Tocopherol, Ubiquinones and Ubichromenols in Yeasts and Mushrooms

Abstract

DURING work on vitamin E, we have been interested in obtaining animal diets rigorously freed of tocopherol. Methods of analysis now available^1,2 allow amounts of tocopherol much less than 1 (µgm./gm. of diet to be determined and have already shown that many constituents of ‘Vitamin E-free’ diets in fact contain appreciable amounts of tocopherol. Of particular interest is yeast, which has usually been held to be devoid of tocopherol (for example, Forbes and György³). When several kinds of commercial dried bakers' yeast were analysed by the above methods they were found to contain small quantities of α-tocopherol (of the order of 0.3 µgm./gm.) Eventually, fresh compressed bakers' yeast (Distillers Co., Ltd., 3 kgm.) was lysed by a method⁴ using diethylamine as catalyst, and the solid residue was extracted with hot ethyl acetate. The extract was purified and analysed¹ for α-tocopherol, ubiquinone-30 and ubichromenol-30. In Table 1 the results are compared with those found on a replicate batch of yeast autolysed with ethyl acetate and extracted with hot benzene–alcohol (a method⁵ used for ergo-sterol). It would appear that the former method is superior to the latter. The ubichromenol-30 was identified by comparing it with a synthetic specimen, prepared from ubiquinone-30 by Links's method⁶. Certain batches of yeast appeared to contain ubiquinone-35 instead of ubiquinone-30. The identity of the α-tocopherol was confirmed by isolating it chromatographically. The substance was strongly reducing, ran identically with α-tocopherol in two chromatographic systems, had an ultra-violet maximum at 291 mµ and an infra-red spectrum consistent with it being α-tocopherol.