Effects of dietary ethanol extracts from sake rice and sake lees on intestinal impairment in mice

Glucosylceramide (GlcCer), a major sphingolipid in plants and fungi, is known to have food functions, such as preventing intestinal impairment and enhancing the moisture content of skin. This study investigated the influence of fermentation on the composition and function of lipophilic components containing GlcCer in plant-based foods; we compared the effects of ethanol extracts from sake rice (SR) and sake lees (SL) on colon impairment in mice. GlcCer and ceramide (Cer) levels in SL were much higher than those in SR, and GlcCer in SL contained 9-methyl-trans-4,trans-8-sphingadienine as a fungi-specific sphingoid base. 1,2-dimethylhydrazine (DMH) treatment markedly increased the formation of aberrant crypt foci (ACF) and the levels of TNF-α and lipid oxidation in mice colons. However, dietary SR or SL significantly suppressed these DMH-induced changes, and SR demonstrated stronger effects than SL. In addition, dietary SR or SL suppressed the expression of apoptotic and anti-apoptotic proteins induced by DMH treatment. This study suggests that SR or SL intake could reduce colon ACF formation via the suppression of inflammation and oxidation-induced cell cycle disturbances. When compared to SR, the weaked effects of SL rich in GlcCer may be the result of the changes in sphingolipid composition (sphingoid base and Cer) and differences in the concentration of other bioactive compounds produced or digested during fermentation.