LL-37

Overview

LL-37 is the sole cathelicidin-family antimicrobial peptide found in humans. It is released by proteolytic cleavage from the precursor protein hCAP18 and takes its name from the two leucine residues at its N-terminus followed by its 37-residue length. It adopts an amphipathic alpha-helical conformation, a structural feature common to many cationic antimicrobial peptides and central to its proposed membrane-directed mechanism. The published literature describes it as a multifunctional peptide: alongside direct antimicrobial activity it is studied for immunomodulatory signalling and roles in tissue repair. Notably, the literature also examines contexts in which LL-37 activity appears detrimental rather than beneficial, including its interaction with amyloid-forming proteins.

For research use only · Not FDA/EMA approved · Not for human consumption

Mechanism of Action

Published research describes LL-37 as cationic and amphipathic, allowing it to associate with negatively charged bacterial membranes and disrupt membrane integrity — the direct antimicrobial mechanism. Beyond this, the literature describes receptor-mediated immunomodulatory actions, including signalling through formyl peptide receptor 2 (FPR2), with reported effects on chemotaxis of immune cells, cytokine responses and angiogenesis. Published work on wound repair describes effects on keratinocyte migration and re-epithelialisation, and a 2024 study in diabetic mice reported a mechanism involving TFEB-dependent autophagy. A separate strand of published work characterises LL-37's influence on amyloid aggregation, which is examined as a potential pathological interaction rather than a therapeutic one.

For research use only · Not FDA/EMA approved · Not for human consumption

Key Research Areas

• Direct antimicrobial activity against bacteria and biofilms
• Wound healing and re-epithelialisation in preclinical models
• Immunomodulatory signalling via formyl peptide receptor 2
• Structure-function relationships of the amphipathic helix
• Interaction with amyloid-related disease processes

For research use only · Not FDA/EMA approved · Not for human consumption

Published Studies (4 cited)

For research use only · Not FDA/EMA approved · Not for human consumption

Dosage in Published Research

The published literature on LL-37 is predominantly in vitro and preclinical. Antimicrobial and cell-culture studies report activity at micromolar concentrations, with minimum inhibitory concentrations varying by organism, by assay conditions and notably by salt concentration, which published work identifies as strongly influencing activity. Animal wound-healing studies have used topical application protocols. No standardised dosing protocol exists. All figures are reported from published literature for reference purposes only.

For research use only · Not FDA/EMA approved · Not for human consumption

Storage & Handling

Store lyophilized powder at -20°C for long-term storage, protected from light and moisture. Once reconstituted, store at 2–8°C and use within 14 days. As a cationic peptide, LL-37 adsorbs to some plastic surfaces; low-binding labware is used in published protocols. Activity is described in the literature as salt-sensitive, so buffer composition matters. Avoid repeated freeze-thaw cycles. Handle under sterile laboratory conditions using appropriate PPE.

For research use only · Not FDA/EMA approved · Not for human consumption

Safety Profile (Literature Only)

Published in vitro work describes concentration-dependent cytotoxicity toward mammalian cells at higher concentrations, and haemolytic activity has been characterised as part of the structure-function literature on cationic amphipathic peptides. The published record is largely in vitro and preclinical; no human clinical safety profile is established. This compound is supplied for laboratory research use only.

For research use only · Not FDA/EMA approved · Not for human consumption