592 VI. CAROTENOIDS AND RELATED COMPOUNDS 



sumed that one /3-ionone ring is unattached. The following structure 

 has been postulated. ^- 



HjC CHj H,C CHj 



\ / \ / 



p GH3 CH], CHi GH- p 



/\ hhIhhhIhhhhIhhhIhh /\ 

 HjC C-C:C-c:C-c:C-C:C-c:C-C:C-C:C-C:C-C:C-C CH? 



I II II I 



HjC C C CHz 



\ / \ / \ / 



C CHj HjC C 



Hj 



Echinenone 



Echinenone can be crystallized from a mixture of petroleum ether and 

 benzene, in violet needles with a metallic luster which melt at 178-179°C. 

 Absorption maxima in carbon disulfide are 520, 488, and 450 m/x. Drumm 

 and O'Connor^"^ and DiTimm ei al.^^^ have prepared crystalline echinenone 

 from the red rock sponge {Hymeniacidon sanguineum Grant). The demon- 

 stration that echinenone occurs in both the red sponge and the sea urchin 

 provides a hitherto unrecognized chemical link between the Porifera and 

 the Echinodermata. 



(4) Other Animal Carotenoids 



There are a number of animal pigments of the C40 series about which 

 information is still quite incomplete. 



a. Sulcatoxanthin, C40H52O8. This has been isolated from the sea 

 anemone {Anemo7iia sulcata) by Heilbron and co-workers. ^*^ The solu- 

 bility of this carotenoid in 65% methanol is in hamiony with its high oxy- 

 gen content as indicated in the empirical formula. It is insoluble in petro- 

 leum ether, slightly soluble in carbon disulfide, and it dissolves readily in 

 benzene and ethanol. It crystallizes from a mixture of ether and petro- 

 leum ether in deep scarlet-red needles which have no sharp melting point, 

 but which shrivel at 110°C., soften at 125°C., and melt at 130°C. 



b. Pentaxanthin, C40H56O5 (±H2). Lederer^* isolated echinenone 

 from the Atlantic sea urchin {Strongylocentrotus lividus). This same 

 author'^^ found a second, hitherto unknown carotenoid, pentaxanthin, in 

 the edible sea urchin {Echinus esculentus). It possesses 3 hydroxy 1 groups 

 and is believed to have 1 1 conjugated double bonds. It can be crystallized 

 from benzene in red needles melting at 209-210°C. The pigment is readily 

 soluble in chloroform and carbon disulfide, somewhat less so in benzene, 

 and quite poorly in diethyl ether and petroleum ether. 



c. Pectenoxanthin, C40H54O2 (=^H2). Lederer^o^.^sg j^g^g reported the 

 presence of a carotenoid pigment which appears during the development 



"8 1. M. Heilbron, H. Jackson, and R. N. Jones, Biochem. J., 29, 1384-1388 (l'J35). 

 "s A. Lederer, Compt. rend. sue. biol, 116, 150-153 (1934). 



