Abstract: A method for preventing the formation of platelet-rich clots or thrombus, and for deaggregating platelet-rich clots or thrombus, using hementin, a polypeptide derived from leech salivary glands. Hementin may be administered for this purpose in a pharmaceutically acceptable carrier or excipient, with or without additional anticoagulants such as hirudin, hirudin analogues, or an inhibitor of factor Xa.

Abstract: A polypeptide derived from leeches of the species Hirudinaria manillensis has the following amino acid sequence: ##STR1## wherein Xaa indicates any amino acid residue; D indicates Cys or Pro; E indicates Glu, Asp or His; F indicates Asp, Lys or Trp; or a pharmaceutically acceptable salt, derivative or bioprecursor thereof. The polypeptide, and fragments thereof, is a specific anti-thrombin useful as a medicament.

Abstract: The hyaluronidase, which is a hyaluronic acid-specific endo-.beta.-glucuronidase, having a molecular weight of about 28,500 in non-reduced form, is derived from buffalo leeches (that is, leeches of the sub-family Hirudinariinae, such as the species Hirudinaria manillensis or Poecilobdella granulosa).The hyaluronidase, which cleaves hyaluronic acid, but not chondroitin, chondroitin -4- sulphate, chondroitin -6- sulphate or heparin, is considerably more stable at high temperatures and extremes of pH than known leech hyaluronidase. It has a wide range of uses where breakdown of hyaluronic acid is required; of particular interest is in pharmaceutical or veterinary formulations, either as an active agent or a spreading or percutaneous factor. The hyaluronidase is useful for stimulating flow of physiological fluids in the eye (for example, in the treatment of glaucoma).