American Society of Hirudotherapy

Leech Cystatin-Like Inhibitor

Cystatin-family cysteine protease inhibitor identified in leech salivary transcriptome — inhibits cathepsin-like host enzymes.

Preclinical / mechanisticLast updated: 2026-05-26 · Reviewed by ASH Editorial Board
Molecular weight of Leech Cystatin-Like Inhibitor 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 kDaLeech Cystatin-Like Inhibitor13 kDa
Molecular weight (kilodaltons) of Leech Cystatin-Like Inhibitor (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
Cystatin-family cysteine protease inhibitor identified in leech salivary transcriptome — inhibits cathepsin-like host enzymes.
Evidence level
In vitro
Drug vs leech
Purified natural compound

Clinical translation limit

Predicted cystatin activity does NOT establish clinical efficacy. No FDA-approved derivative exists.

Molecular Profile

Category
Proteinase Inhibitor
Evidence tier
Preclinical
Molecular weight
13,000 Da
Source species
Hirudo medicinalis
Discovered
2018
Leech Cystatin-Like Inhibitor molecular structure

Biological Targets

  • → cathepsin B
  • → cathepsin L
  • → papain-family cysteine proteases

External Resources

    Related Proteinase Inhibitor Compounds

    Hirustasin

    Serine proteinase inhibitor targeting tissue kallikrein — anti-inflammatory pathway.

    Eglin C

    Potent inhibitor of human leukocyte elastase and cathepsin G — anti-inflammatory protein widely used as research tool.

    Bdellin B3

    Kazal-type proteinase inhibitor targeting trypsin and plasmin — modulates inflammatory cascade.

    LDTI (Leech-Derived Tryptase Inhibitor)

    Selective inhibitor of human mast cell tryptase — anti-inflammatory pathway.

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    This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.