Abstract
Vitamin B_6 contents in cereals and other seeds were determined using Saccharomyces carlsbergensis 4228 as test organism after buffer extraction, acid hydrolysis, and takadiastase digestion of the specimens. For some samples, takadiastase digestion sufficed to liberate most of vitamin B_6,but did not for other samples including kaoliang, trefoil and rice bran ; acid hydrolysis was required to liberate maximum amount of vitamin B_6 from the latter samples. A large part of vitamin B_6 occurred in bound form(s) which was microbially inactive unless hydrolyzed. In rice bran, pyridoxine (PIN) was the principal form of B_6 present both in free and bound forms. Difference between 19.5 and 10.5 μg vitamin B_6/g bran, the values obtained after acid hydrolysis and takadiastase digestion respectively, appeared to represent an amount of unknown takadiastase-resistant PIN derivative. About 4μg/g was susceptible to β-glucosidase and about 1μg/g to acid phosphatase, these corresponding to a PIN-β-glucoside or its likeness and to PIN-5'-phosphate respectively. PIN derivatives in rice bran were fractionated by gel filtration on a Sephadex G-10 column. Most components in the resolved fractions behaved as low molecular weight substances. Chemical nature of a takadiastase-sensitive component and a takadiastase-resistant but acid-hydrolyzable one, both being resolved in gel filtration, remained unidentified.
