Abstract
The soybean is famous for being abundant in phytochemicals such as saponin and isoflavone. The isoflavone in particular is known to show estrogenic activity. In addition, the diuretic effects of the saponin are well-known effects of edible beans. On the other hand, Pueraria flowers show hepatoprotective activity, but the structutes of active principles closely resemble those of the soybean phytochemicals. We performed an experiment using intestinal bacteria of human origin, since the metabolic reaction showing how biological activity is affected by slight structural differences can be inferred by intestinal microbiota. The results were as follows. 1a) The Pueraria flower saponins showed more potent hepatoprotective activity because of the methyl group at C-24. 1b) The Pueraria flower isoflavones show more potent hepatoprotective activity than those of the soybean isoflavones. 2) The soybean isoflavones only showed estrogenic activity since their structures are more simple than those of the Pueraria flower isoflavones. 3) The soybean saponins showed more potent anti-complement (nephroprotective) activity than those of the Pueraria flower saponins. 4) The contribution of activities induced by intestinal bacteria was very large.
