Chemical structures of mono-, di-, tri-, and tetraglycosyl glycerides in rice bran.

1. Monoglycosyl monoglyceride, mono-, di-, tri- and tetraglycosyl diglycerides were isolated from rice bran and characterized for their chemical structures. 2. Monoglycosyl monoglycerides were characterized as Gal(beta 1' leads to 3)-1- or 2-monoacyl-sn-glycerol and Glc(beta 1' leads to 3)-1- or 2-monoacyl-sn-glycerol. 3. The structures of monoglycosyl diglyceride were Gal(beta 1' leads to 3)-1,2-diacyl-sn-glycerol and Glc(beta 1' leads to 3)-1,2diacyl-sn-glycerol. Epimeric separation of the galactosyl and glucosyl glycerides was for the first time achieved by thin-layer chromatography. 4. The main diglycosyl diglyceride was shown to be Gal(alpha 1'' leads to 6')-Gal(beta 1' leads to 3)-1,2-diacyl-sn-glycerol. 5. The major structure of triglycosyl diglyceride was characterized as Gal(alpha 1''' leads to 6'')-Gal(alpha 1'' leads to 6')-Gal(beta 1' leads to 3)-1,2-diacyl-sn-glycerol. 6. The representative structure of tetraglycosyl diglyceride was for the first time established as Gal(alpha 1'''' leads to 6''')-Gal(alpha 1''' leads to 6'')-Gal(a-pha 1'' leads to 6')-Gal(beta1' leads to 3)-1,2-diacyl-sn-glycerol.