食品由来有害成分の毒性発現とその栄養条件による修飾

抄録

1) Pheophorbide a, which is one of the decomposition products from chlorophyll, is widely distributed in foodstuffs, e.g. in salted vegetables and abalone viscera. This compounds is known to cause photosensitivity in human and animals. We have studied the mechanism of this phenomenon and shown that in the presence of pheophorbide a, visible light irradiation leads to the production of singlet oxygen. This, in turn, results in cell damage by oxydation of lipids, especially in the cell membranes. Further, we discovered that some kinds of vitamins display a preventive action against the photosensitivity caused by pheophorbide a. 2) It is well known that iodine dificiency caused edemic goiter in human subjects. On the other hand, many goitrogenic substances were found in various vegetables. We have studied the goitrogenic activity of soybean, and found that goitrogenic factors are some glucosides, saponine and isoflavonoides such as genistin and daidzin. In the process of this study, hyperplastic goiters were observed frequently in rats when they were given soybean under conditions of iodine deficiency for as long a term as 6 to 12 months. However, enlargement of thyroid and malignancy was completely inhibited when a small amount of iodine was added to the diet. The study was undertaken to determine the involvement of intestinal bacteria in the induction of goitrogens from soybean glucosides using germ-free mice. It was found that germ-free mice were more sensitive to iodine deficiency than conventional mice, and it was suggested that iodine metabolism was modified significantly with intestinal flora.