A color reaction associated with vitamin D.

Abstract

“The chemical relationship between activated cholesterol and the naturally antirachitic substances, such as cod liver oil, yolk of egg, and bone marrow, is one of prime importance in a consideration of the etiology of rickets.” 1

It is definitely established that substances which contain either cholesterol or phytosterol can be made antirachitic by exposure to ultra-violet light. Cholesterol and phytosterol themselves, ordinarily without any curative effect on rickets, can be made antirachitic by irradiation. The criterion for the presence of the antirachitic factor (here called vitamin D) is the “line test” of McCollum and his coworkers. 2 Rachitic animals showing a wide metaphysis free from calcification are fed the substance to be tested in addition to the rickets-producing diet. Deposition of calcium salts, giving a positive line test, shows the presence of vitamin D in the food. This biological test is both expensive and time consuming. A chemical test for vitamin D would save time and effort, and in addition might lead to an understanding of the chemical nature of the vitamin. Hess and Weinstock 3 studied the changes in the ultra-violet light transmission of cholesterol before and after irradiation. Although they obtained a difference, its significance is at present not established. Besides, the method is not generally applicable. The color reactions of substances containing the fat soluble vitamins have been studied by Drummond, Rosenheim and their associates. Of the reagents studied, Rosenheim and Drummond 4 found AsC1₂ the most sensitive. They claim that their color test parallels the biological test for the presence of vitamin A.

Harden and Robison 5 state that the purple color given by liver oils when treated with H₂SO₄ can be closely simulated by adding furfural or a substituted furfural to cholesterol or butter.