The Vitamin B6 Group

In a previous paper (1) evidence for the occurrence in natural products of one or more substances which far surpassed pyridoxine in growthpromoting activity for various species of lactic acid bacteria was described.Pyridoxine was partially transformed inOo this substance by the animal organism.The substance responsible for the increased activity was tentatively called "pseudopyridoxine."Subsequently, it was found that.substances of similarly high activity for these organisms were formed when pyridoxine was subjected to procedures causing amination or partial oxidation ( 24).The active substances formed by these procedures were identified and named pyridoxamine and pyridoxal, respectively (4-6).The comparative activity of pyridoxamine, pyridoxine, and pyridoxal in promoting growth of a number of organisms has been described (4, 6).Among these organisms were three which behaved very differently toward the three compounds.For Xczccharomyces carlsbergensis the three compounds were approximately equally active on the molar basis.For Xtreptococcus faecalis R, pyridoxamine was highly active, pyridoxal somewhat less active, and pyridoxine practically inactive.For Lactobacillus casei pyridoxal was highly active; pyridoxamine and pyridoxine were comparatively only very slightly active.Unless the latter two compounds were present in very high concentration relative to the pyridoxal concentration, activity due to them could be safely neglected without introducing significant error into the determination of pyridoxal.By using all three organisms with proper standards, it is thus possible, by solving a very simple set of simultaneous equations, to determine the amount of any one of these compounds present in a mixture of the three.Application of the differential assay to natural materials would, of course, result in classification of the growth-promoting substances present into three fractions, depending upon whether they behaved toward the test organisms as pyridoxine, pyridoxamine, or pyridoxal.