Xcv. the Specificity of Ergosterol as Parent Substance of Vitamin D. by Otto Rosenheim and Thomas Arthur Webster
نویسنده
چکیده
THE study of the antirachitic activity induced in various sterols by irradiation, which led to the discovery of ergosterol as the most potent source of vitamin D [Rosenheim and Webster, 1926; 1927, 1], has subsequently brought to light an interesting relationship between chemical structure and potential biological activity. The most characteristic general features of the sterol structure are the presence in the molecule of (1) a hydroxyl group, (2) one or more unsaturated carbon linkages, and (3) a system of four reduced rings. An analysis of these molecular structures in their relation to induced antirachitic potency has so far failed to clarify the position with regard to the function of the hydroxyl group. We have shown [Rosenheim and Webster, 1927, 2] that two esters of ergosterol, the acetate and the benzoate, are rendered as highly antirachitic as ergosterol itself by irradiation. This activation may, however, be feasibly preceded by a photochemical hydrolysis, and since the removal or replacement of the hydroxyl group in ergosterol cannot be effected without destruction of the molecule [Reindel, Walter and Rauch, 1927] the bearing of the OH group on the vitamin formation cannot at present be experimentally studied from this direction. On the other hatid, it has become evident that not only the presence of the unsaturated carbon linkages, but also their number, is a deciding factor in the photochemical production of vitamin D. For it was found that the naturally occurring saturated sterols, coprosterol and a-amyrol, as well as the artificially reduced sterols, dihydrocholesterol and dihydrositosterol, remain inactive after irradiation. Further, neither cholesterol nor sitosteroll, -with one double bond, nor stigmasterol, cholesterylene and oxycholesterylene,
منابع مشابه
Clxxvii. the Biological Inertness of Irradiated Mycosterols Other than Ergosterol. by Otto Rosenheim and Thomas Arthur
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