SGS Compound Reference
Complete bioactive component database for medicinal leech SGS
Medicinal leech salivary gland secretion (SGS) contains a diverse complement of protein (peptide), lipid, and carbohydrate compounds whose full composition is still not determined; a 2020 proteomic study identified 189 proteins in the salivary secretion of Hirudo medicinalis. The table below summarizes the major pharmacologically active components with their molecular properties, biological targets, and pharmaceutical derivatives. This reference is derived from the thorough analysis of Baskova (2004) and subsequent molecular characterization studies.
Major SGS Components
| Compound | MW (Da) | Target | Function | Pharma Derivative |
|---|---|---|---|---|
| Hirudin | ~7,000 | Thrombin (active site + exosite I) | Most potent natural thrombin inhibitor (dissociation constant ≈ 20 fM (2×10⁻¹⁴ M)) | Lepirudin, Desirudin, Bivalirudin |
| Calin | ~65,000 | Collagen-vWF binding | Inhibits collagen-mediated platelet aggregation; prolongs bleeding | — |
| Destabilase | ~12,300 | Cross-linked fibrin (ε-lysyl-γ-glutamyl bonds) | Thrombolytic; neurotrophic at 10⁻¹² M | Under investigation |
| Eglins b/c | ~8,100 | Neutrophil elastase, cathepsin G | Anti-inflammatory (potato inhibitor I family) | Recombinant eglins studied |
| Bdellins A/B | ~6,200-6,500 | Trypsin, plasmin, acrosin | Anti-inflammatory; prevents premature fibrinolysis | — |
| LDTI | ~4,700 | Mast cell tryptase | Anti-allergic; anti-inflammatory (Kazal-type inhibitor) | Under investigation |
| Hyaluronidase | ~27,500 | Hyaluronic acid in ECM | "Spreading factor" — facilitates SGS penetration into tissues | Hylenex (recombinant) |
| Antistasin | ~15,000 | Factor Xa | Anticoagulant; antistasin superfamily founder | Early tool for studying factor Xa as a target (FXa drugs are synthetic) |
| Ghilanten | ~14,000 | Factor XIIIa | Inhibits fibrin cross-linking (synergizes with destabilase) | — |
| Decorsin | ~4,400 | GPIIb/IIIa integrin | RGD peptide; potent platelet aggregation inhibitor | RGD peptide research |
| Ornatin | ~5,700 | GPIIb/IIIa integrin | RGD peptide from Placobdella ornata | RGD peptide research |
| LCI | ~6,800 | Carboxypeptidase A | Prevents removal of C-terminal lysines from fibrin (modulates fibrinolysis) | — |
| C1s Inhibitor | Variable | Complement C1s | Classical complement pathway inhibition | — |
| Apyrase | Variable | ADP | Hydrolyzes ADP; inhibits ADP-mediated platelet aggregation | — |
| Collagenase | Variable | Collagen | ECM degradation; tissue penetration | — |
| Histamine-like | Low MW | Histamine receptors | Vasodilation; increases local blood flow to bite site | — |
| Anesthetic | Low MW | Nociceptors | Local analgesia at bite site (onset 1-2 min) | — |
Functional Categories
Anticoagulant
Hirudin (thrombin), antistasin (factor Xa), LCI (carboxypeptidase A), ghilanten (factor XIIIa). Multi-target cascade inhibition at 4+ points.
Antiplatelet
Calin (collagen-vWF), decorsin/ornatin (GPIIb/IIIa), apyrase (ADP). Three independent antiplatelet mechanisms.
Thrombolytic
Destabilase (cross-linked fibrin). Unique isopeptidase activity cleaving ε-lysyl-γ-glutamyl bonds in stabilized fibrin.
Anti-Inflammatory
Eglins (elastase, cathepsin G), bdellins (trypsin, plasmin), LDTI (mast cell tryptase), C1s inhibitor (complement).
Tissue Penetration
Hyaluronidase (ECM), collagenase (collagen), histamine-like compounds (vasodilation). Enable SGS components to reach systemic circulation.
Neurotrophic
Destabilase, bdellins, eglins. Neurite outgrowth stimulation in chick embryo ganglia. Destabilase active at 10⁻¹² M.
Pharmaceutical Legacy
FDA-Approved Thrombin Inhibitors: Leech-Derived and Synthetic
| Drug | SGS Origin | FDA Year | Indication |
|---|---|---|---|
| Bivalirudin (Angiomax) | Hirudin C-terminal peptide | 2000 | PCI anticoagulation |
| Desirudin (Iprivask) | Recombinant hirudin | 2003 | DVT prophylaxis |
| Dabigatran (Pradaxa) | Synthetic: designed from the inhibitor NAPAP, not from hirudin | 2010 | Stroke prevention in AF |