LL37 high purity and High Quality

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1. Core Molecular & Physicochemical Specifications

2. Mechanism of Action

1. Antimicrobial Activity:
   • Membrane disruption: “Carpet model” or “barrel‑stave pore formation” disrupts bacterial/fungal membranes via electrostatic interactions with anionic phospholipids.
   • Endotoxin neutralization: Binds LPS/LTA to block TLR4/TLR2 activation, reducing sepsis risk.
   • Biofilm dissolution: Disperses mature biofilms and inhibits quorum sensing in Gram‑positive/negative bacteria.
   
   
2. Immunomodulation:
   • Chemotaxis: Recruits neutrophils, monocytes, and T cells via FPRL1 receptor.
   • TLR signaling balance: Inhibits TLR2/TLR4 (lipid agonists) while enhancing TLR3/TLR7–TLR9 (nucleic acid agonists) via nucleic acid complexation.
   • Inflammasome regulation: Blocks AIM2 inflammasome assembly via LL37–DNA complex steric hindrance.
   
   
3. Tissue Repair: Stimulates VEGF secretion and epithelial/endothelial cell migration to promote angiogenesis and wound closure.

3. Biological Functions & Application Fields

3.1 Core Physiological Effects

• Broad‑Spectrum Pathogen Killing: Active against Gram‑positive (S. aureus) and Gram‑negative (E. coli) bacteria, fungi (C. albicans), and enveloped viruses (HIV‑1, influenza).
• Inflammation Resolution: Mitigates LPS‑induced sepsis, reduces pro‑inflammatory cytokines (TNF‑α, IL‑6), and enhances anti‑inflammatory IL‑10 release.
• Wound & Tissue Regeneration: Accelerates re‑epithelialization, angiogenesis, and collagen deposition; reduces scarring.
• Anti‑Cancer Potential: Induces cancer cell apoptosis and inhibits metastasis via membrane permeabilization and signaling modulation.

3.2 Application Fields

4. Production & Quality Control

4.1 Manufacturing Processes

1. Precursor & Synthesis: Precursor hCAP18 is processed by serine protease 3/kallikrein 5 to yield LL37; synthetic production uses Fmoc SPPS with C18 RP‑HPLC purification.
2. Lyophilization: Purified peptide is lyophilized to a stable powder and vacuum‑sealed with desiccant to avoid moisture‑induced degradation.
3. Quality Validation: Identity confirmed via mass spectrometry; purity verified by HPLC; endotoxin tested via LAL assay.

4.2 Quality Testing Standards

5. Administration, Safety & Regulatory Status

5.1 Administration Routes & Dosage

• Preclinical Injection: Intraperitoneal (IP) 1–5 mg/kg/day; subcutaneous (SC) 0.5–2 mg/kg 3×/week for systemic infection models.
• Topical Use: 0.1%–1% peptide in hydrogel/cream for wound healing studies; applied twice daily.
• Cell Culture: 0.1–10 μM for antimicrobial or immune signaling assays.

5.2 Safety Profile

• Low Toxicity: LD₅₀ > 100 mg/kg in rodents; minimal hemolysis at therapeutic concentrations.
• Side Effects: Transient local irritation at injection sites; no off‑target organ damage reported in preclinical studies.
• Contraindications: Hypersensitivity to LL37; caution in pregnant/lactating animals (limited data).
• Regulatory Status: Research use only; no FDA‑approved human therapeutics yet (2026).

5.3 Handling Guidelines

• Storage: Lyophilized powder at −20°C; reconstituted solution at 4°C (avoid repeated freeze–thaw cycles).
• Reconstitution: Use sterile water or PBS (pH 7.0–7.4); avoid high‑salt buffers to prevent aggregation.
• Transport: Cold chain (2–8°C) to maintain stability.

6. Key Advantages & Limitations

6.1 Advantages

1. Multi‑Functional Activity: Combines antimicrobial, anti‑inflammatory, and tissue‑repair effects, outperforming single‑target agents.
2. Resistance‑Resistant: Membrane‑disruptive mechanism reduces likelihood of microbial resistance compared to traditional antibiotics.
3. Immune Homeostasis: Balances pro‑ and anti‑inflammatory pathways to avoid excessive inflammation.
4. Broad Tissue Utility: Effective in skin, respiratory, and gastrointestinal models, supporting cross‑disciplinary research.

6.2 Limitations

1. Short Half‑Life: Plasma half‑life ~30–60 minutes; requires frequent dosing or sustained‑release formulations.
2. Salt Sensitivity: Cationic charge leads to aggregation in high‑salt environments, reducing activity.
3. Dual Role in Disease: May exacerbate autoimmune diseases (e.g., psoriasis) via TLR activation in some contexts.

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