CAROTENOLS AND OXYCAROTENOLS OF THE C40 SERIES 571 



demonstrated in a few species of red marine algae,^^-^*^ including Ceramium 

 ruhruni a.nd Dilsea edulis. However, Carter et aL'*^ doubt the presence of 

 taraxanthin in these algae, and suggest that the pigment found was neolu- 

 tein A or B. Taraxanthin has been observed in green algae. ^* S0renson^^^ 

 has reported the presence of this carotenol in the liver of the sea devil fish 

 or angler (Lophius piscatorius) . 



{10) Fucoxanthin 



As early as 1867, Rosanoff^^^ postulated that brown algae contain a 

 yellow pigment in addition to chlorophyll. This coloring matter was first 

 observed by Kraus and Millardet,'^^'' who named it "phycoxanthin." 

 Sorby^" was able to prove that olive-brown algae contained three different 

 pigments, which he called orange xanthophyll, lichnoxanthin, and fu- 

 coxanthin. These pigments were further characterized chromatographi- 

 cally by Tswett as carotene, fucoxanthophyll, and fucoxanthin. '^^ Will- 

 statter and Page^" were the first to isolate fucoxanthin in crystalline form, 

 and to pursue investigations of the pure pigment. The structure of this 

 polyene has only recently been established with reasonable certainty. It is 

 chiefly characterized by its high oxygen content. 



a. Structure. It has been shown by Heilbron and Phipers^^^ that 

 fucoxanthin has an empirical formula of C40H60O6 instead of C40H56O6, as 

 originally postulated by Karrer et al}° The latter workers also proved 

 that it is optically inactive, in contradistinction to the earlier view that it 

 possesses optical activity. The brown algae pigments take up nine 

 molecules of hj^drogen on catalytic hydrogenation, proving that fucoxan- 

 thin contains two less double bonds than does carotene. The Zerewitinoff 

 value indicates between four and five active hydrogens; there are at least 

 four hydroxyl groups, while the combinations of the remaining oxygen 

 atoms are probably as ketones. Esters containing only two fatty acids 

 have been prepared. On decomposition with alkaline permanganate, 

 dimethylmalonic acid, HOOC-C(CH3)2-COOH, alone has been isolated. 

 Karrer et al.^° consider that the unusually high number of hj'-droxyl groups 

 of fucoxanthin prevents the formation of dicarboxylic acids higher than 



3« H. Kylin, Kgl. Fysiograf. SdlMap. Lund. Forh., 9, 213-231 (1939). 



"' P. W. Carter, I. M. Heilbron, and B. Lythgoe, Proc. Roy. Soc. London, B128, 82- 

 109 (1939). 



"'i N. A. S^reusen, Chtni. Zenlr., WS4, //, 082. Cited by P. Karrer and E. Jucker, 

 Carotinoide, Birkhauser, Basle, 1948, p. 330. 



2*9 S. Rosanoff, Mem. Soc. sci. nat. Cherbourg, 13, 195 (1867). Cited by P. Karrer and 

 E. Jucker, Carotinoide, p. 318. 



350 G. Kraus and A. Millardet, Compt. rend., 66, 505-508 (1868); 68, 462-466 (1869). 



^1 H. C. Sorby, Proc. Roy. Soc. London, 21, 442-483 (1873). 



«2 M. Tswett, Ber. deal, botan. (?es., £4, 235-244 (1906). 



»' R. Willstatter and H. J. Page, Ann., 404, 237-271 (1914). 



^* I. M. Heilbron and R. F. Phipers, Biochem. J., 29, 1369-1375 (1935). 



