CAROTINOIDS 331 



been found to occur in the arillus of the seed of the yew and 

 to be responsible for the red colour of Thuja occidentalis. 

 Its isolation has been described by Monteverde and Lubim- 

 enko.* Rhodoxanthin is sparingly soluble in petroleum ether ; 

 it dissolves in glacial acetic acid, giving a red solution, and in 

 carbon disulphide, giving a violet-red solution. 



FUCOXANTHIN, QoHj^Ob. 



This substance was first isolated from fresh brown algae by 

 Willstatter and Page.f It is more difficult to extract this 

 substance from dried algae. Fucoxanthin is a brownish-red 

 substance, which crystallizes from methyl alcohol or light 

 petroleum, and melts at i59-5°-i6o-5°. It absorbs iodine to 

 form a compound C40H54O6I4. Unlike carotin and xantho- 

 phyll, which are neutral substances, fucoxanthin has basic pro- 

 perties, and forms blue salts with hydrochloric and sulphuric 

 acids. 



FURTHER REFERENCE. 



Palmer : " Carotinoids and Related Pigments," New York, 1922. 



ANTHOXANTHINS. 



FLAVONES AND XANTHONES. 



Under the headings of Flavones and Xanthones (two words 

 derived from the Latin and Greek for yellow) are included a 

 number of yellow pigments occurring in the vegetative organs 

 and in the petals of many plants. Owing to their close re- 

 lationship to the blue colouring matters known as Antho- 

 cyanins, Willstatter and Everest % have proposed the adoption 

 for them of the generic term, Anthoxanthin, at first suggested 

 by Marquart in 1835. They occur naturally in combination 

 with rhamnose or glucose as glucosides and in some cases 

 uncombined, and frequently are also associated with tannins. 



The anthoxanthins in the form of their glucosides frequently 

 are but faintly yellow in colour, the sugar-free compound 



* Monteverde and Lubimenko : " Bull. Acad. Sci. Petrograd," 191 3, 

 [6], 7, 1 105. 



t Willstatter and Page : " Annalen," 1914, 404, 237. 

 X Willstatter and Everest : id., 1913, 401, 189. 



