LL-37 is the only human cathelicidin antimicrobial peptide, a 37-amino-acid cationic peptide (sequence: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) with broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, viruses, and biofilms. Beyond direct pathogen killing, LL-37 has immunomodulatory, wound-healing, and angiogenic properties. It is naturally produced by epithelial cells and immune cells as part of innate immunity, with vitamin D stimulating its endogenous production. A randomized controlled trial has evaluated topical LL-37 in venous leg ulcers.
13 vendors tracked by PeptideAtlas list LL-37, priced from $44.99 to $129. The lowest price per milligram is $5.00/mg at Growth Guys (10mg).
Category: Antimicrobial / Immune. Evidence rating: D (animal/preclinical only).
Clinical status: Investigational / Limited clinical trial data (topical wound healing RCT exists)
LL-37 (C120H232N42O38) carries a net positive charge (+6) that binds negatively charged bacterial membranes, creating transmembrane pores causing cell lysis. It also has anti-biofilm activity. Immunomodulatory functions include both pro- and anti-inflammatory responses: it neutralizes endotoxins…
Research base: 13 registered clinical trials and 28 indexed publications reference LL-37.
Safety considerations: No large-scale completed human safety trials for systemic therapeutic use; Endogenous peptide -- naturally produced; levels are tightly regulated in healthy tissue; Injection site reactions: redness, itching, swelling due to mild inflammatory properties and local immune cell recruitment (~5-10% of users).
Reviewed by the PeptideAtlas Editorial Team.
| Amino-acid sequence | 37-amino acid cathelicidin antimicrobial peptide |
|---|---|
| Molecular weight | ~4493.3 g/mol |
| Half-life | Minutes in plasma; tissue activity persists longer |
| Production method | synthetic |
| Anti-doping status | not-listed |
| US regulatory status | Not FDA-approved. Removed from FDA Category 2 on April 15, 2026. PCAC review scheduled July 23-24, 2026. Previously classified as Category 2, prohibiting compounding. No FDA-approved therapeutic formulation. |
| Vendor | Size | Price | Price per mg |
|---|---|---|---|
| Growth Guys | 10mg | $50.00 | $5.00/mg |
| Pacific Peptide | 10mg | $70.00 | $7.00/mg |
| Ameano Peptides | 10mg | $80.00 | $8.00/mg |
| Orbitrex Peptides | 5mg | $44.99 | $9.00/mg |
| Athena Peptides | 5MG | $45.00 | $9.00/mg |
| PureRx Peptides | 5mg | $49.00 | $9.80/mg |
| Red Fox Peptides | 5 mg | $55.00 | $11.00/mg |
| Liberty Peptides | 5mg | $59.00 | $11.80/mg |
| Wholesale Peptide | 5mg | $59.49 | $11.90/mg |
| Ascension Peptides | 10MG | $120 | $12.00/mg |
| Lucky Link Peptides | 10MG | $129 | $12.90/mg |
| Protide Health | 5mg | $75.00 | $15.00/mg |
| NUPEPS Peptides | 5mg | $85.00 | $17.00/mg |
Related peptides: Beta-Defensins, Alpha-Defensins, Lactoferricin.
Yes. LL-37 is produced by epithelial cells, neutrophils, and other immune cells as part of the innate immune response. Vitamin D stimulates its endogenous production, which is one reason vitamin D status is linked to immune function.
Injectable research protocols typically use 100-200 mcg per injection SC, 1-3 times per week, cycling 2-4 weeks on with an equal break. Topical applications use 0.5-1% concentrations. Lower doses are safer and more physiologically mimetic of native cathelicidin responses.
Potentially yes. LL-37 can stimulate dendritic cells and inflammasomes (via P2X7 receptor), which could worsen symptoms in individuals with autoimmune predispositions or chronic inflammatory conditions. Systemic use should be avoided without medical oversight in these patients.
Yes. LL-37 has demonstrated anti-biofilm activity in addition to its direct antimicrobial effects, making it of particular interest for chronic wound infections where biofilms are a major barrier to healing.
A randomized controlled trial evaluated topical LL-37 in venous leg ulcers. Systemic injectable use has not been evaluated in large clinical trials. Most evidence comes from preclinical studies and ex vivo human tissue experiments.
Vendors stocking it: Polar Peptides, Liberty Peptides, NUPEPS Peptides, Ameano Peptides, Pacific Peptide, Ascension Peptides, Wholesale Peptide, Athena Peptides, PureRx Peptides, RipTidez, Catalyst Peptides, Protide Health, Tide Labs, Bluewell Peptides, utherpeptide, Uther, Disguised Alpha, Growth Guys, Pure Peptides UK, Orbitrex Peptides, Wuhan Newtop Biotech, BPX Research, Mile High Compounds, Topstide.