Healing & Recovery

LL-37

Also known as: CAP-18, Catelicidina

Molecular Identifiers

Molecular Formula

C205H340N60O53

CAS Number

597562-32-8

PubChem CID

16198951

Molecular Weight

4493.33 Da

Overview

Human antimicrobial peptide from the cathelicidin family, composed of 37 amino acids. Derived from the hCAP-18 precursor (Human Cationic Antimicrobial Protein), it is naturally produced by neutrophils, macrophages, and epithelial cells. Has a molecular weight of approximately 4,493.33 Da and broad-spectrum antimicrobial activity against bacteria, viruses, fungi, and biofilms.

The main clinical interest around LL-37 is its role as a human innate defense peptide: broad-spectrum antimicrobial activity against bacteria, viruses, and fungi, biofilm disruption capacity, and immunomodulatory action via recruitment and activation of immune cells. This dual profile — antimicrobial plus wound-healing — drives interest in resistant infections, chronic wounds, biofilm infections, and modulation of inflammatory skin diseases.

LL-37 currently has no regulatory approval from any agency (FDA, EMA, ANVISA). It is most often dispensed by compounding pharmacies as off-label use in experimental contexts, in short cycles with subcutaneous administration near the site of interest. As an endogenous human peptide described in the 1990s, it is the only cathelicidin identified in humans and a central part of innate immune defense in skin and mucosa.

Sequence (1 letter): LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES

Extended notation:

Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-Val-Gln-Arg-Ile-Lys-Asp-Phe-Leu-Arg-Asn-Leu-Val-Pro-Arg-Thr-Glu-Ser

Half-life

~4-6 hours

Administration Route

Subcutaneous

Mechanism of Action

Broad-spectrum antimicrobial action through disruption of microbial membranes
Immunomodulation via recruitment and activation of immune cells
Promotion of wound healing and tissue repair
Disruption of bacterial biofilms
Modulation of inflammatory response via formyl peptide receptors

Dosage Protocol

Data compiled from the literature. This does not constitute medical advice.

Parameter	Value
Dose	50-200 mcg per injection
Frequency	Once daily
Timing	Morning
Duration	2-4 weeks

Reported Side Effects

Adverse effects described in the literature. Severity and frequency vary between individuals.

Pain at injection site
Redness
Local edema
Transient fever (rare)

Product Properties

Purity	>95%
Appearance	White lyophilized powder
Solubility	Soluble in water and bacteriostatic water
Source	Solid-phase peptide synthesis (SPPS)
Storage	Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 4 weeks, or -20°C for longer-term storage. Protect from light and moisture. Avoid repeated freeze-thaw cycles.