Abstract
Sphingolipid has a unique physiological function in animal cells such as cell growth and apoptosis. In this study, we investigated the properties and physiological effects of plant glucosylceramides (GlcCer). The major sphingoid bases of GlcCer from soybean, maize, and rice bran were trans-4, cis or trans-8-sphingadienine. However, the major sphingoid base in wheat and rye grains were 8sphingenine mainly with the cis-configuration (more than 60%). Examination was made of the apoptosis-inducing activity of sphingoid bases from plant and fungal sphingolipids. Sphingoid bases from plant and fungi were found to bring about apoptosis in Caco-2 human colon cancer cells. In differentiated Caco-2 cells, the model for normal intestine cells, no apoptosis by sphingoid bases was noted to occur. For clarification of physiological effects of dietary plant and fungal sphingolipids on colon cancer in vivo, investigation was made to determine the manner in which dietary maize and yeast GlcCer affect 1, 2-dimethylhydrazine (DMH) -induced aberrant crypt foci (ACF) formation in mice large intestine. At 10 weeks of maize and yeast GlcCer feeding and DMH administration, ACF formation was found to be significantly suppressed in all large intestines of the mice. The daily ingestion of these com-pounds should thus serve to suppress colon carcinoma in humans.
