PLANT PIGMENTS 

 The chemistry of plant pigments other than chlorophylP 



CLARENCE J. WEST 



Accompanying Chlorophyll in the chloroplasts of green plants 

 and leaves there are two yellow pigments, Carotin and xanthophyll. 

 Isomers of each of these have been found in lycopin, the color- 

 ing matter of the tomato; and lutein, the pigment found in the yolk 

 of eggs. Fucoxanthin, a xanthophyll-like substance, found in brown 

 algae, has also been described. 



The principal result of the studies thus far made upon these 

 pigments is that a satisfactory method for their Isolation and purifi- 

 cation has been worked out. Very little if anything is known con- 

 cerning their Constitution. Owing to the difficulty of obtaining them 

 in large quantities, to their ease of oxidation during the process of 

 purification, and to the fact that upon decomposition they yield only 

 amorphous products, it may be a long time before their Constitution 

 is established. 



Carotin. Carotin is widely distributed, being generally asso- 

 ciated with Chlorophyll in the chloroplasts. It is also found in 

 various parts of many plants. The color of yellow or orange petals 

 is frequently due to it, e. g., the Corona of the common narcissus. 

 It is largely responsible for the color of the carrot root, being pres- 

 ent as innumerable small intracellulaf crystals. The tint of many 

 fruits is due to amorphous granules of Carotin. 



The most recent chemical study of Carotin has been made by 

 Willstätter,^ who isolated it from the leaves of stinging nettle and 

 f rom carrots, and showed the complete identity of the two prepara- 



^ A review of recent work on the chemistry of Chlorophyll will be found in 

 the BiocHEMiCAL Bulletin, iii, pp. 229-258, 1914. These two reviews include 

 all the work on plant pigments published by Willstätter and his pupils. A later 

 review will discuss the work on flower pigments, the anthocyanins and related 

 Compounds. 



2 Willstätter and Mieg : Ann. d. Chan., 355, i, 1907. Willstätter and Escher : 

 Ztschr. f. physiol. Chem., 64, 47, 1910; 76, 214, 1912. Escher: Ibid., 83, 198, 1913. 



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