Determination of the Thrombolytic Activity of Natto Extract

INTRODUCTION Bacillus subtilis, the species to which natto bacillus belongs, has been reported to secrete several proteases extracellularly during growth (1-4). Among these proteases, the physiological activity or clinical applications of antithrombotic substances contained in natto, such as the peptidase subtilisin, have been reported (5-8). Based on the results of this research, functional foods have been developed and some thrombolytic activity assay methods have been proposed for use in quality specifications. One of these methods is "the standard of natto bacillus culture extract food (January 15, 2003)" distributed to its members by the Japan Health Food & Nutrition Food Association (Table 1). This standard classifies the products into processed foods, supplemented foods, and raw materials, according to the activity per reference amount for one day as measured by the described method.