Hepatoprotective effects of a concentrate and components of sake against galactosamine (GalN)-induced liver injury in mice

Abstract

We investigated the hepatoprotective effects of a concentrate of sake (CS) and its components against D-galactosamine (GalN)-induced liver injury by measuring the plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in mice. CS significantly suppressed the GalN-induced elevation of ALT and AST activities. Each of four concentrated fractions extracted from sake (respectively consisting mainly of basic amino acids, neutral and acidic amino acids, organic acids and sugars) suppressed the GalN-induced elevation of ALT and AST activities. We focused on the sugar fraction containing glucose and ethyl α-D-glucoside (α-EG), which is a sake-specific sugar, as the major components and demonstrated that only α-EG showed significant suppression of the GalN-induced elevation of ALT and AST activities. We compared the effects of the α-EG analogues, methyl α-D-glucoside and ethyl α-D-glucoside, on GalN-induced liver injury and confirmed that only α-EG significantly suppressed both the ALT and AST activities. Moreover, CS and α-EG suppressed the GalN-induced production of interleukin 6 (IL-6) and liver DNA fragmentation. Together these results show that CS and its component, α-EG, suppressed GalN-induced liver injury by inhibiting IL-6 production.