Isolation of N-acetylneuraminic Acid and N-glycolylneuraminic Acid from Pleurocybella porrigens

Pleurocybella porrigens (P porrigens) is a traditional food consumed in Japan. Toxicity was first reported in 2004, following which a series of poisonings were reported in 2007. More than 59 people who consumed P. porrigens Suffered from similar severe cryptogenic encephalitis, with an overall death rate of approximately 29%. P. porrigens is believed to be a major etiological agent of this disease, but the mechanism of pathogenesis is not clear. To elucidate the toxic properties of P. porrigens in the 2004 and 2007 poisonings, we compared the oligosaccharide constituents of mushroom samples collected in these years with those collected in other years. Water extracts (90 degrees C and 4 degrees C) of P. porrigens were dialyzed, and the oligosaccharides obtained from the high-molecular-weight fraction (> 7.8 kDa) were subjected to acid hydrolysis for modification and labeling. Resultant saccharides were analyzed by high performance liquid chromatography on an octadecyl silane (ODS) column. Our analysis revealed that the concentration of N-acetylneuraminic acid (NeuAc) was abundant in all samples, however, N-glycolylneuraminic acid (NeuGc) was present only in significant amounts in the P porrigens samples collected in 2004 and 2007.