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Many physiologically active hepatoprotective substances, such as those with antifibrotic activity, have been found in tea, fruits, and vegetables.1,2) The edible mushroom Lentinula edodes (shiitake) contains several bioactive compounds, including compounds with immunoprotective and antiatherogenic activities and one compound with an anti-human immunodeficiency virus (HIV) effect. [3][4][5] The mycelia of L. edodes can be cultured in solid medium, and the extract obtained by hot-water treatment (L.E.M.) is commercially available as a nutritional supplement. In our previous study, we found that L.E.M. exerts a hepatoprotective effect on dimethylnitrosamine (DMN)-induced liver fibrosis and Dgalactosamine-induced acute liver injury. 6,7) In the chronic liver injury model that uses DMN, the L.E.M. treatment suppressed the activation of hepatic stellate cells, which play a central role in liver fibrosis. The L.E.M. treatment also protected hepatocytes in the acute liver injury model that uses Dgalactosamine. We also found that the oral or intraperitoneal administration of L.E.M. suppressed immune-mediated liver injury. Therefore, L.E.M. is a promising plant extract for the prevention of liver failure. With the aim of developing effective drugs for liver diseases, we examined the protective effect of a single L.E.M. component against liver injury.The main components of L.E.M. are sugars, proteins, and polyphenolic compounds. The polyphenols act as antioxidants by scavenging reactive oxygen species (ROS), which produce oxidative stress and can adversely affect many cellular processes. Polyphenols have been proposed to protect against several diseases, including cancers, cardiovascular disease, and neurodegenerative disorders. [8][9][10] In our previous study, we found that the polyphenol-rich fraction of L.E.M. inhibits hepatic stellate cell activation, which is the

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Fucoidan, a sulfated polysaccharide extracted from brown algae, has a wide range of biological activities, including anti-inflammatory, anti-viral, and anti-tumor activities. In the present study, we investigated the effects of fucoidan on CCl4-induced liver fibrosis. Administration of fucoidan reduced CCl4-induced acute and chronic liver failure. Hepatic fibrosis induced by CCl4 was also attenuated by injection of fucoidan. Damage to hepatocytes and activation of hepatic stellate cells are key events in liver fibrosis, and, interestingly, treatment of hepatocytes with fucoidan prevented CCl4-induced cell death and inhibited the proliferation hepatic stellate cells. These results indicate that fucoidan might be a promising anti-fibrotic agent possessing dual functions, namely, protection of hepatocytes and inhibition of hepatic stellate cell proliferation.

An arsenite biosensor plasmid was constructed in Escherichia coli by inserting the operator/promoter region of the ars operon and the arsR gene from E. coli and the crtA gene, which is responsible for carotenoid synthesis in the photosynthetic bacterium, Rhodovulum sulfidophilum, into the broad-host-range plasmid vector, pRK415. The biosensor plasmid, pSENSE-As, was introduced into a crtA-deleted mutant strain of R. sulfidophilum (CDM2), which is yellow in culture due to its content of spheroiden (SE) and demethylspheroidene (DMSE). CDM2 containing pSENSE-As changed from yellow to red by the addition of arsenite, which caused enzymatic transformation of SE and DMSE to spheroidenone (SO) and demethylspheroidenone (DMSO). Reverse transcriptase PCR analysis showed that the color change depended on transcription of the crtA gene in pSENSE-As. The color change could be clearly recognized with the naked eye at 5 microg/l arsenite. The biosensor strain did not respond to other metals except for bismuth and antimony, which caused significant accumulation of SO and DMSO in the cells at 60 and 600 microg/l, respectively. This biosensor indicates the presence of arsenite with a bacterial color change without the need to add a special reagent or substrate for color development, enabling this pollutant to be monitored in samples by the naked eye in sunlight, even where electricity is not available.