LL-37

Lyophilized powder

LL-37 is the only human cathelicidin, a 37-amino-acid antimicrobial peptide made by immune and skin cells as part of innate immunity, studied for infection, inflammation and wound biology. Below: today's vial sizes, prices through our link and the vendor's COA details.

Size

$3.90/mg · In stock

Price

$39.00

List

$78.00

Buy 10 mg at Ascension Peptides

Price shown includes the 50% discount Ascension Peptides applies through our link.

Volume pricing at Ascension Peptides

3+ vials3% offin cart
5+ vials5% offin cart
10+ vials10% offin cart

Applied in Ascension Peptides's cart; how it combines with our discount is set at checkout.

Sold by Ascension Peptides. The Peptide Catalog does not sell peptides; we earn a commission if you buy through this link, at no extra cost to you. For laboratory research use only, not for human or veterinary use. Not FDA-approved. Nothing on this page is medical or dosing advice.

LL-37Ascension Peptides

Third-party testedResearch use only

Certificate of AnalysisVendor-stated: Third-party tested · HPLC · public COAView

Vendor-stated testing: Third-party tested · HPLC · public COA
Listed on our ll-37 vendor comparison, ordered by our vendor rankings
Lyophilized powder · laboratory research use only

Research-context information only. LL-37 is a research peptide. Protocols, doses, and reactions reported below come from published research and self-reported community sources. This article reports what has been documented, not what should be done. Consult a licensed physician for personal medical decisions.

Vial sizes listed by the vendor

LL-37 Vial Sizes & Prices

LL-37 vial sizes, prices and lots at Ascension Peptides
Size	List	Price	Per mg	Availability
10 mg	$78.00	$39.00	$3.90	In stock

Prices checked today, 5:02 AM CT on Ascension Peptides's site. Vendor-stated testing: Third-party tested · HPLC · public COA. The lot certificate is on Ascension Peptides's product page. Sizes not re-checked in the last 7 days are hidden. The vendor's checkout is final.

Test results

LL-37 Certificate of Analysis

Ascension Peptides publishes its certificates publicly (vendor-stated: Third-party tested · HPLC · public COA). Match the lot number on the vial to its certificate.

View the LL-37 certificate on Ascension Peptides's product page.

How to check one: how to verify a peptide COA.

LL-37 Dosing in Clinical Research

Immunity / Antimicrobial

Educational reference only. Individual responses vary. Consult healthcare provider before use.

Vial Size

5 mg

Reconstitution

2 ml BAC water

Dose

125 mcg (5 units on 1ml syringe)

Timing

Frequency

Daily

Duration

50 days straight, then 4 weeks off

Protocol Notes

Human antimicrobial peptide. Often used during acute infections or for immune support protocols.

Why This Dosing Protocol

Why 50 days straight? Antimicrobial protocols require sustained levels to fully resolve infections, especially biofilm-protected ones. The extended daily dosing ensures consistent antimicrobial pressure.

Why 4 weeks off after? Allows the immune system to recalibrate after the intensive antimicrobial protocol. LL-37 modulates immune responses — cycling prevents potential immune overactivation.

Full Dosing Guide Reconstitution Calculator Cycle Cost Calculator

How LL-37 Works

Antimicrobial Peptide — Human Cathelicidin

Target → Membrane Disruption → Immune Defense → Outcomes

Target

Microbial Membranes + Immune Cell Recruitment

LL-37 is the only human cathelicidin — an endogenous antimicrobial peptide your body naturally produces. It directly disrupts bacterial, viral, and fungal membranes while simultaneously recruiting and activating immune cells.

Cellular Signal

Membrane Disruption + Chemokine Release + Biofilm Attack

LL-37 inserts into microbial membranes, creating pores that kill pathogens. It also triggers chemokine release to recruit immune cells, modulates inflammatory responses, and disrupts bacterial biofilms — protective structures that make infections resistant to antibiotics.

Systemic Effect

Broad-Spectrum Antimicrobial + Immune Modulation

Direct killing of bacteria, viruses, and fungi. Biofilm disruption makes resistant infections more vulnerable. Immune cell activation enhances the body's own defense response. Also promotes wound healing through angiogenesis stimulation.

What You Notice

Immune Support → Infection Resolution → Wound Healing

Often used during acute infections or for immune support protocols. May help resolve stubborn or biofilm-protected infections. Supports wound healing. Vitamin D increases natural LL-37 production — part of why vitamin D supports immune health.

What Makes This Peptide Different

LL-37 is the only human cathelicidin— your body already makes it. Unlike synthetic antimicrobials, it works through multiple mechanisms simultaneously (membrane disruption, biofilm attack, immune recruitment, wound healing). Its connection to vitamin D is notable — vitamin D upregulates LL-37 expression, which is part of vitamin D's immune-supporting mechanism.

LL-37 Clinical Evidence

Two parallel grades per outcome — clinical RCT depth and real-world community adoption. See the Research Overview below for citations and detail.

Outcome	Clinical Evidence	Community Evidence
Wound healing / re-epithelialization	Weak	Weak
Antimicrobial activity (broad-spectrum)	Moderate	Weak
Chronic wound closure (clinical)	Preliminary	Weak
Pro-inflammatory effects in rosacea	Moderate	Weak

LL-37 Research Overview

Outcome-by-outcome look at what the evidence actually supports for LL-37, including human vs. animal study counts and our editorial take on each.

Wound healing / re-epithelialization

Clinical:WeakCommunity:Weak

Heilborn 2003 showed that LL-37 expression is upregulated at the leading edge of healing acute wounds but absent in chronic ulcer epithelium, suggesting endogenous deficit drives non-healing. Carretero 2008 demonstrated that recombinant LL-37 transferred via adenovirus accelerated re-epithelialization in ob/ob diabetic mice. A Phase 2 venous ulcer trial of synthetic LL-37 was reported but cleanly indexing the primary publication remains a verification challenge.

1 human study · 6 animal studies

Key findings & citations

LL-37 strongly expressed at acute wound edges; absent in chronic ulcer epithelium.
Adenoviral LL-37 transfer accelerated re-epithelialization in diabetic mouse wounds.
Phase 2 venous leg ulcer trial of synthetic LL-37 reported clinical benefit at intermediate doses.

Top citations

Our take

Mechanism is solid, the clinical trial program never reached approval. Reasonable as adjunct in non-healing wounds where standard care fails, but data is thin.

Antimicrobial activity

Clinical:ModerateCommunity:Weak

LL-37 has well-characterized broad-spectrum antimicrobial activity against bacteria, fungi, and some viruses via membrane disruption. Vandamme 2012 reviews the in vitro activity comprehensively. Translation to human infection treatment has been hindered by serum protein binding and salt sensitivity reducing in vivo potency.

0 human studies · 4 animal studies

Key findings & citations

Broad-spectrum activity vs Gram-positive, Gram-negative, fungi, biofilms in vitro.
Membrane-disrupting mechanism reduces resistance evolution risk.
Activity is salt- and serum-sensitive — limits systemic therapeutic potential.

Top citations

Our take

Genuinely interesting antimicrobial pharmacology, but topical use only is realistic. Don't expect injectable LL-37 to act like an antibiotic.

Inflammatory skin disease (rosacea)

Clinical:ModerateCommunity:Weak

This is the cautionary side. Yamasaki 2007 showed that abnormal LL-37 processing drives rosacea pathogenesis — facial skin in rosacea patients overexpresses LL-37 fragments that trigger inflammation and vascular changes. Subsequent NLRP3 inflammasome work confirmed the pro-inflammatory mechanism.

2 human studies · 5 animal studies

Key findings & citations

Rosacea facial skin contains abnormally elevated cathelicidin and KLK5.
LL-37 fragments activate the NLRP3 inflammasome in keratinocytes.
Treatments that work for rosacea (azelaic acid, ivermectin) reduce LL-37 / KLK5 expression.

Top citations

Our take

If you have rosacea-prone skin, exogenous LL-37 is exactly the wrong move. The peptide that helps a chronic ulcer can drive a flush.

What LL-37 doesn't do

Claims that current evidence does not support. Worth knowing before you set expectations.

Use on rosacea-prone or sensitive facial skin
LL-37 is causally implicated in rosacea pathogenesis (Yamasaki 2007). Adding more is exactly the wrong direction for inflammatory facial skin.
Replacement for systemic antibiotics
Antimicrobial activity is salt- and serum-sensitive. Effective systemic levels are not achievable with current formulations and pharmacokinetics.
Routine immune support in healthy users
LL-37 is a context-dependent immune mediator. Excess LL-37 is associated with autoimmune skin disease (psoriasis, lupus); supplementation in healthy users has no rationale.

Technical specifications

LL-37 chemical & analytical data

Receptor targets: Bacterial membrane disruption / FPR2 (host cells)
Backbone length: 37 amino acids
Modifications: Cathelicidin-derived antimicrobial peptide
Half-life (clinical PK): ~1 hour (stable when bound to membranes)
Form: Lyophilized (freeze-dried) powder in a sealed vial
Presentation: 10 mg
Regulatory status: Research peptide; research-grade vials are not FDA-approved.

LL-37 Reconstitution Calculator

Dilution math and unit conversions. Prefilled using a common vial size for this peptide.

Open calculator

Storage & Handling

Storage at a glance

Proper storage temperatures, shelf life, reconstitution best practices, and travel tips for lyophilized and reconstituted peptides.

Powder: Freezer

1+ year at -20°C

Reconstituted: Fridge

4 weeks max at 2-8°C

View Complete Storage Guide

Handling specifics

Educational overview on storage, labeling, and traceability considerations for lab environments. Consult primary literature and vendor documentation for specifics.

Powder storage (very stable)

Freezer (-20°C): 1+ year
Refrigerator (2-8°C): 1-3 months
Room temperature: 2-3 weeks (emergency only)

Reconstituted storage (fragile)

MUST refrigerate at 2-8°C
4-week maximum shelf life
NEVER freeze after reconstitution
Use bacteriostatic water for multi-dose

9 answers

LL-37 FAQ: Buying, COA, Storage & Research

What is LL-37?

LL-37 is the only human cathelicidin antimicrobial peptide, a 37-amino acid peptide that plays a crucial role in innate immunity. It has broad-spectrum antimicrobial activity against bacteria, viruses, and fungi, plus immunomodulatory properties. Produced naturally by immune cells, skin, and mucosal tissues.

How does LL-37 kill pathogens?

LL-37 kills microbes primarily by disrupting their cell membranes. Its positive charge attracts it to negatively charged bacterial membranes, where it inserts and creates pores, causing cell death. It also neutralizes bacterial toxins (like LPS) and can disrupt viral envelopes. Human cells are protected because their membranes have a different composition.

What is LL-37's anti-biofilm activity?

Biofilms are protective structures bacteria create that make them resistant to antibiotics. LL-37 can penetrate and disrupt biofilms, making the bacteria vulnerable again. This is particularly relevant for chronic infections like those in wounds, implants, or the lungs in cystic fibrosis patients.

What is the connection between Vitamin D and LL-37?

Vitamin D directly upregulates LL-37 production — this is a major mechanism behind vitamin D's immune benefits. When vitamin D binds its receptor, it activates the gene for LL-37. This explains why vitamin D deficiency is linked to increased infection susceptibility. Sun exposure and vitamin D supplementation both increase LL-37 levels.

What conditions is LL-37 being researched for?

Research areas include chronic wounds, diabetic ulcers, bacterial infections (including antibiotic-resistant strains), viral infections, cystic fibrosis lung infections, periodontal disease, and as a potential cancer therapy due to effects on tumor cells. It's also studied for inflammatory conditions due to its immune-modulating properties.

What are the side effects of LL-37?

As a naturally occurring human peptide, LL-37 is generally well-tolerated. Potential side effects may include injection site reactions (pain, redness) and rarely mild flu-like symptoms. High concentrations can be cytotoxic, so proper dosing is important. Most research uses low doses that are well-tolerated.

How long does reconstituted peptide last?

Once mixed with bacteriostatic water, peptides remain stable for up to 4 weeks when refrigerated at 2-8°C (36-46°F). Unopened powder can last 1+ year in the freezer. Get our complete Storage & Travel Guide.

Is this peptide legal to purchase?

Peptides sold "for research purposes only" are legal to purchase in the US, but are not FDA-approved for human use outside of specific medical applications. Always consult a healthcare provider before use.

New to peptides?

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LL-37 Studies & Sources

The following peer-reviewed studies and official resources provide additional scientific context for this peptide:

LL-37 Research Articles

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LL-37

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LL-37 Certificate of Analysis