222 PYRIDOXINE AND RELATED COMPOUNDS 



II. Chemistry 



JOHN C. KERESZTESY 



A. ISOLATION 

 1. Introduction 



The apparent and specific chemical properties of vitamin Be (pyridoxine) 

 as present in crude concentrates were definitely established by Birch and 

 Gyorgy.^ Within a few years of their publication the nitrogen base postu- 

 lated as the active vitamin by these authors was isolated in several labora- 

 tories almost simultaneously. There was no long lapse between the recogni- 

 tion of the existence of this vitamin and its separation in pure form as had 

 been the case with the first of the B vitamins. To be sure, pyridoxine is a 

 much more stable substance than thiamine. Within approximately two 

 years of the original observations of Birch and Gyorgy, five independent 

 reports appeared announcing its isolation. Lepkovsky,^ Keresztesy and 

 Stevens,^ Gyorgy,'* Kuhn and Wendt,^ and Ichiba and Michi^ had suc- 

 ceeded in isolating pyridoxine from various natural materials. The compound 

 was now available for the study and the elucidation of its chemistry and 

 structure which lead directly to its synthesis. It must be noted here that 

 as early as 1932, Ohdake'^ in his systematic study of the constituents of rice 

 polishings extract had isolated the hydrochloride of an unknown nitrogen 

 base to which he had assigned the improbable empirical formula 

 CsHioNOs'HCl. Its identity with pyridoxine was pointed out later bj^ 

 Wiardi.^ At this stage in the development of the \'itamin, animal assays 

 were required to follow^ the biological activities of fractions obtained in the 

 respective isolation procedures. Such assays are costly in both time and 

 material as compared with the microbiological assay methods now emploj^ed 

 to follow the fractionation procedures for growth factors. Since pyridoxal 

 and pyridoxamine are the microbiologically active forms, the question arises 

 whether pyridoxine itself would have been isolated if the latter assay meth- 

 ods had been used. 



1 T. W. Birch and P. Gyorgy, Biuchem. J. 30, 304 (1936). 



2 S. Lepkovsky, Science 87, 169 (1938). 



3 J. C. Keresztesy and J. R. Stevens, Proc. Soc. Exptl. Biol. Med. 38, 64 (1938). 

 ' P. Gyorgy, /. Am. Chem. Soc. 60, 983 (1938). 



6 R. Kuhn and G. Wendt, Ber. 71, 780 (1938). 



6 A. Ichiba and K. Miclii, Sci. Papers Inst. Phi/s. Chem. Research (7\;A-//o) 34, 623 



(1938). 

 ■' S. Ohdakc, Bull. Agr. Chem. Soc. Japan 8, 11 (19:52). 

 " P. W. Wiardi, Nature 142, 1158 (1938). 



