Buy LL-37 Cathelicidin Peptide 5mg | Broad-Spectrum Antimicrobial & Wound Healing Research

Most antimicrobial compounds do one job. They kill pathogens — and in doing so, they disrupt the microbiome, accelerate resistance, and leave the immune system to clean up the damage alone. LL-37 does something fundamentally different. It kills pathogens directly, dismantles their biofilms, modulates the immune response, promotes new blood vessel formation, and accelerates wound closure — simultaneously, through the same compound.

LL-37 is not a synthetic invention built in a laboratory. It is the only human cathelicidin — a 37-amino acid antimicrobial peptide produced naturally by neutrophils, macrophages, mast cells, and epithelial cells as the body’s first line of innate immune defence. It is released precisely at sites of infection and inflammation, where it eliminates threats and coordinates the healing response in the same action. Researchers studying antimicrobial resistance, chronic wound healing, innate immunity, antiviral defence, and oncology are working with LL-37 because no synthetic antibiotic replicates this dual-function biological profile.

LL-37 effectively combats over 38 bacteria, 16 fungi, and 16 viruses through multiple mechanisms including membrane rupture, targeting, and biofilm suppression. Research has shown LL-37 reduces biofilm density by up to 60% — a finding that directly addresses one of the most stubborn problems in chronic wound and antibiotic-resistance research. ScienceDirectMDPI

Get research-grade LL-37 from PeptideNexusLab — 5mg per vial, ≥98% purity, COA included, fast global shipping.

What Is LL-37?

LL-37 is the active human cathelicidin antimicrobial peptide — a naturally occurring 37-amino acid peptide that constitutes a primary innate immune defence against bacterial and fungal pathogens. It is produced by white blood cells, particularly neutrophils and macrophages, and is released at sites of infection or inflammation where it kills pathogens directly through multiple mechanisms.

The name LL-37 refers to its structure: it begins with two leucine (L) residues and contains 37 amino acids in total. Its full designation is CAMP (cathelicidin antimicrobial peptide), also known as hCAP18 in its precursor form. In humans, LL-37 is the only cathelicidin, making it a critical and non-redundant component of innate immunity.

What makes LL-37 structurally unique among antimicrobial peptides is its amphipathic alpha-helix conformation — one face of the helix is hydrophobic, the other is positively charged. This architecture allows it to interact directly with negatively charged bacterial cell membranes, insert into them, and disrupt their integrity from within. It cannot develop resistance the way conventional antibiotics can because it targets the fundamental physical properties of bacterial membranes rather than a specific protein target that can mutate.

The C-terminal region of LL-37 is crucial for its antimicrobial, anticancer, and antiviral activities, while the N-terminal region contributes to chemotaxis and immune cell recruitment. This regional specialisation within a single 37-residue peptide is part of what makes LL-37 one of the most research-active compounds in the antimicrobial peptide field.

Mechanism of Action

Direct membrane disruption

LL-37’s primary antimicrobial mechanism is direct physical disruption of pathogen cell membranes. Its amphipathic helix inserts into the lipid bilayer of bacterial membranes, forming pores or causing complete membrane destabilisation through a carpet model of disruption. The positive charge of LL-37 is attracted to the negatively charged phospholipids dominant in bacterial membranes — a selectivity that spares mammalian cells whose outer membranes carry predominantly neutral lipids. This electrostatic selectivity is the mechanistic basis for LL-37’s therapeutic window.

Biofilm disruption and prevention

LL-37 has demonstrated antimicrobial and anti-biofilm activity against multiple Gram-positive and Gram-negative human pathogens. Biofilms are structured bacterial communities encased in a protective extracellular matrix that makes them 10–1,000 times more resistant to conventional antibiotics than planktonic bacteria. LL-37 disrupts biofilm architecture both by killing the bacteria within it and by interfering with the quorum-sensing signals bacteria use to coordinate biofilm formation. Research has demonstrated LL-37 reduces biofilm density by up to 60% — making it one of the most effective anti-biofilm compounds documented in the preclinical literature.

Immune modulation and chemotaxis

Beyond direct pathogen killing, LL-37 acts as an immunomodulatory signal. It recruits neutrophils, monocytes, and mast cells to infection sites through chemotactic receptor activation. It modulates Toll-like receptor (TLR) signalling — reducing excessive inflammatory responses that cause tissue damage while maintaining the immune system’s ability to eliminate pathogens. This balanced immunomodulation positions LL-37 as a compound that fights infection without the collateral inflammatory damage characteristic of many innate immune responses.

Angiogenesis promotion

LL-37 promotes angiogenesis — the formation of new blood vessels — through upregulation of VEGF (vascular endothelial growth factor) and activation of the FPRL-1 (formyl peptide receptor-like 1) receptor on endothelial cells. New vessel formation is a critical requirement for wound healing, as damaged tissue cannot repair without adequate blood supply. This angiogenic activity contributes directly to LL-37’s wound healing properties in chronic wound models.

Wound healing and re-epithelialisation

LL-37 modulates wound healing and has been shown to increase the migration rate of keratinocytes — the skin cells responsible for re-epithelialisation and wound closure. It also activates fibroblast proliferation and collagen synthesis, addressing both the cellular and structural components of wound repair. The combination of anti-biofilm effect and wound-healing properties of LL-37 may make it highly effective in resolving polymicrobially infected wounds when topically applied.

Antiviral activity

LL-37 has garnered significant interest due to its potent antimicrobial, antiviral, antifungal, antiparasitic, and antitumour properties. Its antiviral mechanism involves direct disruption of viral envelopes, inhibition of viral attachment to host cell receptors, and immune activation that accelerates viral clearance. It has demonstrated activity against influenza, HIV, herpes simplex virus, and respiratory syncytial virus in preclinical models.

Anticancer activity — dose-dependent and context-specific

LL-37’s relationship with cancer research is nuanced and requires careful understanding. At higher concentrations, LL-37 induces anti-cancer effects in colon cancer, gastric cancer, hematologic malignancies, and oral squamous cell carcinoma. The mechanism at higher concentrations involves direct cytotoxicity through membrane disruption of cancer cells, induction of apoptosis, and immune activation against tumour cells. At lower concentrations, however, some pro-tumorigenic effects have been documented in certain cancer types. Researchers studying oncology applications must design protocols accounting for this concentration-dependent duality.

Research Evidence

Chronic wound and infected wound healing

The most directly translational evidence base for LL-37 concerns chronic and infected wound healing. The single human cathelicidin peptide LL-37 has been shown to have antimicrobial and anti-biofilm activity against multiple Gram-positive and Gram-negative human pathogens, and wound-healing effects on the host. In infected wound models combining bacterial infection with impaired healing — conditions that mirror clinical chronic wounds — LL-37 addressed both the infectious and regenerative deficits simultaneously.

Topical application has been the most studied delivery route for wound applications, with studies demonstrating LL-37’s ability to clear biofilm-forming organisms, reduce local inflammation, and accelerate closure through keratinocyte migration and fibroblast activation in the same protocol.

Skin research — UV protection and photodamage repair

LL-37 at 50 µM demonstrated effective photodamage repair, increasing the survival of UVB-irradiated keratinocytes by 14.6% and UVA-irradiated human dermal fibroblasts by 11.8% in 2025 research. The same study confirmed no cytotoxicity to these cell types at this concentration — an important safety signal for dermatological research applications.

Pancreatic cancer research

LL-37 inhibited the growth of pancreatic cancer both in vitro and in vivo. Mechanistic studies demonstrated that LL-37 induced DNA damage and cell cycle arrest through induction of reactive oxygen species (ROS), and suppressed autophagy in pancreatic cancer cells through activation of mTOR signalling, leading to accumulation of ROS production and induction of mitochondrial dysfunction. Pancreatic cancer is among the most treatment-resistant malignancies — evidence of LL-37 activity in this model represents a significant research finding.

Antimicrobial resistance research

LL-37’s membrane-disruption mechanism makes resistance development substantially more difficult than for conventional antibiotics, which typically target specific proteins that can mutate. This property makes LL-37 a compound of high interest for antimicrobial resistance research — studying its activity in antibiotic-resistant pathogen models, using it as a sensitising agent alongside sub-inhibitory antibiotic concentrations, or characterising its activity in biofilm models of MRSA and other resistant organisms.

Bone biology

Research published in Physiological Research documented LL-37 improving bone metabolism via the Wnt/β-Catenin pathway — an emerging application area for osteoporosis and bone remodelling research programmes.

Dosing Protocols — Preclinical Research Reference

⚠️ The following is drawn entirely from published preclinical studies and in vitro research protocols. No standardised human clinical dosing exists for LL-37 as a standalone research peptide. This information is provided for research planning and educational reference only. PeptideNexusLab does not recommend or endorse human self-administration.

Subcutaneous injection (systemic research)

Research dose range: 100–500 mcg daily Frequency: Once daily in most published protocols Common stack: LL-37 subcutaneous combined with KPV for synergistic antimicrobial and anti-inflammatory coverage, particularly in infected wound and inflammatory skin models

Topical application (wound and skin research)

Concentration range: 1–50 µM in solution or compounded formulations Application: Direct application to target tissue area once or twice daily Best studied for: Infected wound healing, biofilm disruption, chronic wound models, UV photodamage repair Evidence basis: 2025 keratinocyte migration and UV repair studies; multiple biofilm disruption studies; polymicrobial wound models

In vitro research concentrations

For cell culture work: 5–50 µg/mL is the most commonly referenced range across the published literature. Cytotoxicity to human keratinocytes and dermal fibroblasts was not observed at 50 µM in 2025 research — a useful safety reference point for in vitro protocol design.

Reconstitution Guide

What you need

Step-by-step reconstitution

Step 1 — Remove the LL-37 vial from cold storage 10–15 minutes before use. Allow it to reach room temperature naturally. Do not force-warm.

Step 2 — Wipe the rubber stopper with a 70% IPA swab and allow 30 seconds to dry fully. Repeat every time you access the vial without exception.

Step 3 — Draw your target BAC water volume into the syringe. Inject slowly down the inner glass wall of the vial — not directly onto the powder. This prevents foaming and mechanical stress on the peptide structure.

Step 4 — Swirl gently between your palms in slow circular motions for 2–3 minutes. Do not shake. LL-37’s alpha-helical structure is sensitive to mechanical agitation. Swirl until you have a clear, uniform solution.

Step 5 — Inspect the solution. Clear to slightly pale is expected and correct. Cloudy, discoloured, or particulate — discard immediately.

Step 6 — Label with reconstitution date and concentration. Refrigerate immediately at 2–8°C. Use within 28 days. Protect from direct light between uses.

Standard concentration reference

Add 1 mL bacteriostatic water to a 5 mg vial → 5,000 mcg/mL solution. A 500 mcg research dose = 0.10 mL = 10 units on a U-100 insulin syringe. LL-37 is dosed in micrograms — label vials clearly when stacking with milligram-dosed peptides.

Storage Guide

LL-37 Stacking Protocols

LL-37 + KPV — antimicrobial and anti-inflammatory stack

The most directly complementary LL-37 combination. LL-37 kills pathogens directly and disrupts biofilms. KPV suppresses the NF-κB and NLRP3 inflammatory signalling that infected and damaged tissue generates — reducing the excessive inflammatory response that impairs wound closure even after the infection is cleared. Together they address both the infectious and inflammatory obstacles to healing simultaneously. Particularly relevant for chronic wound, skin infection, and gut inflammation research models.

LL-37 + GHK-Cu — advanced wound healing stack

GHK-Cu drives collagen synthesis, fibroblast proliferation, and angiogenesis — the structural repair components of wound healing. LL-37 provides antimicrobial protection and keratinocyte migration stimulus. Combined, this stack covers the full wound healing sequence: infection clearance, inflammation modulation, vascular ingrowth, and structural tissue regeneration. Among the most comprehensively studied topical peptide combinations for chronic wound models.

LL-37 + BPC-157 — tissue repair and infection control stack

BPC-157 drives structural tissue repair through VEGF and growth hormone receptor upregulation. LL-37 provides direct pathogen clearance and immune modulation. In wound models where infection and structural tissue damage co-exist, this combination addresses both components independently through non-overlapping mechanisms.

Vial Specifications

Global Regulatory Status

United States — Not FDA-approved for any indication. Not a scheduled controlled substance. Available for qualified laboratory and in vitro research use. Not for human consumption or clinical administration.

United Kingdom — Not classified under the Misuse of Drugs Act 1971. Not licensed as a medicinal product by the MHRA. Legal to purchase for bona fide laboratory research purposes.

European Union — Not approved by the EMA. Research chemical status applies; human administration not approved. Researchers should verify country-specific import requirements.

Australia — Not listed on the ARTG. Research chemical status; TGA has not approved human use.

Canada — Not scheduled under the CDSA. Available for legitimate laboratory research.

WADA — Not currently listed on the WADA Prohibited List as of 2026. Athletes subject to anti-doping regulations should confirm current status before procurement.

Frequently Asked Questions

What is LL-37 used for in research? LL-37 is studied for its broad-spectrum antimicrobial activity, biofilm disruption, wound healing promotion, innate immune modulation, antiviral defence, and — at higher concentrations — anticancer activity in gastrointestinal and haematological cancer models. It is the only human cathelicidin, making it a foundational compound in innate immunity research.

How does LL-37 kill bacteria without creating resistance? LL-37 physically disrupts bacterial cell membranes through its amphipathic alpha-helix structure — targeting the negatively charged lipids fundamental to bacterial membrane composition. Because this mechanism targets a basic physical property of bacterial membranes rather than a specific protein, bacteria cannot easily mutate away from it the way they do with conventional antibiotics. This makes LL-37 particularly relevant for antimicrobial resistance research.

What is the difference between LL-37 and conventional antibiotics? Conventional antibiotics typically target one specific bacterial protein or pathway — a selectivity that makes resistance easy to develop. LL-37 disrupts bacterial membranes physically, kills multiple pathogen types (bacteria, fungi, viruses) through overlapping mechanisms, dismantles biofilms, modulates host immune response, and promotes wound healing. No conventional antibiotic replicates this multi-functional profile.

Does LL-37 have anticancer properties? Yes — but the relationship is concentration-dependent. At higher concentrations in preclinical models, LL-37 demonstrates cytotoxic and anti-tumour effects in colon, gastric, pancreatic, and haematological cancer models. At lower concentrations, some pro-tumorigenic effects have been documented in certain cancer types. Oncology researchers must design protocols that account carefully for this dose-dependent duality.

Can LL-37 be used topically? Yes. Topical application is the most studied delivery route for LL-37’s wound healing and skin research applications. Studies have demonstrated keratinocyte migration, UV photodamage repair, biofilm disruption, and anti-inflammatory activity via topical administration in preclinical models.

How does LL-37 compare to KPV for wound research? They address different aspects of the same problem. LL-37 kills pathogens directly, disrupts biofilms, and stimulates keratinocyte migration — targeting the infectious and structural components of wound healing. KPV suppresses NF-κB and NLRP3 inflammatory signalling — targeting the inflammatory environment that impairs healing. In infected wound models, both mechanisms are required. They are among the most complementary stacking combinations in the recovery and healing peptide category.

Is LL-37 the same as hCAP18? No — but they are related. hCAP18 is the full-length 170-amino acid precursor protein. LL-37 is the active 37-amino acid C-terminal peptide cleaved from hCAP18 by the protease proteinase 3. Research preparations use the active LL-37 fragment, not the full-length precursor.

Does LL-37 affect the microbiome? Unlike broad-spectrum antibiotics which cause widespread microbiome disruption, LL-37’s selectivity for negatively charged bacterial membranes — combined with its immunomodulatory rather than purely bactericidal mechanism at sub-lethal concentrations — makes it less disruptive to commensal microbiota than conventional antibiotics. This property is actively studied in gut and skin microbiome research contexts.

References

1. Zhang ZT, Wu YC, Dong CM. (2025). Cathelicidin LL-37: mechanisms of action and research progress. Infectious Disease Research, 6(4):19.
2. Voronko OE, et al. (2025). Antimicrobial peptides of the cathelicidin family: focus on LL-37 and its modifications. International Journal of Molecular Sciences, 26(16):8103.
3. Souto EB, et al. (2025). Wound healing: molecular mechanisms, antimicrobial peptides, and emerging technologies in regenerative medicine. Pharmaceuticals, 18(10):1525.
4. Liang J, et al. Cathelicidin LL-37 improves bone metabolism via the Wnt/β-Catenin pathway. Physiological Research.
5. Dong H, et al. (2022). The human cathelicidin peptide LL-37 inhibits pancreatic cancer growth by suppressing autophagy and reprogramming of the tumour immune microenvironment. Frontiers in Pharmacology.
6. Dean SN, et al. (2011). The human cathelicidin antimicrobial peptide LL-37 as a potential treatment for polymicrobial infected wounds. Frontiers in Microbiology.

⚠️ Research Use Only: LL-37 is intended strictly for qualified in vitro laboratory research by trained professionals. Not for human or animal consumption. Not evaluated or approved by the FDA, EMA, MHRA, or TGA. Purchasers confirm compliance with all applicable local regulations.