VITAMINS

E. coli KG 980,a vitamin B_6 auxotroph, could not utilize for its growth three phosphate forms of vitamin B_6 at the concentrations ranging from 10^<-7>M to 10^<-5>M in the minimum medium of Davis and Mingioli supplemented with glucose. The bacterium, however, utilized the phosphate forms in the phosphate starving medium of Garen and Levinthal which is known to derepress alkaline phosphatase, and it grew well on 10^<-6>M pyridoxine phosphate, 10^<-6>M pyridoxal phosphate or 10^<-5>M pyridoxamine phosphate. Correspondingly, the bacterial cells grown in the minimum medium could not take up the phosphate esters of tritium labelled vitamin B_6 compounds at 10^<-6>M concentrations in the same medium, whereas the cells grown in the phosphate starving medium significantly took up the labelled compounds in the same medium. The main labelled vitamin B_6 compound in the phosphate starving medium after 30-min incubation of labelled pyridoxine phosphate with the cells grown in the same medium was found to be pyridoxine. Furthermore, uptake of the labelled pyridoxine phosphate by E. coli K 12 cells was essentially similar to that by E. coli KG 980 cells. These results indicate that the phosphate forms of vitamin B_6 can be taken up and utilized after de phosphorylation by alkaline phosphatase, but not taken up in their intact form.

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When male albino rats were fed with a vitamin B_1-deficient diet designed by Gubler, ^<1)> the contents of vitamin B_6 and vitamin B_<12> in the blood after 3 weeks feeding decreased to 1/2 and 1/3 those of the pair-fed animals, respectively. Daily oral administration of insufficient amounts of vitamin B_1 to the vitamin B_1-deficient animals maintained their lives for 8 days or so. Daily supplement of vitamin B_6 and vitamin B_<12> to the B_1-insufficient level could elongate the survival of the vitamin B_1-deficient rate more than 20 days. These facts suggest that there would exist some interrelationships among vitamin B_1,B_6 and B_<12> in their blood contents and physiological functions in the animal.

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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.

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