Hirudin is a naturally occurring peptide in the salivary glands of medicinal leeches (Hirudo medicinalis) that has a blood anticoagulant property. This is fundamental for the leeches' alimentary habit of hematophagy, since it keeps the blood flowing after the initial phlebotomy performed by the worm on the host's skin.

Key Applications:

• Anticoagulant Medicine: Highly promising for treating various thrombus diseases.
• Thrombosis Treatment: Effective for venous thrombosis and diffuse blood vessel coagulation.
• Tumor Research: Research suggests roles in preventing metastasis in tumors like fibrosarcoma, melanoma, and leukemia.

Hirudin is the strongest thrombin retarder discovered so far. It fuses with thrombin to produce a non-covalent synthase with an extremely fast reaction rate and high infectivity (1μg can neutralize 5μg thrombin).