Cclxxiv. Studies on Carotenoids.' Iii. an Isomeride of Lutein Isolated from the Furze (ulex Europaeus)

WE have isolated from the yellow flowers of the furze a new carotenoid which in its properties is very similar to lutein. It crystallizes from absolute methyl alcohol in stellate groups of pale yellow twinned prisms. The crystals are dichroic and have a strong birefringence. Like lutein this yellow form, which does not contain methyl alcohol of crystallization, changes in contact with the solvent in the course of 2 or 3 days into a red form of metallic brightness containing methyl alcohol, which cannot be distinguished from lutein bythe shape ofthe crystals. The absorption bands in different solvents are the same as those of lutein, in carbon disulphide 508, 475m,u, in ethyl alcohol 475, 447 mpu, in methyl alcohol 473,445mt. During chromatographic analysis in mixture with lutein on calcium carbonate, the new carotenoid forms a uniform orange-coloured zone, and in this way it cannot be separated from lutein. It shows, however, a marked difference from lutein in its M.P., which for the yellow methyl alcohol-free form was found to be 201-202° (uncorr., in evacuated tube; corr. 205-206°). The red crystals lose methyl alcohol at 120-130° and melt at 199-200° (uncorr.). Pure lutein from Genista tridentata melted 100 lower, at 190° (uncorr.). For the reasons above mentioned we suppose that we are dealing with a stereoisomeric form of lutein. An analysis could not be made because of the small quantity available. The carotenoid is sparingly soluble in cold carbon disulphide, very sparingly in cold ethyl alcohol and still more sparingly in cold methyl alcohol. The carotenoids of the furze (Ulex europaeus). We have begun a systematic investigation of the carotenoids of diverse furze and broom species of the family of Leguminosae the preliminary results of which we report in this and the following papers. The yellow flowers of the furze were investigated long ago by Schunck [1903], who demonstrated the presence of a xanthophyll-named by him xanthophyll Y-which is distinguished by a strong blue colour reaction with concentrated hydrochloric acid. Schunck gives a photograph of the absorption spectrum of the xanthophyll as well as the spectrum of the product formed by hydrochloric acid, and from his data one may conclude that he dealt with violaxanthin.