3IO CAROTENOIDS OF UNCERTAIN STRUCTURE XIV 



1837 SoRBY^^ shows that brown algae contains not only one but, in his view, 



three yellow pigments which he terms xanthophyll, lichnoxanthin and 



fucoxanthin. 

 1906 TswETT^^succeeds in separating the pigments of brown algae into carotene, 



fucoxanthophyll and fucoxanthin by chromatographic adsorption. 

 1914 WiLLSTATTER and Page^^ isolate fucoxanthin in the crystalline state for 



the first time and investigate this pigment in detail. 

 1931-35 Karrer and co-workers^^, Kuhn and Winterstein^^ and Heilbron 



and Phipers^* carry out investigations on the constitution of fucoxanthin. 



Occurrence 



Fucoxanthin has been found mainly in Phaeophyceae where it occurs together 

 with chlorophyll (mainly chlorophyll a) and other carotenoids such as carotene 

 and xanthophyll. The following species of brown algae contain the pigment." 

 Fucus virsoides, Dictyota, Cystosira and Laminaria^^. According to Heilbron 

 and Phipers^*, dried brown algae {Fucus vesiculosus) contain j3-carotene and 

 zeaxanthin, whereas fresh algae contain /S-carotene and fucoxanthin. More 

 recent investigations^'*^ show that j8-carotene is the main carotenoid pigment 

 of the male gametes, while fucoxanthin is present mainly in the female gametes. 

 Fucoxanthin also occurs in Zygnema pectinatum, Polysiphonia nigrescens^^ and 

 in diatoms^^'^'. 



Preparation^^ 



Air-dried brown algae are minced in a mincing machine and exhaustively 

 extracted at room temperature with 90 % methanol. After dilution with water, 

 chlorophyll is extracted from this solution with petroleum ether and the mother 

 liquors are diluted with more water, covered with petroleum ether and allowed to 

 stand for 24 hours. At the end of this period most of the fucoxanthin has separated 

 as a brown precipitate at the boundary between the two solvents, and can be 

 filtered off. The mother liquors which contain very little additional pigment, are 

 discarded. The pigment is purified by crystallisation from methanol and a little 

 water, and a second time from methanol alone. The yield of pure pigment from 

 about 15 kg of air dried algae amounts to about 2 g. If, on the other hand, the algae 

 are several weeks old, the pigment can no longer be isolated and only a veiy small 

 amount of impure pigment is obtained^®. 



Using the procedure of Karrer and co-workens'^ just described, only fuco- 

 xanthin is isolated from brown algae. WiLLSxAtter and Page^* have described a 

 considerably more complicated method of preparation in which xanthophyll is also 

 isolated and subsequently separated from fucoxanthin. 



Chemical Constitution 



Karrer and coworkers^^ obtained the molecular formula C4oHgg06 for 

 fucoxanthin whereas I. M. Heilbron and R. F. Phipers*" obtained the formula 

 References p. 341-343. 



