Abstract
The experiments of Boer et al., 1 who isolated 7-dehydro-cholesterol from cholesterol of animal origin were followed by the discoveries of Brockman, Drummond, Simons et al., 2 3 4 who identified activated 7-dehydrocholesterol as the main constituent of the natural Vitamin D in fish liver oils, indicating that the Vitamin D found in the animal organism is Vitamin D3 in contra-distinction to Vitamin D2 which is formed by activation of ergosterol.
In view of the ability of the animal organism to form biologically highly active sterol derivatives of a hormone nature, it was considered of importance to determine whether the animal organism, per se, possesses the means of transforming cholesterol or cholesterol-derivatives into Vitamin D3. Several of these compounds are now being investigated, namely, 7-keto-cholesterol, 7-hydroxy-cholesterol and 7-dehydro-cholesterol. This report concerns the fate of 7-dehydro-cholesterol in the rat.
A sample of 7-dehydro-cholesterol was prepared from cholesterol by the method of Windaus. 5 The product was repeatedly recrystallized from methyl alcohol in darkness; 0.0053 g of the purified substance was finally dissolved in 50 ml of propylene-glycol, C. P.
The activated 7-dehydro-cholesterol used in these experiments was made by irradiating an aliquot of the solution of the provitamin by pouring the solution into a Petridish. The source of irradiation was a 2-arc therapeutic lamp held over the dish at a distance of 12 in for 30 min. The arc was held in such a position that the incident rays formed an angle of 45° with the surface of the solution.
Forty-two rats which had been on a rachitogenic diet for 21 days and which showed to be fully depleted by appearance as well as by examination of control rats were divided in groups of 7, continued on the rachitogenic diet and treated as follows:
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