Experiments on Activation of Cholesterol Derivatives and Allied Sterols by Ultra-violet Irradiation.

Abstract

It has been shown repeatedly that cholesterol can be rendered antirachitic by subjection to ultra-violet rays. In a previous paper 1 it has been pointed out that “the saturated reduction products of cholesterol and phytosterol—dihydrocholesterol and dihydrophytosterol—were not activated by irradiation and did not acquire antirachitic properties.” It was further shown that “cholesterol acetate, an unsaturated ester of cholesterol, developed antirachitic potency as the result of irradiation.” 2 These results were “regarded as additional evidence that the double bond plays an essential rôle in activation.” It has recently been shown by Rosenheim and Webster that in addition to the unsaturated carbon linkage of the sterol molecule, the secondary alcohol group is intimately concerned in the activation by ultra-violet rays. 3

The present communication concerns itself with the effect of irradiation on a large number of cholesterol derivatives prepared by one of us (Windaus). The following derivatives were tested: B-cholesterol, hetero-cholesterol, α-phytosterol; cholesteryl-chloride, cholesteryl-amin-acetate; cholesten, pseudo-cholesten; cholesterilen, cholestan-4-7 diol, cholestan 4-on 7-ol, cholestenon; stigmasterol, α-amyrol, cholesteryl-ether, cholesterol-dibromide, cholesterol-ozonide (non-irradiated and irradiated), apocholic acid.