The root tubers of Dioscorea bulbzfera L., although considered poisonous because of
cytotoxic activity, have been used in Chinese medicine as a remedy for sore throat and
for struma. However, both our group and the group of Professor Shoyama have shown
that this plant possesses other important properties, namely antitumor effects and
antifeeding activity against silkworms, thus providing self-defense against predators
(Shoyama, unpublished results).
Initial attempts to isolate saponins, for example of the dioscin type, from this plant by
the plant saponin method failed because of a step which included purification on silica gel.
The whole material had been lost due to adsorption on the silica gel. Using the procedure
shown in Fig 1, we were finally able to isolate diosbulbin B in a more traditional way
(Yonemitsu et al., 1993).