Scientifically reviewed by Dr Stephan Hansberg
LL-37 peptide: structure, research and legal status (2026)
LL-37 is the only human cathelicidin, a 37-amino-acid antimicrobial peptide cut from the hCAP18 precursor. Its identity data, discovery, research by model, registered trials and regulatory status in 2026.
Key takeaways
- •LL-37 is a 37-amino-acid peptide (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES), the active fragment of the human cathelicidin precursor hCAP18, encoded by the CAMP gene.
- •Its international non-proprietary name is ropocamptide. It was identified in 1995 to 1996 by Agerberth, Gudmundsson and colleagues.
- •It is studied as an antimicrobial and immune-signalling peptide in cell work, and in small human trials in hard-to-heal venous leg ulcers and diabetic foot ulcers.
- •It is not an approved medicine in the US, UK or Australia and was not part of the July 2026 FDA compounding review.
- •Research also links LL-37 to inflammatory skin disease and to toxicity in some human cell types, which is part of why its biology is described as double-edged. Celyfe does not sell LL-37.
What is LL-37?
LL-37 is a 37-amino-acid antimicrobial peptide produced by the human body, named after its first two residues (two leucines) and its length. It is the only member of the cathelicidin family in humans and is cut from a larger precursor protein, hCAP18, mainly in white blood cells and epithelial tissues.
In research it is studied as part of innate immunity: it can disrupt bacterial membranes in laboratory assays and also acts as a signalling molecule on human immune cells. Small randomised trials have tested topical LL-37 in chronic leg and foot ulcers, but it is not an approved medicine.
Identity at a glance
Identifiers checked against PubChem and UniProt.
| Property | LL-37 |
|---|---|
| Aliases | Cathelicidin LL-37, ropocamptide (INN), CAP18 fragment; precursor hCAP18; gene CAMP |
| Sequence (37 aa) | LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES |
| Molecular formula | C205H340N60O53 |
| Molar mass | approx. 4493 g/mol |
| CAS number | 154947-66-7 |
| PubChem CID | 16198951 |
| FDA UNII | 3DD771JO2H |
| UniProt (precursor) | P49913 (CAMP_HUMAN); LL-37 is the C-terminal 37 residues |
Origin and discovery
In 1995 Agerberth and colleagues described FALL-39, a putative human antibacterial peptide, from a cDNA expressed in bone marrow and testis. In 1996 Gudmundsson and colleagues characterised the human gene and showed that the processed peptide found in granulocytes is two residues shorter, starting with two leucines, which gave it the name LL-37.
Dürr and colleagues' 2006 review describes LL-37 as the only human member of the cathelicidin family. In 2005 Gombart and colleagues showed that the CAMP gene is a direct target of the vitamin D receptor, linking LL-37 research to vitamin D biology in human cells.
What has been studied, by model
Representative published studies are below, with the model for each. Human trial rows describe what was tested, not established outcomes.
| Research area | Model | Example study (year, PMID) |
|---|---|---|
| Vitamin D regulation of the CAMP gene | Human cells | Gombart et al., FASEB J (2005), PMID 15985530 |
| Self-DNA sensing by plasmacytoid dendritic cells (psoriasis) | Human cells and patient skin samples | Lande et al., Nature (2007), PMID 17873860 |
| Structure in lipid micelles | Biophysical (NMR) | Wang, J Biol Chem (2008), PMID 18818205 |
| Hard-to-heal venous leg ulcers | Human, Phase I/II randomised | Gronberg et al., Wound Repair Regen (2014), PMID 25041740 |
| Hard-to-heal venous leg ulcers, multicentre | Human, randomised placebo-controlled | Mahlapuu et al., Wound Repair Regen (2021), PMID 34687253 |
| Diabetic foot ulcer, topical cream | Human, randomised double-blind | Miranda et al., Arch Dermatol Res (2023), PMID 37480520 |
| Osteoblast cytotoxicity | Human cells | Aidoukovitch et al., Biochem Biophys Res Commun (2024), PMID 38642493 |
Human trial status
Registered human studies of LL-37 as an intervention are few. Two are listed on ClinicalTrials.gov; the European venous leg ulcer trials above were published in Wound Repair and Regeneration. Many other ClinicalTrials.gov records mention LL-37 only as a biomarker, for example in vitamin D studies, and are not trials of the peptide.
| ClinicalTrials.gov ID | Study | Phase | Status (Oct 2026) |
|---|---|---|---|
| NCT02225366 | Intratumoral LL37, melanoma (MD Anderson Cancer Center) | Phase 1/2 | Completed |
| NCT04098562 | LL-37 cream, diabetic foot ulcers (Universitas Indonesia) | Phase 2 | Unknown |
Regulatory status in 2026
LL-37 has no marketing authorisation in the US, UK or Australia, and it was not one of the seven peptides at the FDA's July 2026 compounding advisory meeting.
| Authority | Status (checked October 2026) |
|---|---|
| US FDA | Not an approved drug. Not reviewed at the July 2026 Pharmacy Compounding Advisory Committee. |
| UK MHRA | No UK marketing authorisation. Medicines law applies if it is supplied for human use. |
| AU TGA | Not named in the Poisons Standard (October 2026 instrument). General rules for unapproved therapeutic goods still apply. |
| WADA 2026 | Not named. The S0 class covers substances with no current governmental approval for human therapeutic use; check with your anti-doping organisation. |
Stability and handling notes
LL-37 is long for a synthetic peptide and strongly cationic, with many lysines and arginines. In membrane-like environments it adopts an amphipathic helix, as Wang's 2008 NMR work showed, and amphipathic cationic peptides of this kind tend to self-associate and to stick to surfaces, which can complicate handling and analysis.
Its many lysine and arginine residues are also cleavage sites for trypsin-like proteases, so proteolytic fragments are a plausible impurity and degradation class. At this length, synthesis-related deletion sequences are a normal concern, which is why both HPLC purity and mass confirmation matter on a certificate.
Open questions
LL-37 is described as double-edged: alongside its antimicrobial role, it has been implicated in inflammatory skin disease such as psoriasis and shows toxicity to some human cell types in vitro. How those properties balance in any applied setting remains open. The larger 2021 multicentre venous leg ulcer trial reported no significant difference from placebo across its whole study cohort, so the clinical picture is unresolved.
Where Celyfe fits
Celyfe does not sell LL-37, and no Celyfe pen contains it. For any LL-37 source, ask for a batch certificate showing HPLC purity and mass confirmation for the specific batch. The COA library at /coa shows Celyfe's own published certificates, NAD+ batch A26085 and WOLVERINE batch C26071, both issued by Analiza Bialek, Wroclaw, on 2 October 2026.
Sources
Primary and official sources checked October 2026:
- PubChem: LL-37 (ropocamptide), CID 16198951 (pubchem.ncbi.nlm.nih.gov)
- UniProt: P49913, Cathelicidin antimicrobial peptide, Homo sapiens (uniprot.org)
- Agerberth B et al. FALL-39, a putative human peptide antibiotic, is cysteine-free and expressed in bone marrow and testis. Proc Natl Acad Sci USA, 1995. PMID 7529412
- Gudmundsson GH et al. The human gene FALL39 and processing of the cathelin precursor to the antibacterial peptide LL-37 in granulocytes. Eur J Biochem, 1996. PMID 8681941
- Gombart AF et al. Human cathelicidin antimicrobial peptide (CAMP) gene is a direct target of the vitamin D receptor. FASEB J, 2005. PMID 15985530
- Durr UH et al. LL-37, the only human member of the cathelicidin family of antimicrobial peptides. Biochim Biophys Acta, 2006. PMID 16716248
- Lande R et al. Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide. Nature, 2007. PMID 17873860
- Wang G. Structures of human host defense cathelicidin LL-37 and its smallest antimicrobial peptide KR-12 in lipid micelles. J Biol Chem, 2008. PMID 18818205
- Gronberg A et al. Randomised, placebo-controlled phase I/II trial of LL-37 in hard-to-heal venous leg ulcers. Wound Repair Regen, 2014. PMID 25041740
- Mahlapuu M et al. Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial. Wound Repair Regen, 2021. PMID 34687253
- Miranda E et al. Randomised double-blind controlled trial of LL-37 cream in diabetic foot ulcer. Arch Dermatol Res, 2023. PMID 37480520
- Aidoukovitch A et al. Vitamin D triggers hCAP18/LL-37 production: implications for LL-37-induced human osteoblast cytotoxicity. Biochem Biophys Res Commun, 2024. PMID 38642493
- ClinicalTrials.gov records NCT02225366, NCT04098562
- WADA: Prohibited List 2026, in force 1 January 2026 (wada-ama.org)
Research use only
Celyfe supplies research peptides for laboratory and research use only. Nothing on this page is guidance on use in humans or animals.
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