Discovery and development of direct Xa inhibitors Xa was identified as a promising target for the development of new anticoagulants in the early 1980s. In 1987 the first factor Xa inhibitor, the naturally occurring compound antistasin, was isolated from the salivary glands of the Mexican leech "Haementeria officinalis". Antistasin is a polypeptide and a potent Xa inhibitor. In 1990 another naturally occurring Xa inhibitor was isolated, tick anticoagulant peptide (TAP) from extracts of the tick "Ornithodoros moubata". TAP and antistasin were used to estimate factor Xa as a drug target. Blood coagulation is a complex process by which the blood forms clots. It is an essential part
Salivary gland by decreasing clotting time and increasing wound contraction. Saliva contains the enzyme amylase, which hydrolyses starch into maltose and dextrin. As a result, saliva allows digestion to occur before the food reaches the stomach. Saliva acts as a solvent in which solid particles can dissolve in and enter the taste buds through oral mucosa located on the tongue. These taste buds are found within foliate and circumvallate papillae, where minor salivary glands secrete saliva. A sialolithiasis (a salivary calculus or stone) may cause blockage of the ducts, most commonly the submandibular ducts, causing pain and swelling of the gland. Salivary