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United States Department of Agriculture

Agricultural Research Service

Research Project: Molecular Biology of Human Pathogens Associated with Food

Location: Produce Safety and Microbiology Research

Title: A polysaccharide isolated from the liquid culture of Lentinus edodes (shiitake) mushroom mycelia containing black rice bran protects mice against a Salmonella lipopolysaccharide-induced endotoxemia

Authors
item Kim, Sung Phil -
item Park, Sun Ok -
item Lee, Sang Jong -
item Nam, Seok Hyun -
item Friedman, Mendel

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 28, 2013
Publication Date: November 8, 2013
Citation: Kim, S., Park, S., Lee, S., Nam, S., Friedman, M. 2013. A polysaccharide isolated from the liquid culture of Lentinus edodes (shiitake) mushroom mycelia containing black rice bran protects mice against a Salmonella lipopolysaccharide-induced endotoxemia. Journal of Agricultural and Food Chemistry. 61(46):10987-10994. DOI: 10.1021/jf403173k.

Interpretive Summary: Endotoxemia (sepsis, septic shock) is a systemic infection caused by release into the bloodstream of endogenous mediators of inflammation and the response of the immune system to infections bacteria, fungi, viruses, and parasites in the blood, liver, kidney, lungs, and skin. The often fatal disease to which pregnant women and immunocompromised individuals are especially susceptible, is accompanied by failure of multiple organs, including liver, lungs, and kidneys. In the United States, about 750,000 individuals are afflicted with sepsis annually, with a 28-50% mortality rate. In England, about 7.7% of all deaths during 2010 are estimated to be sepsis-related. Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria such as Salmonella, is a major virulence factor for the pathogenesis of endotoxemias. In a collaborative study, we evaluated the potential of the natural biopolymer produced in cultures of Lentinus edodes (shiitake) mushroom mycelia with supplemented black rice bran to protect mice against Salmonella-LPS/D-galactosamine (GalN)- induced endotoxemia. The new polysaccharide contained both sugars and amino sugars and eluted as a single peak on an HPLC chromatogram. The polysaccharide protected mice against the induced sepsis. The protective effect seems to involve stimulation of the innate immune system and amelioration of pathological effects in the liver, lung, and kidney tissues. The observed beneficial properties suggest that the new food-derived polysaccharide has the potential to serve as a functional food.

Technical Abstract: Endotoxemia (sepsis, septic shock) is an inflammatory, virulent disease that results mainly from bacterial infection. The present study investigates the inhibitory effect of the bio-processed polysaccharide (BPP) isolated from the edible Lentinus edodes liquid mycelial mushroom culture supplemented with black rice bran against murine endotoxemia induced by the Salmonella lipopolysaccharide and D-galactosamine (LPS/GalN). BPP was obtained after dialysis against water using a cellulose tube with a molecular weight cutoff of 10,000. BPP eluted as a single peak on an HPLC chromatogram. Acid hydrolysis of BPP showed the presence of the following sugars: fucose, galactose, galactosamine, glucose, glucosamine, mannose, rhamnose, and xylose. Treatment of BPP with ß-glucanase reduced its immunostimulating activity, suggesting that the polysaccharide has a ß-glucan structure. Pre-treatment of mice with BPP via oral or intraperitoneal (ip) administration for two weeks resulted in the suppression of LPS/GalN-induced catalase, superoxide dismutase (SOD), and transaminase (GOT/GPT) liver enzymes, amelioration of necrotic liver lesions, reduction of tumor necrosis factor a (TNF-a) and nitrite serum levels, and myeloperoxidase (MPO) activity, an index of necrotic injury. Immunostimulating macrophage activity was up to 5.4-fold greater than that observed with the culture without the rice bran. BPP also extended the lifespan of the toxemic mice. These positive results with inflammation biomarkers and lifespan studies suggest that the BPP can protect mice against LPS/GalN-induced liver, lung, and kidney injuries and inflammation by blocking oxidative stress and the tumor necrosis factor (TNF-a) production, thus increasing the survival of the toxic shock-induced mice. The polysaccharide has the potential to serve as new functional food.

Last Modified: 10/1/2014
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