I. The Provitamin A Content of American Whole Wheat Flour and Whole Wheat Bread. II. Isolation of Prolycopene and Pro-γ-Carotene from Evonymus Fortunei. III. The Stereochemistry of Methylbixin

A chromatographic investigation of the carotenoid pigments of whole wheat flour has been made to establish its pro~ vitamin A activity. While xanthophyll (lutein) was found to predominate, 0.02 to 0.06 milligrams of β-carotene was detected in a kilogram of flour and its identity was established by the mixed chromatogram method. Whole wheat bread was found to be even poorer in carotene. Investigations of rye flour and bread gave essentially the same qualitative and quantitative results. From one kilogram of the ripe seeds of Evonymus fortunei Rehd., 11 milli-grams of prolycopene and 0.5 milligrams of pro-γ-carotene have been isolated. Two new stereoisomers of methylbixin have been obtained in crystalline form and a third has been observed in solution. Various isomerization procedures have been tried on the four crystalline materials and the interconversion of these isomers has been demonstrated. A consideration of the absorption data has been used to assign tentative configurations to the four principal members isolated from the methylbixin set of stereoisomers.