CONVERSION OF PROVITAMINS TO VITAMINS D 769 



sert^"^ (toxisterin) . Morton, Heilbron, and Kamm^"- originally demon- 

 strated that, on irradiation of ergosterol, the three absorption maxima at 

 293.5, 282, and 270 m/x were gradually replaced by a band of great intensity 

 at 247-248 mju (see Fig. 5). These latter investigators incorrectly ascribed 

 the single absorption band to vitamin D. However, Smakula"^ concluded 

 that the substance responsible for the absorption band at 248 m/x is not 

 vitamin D. This assumption gained firm support from the experiments of 

 Bills, Honeywell, and Cox, ™ who showed that the appearance of this band 

 coincided not with the development of vitamin D, but rather with the dis- 

 appearance of its antirachitic potency. 



Toxisterol has not been isolated in pure form. Bills et al."^ and van 

 Wijk and Reerink-"^ regarded it as an isoergosterol. However, it was later 

 shown to differ from this class, since it is not precipitable with digitonin.^"^ 

 Apparently, toxisterol is formed more readily when the irradiation is car- 

 ried out in alcohol than when ether or oil is employed. ™'^''^'^°^~2°^ 



When vitamin D is moderately over-irradiated, a toxic-calcifying prop- 

 erty all out of proportion to the antirachitic property appears. ^^^-2'*'' 

 The earlier preparation of vitamin D, Vigantol, first made by I. G. Farben- 

 industrie,^*''^''''^^^ apparently contained toxisterol along with vitamin D; 

 this was responsible for the toxic reactions following its administration. 

 The deleterious effects of toxisterol have also been pointed out by Laquer 

 and Linsert^''^ and by Windaus et al.^^'^ It has no antirachitic activity. ^''^ 



(5) Suprasterols I and II 



Two additional products of over-irradiation were first recognized by 

 Windaus, Gaede, Koser, and Stein^^^ in 1930. These workers coined the 

 name suprasterine for these two substances. Setz^** assumes that the 

 suprasterols I and H are formed simultaneously. Bills^^ considers that the 

 formation of toxisterol precedes that of suprasterols I and II; the latter 

 products, however, may be formed simultaneously. The assumption is 

 based upon the fact that the absorption spectrum of Substance 248 is es- 

 sentially that of the suprasterols rather than of a mixture of toxisterol and 



2" F. Laquer and 0. Linsert, Klin. Wochschr., 12, 753-754 (1933). 



202 R. A. Morton, I. M. Heilbron, and E. D. Kamm, J. Chem. Soc, 1927, 2000-2005T. 



203 A. van Wijk and E. H. Reerink, Nature, 122, 648 (1928). 



20" W. M. Cox and C. E. Bills, /. Biol. Chem., 88, 709-713 (1930). 



205 W. E. Dixon and J. C. Hoyle, Brit. Med. J., 2, 832-835 (1928). 



206 L. J. Harris and T. Moore, Biochem. J., 23, 261-273 (1929). 

 20' J. C. Hoyle, /. Pharm., 40, 351-372 (1930). 



208 J. C. Hoyle and H. Buckland, Biochem. J., 23, 558-565 (1929). 



209 R. Kern, M. F. Montgomery, and E. U. Still, /. Biol. Chem., 93, 365-380 (1931). 

 210 1. G. Farbenindustrie, British Patent No. 296,093 (Nov. 15, 1928). 



2" J. Y. Johnson (to I. G. Farbenindustrie), British Patent No. 316,803 (Sept. 25, 

 1929). 1. G. Farbenindustrie, German Patent No. 499,524 (Aug. 28, 1930). 

 212 A. Windaus, J. Gaede, J. Koser, and G. Stein, Ann., /,SS, 17-30 (1930). 



