Glycoinositolphosphosphingolipids (basidiolipids) of higher mushrooms

The basidiolipids of six mushroom species, i.e. the basidiomycetes Amanita virosa (engl., death cup), Calvatia exipuliformis (engl., puffball), Cantharellus cibarius (engl., chanterelle), Leccinum scabrum (engl., red birch boletus), Lentinus edodes (jap., Shiitake) , and Pleurotus ostreatus (engl., oystermushroom), were isolated, and their chemical structures investigated. All glycolipids are structurally related to those of the Agaricales (engl., field mushroom). They are glycoinositolphosphosphingolipids, their ceramide moiety consisting of t18:0‐trihydroxysphinganine and an α‐hydroxy long‐chain fatty acid. In contrast to a previous study [Jennemann, R., Bauer, B.L., Bertalanffy, H., Geyer, R., Gschwind, R.M., Selmer, T. & Wiegandt, H. (1999) Eur. J. Biochem. 259 , 331–338], the glycoside anomery of the hexose (mannose) connected to the inositol of all investigated basidiomycete glycolipids, including the basidiolipids of Agaricus bisporus , was determined unequivocally to be alpha. Therefore, the root structure of all basidiolipids consists of α‐ d Man p ‐2Ins1‐[ P O 4 ]‐Cer. In addition, for some mushroom species, the occurrence of an inositol substitution position variant, α‐Man p ‐4Ins1‐[ P O 4 ]‐Cer, is shown. The carbohydrate of chanterelle basidiolipids consists solely of mannose, i.e. Cc 1 , Manα‐3 or ‐6Manα; Cc 2 , Manα‐3(Manα‐6)Manα‐. All other species investigated show extension of the α‐mannoside in the 6‐position by β‐galactoside, which, in some instances, is α‐fucosylated in 2‐position (Fucα‐2)Galβ‐6Manα‐. Further sugar chain elongation at the β‐galactoside may be in 3‐ and/or 6‐position by α‐galactoside, e.g. Ce 4, Po 2 , Galα‐3‐(Galα‐6)(Fucα‐2)Galβ‐6Manα‐, whereas A. virosa , Av‐3, has a more complex, highly α‐fucosylated terminus, Galα‐3 (Fucα‐2)(Fucα‐6)Galα‐2(Galα‐3)Galβ‐6Manα‐. L. edodes basidiolipids show further elongation by α‐mannoside, e.g. Le 3 , Manα‐2Manα‐6Galα‐3(Fucα‐2)Galβ‐6Manα‐, C. exipuliformis glycolipid by α‐glucoside, i.e. Ce 3 , Glcα‐6Galβ‐6Manα‐. Basidiolipid Ls 1 from L. scabrum, notably, has a 3‐α‐mannosylated α‐fucose, i.e. Galα‐6(Manα‐3Fucα‐2)Galα‐6Galβ‐6Manα‐. In conclusion, basidiolipids, though identical in their ceramide constitution, display wide and systematic mushroom species dependent variabilities of their chemical structures.