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No. 041 · Longevity & Immune · Immune Peptide

LL-37

Cathelicidin LL-37CAMP (cathelicidin antimicrobial peptide)

A Tier A · Controlled human trials how tiers work →
  • Not FDA approved
  • WADA ✗ S0
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37 residues C205H340N60O53
O O O O O H O O O O O O O H O O H O H O O O O O H O O O O O O O O O O O O O O O O O O H O O O H O H O O O O O O O O O O H O N N H N H N H N H N H N H N H N 2 H N H N H N H N 2 H N H N H N H N 2 H N H N H N H N H N H N H N H N H N H N 2 H N H N H N H N H N 2 H N H N H N 2 H N H N 2 H N H N H N H N H N 2 H N H N H N H N 2 H N H N 2 H N H N 2 H N H N H N 2 H N H N H N H N H N 2 H N 2 H N H

2D structure from PubChem CID 16198951 (LL-37), matched by molecular formula. Hydrogens on carbon are implied.

LL-37 sequence fingerprint
  • Nonpolar 16
  • Polar 5
  • Positive charge 11
  • Negative charge 5

Each dot is a residue placed around the ring from N- to C-terminus; its distance from the centre reflects its chemistry.

01

Quick answers

What is LL-37?
The only human cathelicidin antimicrobial peptide, LL-37 plays a key role in innate immunity by disrupting microbial membranes and modulating inflammatory signaling.
How strong is the evidence for LL-37?
Tier A (controlled human trials) on the peptidemeta evidence scale. Randomized placebo-controlled trials of topical LL-37 for venous leg ulcers (2014 phase 1/2; 2021 multicentre phase 2b) and diabetic foot ulcers (2023). Not approved anywhere.
Is LL-37 FDA-approved?
No. LL-37 is not approved by the FDA for any use.
Is LL-37 banned in sport?
Yes. LL-37 is prohibited in sport by the World Anti-Doping Agency under S0 (non-approved substances).
How does LL-37 work?
LL-37 is a 37-amino-acid amphipathic alpha-helical peptide that disrupts microbial membranes through electrostatic interaction with negatively charged lipid bilayers. Beyond direct antimicrobial killing, it acts as an immune alarmin by binding formyl peptide receptor 2 (FPR2) to recruit neutrophils, monocytes, and T-cells, and it disrupts bacterial biofilms.
What is known about the safety of LL-37?
Endogenous human peptide with well-established innate immune biology. Injection of exogenous LL-37 carries risk of excessive inflammation at high doses.

Last reviewed · editorial policy · markdown

02

Evidence

  1. D In vitro
  2. C Animal
  3. B Human pilot
  4. A RCT
  5. S Approved

TIER A — At least one published randomized controlled trial in humans.

Randomized placebo-controlled trials of topical LL-37 for venous leg ulcers (2014 phase 1/2; 2021 multicentre phase 2b) and diabetic foot ulcers (2023). Not approved anywhere.

Tiers rate the strength of published evidence — not effectiveness, safety, or a recommendation.

03

At a glance

Residues
37 amino acids, N→C
Molecular weight
4,493 Da
Formula
C205H340N60O53
Routes studied
Subcutaneous, Intramuscular Routes used in published research
FDA
Not approved
WADA
Prohibited · S0 Non-approved substances
04

Sequence

N → C · 37 residues · hover, tap, or use arrow keys to inspect

Note Residues 134–170 of the human cathelicidin precursor hCAP18 (UniProt P49913).

05

Overview

The only human cathelicidin antimicrobial peptide, LL-37 plays a key role in innate immunity by disrupting microbial membranes and modulating inflammatory signaling.

Research status Extensive basic science research; randomized placebo-controlled trials of topical LL-37 for venous leg ulcers (2014, 2021) and diabetic foot ulcers (2023); no approved product

06

Mechanism

LL-37 is a 37-amino-acid amphipathic alpha-helical peptide that disrupts microbial membranes through electrostatic interaction with negatively charged lipid bilayers. Beyond direct antimicrobial killing, it acts as an immune alarmin by binding formyl peptide receptor 2 (FPR2) to recruit neutrophils, monocytes, and T-cells, and it disrupts bacterial biofilms.

07

Effects reported in research

Reported outcomes, not promises. Some come from controlled human trials; others may be from smaller or preclinical studies — check the studies below.

  • Broad-spectrum antimicrobial activity
  • Biofilm disruption on mucosal surfaces
  • Immune cell chemotaxis and activation
  • Wound healing acceleration
08

Safety & unknowns

Endogenous human peptide with well-established innate immune biology. Injection of exogenous LL-37 carries risk of excessive inflammation at high doses. Potential for mast cell activation. Limited formal clinical trial data for therapeutic injection. Not FDA-approved.

Unknowns. Trial safety data apply to the populations, formulations and conditions studied.

Informational only — not medical advice. peptidemeta publishes no dosing, protocols, or sourcing. Talk to a qualified clinician about any treatment decision.

09

Studies [2]

  1. Clinical trial 2014

    Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial

    Grönberg A, Mahlapuu M, Ståhle M, et al. Wound Repair and Regeneration

    Randomized placebo-controlled trial of topical LL-37 in patients with hard-to-heal venous leg ulcers, assessing safety and ulcer healing.

    [pubmed] [doi]

  2. Review 2012

    A comprehensive summary of LL-37, the factotum human cathelicidin peptide

    Vandamme D, Landuyt B, Luyten W, et al. Cellular Immunology

    Review of LL-37 covering its antibacterial, antifungal and antiviral activity, chemotactic and immunomodulatory effects, and roles in wound healing.

    [pubmed] [doi]

11

Status sources

Sources behind the tier, regulatory status, sequence and dates on this page.

12

Cite this entry

$ cite --format=apa

peptidemeta. (2026). LL-37. In peptidemeta: The peptide library, ranked by evidence. Retrieved November 8, 2026, from https://peptidemeta.com/p/ll-37/

$ cite --format=bibtex 
@misc{peptidemeta-ll-37,
  title = {LL-37},
  author = {{peptidemeta}},
  year = {2026},
  howpublished = {\url{https://peptidemeta.com/p/ll-37/}},
  note = {Accessed 2026-11-08}
}

Accessed date reflects when you opened this page. Cite primary studies for scientific claims.

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