko 1998. Second, the parent's own enzyme target sits at that same end: in human plasma, Selank is more specific for carboxypeptidases and dipeptidylcarboxypeptidases, while aminopeptidases account for roughly 80% of total enkephalin-degrading activity Zolotarev 2004. The acetyl group guards a door the traffic does not use, and the amide guards the door everything goes through.

And here is the named receptor, which no page about this compound family mentions. Tuftsin — the active metabolite — binds selectively to neuropilin-1 and blocks vascular endothelial growth factor binding to that receptor von Wronski 2006. Neuropilin-1 recognizes peptides by the C-end rule, and that motif is active only when the second basic residue is exposed at the C-terminus of the peptide Teesalu 2013. In tuftsin, the arginine is that exposed C-terminal residue. In Selank it is buried under Pro-Gly-Pro, so intact Selank cannot engage neuropilin-1 — only its trimmed metabolite can. Cap that C-terminus with an amide and you have blocked the carboxypeptidase step that generates the metabolite, and defeated the free-carboxylate requirement that lets the metabolite bind. That is a specific, structural, falsifiable objection to the claim that this molecule is simply a longer-lasting Selank.

Cell, rodent, human — and where it stops

There is no translation chain for this molecule, because there is no primary literature for it. No cell study, no rodent study, no human study of N-acetyl Selank amidate could be resolved against NCBI for this page. Not one. Every number anybody quotes for this compound belongs to the unmodified heptapeptide, which has its own page on this site and its own evidence.

What that inheritance is being asked to carry. The parent's human record is 62 patients with generalized anxiety disorder and neurasthenia, 30 on Selank against 32 on medazepam, rated on Hamilton, Zung and CGI, with serum enkephalin half-life measured alongside Zozulia 2008. The parent's mechanism record is inhibition of plasma enkephalin hydrolysis with an IC50 near 15 micromolar Zozulya 2001, weighted toward carboxypeptidases Zolotarev 2004, and a rodent plasma residence of 7–10 minutes ending in tuftsin Boiko 1998.

The obstacle, stated fairly rather than as a strawman. This site's card says the modification changes pharmacokinetics and not pharmacology, and that anyone claiming a different effect profile is describing dose. For most N-terminal acetylations that is exactly right, and it is the correct default. It becomes questionable here for one specific reason: the parent's own published record names a metabolite as the principal pharmacologically active species Boiko 1998, and that metabolite is produced by cleaving the end this molecule has capped. A modification that slows the production of the active species does not inherit the parent's evidence — it changes what the drug is. Whether it slows it a little or abolishes it is unmeasured in either direction, and that is the honest state of knowledge rather than a verdict.

The second obstacle, which applies to the whole family. Even the parent's human evidence is a single-country, Russian-language, benzodiazepine-comparator trial base of under two hundred people Zozulia 2008. Inheriting it requires the inheritance argument to hold, and it is a small estate to begin with.

N-Acetyl Selank pharmacokinetics — how much of it actually gets in

No pharmacokinetic study of the acetylated amidated form exists in any species. What follows is what the parent's kinetics and this molecule's chemistry jointly constrain, which is more than the card's ‘~2–3 hrs’ has behind it.

What degrades it, end by end. The N-terminus is capped, so aminopeptidase attack there is blocked — and the Pro-Gly-Pro tail already resisted most aminopeptidases anyway, which is why the parent lasts minutes rather than seconds. The C-terminus is amidated, and carboxypeptidases require a free alpha-carboxylate, so the trimming step that produces tuftsin in the parent Boiko 1998 is the specific reaction this modification obstructs. What is left unguarded is the middle: endopeptidases cutting internal bonds, which for a proline-rich sequence is slow but not zero. The prediction from that is a longer plasma residence of the intact heptapeptide and less tuftsin generated. Neither half has been measured.

The arithmetic that decides whether the enzyme mechanism can be running at all, and nobody has done it. This site's dose is 250–750 micrograms. Take the top of it: 750 micrograms of a 792.9 Da molecule is 0.95 micromoles. Distribute that through roughly 5 liters of plasma, assuming complete absorption, and the peak plasma concentration is about 0.19 micromolar. The parent's measured IC50 against plasma enkephalin hydrolysis is 15 micromolar Zozulya 2001. That is a shortfall of roughly eighty-fold, before accounting for the fact that nasal delivery of a permanently cationic 793 Da peptide is nowhere near complete absorption. Whatever this compound does at this dose, the plasma enkephalinase mechanism is not a plausible account of it — and that conclusion follows from two published numbers and a division.

The oral and nasal barriers. Swallowed, a seven-residue peptide meets gastric acid, pancreatic proteases and brush-border peptidases; the enterocyte's peptide carrier PepT1 handles di- and tripeptides, so a heptapeptide is outside its substrate range whether or not its ends are capped. Nasally, the molecule is permanently dicationic at 793 Da, which rules out passive transcellular diffusion and leaves the paracellular route through tight junctions — size- and charge-limited, and not improved by acetylation, because the modification did not change the charge. Route: nasal spray in this site's protocol, with an injectable variant also listed. Injection removes the gut but not plasma peptidases, and no injected pharmacokinetic curve exists for this molecule either.

What would have to be true, and how you would know it was not

Four predictions. Two of them come out of the neuropilin-1 mechanism and have never been proposed for any compound in this family.

1. Against the product's whole selling point: this should feel less potent per microgram than plain Selank, not more. If the active species is the tuftsin metabolite Boiko 1998 and the amide blocks the cleavage that makes it, then microgram for microgram the capped peptide should deliver less of what does the work. The test is a within-person crossover: two weeks on Selank, two weeks on N-acetyl Selank amidate at the same molar dose — which is not the same milligram dose, because 792.9 Da against 751.89 Da means you need about 5.5% more mass to deliver the same number of molecules. Score a fixed anxiety instrument at fixed times. Prediction: the modified peptide is not stronger, and if it feels longer that is a different claim from being better.

2. Flow-mediated dilation is the marker nobody has thought to draw, and it is where the mechanism predicts a cost. Tuftsin binds neuropilin-1 and blocks VEGF binding to it von Wronski 2006. Neuropilin-1 is a co-receptor for VEGF signaling in endothelium, and VEGF signaling maintains endothelial nitric oxide output. The chain from there to vascular function is extrapolation and is labeled as such — but it is a directional, falsifiable extrapolation: if enough tuftsin were generated to matter systemically, flow-mediated dilation should fall, and pulse wave velocity should rise. Measure FMD at baseline and after an eight-week course. And read the null carefully, because it is informative in the opposite direction: no change would be evidence that systemic tuftsin exposure at these microgram doses is negligible, which would in turn undermine the tuftsin-mediated account of the whole compound family.

3. The duration claim is testable with actigraphy, and it is the only claim specific to this molecule. The stated reason to buy the acetylated form is that it lasts longer. Sleep onset latency and wake-after-sleep-onset from a wrist actigraphy device are cheap, objective, collected nightly, and sensitive to an anxiolytic. Two weeks of baseline, four weeks on, dosing at a fixed time. Prediction: if the modification does what it claims, the effect on sleep onset should persist further from the dose than the parent's does. If both look identical, the pharmacokinetic argument for paying more is empty.

4. Against, and it argues the modification is invisible: the charge did not change. Nasal absorption of peptides is governed by size and charge, and this modification altered neither — computed net charge +1.94 becomes +2.00, mass rises 5.5%. Prediction: nasal bioavailability is indistinguishable between the two forms. Anyone claiming the acetylated version ‘absorbs better’ is making a claim the chemistry does not support and that nobody has measured.

What nobody has tested yet

Five experiments. Every one of them is about the modification rather than the peptide, and not one has been done.

1. Nobody has published a mass spectrum of a commercial vial. This is the rare case where the identity question has a clean analytical answer: 792.9 Da is the acetylated amidate, 751.9 Da is plain Selank, and 41 Da is a gap no instrument can miss. A buyer paying a premium for the modified peptide has no way to know which one is in the bottle, and one afternoon of LC-MS on five vendors' product would tell the whole market.

2. Nobody has measured whether the capped peptide still generates tuftsin. Give both forms to rats, sample plasma over 30 minutes, quantify the tetrapeptide. The parent's answer is already published Boiko 1998; the modified form's has never been asked. This is the single experiment that decides whether the two compounds are the same drug.

3. Nobody has run the enzyme assay on the modified form. The parent's IC50 against plasma enkephalin hydrolysis is 15 micromolar Zozulya 2001 and its specificity is toward carboxypeptidases Zolotarev 2004 — both measured in human plasma with established methods. Running the same assay with the acetylated amidate beside the parent takes one afternoon and would test the ‘same pharmacology’ claim directly rather than by assertion.

4. Nobody has put either peptide in front of neuropilin-1. The receptor is named, the competition assay against VEGF is standard von Wronski 2006, and the C-end rule makes a specific structural prediction — tuftsin binds, Selank should not, and the amidated form should not either Teesalu 2013. Three peptides, one binding plate. It would be the first receptor-level measurement anyone in this family has made.

5. Nobody has compared the two forms in a person on any endpoint. The entire case for the modified peptide is a pharmacokinetic argument that has never been tested pharmacokinetically, supporting a clinical claim that has never been tested clinically. A twenty-person crossover with a validated anxiety scale would be the first evidence of any kind that this molecule does something its parent does not.

N-Acetyl Selank — its own safety story, not its class's

The class block is written for cognitive enhancers in general. This molecule's own risks are about identity, about a receptor nobody has considered, and about a regulatory gap that does not apply to its parent.

1. The human exposure record for this exact molecule is zero. The parent's record is under two hundred people in single-country trials Zozulia 2008. That record belongs to a 751.89 Da peptide. Whatever is in a vial labeled N-acetyl Selank amidate weighs 792.9 Da, has both termini blocked, and has never been given to a person in a published study. Safety by inheritance is exactly the argument this page has spent five sections questioning.

2. The anti-doping status differs from the parent's, and the difference is precise. WADA's section S0 prohibits at all times anything pharmacological that no section of the List already covers and that no government health authority anywhere has approved for human therapeutic use. Selank itself carries a Russian registration, which is an argument — not a settled one — against S0 applying to it. N-acetyl Selank amidate is a chemically distinct molecule registered nowhere, which removes that argument entirely. A tested athlete should treat this as an S0 substance and check the current Prohibited List rather than this paragraph.

3. The neuropilin-1 finding is a risk consideration nobody has raised, and it cuts both ways. If tuftsin is generated in meaningful quantity, then a course of this compound involves chronic low-level antagonism of VEGF binding at neuropilin-1 von Wronski 2006 — a pathway whose deliberate blockade is the mechanism of anti-angiogenic drugs. That is an extrapolation from a binding study to a whole-body effect and it is flagged as one. Its mirror image is equally worth stating: if the amidation blocks tuftsin generation as the chemistry suggests, this concern disappears — and so does most of the compound's claimed activity. You cannot have the reassurance and the potency from the same argument.

4. What a nasal spray adds that a powder does not. This is sold as a solution sprayed onto respiratory epithelium, so what you are dosing daily includes the vehicle: the preservative, the pH and the tonicity, none of which appear on a peptide certificate of analysis. For a permanently dicationic peptide the formulation is not incidental, because charge governs how much binds anionic mucin and never reaches the epithelium at all. No vendor publishes a formulation, and no stability datum for the acetylated amidate in solution exists.

Sources read for this page

• Zolotarev IuA, Sokolov OIu, Kost NV, Vas'kovskii BV, Miasoedov NF, Zozulia AA. [Leu-enkephalin homogeneously labeled with tritium in studying the Selank inhibiting effect on the enkephalin-degrading enzymes of human plasma]. Bioorganicheskaia Khimiia 2004;30(3):234-240 · PMID 15344652
• von Wronski MA, Raju N, Pillai R, Bogdan NJ, Marinelli ER, Nanjappan P, Ramalingam K, Arunachalam T, Eaton S, Linder KE, et al. Tuftsin binds neuropilin-1 through a sequence similar to that encoded by exon 8 of vascular endothelial growth factor. Journal of Biological Chemistry 2006;281(9):5702-5710 · PMID 16371354
• Teesalu T, Sugahara KN, Ruoslahti E. Tumor-penetrating peptides. Frontiers in Oncology 2013;3:216 · PMID 23986882
• Boiko SS, et al. The pharmacokinetics and metabolism of heptapeptide--a prospective synthetic analog of tuftsin with psychostimulating action in rats. Eksperimentalnaia i Klinicheskaia Farmakologiia 1998 · PMID 9854633
• Zozulya AA, Neznamov GG, et al. The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Bulletin of Experimental Biology and Medicine 2001 · PMID 11550013
• Zozulia AA, Neznamov GG, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zhurnal Nevrologii i Psikhiatrii im S S Korsakova 2008 · PMID 18454096

N-Acetyl Selank — safety, predicted from mechanism

N-Acetyl Selank — interference & stacking

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