Assay of Inositol by Yeast Growth and Specificity

Yeast growth has been used as an assay-method for inositol (358, 431, 443). Woolley (443) examined the specificity of inositol by the yeast growth response (Hansen No. 1 strain of Toronto yeast) and for the curative effect on mice with an alopecia due to inositol deficiency (Table XXVII). The results were of the same type as with other growth factors apparently those compoimds are active w hich can readily form inositol, and any marked departure from this results in inactivity, e.g., quercitol, inosose, and quinic acid. Although the mytilitol was a natural product it was concluded by Woolley that its activity could not be ascribed to contaminating inositol. 

Activity of Compounds Related to Inositol for Mice and for Yeast (443) 

Compound Cumtive effect on mice Dose Activi ttg.fiOO g. rahon Yemst growth activity % 

Inactive for both organisms meso-inositol hexa-acetate, f-inositol, d-inositol, quercitol, quebrachitol, and pinitol. In addition Ka phytate and inosose were inactive for yeast. 

In contrast with yeast, the mice were able to use phytin, soybean cephalin [which contains an inositol-containing phosphatide (150)] and inositol hexa-acetate. Thus the yeast appears unable to hydrolyze these esters, and inositol cannot enter the metabolism of yeast in these forms the mouse may hydrolyze the esters or utilize them more directly. 

---