The Multiple Nature of Vitamin B6. Critique of Methods for the Determination of the Complex and Its Components

Vitamin B6 Group. Extraction procedures for the Microbiological Determination of Vitamin B6

“…From the limited data available, pyridoxal appears to constitute a minor fraction of the total vitamin Be present in hydrolyzed extracts of most natural materials, including yeast (5,11). This point requires further investigation with improved hydrolytic procedures, but if true, hydrolysis of pyridoxal phosphate cannot explain increases in total vitamin Be of the magnitude noted following hydrolysis with low concentrations of mineral acids.…”

“…14) also occurs naturally, the hydrolysis of which contributes to the observed increase. That a bound form of pyridoxine of unknown nature occurs in rice bran concentrates is well known (5,11). This conjugate appears not to be present in yeast or animal tissues, and furthermore is hydrolyzed only by relatively high concentrations of acid (5).…”

“…That a bound form of pyridoxine of unknown nature occurs in rice bran concentrates is well known (5,11). This conjugate appears not to be present in yeast or animal tissues, and furthermore is hydrolyzed only by relatively high concentrations of acid (5). Its possible presence would not, therefore, explain increases of the magnitude observed with animal tissue and yeast following hydrolysis with 0.055 N hydrochloric acid.…”

Food

“…Of critical importance in the estimation of vitamin Be in natural materials is the hydrolytic procedure employed as well as the choice of test organisms. Following the observation (242) that 2 iV sulfuric acid extracts only part of the total vitamin B, activity of yeast (according to the Saccharomyces carlsbergensis assay), it was shown (315) that 0.055 N sulfuric acid was a more efficient extractant. This has been confirmed by subsequent work (299) in which autoclaving at 20 pounds pressure for 5 hours in 0.055 N sulfuric acid is recommended as a general extraction procedure.…”

Stability assays of aged pharmaceutical formulas for thiamine and pyridoxine by high performance thin-layer chromatography and derivative ultraviolet spectrometry

“…As for pyridoxine, the present official U.S.P. XIX (8) method of photometric assay with 2,6-dichloroquinone-chlorimide (9) is not specific either, and requires special skill as the color obtained is rather unstable (2).…”