# LL-37

> Human cathelicidin antimicrobial peptide active across bacteria, fungi, and viruses.

- Also known as: Cathelicidin, hCAP-18 fragment
- Class: Immune, Healing & Repair
- FDA approved: No
- Canonical page: https://www.americanpeptide.com/catalog/ll-37

## Overview

LL-37 is the C-terminal 37-residue fragment of human cathelicidin hCAP-18 and the only cathelicidin expressed in humans. Roles span direct antimicrobial activity, chemotaxis, and wound healing.

LL-37 is the only cathelicidin antimicrobial peptide expressed in humans — a 37-residue fragment released from the precursor protein hCAP-18. It is a frontline component of innate immunity, found in neutrophils, epithelial cells, and skin.

Beyond directly disrupting the membranes of bacteria, fungi, and some viruses, LL-37 also acts as a signaling molecule that recruits immune cells and supports wound healing. Interest has grown as antibiotic resistance renews attention on host-defense peptides. It is studied as a research compound.

## Mechanism

Membrane disruption of pathogens; immunomodulatory signaling via FPRL1.

## Chemistry

| Property | Value |
| --- | --- |
| Molecular formula | C205H340N60O53 |
| Molecular weight | 4493.3 Da |
| CAS number | 154947-66-7 |
| PubChem CID | [16198951](https://pubchem.ncbi.nlm.nih.gov/compound/16198951) |

## Research areas

Studied in: Antimicrobial resistance, Chronic wound healing, Innate immunity.

Guides on this site:

- [Wound Healing & Tissue Repair](https://www.americanpeptide.com/research-areas/wound-healing): Regenerative peptides studied for soft-tissue, tendon, and vascular repair.
- [Immune & Inflammation](https://www.americanpeptide.com/research-areas/immune-inflammation): Thymic and host-defense peptides studied for immune modulation.

## Key research

- Broad antimicrobial activity — membrane disruption across bacteria, fungi, and viruses.
- Antimicrobial resistance — host-defense peptides studied as an alternative strategy.
- Wound healing — chemotaxis and tissue-repair signaling.
- Immunomodulation — signaling via the FPRL1 receptor.
- Research compound — not an approved medicine.

## FAQs

### What is LL-37?

LL-37 is the only human cathelicidin antimicrobial peptide, part of innate immunity, with direct antimicrobial and wound-healing roles.

### Why is it of interest for antibiotic resistance?

As a host-defense peptide that disrupts microbial membranes, it represents a mechanism distinct from conventional antibiotics, of growing interest as resistance spreads.

### What is it studied for?

Antimicrobial-resistance research, chronic wound healing, and innate immunity.

### Is it approved?

No — it is a research compound. This page is a research and educational reference.

## Latest research

Recent trials and publications mentioning LL-37, pulled automatically from ClinicalTrials.gov and PubMed (unfiltered search results, refreshed daily).

### Recent trials

- [Crosstalk Between Mucosal-Associated Invariant T (MAIT) Cells and the Gut Microbiota and Mucosa in the Development of Type 1 Diabetes in Children](https://clinicaltrials.gov/study/NCT05054361) — RECRUITING · NCT05054361
- [An Intervention Study in Healthy Infants Aged 0-6 Months With Probiotics Lacticaseibacillus Rhamnosus LRa05 (LRa05) and Bifidobacterium Animalis Subsp. Lactis BLa80 (BLa80) vs. Placebo, for Promoting Gut Microbiome Development.](https://clinicaltrials.gov/study/NCT07505329) — NOT_YET_RECRUITING · NA · NCT07505329
- [To Investigate the Effects of Bifidobacterium Animalis Subsp. Lactis XLTG11 on Growth and Development, Incidence of Allergy and Immune Function in Infants](https://clinicaltrials.gov/study/NCT07490587) — RECRUITING · PHASE2 · NCT07490587
- [Relationship Between Nutritional Status, Physical Activity and Periodontal Status](https://clinicaltrials.gov/study/NCT07496710) — COMPLETED · NCT07496710
- [Salivary Antimicrobial Peptides and Severe Early Childhood Caries in Turkish Children](https://clinicaltrials.gov/study/NCT07414030) — COMPLETED · NCT07414030
- [Evaluation of 25(OH)D3 and LL-37 Levels in Periimplant Sulcus Fluid](https://clinicaltrials.gov/study/NCT07280754) — NOT_YET_RECRUITING · NCT07280754

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Source: AmericanPeptide.com — https://www.americanpeptide.com/catalog/ll-37
Data license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Attribution: AmericanPeptide.com.
Research reference only — computational and educational content, not medical advice.