II. CHEMISTRY 399 



In this way, the presence of four active factors in Hv^r extracts was dem- 

 onstrated."' Two of these are evidently the colored fractions previously 

 dcscrilied^ (vitamin B].. and a closely related factor); another is evidently 

 thymidine. B3' somewhat similar procedures'* inv^olving paper chromatog- 

 raphy and tul)e assay, the presence in crude extracts of five active con- 

 stituents other than vitamin Bvi has been recognized. These appeared to be 

 desoxy ribosides. ' "" ' - 



As a result of further study of natural sources of vitamin B12, other closely 

 related substances with similar activity were discovered. When extractives 

 from the fermentation broths of Streptomyces aureofaciens were subjected 

 to chromatography on charcoal followed by elution and chromatography 

 on silicic acid columns, vitamin B12 and a second red crystalline compound 

 were isolated.'^ This second red (;ompound, named vitamin Bi2b, was closely 

 related to \'itamin B12 in physical and biological properties, but differed 

 in certain characteristics.'"* ■ '^ Crystalline vitamin Bi2b has also been isolated 

 from neomycin fermentations.'^ In the isolation procedure, the fermentation 

 medium was acidified and heated to extract the active substance from the 

 mycelium; the active substance was then adsorbed on charcoal. After elu- 

 tion the purity was increased by solvent partition through a series of separa- 

 tions. These were followed by a series of chromatographic adsorptions on 

 charcoal ; the purified eluates yielded crystalline vitamin Bi2b from aqueous 

 acetone. 



From S. griseus, two other closely related substances have been isolated 

 in crystalline form and called vitamins Bi2c and Bi2d ;" they appeared to be 

 equally active clinically with vitamin B12 in the treatment of pernicious 

 anemia. Vitamin Bi2d was later found to be identical with vitamin Bi2b-'^ 



The literature has become somewhat confused by the nomenclature used 

 in publications on these various modifications of vitamin B12. The dis- 

 cussion of the chemical nature of these closely related compounds in the 

 section on constitution should serve to clarify this unfortunate confusion. 



" W. A. Winsten and E. Eigen, J. Biol. Chem. 181, 109 (1949). 



'2 V. Kocher, P. Karrer, and 11. R. Muller, Z. Vitaminforsch. 21, 403 (1950). 



13 J. V. Pierce, A. C. Page, Jr. E. L. R. Stokstad, and T. H. Jukes, J. Ain. Chem. 



Soc. 71, 2952 (1949). 

 " J. V. Pierce, A. C. Page, E. L. R. Stokstad, and T. H. Jukes, /. Am. Chem. Soc. 72, 



2615 (1950). 

 '5 H. Lichtman, J. Watson, V. Ginsberg, J. V. Pierce, E. L. R. Stokstad, and T. H. 



Jukes, Proc. Soc. Exptl. Biol. Med. 72, 643 (1949). 

 i« W. G. Jackson, G. B. Whitfield, W. H. DeVries, H. A. Nelson, and J. S. Evans, 



J. Am. Chem. Soc. 73, 337 (1951). 

 " W. K. Anslow, S. Ball, W. B. Emery, K. H. Fantes, E. L. Smith, and A. D. Walker, 



Chemistnj & Indu^lnj 1950, 574; E. L. Smith, Lancet 258, 3.53 (19.50). 

 18 E. L. Smith, Nature 169, 60 (1952); E. L. Smith, K. H. Fantes, S. Ball, I). M. Ire- 

 land, J. G. Waller, W. B. Emery, W. K. Anslow, and A. D. Walker, Proc. Biochem. 



Soc. Biochem. J. 48, T> (1951); E. L. Smith, Chemistry & Industry 1951, 939. 



