At a glance
- Class
- Cathelicidin antimicrobial peptide
- Receptor targets
- Bacterial membranes, FPR2 and other host receptors
- Length
- 37 amino acids
- Molecular mass
- ≈ 4.49 kDa
- Origin
- Human peptide, produced synthetically
- Research area
- Immune & inflammation research
- Also known as
- Human cathelicidin, hCAP-18 fragment
What LL-37 is
LL-37 is named for its two N-terminal leucines and its length. It is released from the precursor hCAP-18 by the enzyme proteinase 3 and is found in neutrophils, on epithelial surfaces and in body fluids.
In the lab it kills bacteria by disrupting membranes, but it also signals to immune and epithelial cells. That makes results hard to interpret, because an effect that looks antimicrobial in a dish may include host-cell responses, and high concentrations are toxic to host cells in vitro.
What the research literature studies
- Membrane disruption of bacteria in vitro
- Immune-cell signalling through FPR2 and other receptors
- Stability against proteases such as trypsin and neutrophil elastase
Evidence rating: 3/5
Early human trials. Early human trials of topical use. A phase 2b trial did not show a significant overall effect. See our methodology for how levels are assigned.
- The phase 2b trial of topical LL-37 in venous leg ulcers did not find a significant overall difference from placebo.
- Activity varies strongly with concentration, salt and serum, so published numbers are hard to compare.
Regulatory status
LL-37 is not an approved medicine with the MHRA, EMA or FDA. Research-grade material must not be used in people or animals.
Reviewed November 2026.
LL-37 at Nordapep: sizes and price per mg
Every size, its price and the cost per milligram, so you can choose the best-value vial for your protocol.
Not currently listed at Nordapep.
Compare LL-37
LL-37 FAQ
Why is it called LL-37?
It starts with two leucines (LL) and is 37 amino acids long.
Is LL-37 an antibiotic?
It is an antimicrobial peptide made by the human body. It is not an approved antibiotic, and activity in vitro supports no claim about treating infection.
Where can I buy LL-37 for research?
Nordapep does not currently list LL-37. You can ask Nordapep about availability, or compare related compounds that are in stock.
Is LL-37 approved?
LL-37 is not an approved medicine with the MHRA, EMA or FDA. Research-grade material must not be used in people or animals.
Key terms for LL-37
Cite this page
peptide.wiki. (2026). LL-37: research peptide profile. peptide.wiki. https://www.peptide.wiki/peptides/ll-37