Distribution of ascorbic acid analogs and associated glycosides in mushrooms.

Mushrooms contain reducing substances with chemical properties similar to ascorbic acid (AsA). In this study, the four types of reducing substances contained in Flammulina velutipes (Enokitake), Hypsizigus mamoreus (Bunashimeji), Pholiota nameko (Nameko), and Grifola frondosa (Maitake) were respectively purified, and the structure of each was analyzed using nuclear magnetic resonance (NMR) and other methods. The results confirmed that those substances were AsA analogs and associated glycosides (6-deoxy-AsA, 6-deoxy-5-O-(alpha-D-xylopyranosyl)-AsA, 6-deoxy-5-O-(alpha-D-glucopyranosyl)-AsA, and 5-O-alpha-D-glucopyranosyl-erythro-AsA). These substances were characteristic in that saccharide was bonded with the C-5 of the AsA analogs. Osazones were formed from the reducing substances in 19 kinds of edible mushrooms. Using thin-layer chromatography (TLC), they were developed to examine the distribution of the above reducing substances and AsA. The results showed that at least one of the above compounds was certain to be present in any mushroom; that AsA was present in very small quantities if at all; and that several substances similar to the above compounds were present.