IMPROVED CHROMATOGRAPHIC DETERMINATION OF FREE AND GLYCOSYLATED FORMS OF VITAMIN-B6 IN FOODS

Glycosylated forms of vitamin B6, including 5'-O-(beta-D-glucopyranosyl)pyridoxine (PN-glucoside) and several derivatives, often comprise a major fraction of the total vitamin in plant-derived foods. An ion-pair reverse-phase HPLC procedure has been previously reported that is suitable for the measurement of PN-glucoside and all free (nonglycosylated) forms of the vitamin. The present research was conducted to evaluate the efficacy of procedures for selective enzymatic and acid-catalyzed hydrolysis of glycosylated forms of the vitamin. Application of these procedures permits a determination of total vitamin B6 as well as the individual free and glycosylated fractions. Glycosylated forms of pyridoxine were found to comprise 0, 57, 67, 77, and 82% of the total vitamin B6 in oat bran, wheat bran, soy flour, carrots, and rice bran, respectively.