THE VITAMIN Bs GROUP XIV. DISTRIBUTION OF PYRIDOXAL, PYRIDOXAMINE, AND PYRIDOXINE IN SOME NATURAL PRODUCTS* BY JESSE

Although pyridoxal, pyridoxamine, and pyridoxine are all known to occur naturally (l), almost no information concerning the distribution of these individual forms of vitamin Bs is available. Use of three microorganisms for the individual detection of these three substances has been previously suggested (1, 2). Since Lactobacillus casei responds only to pyridoxal,’ this substance could be determined directly. Both pyridoxamine and pyridoxal, but not pyridoxine, promote growth of Streptococcus faecalis;’ pyridoxamine was thus obtained as the difference between the value obtained with this organism and with Lactobacillus casei, corrected for the difference in activity of the two compounds for the former organism. Total vitamin BE was determined with Saccharomyces carlsbergensis 4228, which responds to pyridoxal, pyridoxamine, and pyridoxine. The difference between the assay value obtained with Saccharomyces carlsbergensis and the sum of the values for pyridoxal and pyridoxamine was considered to represent pyridoxine. Validity of this approach to the problem was questioned when it was found that assay of yeast and liver extracts with Streptococcusfaecalis gave higher values for their vitamin Bs content than did assay with Saccharomyces carlsbergensis (3). Subsequently this result was shown to be due chiefly to the presence in natural materials of a “bound” form of vitamin Bs, pyridoxamine phosphate, which was inactive for Saccharomyces carlsbergensis but active for Streptococcus fuecalis (4). Present availability of improved hydrolytic procedure for release of vitamin Bs from tissues (5)