What does alpha-MSH do?

Two separable things: drives pigmentation through melanocortin receptors, and carries anti-inflammatory activity in its C-terminal region.

Where does it come from?

It is cleaved from proopiomelanocortin, the same precursor that yields ACTH and beta-endorphin.

How do KPV and Melanotan II relate?

Both derive from alpha-MSH but take opposite halves of its function — KPV the anti-inflammatory C-terminus, Melanotan II the pigmentation-driving core.

KPV

Alpha-MSH: Pigmentation and Inflammation in One Hormone

JMWritten & reviewed by Jack Muncaster · Founder, UK PeptidesLast reviewed 2026-08-233 cited sources

Alpha-melanocyte-stimulating hormone is a 13-residue peptide at 1,664.9 Da, derived from proopiomelanocortin. It drives pigmentation through melanocortin receptors and separately has well-described anti-inflammatory activity, which localises to its C-terminal tripeptide.

Key facts

Length: 13 residues
Molecular weight: 1,664.9 Da
Formula: C77H109N21O19S
PubChem CID: 16133793
Precursor: Proopiomelanocortin (POMC)
Pigmentation via: Melanocortin-1 receptor
Anti-inflammatory region: C-terminal Lys-Pro-Val

Where it comes from

Alpha-MSH is cleaved from proopiomelanocortin, a precursor protein that also yields ACTH, beta-endorphin and other peptides. One gene product, several signalling molecules — the same architecture that produces GLP-1 and oxyntomodulin from proglucagon. Which peptides emerge depends on which processing enzymes are present in a given tissue.

The pigmentation function

Alpha-MSH acts on the melanocortin-1 receptor on melanocytes, stimulating melanin synthesis. This is the activity the hormone is named for and the one Melanotan II was designed to exploit. It is receptor-mediated, well characterised, and entirely separate from what the C-terminal tripeptide does.

Research material referenced

KPV 10mg — third-party HPLC tested

View — £24.99

The anti-inflammatory function

Alpha-MSH also has described anti-inflammatory activity, reviewed by Luger and colleagues in the Annals of the New York Academy of Sciences in 2003 and by Brzoska and colleagues in 2010. Brzoska's title — terminal signal — refers directly to the finding that this activity is carried by the hormone's C-terminal end rather than the receptor-binding core.

Why one hormone does two unrelated things

Different regions of the molecule. The core sequence engages melanocortin receptors and drives pigmentation; the C-terminal three residues carry anti-inflammatory activity through mechanisms that do not require the same receptor engagement. A single peptide with two functionally separable domains is not unusual, but it is unusually clean here.

The two fragments that followed

The separation produced two quite different research compounds. KPV takes the anti-inflammatory C-terminus without the pigmentation activity. Melanotan II takes the opposite approach — a cyclic analogue built around the melanocortin-receptor-binding portion, designed to maximise the pigmentation effect. Same parent hormone, opposite halves of its function.

Extended research context

The KPV deep dive

Deep dive: two functions in one hormone, and the case for splitting them

Alpha-MSH is a thirteen-residue peptide cleaved from proopiomelanocortin, and it does two things that have almost nothing to do with each other. Its core sequence engages melanocortin receptors on melanocytes and drives melanin synthesis - the activity it is named for. Separately, it carries anti-inflammatory activity that Brzoska and colleagues localised to its C-terminal end, a paper titled 'terminal signal' precisely because the finding was that the signal sits at the terminus rather than in the receptor-binding core. That is an unusually clean functional separation, and it produced two research compounds pulling in opposite directions from one parent. KPV takes the C-terminal three residues and discards the pigmentation activity. Melanotan II does the reverse - a cyclic analogue built around the receptor-binding portion to maximise exactly what KPV was designed to leave behind. Same hormone, opposite halves.

Deep dive: what happens when you shrink a molecule fivefold

Going from alpha-MSH at 1,664.9 Da to KPV at 342.43 Da is not a trim, it is a change of category. A 1,665 Da peptide is firmly a cell-surface ligand - far too large to cross a membrane passively, so whatever it does must begin at a receptor. A 342 Da tripeptide is small enough that intracellular access becomes plausible, which is why KPV's reported mechanism is described in terms of NF-kappaB signalling rather than melanocortin receptor engagement. The consequence is rarely stated: if the fragment acts inside the cell and the parent acts at its surface, then the anti-inflammatory activity of the two is not necessarily the same phenomenon, and read-across between them should run cautiously in both directions. Fragment logic assumes the fragment is the parent minus something. Here it may be the parent minus something plus a different route of access.

Deep dive: the delivery paper is the most informative thing in the literature

Xiao and colleagues published in Molecular Therapy in 2017 on delivering KPV orally using hyaluronic acid-functionalised nanoparticles targeted to inflamed intestinal tissue. Read as a result it is a delivery success. Read as a statement about the compound it is more interesting: nobody builds a targeted nanoparticle carrier for a molecule that already reaches its target. The existence of that work says the free tripeptide's arrival at inflamed tissue was the limiting problem - which follows directly from being 342 Da, highly soluble and rapidly cleared. It is the same signal that CJC-1295's DAC modification carries for growth hormone secretagogues, or that lipidation carries across the whole incretin class: when the engineering effort goes into getting a compound to stay and arrive rather than into making it more active, the pharmacokinetics were the bottleneck.

Research applications

▸Melanocortin fragment structure-activity research
▸NF-kappaB pathway and cytokine production studies in culture
▸Murine models of induced intestinal inflammation
▸Targeted peptide delivery and carrier system development
▸Comparative work on parent hormones and isolated fragments
▸Analytical method development for very short peptides

Handling checklist

✓Verify identity against Lys-Pro-Val, CID 125672, at 342.43 Da
✓Do not search PubChem for 'KPV' - it returns an unrelated organic acid
✓Store lyophilised, cold, dry and dark
✓Use low-binding consumables; a small cationic peptide adsorbs to surfaces
✓Reconstitute gently down the vial wall and swirl, never shake
✓Aliquot into single-use volumes to avoid freeze-thaw cycling
✓Expect no disulfide or oxidation satellites - no cysteine, no methionine

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Searching PubChem for 'KPV' to verify a certificate

Fix: That returns CID 13294447, 2-oxo-5-phenylpentanoic acid at 192.21 Da, an unrelated compound. Search Lys-Pro-Val for CID 125672.

✗ Treating KPV and alpha-MSH findings as interchangeable

Fix: They differ fivefold in mass and the fragment may act intracellularly where the parent cannot. Read across cautiously in both directions.

✗ Assuming a colitis model result speaks to inflammatory bowel disease

Fix: Induced colitis in a mouse is acute and chemical; human IBD is chronic, heterogeneous and immunologically complex.

✗ Expecting to quantify KPV by absorbance at 280 nm

Fix: There is no aromatic residue in the sequence, so there is no usable absorbance there.

✗ Attributing unexplained low recovery to degradation

Fix: KPV is chemically robust - no cysteine, methionine or asparagine. Adsorption to glass and plastic is the more likely cause.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Frequently asked questions

What does alpha-MSH do?: Two separable things: drives pigmentation through melanocortin receptors, and carries anti-inflammatory activity in its C-terminal region.
Where does it come from?: It is cleaved from proopiomelanocortin, the same precursor that yields ACTH and beta-endorphin.
How do KPV and Melanotan II relate?: Both derive from alpha-MSH but take opposite halves of its function — KPV the anti-inflammatory C-terminus, Melanotan II the pigmentation-driving core.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

Written and reviewed by

Jack Muncaster · Founder, UK Peptides

Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.

How we write and check this content Report a factual error in this article

Popular across the research hub

One flagship guide from every other research category — keep exploring.

← Back to Forum