II. CHEMISTRY 207 



(12) The vitamin D from 7-dehydroepicholesterol is, by the same analogy, 

 epicalciferols. 



(13) The compound dihydrotachysterol, better known under its trade 

 names A. T. 10 (anti-tetany compound No. 10) and Hytakerol, possesses 

 some antiricketic activity, in addition to its useful property of elevating 

 blood calcium in parathyroid tetany. It was obtained by von Werder^^s jj^ 

 1939 by the reduction of tachysteryl 3,5-dinitro-4-methylbenzoate with 

 sodium and alcohol, followed by saponification and chromatographic puri- 

 fication. This drug should not be confused with its isomer, 22-dihydro- 

 tachysterol (tachysteroU), which is a product of the irradiation of 22-dihy- 

 droergosterol or of the reduction of tachysteryl acetate adduct with 

 hydrogen. The side-chain double bond in dihydrotachysterol is intact, the 

 reduction being effected in ring A. With the reduction there occurs a migra- 

 tion of the remaining double bonds into the alignment characteristic of 

 calciferol. Thus, although the product is genetically dihydrotachysterol, it is 

 chemically a dihydrocalciferol, differing structurally from the latter only in 

 that the methylene group at C-19 is reduced. With this simple change, the 

 compound loses most of its antiricketic activity, while retaining a relatively 

 large proportion of its blood calcium-elevating activity. 



Dihydrotachysterol, C28H46O, crystallizes in colorless needles from 90% 

 methanol. It is easily soluble in organic solvents. It has m.p. 125° to 127°, 

 [«]d' = +97.5° in chloroform, strong absorption maxima at wavelengths 

 242, 251, and 2G1 m/x.^-^ Somewhat varying reports on its antiricketic 

 effectiveness has been made by von Werder,^-^ Correll,^^^ McChesney,^^" 

 Motzok,^^' and others. It appears to have a potency of about 90 I.U. per 

 milligram for rats, which is between 1400 and }yioo of the potency of 

 calciferol and the same as the potency of tachysterol itself. When compared 

 with cod liver oil or vitamin D3 with rats and chicks, it shows an efficacy 

 ratio of 400 to 750%. Willgeroth et alP- claim that it is somewhat more 

 effective on turkey poults than on chicks. 



(14) In 1928 Bills et al.,^^ repeating the work of the English and German 

 workers in destroying the provitamin D in ordinary cholesterol, found that 

 treatment with charcoal or bromine never resulted in a total, but only in 

 a relative (to about ^^0); reduction of activatability. Samples so treated, 

 when examined spectrographically in sufficiently high concentrations, still 

 show'ed the characteristic provitamin bands, and, also, two new bands at 



328 F. von Werder, Hoppe-Seyler's Z. physiol. Chem. 260, 119 (1939); U. S. Pat. 



2,228,491 (1941). 

 3^9 J. T. Correll and E. C. Wise, /. Nutrition 23, 217 (1942). 

 "» E. W. McChesney, /. Nutrition 26, 81, 487 (1943). 



"' I. Motzok, D. C. Hill, and H. D. Branion, Poultry Sci. 25, 644 (1946). 

 "2 G. B. Willgeroth, J. L. Halpin, H. R. Ilalloran, and J. C. Fritz, J. Assoc. Official 



Agr. Chemists 27, 289 (1944). 



