Molecular Species of Ceramide and Mono-, Di-, Tri-, and Tetraglycosylceramide in Bran and Endosperm of Rice Grains

Ceramide and mono-, di-, tri-, and tetraglycosylceramide were isolated from the bran and endosperm of rice grains and chemically characterized. The detailed compositions of free ceramide were somewhat different between the bran and endosperm, but those of the ceramide moiety in glycosylceramides were substantially the same. There was a tendency in all the sphingolipid molecules in rice grains for hydroxy acids with C₂₀ to be combined largely with the dihydroxy bases while hydroxy acids with C_24< combined mainly with the trihydroxy bases. Representative molecular species of the sphingolipid classes were concluded to be as follows: for ceramide N-2′-hydroxylignoceroyl-4-hydroxysphinganine, for monoglycosylceramide l-O-β-glucosyl-N-2′-hydroxyarachidoyl-4,8-sphingadienine, for diglycosylceramide 1-O-β-mannosyl(1→-4)-O-β-glucosyl]- and 1-O-β-glucosyl(1→4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine, for triglycosylceramide l-O-β-mannosyl(1→4)-O-β-mannosyl(l→4)-O-β-glucosyl]- and l-O-β-glucosyl(l→4)-O-β-mannosyl(1→4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine, and for tetraglycosylceramide 1-0-β-mannosyl(l→4)-O-β-mannosyl (1→4)-O-β-mannosyl(1→4)-O-β-glucosyl]- and l-O-β-glucosyl(1→4)-O-β-mannosyl(l→4)-O-β-mannosyl(1β4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine.