Abstract
Three new pyridoxine-glycosides were isolated from rice bran (10kg) as colorless powder by various chromatographic techniques: compound A, 53mg; compound B, 7.8mg; compound C, 5.8mg. Compound A was shown to consist of pyridoxine and glucose in a 1:2 molar ratio by β-glucosidase hydrolysis, and by 1H-NMR and secondaryion 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-(β-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-(β-D-glucosyl)-5'-0-(β-cellobiosyl) pyridoxine, and compound C to be 5'-O-(β-glucotriosyl) pyridoxine in which a glucose molecule was bound to the cellobiosyl moiety of compound A through β-glycosidic linkage.
