408 



VITAMIN Bi2 



and L. leichmannii show approximately equivalent activity with that of 

 vitamin B12. In the "animal protein factor" assay with rats, the activity of 

 vitamin Bi2a is equivalent to that of vitamin B12. Using chicks as the assay 

 animals, the activity is approximately 50 % of the activity of vitamin B12. 

 Clinical trials with vitamin Bi2a in cases of Addison's pernicious anemia, 

 tropical sprue, nutritional macrocytic anemia, and megaloblastic anemia of 

 infancy have demonstrated the effectiveness of vitamin Bi2a in producing 

 a rise in reticulocytes, red blood cells, white blood cells, platelets, and hemo- 

 globin and promoting a return of the bone marrow to normal. '^^ ^g regards 

 the quantitative dosage relationship between vitamins B12 and Bi2a for 



WAVE LENGTH . ny» . 



Fig. 4. Spectra in water of vitamin Bi2a after drying in vacuo at 100° for 2 hours: 

 , solution at i = ca. 1 minute; — •— — , solution at t = ca. 15 min- 

 utes; , solution at i = 24 hours; spectrum of vitamin Bi2b (Lederle 



NP-92-58-4) after drying at 100° for 2 hours in vacuo; water solution at t = over 30 

 minutes. Reproduced with permission from /. Am. Chem. Soc. 73, 355 (1951). 



human beings, exact data are lacking because of extreme variability from 

 patient to patient; these vitamins appear to be essentially equivalent. 



The isolation of crystalline vitamin Bi2b from culture broths of Strep- 

 tomyces aureofaciens^^ and also from neomycin fermentation broths^ ^ has 

 been mentioned. A number of papers have appeared describing its isola- 

 j^JQj^i3-i5 g^j^^j qIqq j^s formation from vitamin B12 by catal3''tic hydrogena- 

 tion.''' Some early confusion appeared in the literature as to the relation- 

 ship between the two modifications, vitamins Bi2a and Bi2b. It was evident 

 later that the two substances are identical on the basis of all chemical and 

 physical comparisons.^^- *'* Part of the misunderstanding appeared to come 



« J. A. Brockman, J. V. Pierce, E. L. R. Stokstad, H. P. Broquist, and T. H. Jukes, 



J. Am. Chem. Soc. 72, 1042 (1950). 

 "^ H. G. Wijmenga, W. L. C. Veer, and J. Lens, Biochcm. et Biophys. Acta 6, 229 



1950) . 



