Sake Yeast Suppresses Acute Alcohol-Induced Liver Injury in Mice

Abstract

Brewer's and baker's yeasts appear to have components that protect from liver injury. Whether sake yeast, Saccharomyces cerevisiae Kyokai no. 9, also has a hepatoprotective effect has not been examined. Here we show that sake yeast suppresses acute alcoholic liver injury in mice. Male C57BL/6 mice that had been fed a diet containing 1% sake yeast for two weeks received three doses of ethanol (5 g/kg BW). In the mice fed sake yeast, ethanol-induced increases in triglyceride (TG) and glutamate pyruvate transaminase (GPT) were significantly attenuated and hepatic steatosis was improved. In addition, sake yeast-fed mice showed a smaller decrease in hepatic S-adenosylmethionine (SAM) level and a smaller increase in plasma homocysteine (Hcy) level after ethanol treatment than the control mice, suggesting that a disorder of methonine metabolism in the liver caused by ethanol was relieved by sake yeast. These results indicate that sake yeast protects against alcoholic liver injury through maintenance of methionine metabolism in the liver.Key words: Saccharomyces cerevisiae; sake yeast; liver injury; alcohol; methionine metabolismThe physiological effects of brewer's yeast and its components in mammals have been well studied. For example, brewer's yeast cell wall reduces serum lipid levels in rats, 1) and improves defecation by contributing to the fermentation ability, water holding capacity, and swelling force of the large intestine.2) To understand the gene expression of Saccharomyces bayanuis as a lager brewer's yeast during beer fermentation, sequencing of the whole genome was performed.3) This provided further information about the physiological effects of brewer's yeast as well as the brewing of beer.On the other hand, there have been few studies of the physiological effects of sake yeast, Saccharomyces cerevisiae Kyokai yeast, which is used in sake (Japanese rice wine) brewing. Manabe et al. reported that both sake yeast and sake lees, the leftovers of sake brewing, increase spontaneous locomotive activity in rats. 4) They proposed that the effect of sake lees partly depends on sake yeast. The sake lees contain rice components that are not assimilated by sake yeast and sake koji, Aspergillus oryzae, components of sake yeast and sake koji, and their metabolites. Therefore, to understand the physiological effects of sake yeast may help to understand the physiological effcts of sake lees and to find new uses for them.A distinctive characteristic of sake yeast is that it is able to accumulate higher levels of S-adenosylmethionine (SAM) intracellularly than other yeasts, bacteria, molds, and some other microorganisms.5,6) SAM functions as a major methyl group donor in transmethylation of proteins, nucleic acids, polysaccharides, phospholipids, and fatty acids and as a precursor of glutathione. It has been proposed as a chemotherapeutic agent for alcoholic liver disease, 7) depression, 8) osteoarthritis , 9) and Alzheimer's disease. 10) Another distinctive characteristic of sake yeast is that it has a higher ethanol t...

Effect of Silkworm (Bombyx mori) Excrement Powder on the Alcoholic Hepatotoxicit in Rats

“…The concentrations of serum total lipid, triglyceride, total-cholesterol and HDL-cholesterol showed a significant decrease by SEP supplementation in alcohol feeding rats. Many reports indicate that alcohol intake significantly increases the levels of serum triglyceride and cholesterol [11,23], but this is not in agreement with the results in the present study. The current study demonstrated a possibility that SEP would be able to decrease the serum lipid concentrations by the simultaneous addition of alcohol.…”

S-Adenosylmethionine (SAM)-Accumulating Sake Yeast Suppresses Acute Alcohol-Induced Liver Injury in Mice

“…4B). We have shown in a previous report that the ingestion of a diet containing 1% sake yeast suppressed acute alcoholic liver injury; 13) the ethanol-induced increases in TG in the ethanol and 1% sake yeast/ethanol groups were 2.3-and 1.6-fold, respectively; 13) the ethanol-induced increases in ALT in the ethanol and 1% sake yeast/ethanol groups were 6.0-and 1.8-fold, respectively.…”

“…We have demonstrated that a diet containing 1% sake yeast repressed both the ethanol-induced elevation of TG and ALT and the ethanol-induced reduction of the hepatic SAM level. 13) Even though a diet containing 0.25% sake yeast repressed the ethanol-induced reduction of hepatic SAM level (Fig. 5), sake yeast could not fully repress the ethanol-induced elevations of TG and ALT (Figs.…”

“…13) In mice fed sake yeast, ethanol-induced increases in triglyceride (TG) and alanine aminotransferase (ALT) were significantly attenuated and hepatic steatosis was improved. 13) Ethanol consumption causes abnormal methionine metabolism, because ethanol consumption inhibits the activity of methionine synthase 14) which is responsible for the conversion of homocysteine (Hcy) to methionine. SAM is converted from methionine catalyzed by methionine adenosyltransferase.…”

“…Tel: +81-82-420-0814; Fax: +81-82-420-0804; E-mail: izu@nrib.go.jp Abbreviations: TG, triglyceride; ALT, alanine aminotransferase; SAM, S-adenosylmethionine; Hcy, homocysteine; SGF, simulated gastric fluid; BW, body weight which results in a decrease in the hepatic SAM level. [14][15][16][17][18] Sake yeast-fed mice have shown a smaller decrease in hepatic SAM level and a smaller increase in plasma Hcy level after an ethanol treatment than control mice, 13) suggesting that sake yeast protected the liver from abnormal methionine metabolism due to ethanol administration. We expected that SAM accumulated in sake yeast would enhance the suppressive effect of sake yeast on acute alcoholic liver injury, because SAM suppresses liver damage.…”