Attempt was made to determine the activity of trypsin and chymotrypsin inhibitors in edible parts of the winged bean, in which the inhibitory activities have been reported to be the highest among several legume beans.
　Chymotrypsin inhibitors, which have received little attention so far as compared with trypsin inhibitors, were found to exist in seeds two to nine times as much as trypsin inhibitors, and their contents differed a little among varieties.
　The result also indicated that flowers, green pods, leaves and stems were free from the protease inhibitors. Trypsin and chymotrypsin inhibitor contents simultaneously began to increase in the seeds about a month after flowering, when the seeds attained to the maximum size and became germinative. The tubers of winged bean, which functions as storage and propagative organ similar to the seeds, also contained the protease inhibitors. This suggests that these inhibitors might play a role in protecting these organs from predators.