American Society of Hirudotherapy

Macrostomin

Antimicrobial peptide active against Gram-positive bacteria — amphipathic alpha-helix.

Preclinical / mechanisticLast updated: 2026-05-26 · Reviewed by ASH Editorial Board
Molecular weight of Macrostomin compared with other characterized leech-derived compoundsHementerin80 kDaHementin80 kDaHementin-Like Protein (HLP-1)80 kDaLeech Collagenase70 kDaHaemadipsa yanyuanensis Progr…70 kDaLeech Apyrase67 kDaCalin65 kDaHyaluronidase60 kDaAntithrombin III binding prot…58 kDaCollagenolytic Fibrinolysin55 kDaLeech Thrombospondin-Like Pro…50 kDaMacrostomin2.9 kDa
Molecular weight (kilodaltons) of Macrostomin (highlighted) alongside other characterized leech salivary compounds. Smaller proteins/peptides generally diffuse and act faster.

Mechanistic Evidence Box

Preclinical / mechanistic
Page type
Compound profile
Evidence type
Antimicrobial peptide active against Gram-positive bacteria — amphipathic alpha-helix.
Evidence level
In vitro
Drug vs leech
Purified natural compound

Clinical translation limit

Macrostomin's in vitro antimicrobial activity does not establish clinical efficacy as a therapeutic antibiotic. No FDA-approved derivative exists. Mechanism is preclinical/biochemical only.

Molecular Profile

Category
Antimicrobial
Evidence tier
Preclinical
Molecular weight
2,900 Da
Source species
Macrobdella decora
Macrostomin molecular structure

Biological Targets

  • → Gram-positive bacterial membranes

External Resources

    Related Antimicrobial Compounds

    Theromacin

    Antimicrobial peptide active against Gram-negative bacteria — innate immunity of leech.

    Theromyzin

    Antimicrobial peptide; structural analogue of mammalian defensin family.

    Hirunipins

    Newly-characterized antimicrobial peptide family (Kumar 2025) — candidate next-generation antibiotics against AMR pathogens.

    Destabilase Lysozyme Activity

    Lysozyme domain of destabilase — antimicrobial activity against peptidoglycan-containing bacteria.

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