Quick summary
Magainin is a broad-spectrum antimicrobial peptide from frog skin (Xenopus laevis) that established foundational principles of membrane-disrupting AMP drug design. Its analog pexiganan reached Phase III trials for diabetic foot ulcers but failed to achieve superiority over standard antibiotics.
Overview
Magainin is a family of broad-spectrum antimicrobial peptides isolated from the skin of the African clawed frog Xenopus laevis, first characterized by Michael Zasloff in 1987. Magainin-2 is the primary studied isoform — a 23-amino acid cationic peptide with activity against gram-positive and gram-negative bacteria, fungi, and protozoa. It was the first frog-derived AMP to enter clinical development.
Mechanism of action
In aqueous solution, magainin-2 is largely unstructured. Upon contact with negatively charged bacterial membranes, it folds into an amphipathic alpha-helix and inserts into the bilayer via a 'carpet model' or toroidal pore mechanism. At sufficient concentrations, magainin causes membrane thinning, transient pore formation, and eventually membrane disintegration and leakage of cytoplasmic contents. Selectivity for prokaryotic over eukaryotic membranes arises from the abundance of anionic phospholipids in bacterial outer leaflets versus zwitterionic phosphatidylcholine-dominated mammalian membranes.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| antimicrobial research | topical | 10–100 mcg/mL | research use only | MIC typically 10–100 mcg/mL against common gram-negative and gram-positive organisms in vitro |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Magainin research established foundational principles of AMP membrane disruption, influencing drug design of hundreds of synthetic analogs. A magainin analog (pexiganan/MSI-78) reached Phase III trials for diabetic foot ulcer infections but failed to achieve superiority versus standard antibiotic comparators (1999), partly due to regulatory endpoint requirements. Research continues on magainin structural analogs with improved potency and reduced toxicity. Magainin-2 remains a gold-standard positive control in AMP research.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Magainin for synergistic effects.
Legal status
Native magainin-2 is a research peptide not approved for human use. The synthetic analog pexiganan did not receive FDA approval. Research reagents available from peptide suppliers.
Sourcing & access
Research compound
Magainin is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
Magainin is a family of antimicrobial peptides first isolated from the skin of the African clawed frog Xenopus laevis in 1987. Magainin-2, a 23-amino acid cationic peptide, is the primary studied isoform with activity against gram-positive and gram-negative bacteria, fungi, and protozoa.
Magainin-2 folds into an amphipathic alpha-helix upon contact with bacterial membranes and disrupts them via carpet model or toroidal pore mechanisms. It selectively targets prokaryotic membranes due to their abundance of anionic phospholipids, sparing mammalian cells at therapeutic concentrations.
Magainin can be hemolytic at high concentrations and cytotoxic to mammalian cells above the therapeutic window. Its selectivity for bacterial over mammalian membranes provides a therapeutic index, but this was insufficient for the clinical analog pexiganan to gain FDA approval.
Pexiganan (MSI-78), a synthetic magainin analog, reached Phase III trials for diabetic foot ulcer infections in 1999 but failed to demonstrate superiority versus standard antibiotic comparators, partly due to regulatory endpoint requirements. Magainin-2 remains a gold-standard control in AMP research.
Research references
- Magainins: antimicrobial peptides from Xenopus skin with broad spectrum activityPubMed
- Mechanism of action of magainin peptides: membrane permeabilizationPubMed
- Magainin and related peptides as anticancer agents and membrane disruptorsPubMed
- Frog-skin antimicrobial peptides: diversity, structure, and therapeutic prospectsPubMed