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LL-37
Pick your pack · how long it lasts
At 0.700 mg/wk — select pack size
1 × 10-vial pack required for packing — samples add on to any pack
Lab-direct quality — full packs or single-vial samples
Every batch ships straight from the lab that synthesises it — sealed, tamper-evident, and HPLC-verified to >99% purity with a batch-linked Certificate of Analysis. Buying direct means you pay the lab-direct rate on every vial, with nothing stacked on top.
Order a full sealed 10-vial research pack for a complete study supply, or add a single-vial sample alongside your pack to trial a new compound first. Same lab, same batch, same verified purity — scaled to whatever your research needs.
What It's Researched For
In plain terms, LL-37 is the body's own germ-fighting peptide, studied for defence against microbes and for healing. Here is what that looks like across the research.
Antimicrobial defence
Lab research explores how it breaks open the membranes of bacteria, fungi and some viruses, a way of killing germs that they struggle to become resistant to.
Biofilm & stubborn infection
Preclinical studies look at whether it stops bacteria forming the protective films that make chronic infections so hard to clear.
Wound healing
Animal and cell studies explore how it helps skin repair and new blood vessels form while also fighting infection in the wound.
Immune support
Research explores its role as an alarm signal that calls in and coordinates the body's own immune defenders.
Vitamin D link
Studied for the connection between vitamin D levels and how much of this natural defence peptide the body makes.
Overview
LL-37 is the only human cathelicidin - a 37-residue amphipathic antimicrobial peptide that punches holes in bacterial membranes while simultaneously acting as an alarmin that orchestrates the innate immune response.
LL-37 is one of the foundational components of human innate immunity. Your body cleaves it from a precursor protein called hCAP-18 using the serine protease proteinase 3, and the resulting 37-amino-acid peptide is what does the antimicrobial work. It is produced by neutrophils, macrophages, skin keratinocytes, and epithelial cells lining the gut and lungs - essentially wherever the body meets microbes.
The mechanism is direct and physical. LL-37 is strongly cationic (net charge +6), so it sticks to the anionic surface of bacterial membranes, then inserts its amphipathic alpha-helical structure and punches holes. Unlike conventional antibiotics, there is no receptor to mutate around - pathogens have a very hard time evolving resistance to membrane disruption itself.
Beyond direct killing, LL-37 also acts as an alarmin: it activates immune receptors (FPRL-1, P2X7, EGFR), drives neutrophil chemotaxis, promotes angiogenesis and keratinocyte migration during wound healing, and helps orchestrate the broader immune response. Supplied here as sterile lyophilised powder for research.
Mechanism of Action
LL-37 kills bacteria by disrupting their membranes and simultaneously signals the rest of the innate immune system to show up and finish the job.
Wang et al. (Scientific Reports, 2020) used X-ray crystallography and molecular dynamics to show that LL-37 forms water-permeable tetrameric channels in bacterial membranes after electrostatic attachment via LPS (Gram-negative) or LTA (Gram-positive). The peptide adopts a helix-break-helix conformation in membrane environments. Vandamme et al. (Cellular Immunology, 2012) reviewed the alarmin functions. LL-37 expression is vitamin D-dependent and calcitriol supplementation upregulates endogenous production. Production cost and proteolytic sensitivity are the main limitations for therapeutic use.
Common Questions People Are Asking
What is LL-37 and how does it work?
LL-37 is the only human cathelicidin antimicrobial peptide - a 37-amino-acid, positively charged (net +6) amphipathic helix cleaved from the precursor hCAP-18. Its primary mechanism is physical: it binds the anionic surface of microbial membranes and disrupts them, while also neutralising bacterial endotoxin (LPS) and acting as an alarmin that signals the wider innate immune system. New-U supplies it for laboratory research only.
What does the LL-37 research actually show?
Preclinical and cell-based studies report broad-spectrum antimicrobial activity (Gram-positive and Gram-negative bacteria, fungi, enveloped viruses), inhibition of biofilm formation, and roles in wound healing and immune signalling; its dysregulation is also studied in inflammatory skin disease such as rosacea, psoriasis and atopic dermatitis (Reinholz & Ruzicka et al., 2012). These are research findings in models, not a promise of any effect in humans.
Is LL-37 legal, and is it approved for use?
LL-37 is not an FDA-approved drug; it is sold strictly as a research compound for laboratory use, not for human consumption. It has appeared in early-phase clinical research (for example topical wound-healing studies), but it remains investigational. Legal status varies by jurisdiction, so confirm your local rules before purchasing.
Can bacteria develop resistance to LL-37?
Resistance is much harder to evolve against membrane-targeting peptides than against receptor- or enzyme-targeting antibiotics, because there is no single protein for the pathogen to mutate. Some bacteria modify their outer-membrane charge to reduce electrostatic attraction, but full escape is rare - part of why antimicrobial peptides like LL-37 are such an active research area in the antibiotic-resistance era.
What is the vitamin D connection?
Cathelicidin (CAMP) gene expression is directly regulated by the vitamin D receptor. Calcitriol (the active form of vitamin D) upregulates endogenous LL-37 production, which is one of the mechanisms behind the observed relationship between vitamin D status and susceptibility to respiratory and tuberculosis infections.
Why is LL-37 dose-dependent for cytotoxicity?
Like most amphipathic antimicrobial peptides, LL-37 is selectively toxic to microbial membranes at low concentrations but loses selectivity at high concentrations, affecting host-cell membranes as well. Research protocols need to balance antimicrobial efficacy against host-cell tolerability, which is a general limitation of the class.
How should LL-37 be stored?
Keep the lyophilised powder frozen at −20 °C. After reconstitution with bacteriostatic water, refrigerate at 1-6 °C and protect from light. LL-37 is susceptible to proteolytic degradation, so use reconstituted material promptly and avoid repeated freeze-thaw cycles.
Where can I buy LL-37?
Right here — LL-37 is supplied directly by New-U Research Compounds on this page. Every batch is independently third-party tested to >99% HPLC purity with a batch-linked Certificate of Analysis, supplied as lyophilised research-grade material, and shipped direct from source worldwide in discreet, tracked packaging. Strictly for laboratory research use only — not for human use.
How much does LL-37 cost?
LL-37 pricing is shown live on this page, per pack size — 10-vial research packs as standard, with single-vial sample options on selected compounds. Larger vial strengths lower the per-mg cost, every order includes the batch Certificate of Analysis, and shipping is free on orders over $300.
Is LL-37 third-party tested?
Yes. Every LL-37 batch is verified by independent laboratories (Janoshik Analytics and Freedom Diagnostics) for identity and purity, with a batch-linked Certificate of Analysis confirming >99% purity by HPLC. Every order ships with its COA, and current batch certificates are published on our COA page.
How do I buy LL-37?
Add the LL-37 pack size you need to your cart and check out: enter your shipping details, then choose your payment method — cryptocurrency or card — on the next step. Every order ships with its batch Certificate of Analysis (COA). LL-37 is supplied strictly for laboratory research use only, not for human or veterinary use.
What payment methods can I use to buy LL-37?
At checkout you can pay by cryptocurrency (BTC, ETH, SOL, LTC, USDC, USDT and more) or by card, each handled by a dedicated secure payment provider. You choose your method after confirming your order.
How fast is shipping, and do you ship worldwide?
Yes — we ship worldwide in discreet, unmarked, temperature-stable, tracked packaging. Delivery typically takes 6–14 business days, and shipping is free on orders over $300.
Pharmacokinetics
Evidence Tier
Overall: Mixed (human + animal)
LL-37 is an endogenous human host-defence peptide whose evidence base is predominantly in-vitro, cell-based and structural (e.g. Wang et al. 2020 membrane-channel crystallography and molecular dynamics; Reinholz & Ruzicka et al. 2012 inflammatory-skin-disease review), with animal wound-healing models and only early-phase / investigational human data. It is NOT an approved drug in any indication; the research-grade material supplied here is unapproved laboratory material.
Tier 1 · Human clinical
Tier 2 · Animal
Source References & Further Reading
Last reviewed: 16 June 2026 · New-U Research Compounds
Key Characteristics
Specifications
About LL-37: Human Cathelicidin Antimicrobial & Host-Defence Peptide Research Guide
LL-37 is one of only a handful of molecules that you can legitimately call a foundational component of human innate immunity. It is the only cathelicidin humans make (cleaved from the precursor hCAP-18, encoded by the CAMP gene), and it is produced wherever the body interfaces with microbes - skin keratinocytes, gut, lungs, and at the front line of neutrophil-mediated defence. Its central role in host defence was recognised decades ago, but the structural and skin-disease detail has been filled in more recently (Reinholz & Ruzicka et al., Ann Dermatol, 2012).
What makes LL-37 a useful research tool is that it does two different things at once. The direct antimicrobial activity is mechanically simple - the cationic, amphipathic helix inserts into the anionic microbial membrane, disrupts it, and neutralises endotoxin (LPS) - and is hard to evolve around because it targets the membrane itself rather than a single bacterial protein, with reported activity against Gram-positive and Gram-negative bacteria, fungi and enveloped viruses plus inhibition of biofilm formation. On top of that, LL-37 acts as an alarmin that recruits and activates other immune cells and promotes angiogenesis and keratinocyte migration in wound-healing models - a systems-level role that goes beyond the simple "antibiotic peptide" description. Its expression is vitamin D-dependent, the molecular link behind the observed vitamin D / infection-susceptibility relationship.
New-U Research Compounds supplies LL-37 as a research-grade lyophilised powder at >99% HPLC purity, verified by independent third-party labs. All material is strictly for in-vitro and laboratory research use. LL-37 is not FDA-approved for human therapeutic use, and nothing on this page constitutes medical advice or a dose recommendation.
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