Isolation and structural elucidation of three new pyridoxine-glycosides in rice bran.
Three new pyridoxine-glycosides were isolated from rice bran (10 kg) as colorless powder by various chromatographic techniques: compound A, 53 mg; compound B, 7.8 mg; compound C, 5.8 mg. Compound A was shown to consist of pyridoxine and glucose in a 1:2 molar ratio by beta-glucosidase hydrolysis, and by 1H-NMR and secondary ion mass spectrometry (SI-MS) data. On partial acid hydrolysis of the compound, cellobiose was liberated. Compound A showed the positive Gibbs color reaction, but the reaction was negative in the presence of boric acid. Thus, compound A was identified as 5'-O-(beta-cellobiosyl)pyridoxine. The 13C-NMR spectral data were compatible with this structure. Compounds B and C were proven to be triglucosides of pyridoxine by enzymic hydrolysis and SI-MS data. From the results of the Gibbs color reaction and partial hydrolyses which yielded compound A, compound B was concluded to be 4'-O-(beta-D-glucosyl)-5'-O-(beta-cellobiosyl)pyridoxine, and compound C to be 5'-O-(beta-glucotriosyl)pyridoxine in which a glucose molecule was bound to the cellobiosyl moiety of compound A through beta-glycosidic linkage.
D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D005960:Glucosides / Q000302:isolation & purification*; D006027:Glycosides / Q000302:isolation & purification*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D012275:Oryza / Q000032:analysis*; D011736:Pyridoxine / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification; D013053:Spectrophotometry; D001617:beta-Glucosidase / Q000378:metabolism
D005960:Glucosides; D006027:Glycosides; C057704:5'-O-(cellobiosyl)pyridoxine; C057706:4'-O-(glucosyl)-5'-O-(cellobiosyl)pyridoxine; C057708:5'-O-(glucotriosyl)pyridoxine; D001617:beta-Glucosidase; D011736:Pyridoxine