Antifungal Protein and Saponins in Soybean

Many investigations have been conducted on soybean during the past decade since it is a unique dietary source of isoflavones which display a diversity of biological activities and reduce the risk of some chronic diseases. Soybean is distinctive in that it has a high content of isoflavones which allegedly diminish the risk of cancer, cardiovascular disease, and osteoporosis, and also alleviate menopausal symptoms. Isoflavones are weakly estrogenic. The isoflavone genistein also affects signal transduction. Soyfoods and isoflavones have arrested the attention of many researchers on account of their potential role in preventing and treating cancer and osteoporosis. The low breast cancer mortality rates in Asia and the putative antiestrogenic infer that soyfood intake reduces breast cancer risk. Soy or isoflavones may decrease the risk of prostate cancer. The low estrogenic activity of soybean isoflavones and their structural resemblance to the synthetic isoflavone ipriflavone, which elevates bone mineral density in postmenopausal women, suggest that soy or isoflavones may decrease the risk of osteoporosis. Besides isoflavones, soybean also produces protease inhibitors, lectins, and antifungal proteins, which have important biological activities. This review encompasses a discussion of isoflavones, protease inhibitors, lectins and antifungal proteins.