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N-Acetyl KPV is the tripeptide lysine-proline-valine with an acetyl group on the N terminus, usually supplied with the C terminus amidated as well. The unmodified tripeptide is the last three residues of alpha-melanocyte-stimulating hormone and carries much of that hormone's anti-inflammatory activity in a minimal fragment. This entry exists because the acetylated peptide is a different compound from the parent and has almost no literature of its own. Four published studies have put Ac-Lys-Pro-Val-NH2 itself into an assay: it produced no melanotropic response in a frog skin bioassay [1], it was modelled conformationally by molecular dynamics [2], and it was tested for antibacterial activity twice with opposite results [3][4]. Nothing has measured its anti-inflammatory potency, its transport, its stability in an organism, or its behaviour in a person. Its case therefore rests on the parent tripeptide's record plus the general expectation that acetylating the N terminus slows aminopeptidase attack, and that expectation has never been tested for this peptide. One further complication belongs in any honest description: a large share of the material sold as ordinary KPV is already the acetylated and amidated analogue, so the two product names do not reliably separate two molecules.
- No adverse effect has been characterised, because no safety study has been performed on this molecule
- Gray-market supply carries the usual risks of mislabelling and contamination
Mechanism
The proposed mechanism is inherited rather than demonstrated. The parent tripeptide KPV enters intestinal epithelial and immune cells through the di/tripeptide transporter PepT1, which is induced in inflamed colon, and once inside it suppresses NF-kB signalling and output [8]. The same fragment accounts for much of the anti-inflammatory activity of alpha-melanocyte-stimulating hormone [9], and it does so without containing the sequence motif required to bind any known receptor, which is why its intracellular target is still described as unidentified [10]. None of that has been re-measured on the acetylated .
What the acetyl group is meant to do is a general expectation from chemistry rather than a finding: capping the free N terminus removes the substrate an aminopeptidase recognises, which normally slows the first cleavage. The caution that follows is specific and worth stating. PepT1 is a transporter with its own structural requirements, and blocking the N terminus is exactly the kind of change that can interfere with transport as readily as it protects against proteolysis; whether Ac-KPV is still a PepT1 substrate has not been reported by anyone.
Where the acetylated molecule has been measured directly, the results are narrow. In the frog skin melanotropic bioassay, Ac-Lys-Pro-Val-NH2 produced no measurable pigmentary response even at high concentration [1]. A molecular-dynamics study mapped its accessible conformations and used the lowest-energy families as templates for constrained non- analogues [2]. Its antibacterial behaviour is disputed: one group found Ac-Lys-Pro-Val-NH2 active against Staphylococcus aureus and Escherichia coli across a broad concentration range, no more potent than the parent hormone, and showed that the lysine charge was not required for the effect [3], while a later group testing Ac-KPV-NH2 under several conditions reported no activity at all [4].
A separate line of chemistry extended rather than capped the . Adding a tyrosine to give Ac-Tyr-Lys-Pro-Val-NH2 or Ac-Lys-Pro-Val-Tyr-NH2 produced tetrapeptides that did bind the -1 receptor and raise ; the same paper restates that the plain C-terminal tripeptide has strong anti-inflammatory activity with no known cellular target [5]. Those tetrapeptides are different molecules again and their receptor binding says nothing about Ac-KPV.
receptor fingerprint
Bacterial growth (S. aureus, E. coli)inhibits (disputed)
Melanotropic (pigmentation) responseno measurable activity
NF-kB signalling (inherited, not measured for this analogue)untested
PepT1 transport (inherited, not measured for this analogue)untested
Dosingtypical ranges, not medical advice
interested in protocols and clinical dosages? make an account to see them! ^_^
Safetyrisks and cautions, not medical advice
No safety study has been performed on N-Acetyl KPV. That is the most important sentence in this section, and nothing below changes it.
What exists is a short list of assays that used the acetylated tripeptide for other purposes. In the frog skin melanotropic bioassay, Ac-Lys-Pro-Val-NH2 produced no measurable pigmentary response [1]; that is a genuine finding about this molecule, and it is reassuring in one narrow way, because the pigment-driving activity of the parent hormone is the part of melanocortin pharmacology a user would actually see. A conformational study modelled the same acetylated and amidated tripeptide computationally, with no biological exposure at all [2]. Two groups have run antimicrobial assays on it and disagree: one reported activity against Staphylococcus aureus and Escherichia coli [3], the other reported none under several conditions [4]. A molecule whose simplest measured property is contested does not have a characterised safety profile.
The nearest thing to an in vivo exposure is not this compound. Scalded rats given the acetylated stereoisomer Ac-D-Lys-L-Pro-D-Val retained hepatic glucocorticoid receptor binding capacity and showed blunted rises in circulating IL-1beta and TNF-alpha [6]. The D-amino-acid substitutions make that a different molecule from the all-L acetylated peptide sold under this name, and that study was designed to measure receptor and cytokine endpoints rather than to look for harm.
Nothing carries across from the parent hormone by default either. Plain KPV lacks the sequence motif needed to bind any known melanocortin receptor [10], so the long pharmacology of alpha-melanocyte-stimulating hormone cannot be used as a safety argument for a fragment, and the acetylated version has never been checked against those receptors at all.
Route matters more than the packaging suggests. Plain KPV applied to intact human skin did not cross it at a detectable level by passive diffusion, and moved only after the skin was microporated or an iontophoretic current was applied [11]. No equivalent measurement exists for the acetylated peptide, so a cream or a spray containing it is an untested delivery claim rather than a weaker version of a tested one. No published intranasal study of either molecule was found.
Two handling points follow from the chemistry. The parent tripeptide degrades under acid, alkali and peroxide stress mainly to lys-pro-diketopiperazine [7], a degradant with no toxicology of its own; and acetylation is chosen precisely to change how the molecule is broken down, so degradation behaviour measured on KPV cannot be assumed to describe this one. The last risk is the ordinary one for gray-market peptides, named again in a 2026 review that lists KPV among the peptides circulating in sport and describes an unregulated supply chain in which products are frequently mislabelled or contaminated [12]. Research use only; there is no controlled human safety information of any kind, and no study designed to find harm has been run on this molecule.
History
The tripeptide behind this compound is the C-terminal three residues of alpha-melanocyte-stimulating hormone, and interest in it grew from the finding that the fragment carries much of the hormone's anti-inflammatory activity [9] while lacking the receptor-binding motif and the pigmentary action of the full peptide [10].
The acetylated form appeared in the chemistry literature long before it appeared on a vendor page. Ac-Lys-Pro-Val-NH2 was among the carboxy-terminal analogues Hruby and colleagues prepared in 1987 while mapping the minimal active sequence of alpha-melanotropin, and it was reported as devoid of melanotropic activity in the frog skin bioassay [1]. It was modelled conformationally in 2001 as a template for constrained non-peptide mimics [2], tested for antibacterial activity in 2008 [3], and re-tested in 2018 as the reference compound in a study of glycoalkylated KPV analogues, where it showed none [4].
That is the whole documented history of the molecule, and it is a chemistry trail rather than a pharmacology programme. Its arrival as a separately branded research peptide belongs to the recent wave that put KPV itself into the sport and bodybuilding supply chain [12]. The two names have been tangled ever since: much of the material sold simply as KPV is the acetylated and amidated analogue, so the market distinction is newer and looser than the chemistry.
Reputation
Reputation here runs well ahead of evidence. N-Acetyl KPV is marketed as the more stable, longer-lasting version of KPV, and the stability argument is a reasonable piece of peptide chemistry rather than a measurement. No comparison of the two molecules in a stability assay, a pharmacokinetic study, or any inflammation model has been published. The one property that has been measured twice on the acetylated peptide is antibacterial activity, and the two attempts contradict each other [3][4].
Buyers should also know that the distinction implied by the two product names is often not real. The acetylated and amidated peptide is widely sold under the plain KPV label, so a vial marked one way may contain the other, and a comparison of user reports between the two names is comparing labels rather than molecules.
Resources
This entry is here for reference.
Research
- 1987first citedalpha-Melanotropin: the minimal active sequence in the frog skin bioassay.
- 2026most recentA new era of doping? Use of peptide and peptide-analog drugs in recreational and professional s…
- 1.alpha-Melanotropin: the minimal active sequence in the frog skin bioassay.
- 2.Conformational analysis of tripeptide Ac-Lys-Pro-Val-NH2, COOH-terminal sequence of alpha-MSH.
- 3.Anti-microbial action of melanocortin peptides and identification of a novel X-Pro-D/L-Val sequence in Gram-positive and Gram-negative bacteria.
- 4.Structural modification of the tripeptide KPV by reductive "glycoalkylation" of the lysine residue.
- 5.New melanocortin 1 receptor binding motif based on the C-terminal sequence of alpha-melanocyte-stimulating hormone.
- 6.Downregulation of glucocorticoid receptors of liver cytosols and the role of the inflammatory cytokines in pathological stress in scalded rats.
- 7.Stability-indicating HPLC assay for lysine-proline-valine (KPV) in aqueous solutions and skin homogenates.
- 8.PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation.
- 9.Dissection of the anti-inflammatory effect of the core and C-terminal (KPV) alpha-melanocyte-stimulating hormone peptides.
- 10.Terminal signal: anti-inflammatory effects of α-melanocyte-stimulating hormone related peptides beyond the pharmacophore.
- 11.Transdermal Iontophoretic Delivery of Lysine-Proline-Valine (KPV) Peptide Across Microporated Human Skin.
- 12.A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review.
12 listed here; entry last updated July 2026
Reviews
My notesprivate to this device
FAQ
Is this just KPV with an extra bit stuck on?
Chemically yes, practically it is a different compound with almost no data. The acetyl group caps the N terminus and most product is amidated at the other end as well. Four papers have put the acetylated tripeptide into an assay and none of them measured anti-inflammatory potency, transport or pharmacokinetics.
Does the acetyl group really make it last longer?
That is the expectation, not a finding. Capping the N terminus normally slows the aminopeptidase that would otherwise take off the first residue, which is why the modification is used across peptide chemistry. Nobody has compared the acetylated peptide against plain KPV in a stability or pharmacokinetic study.
Should I use it instead of regular KPV?
There is no result to base that choice on. The parent tripeptide has a real preclinical record for gut and mucosal inflammation; the acetylated version has four papers, two of which contradict each other about whether it kills bacteria. There is also a good chance the two labels refer to the same molecule, because much of what is sold as plain KPV is the acetylated and amidated form.
Can I use it as a nasal spray?
No published intranasal study of this peptide or of plain KPV was found. Nasal products are sold, but the route is a marketing claim here rather than a tested one, and the acetylated peptide has never been measured crossing any barrier.
Is it safe?
That question has no answer for this molecule. No safety study has been run on it, no human has been dosed with it in a published study, and the assays that exist were designed to measure conformation or bacterial growth. The absence of reported harm is a consequence of nobody having looked, not a finding.
Limitations of the evidence
- Four published studies have put the acetylated tripeptide itself into an assay; none measured anti-inflammatory potency
- The two studies that ran the same antimicrobial test on it reached opposite conclusions
- No pharmacokinetic, half-life or stability data exist for the acetylated peptide in any species
- Whether it is still a PepT1 substrate, which is how the parent reaches inflamed gut tissue, has not been reported
- No human has been dosed with it in any published study, and no registered clinical trial exists
- In vivo work on acetylated KPV-family peptides used a D-amino-acid stereoisomer, not the molecule sold here
Adverse effects
- No adverse effect has been characterised, because no safety study has been performed on this molecule
- Gray-market supply carries the usual risks of mislabelling and contamination
Notes and cautions
- Much of the material sold as plain KPV is the acetylated and amidated analogue, so the two product names do not reliably separate two molecules
- Vendor listings disagree on the molecular formula for the acetylated peptide, so none is stated here
- No published intranasal study of this peptide or of plain KPV was found, so nasal products are an untested route
- Plain KPV did not cross intact human skin by passive diffusion at a detectable level; no equivalent measurement exists for the acetylated form