20 SULCATOXANTHIN 327 



For the isolation of the pigment, the phytoxanthin solutions obtained during 

 the preparation of echinenone (p. 325) are washed with water, dried and adsorbed 

 on alumina. After elution, pentaxanthin, which is accompanied by other phyto- 

 xanthins, is again chromatographed on calcium carbonate. This operation is 

 repeated once again and the pigment is then recrystallised from benzene. From 

 400 sea urchins about 40 mg of pure pentaxanthin are obtained. 



The chemical constitution of pentaxanthin is largely unknown. The 

 molecular formula is C40H56O5 (± Hg). Only thiee of the five oxygen atoms 

 appear to be present in the form of hydroxyl groups. Microhydrogenation 

 indicates the presence of 12 double bonds in the molecule. Lederer assumes 

 that II double bonds are in conjugation, while the remainder of the hydrogen 

 is used to saturate a carbonyl group or an isolated ethylenic double bond. It 

 should be remarked, however, that the longest wavelength location of. the 

 absorption maximum in carbon disulphide solution produced by 11 conjugated 

 double bonds would be expected to be near 520 m/^, (e.g. jS-carotene) , whereas 

 the absorption maxima of pentaxanthin are located at 506, 474 and 444 m^. 



The pigment crystallises from benzene in red needles, m.p. 209-210°. 

 Pentaxanthin is adsorbed more strongly than xanthophyll on calcium carbonate. 



Solvent: Absorption niaxitna: 



Carbon disulphide 506 474 444 m^a 



Benzene 487 456 424 m/i 



Methanol (445) 475 (505) m/i 



The pigment is very sparingly soluble in ether and petroleum ether, some- 

 what more soluble in benzene and readily soluble in carbon disulphide and 

 chloroform. 



20. SULCATOXANTHIN 



Heilbron and co-workers^ isolated a previously unknown carotenoid, 

 sulcatoxanthin, from Anemonia sulcata. 



500 finely cut plants were extracted with a mixture of acetone and ether (1:1), 

 the combined extracts were concentrated in vacuum, and the pigments were 

 extracted with petroleum ether. The solution was then repeatedly shaken with 65 % 

 methanol. Only a small quantity of pigment exhibiting absorption maxima at 

 478 and 450 m/i in carbon disulphide remained in the ether layer. The sulcato- 

 xanthin was extracted from the methanolic solution with petroleum ether and 

 chromatographed on alumina. It was then adsorbed on calcium carbonate from 

 carbon disulphide solution and finally recrystallised from a mixture of ether and 

 petroleum ether. The yield amounted to about 50 mg. 



Very little is known about the chemical constitution of sulcatoxanthin. 

 The molecular formula appears to be C40H52O8. The high oxygen content is 

 References p. 341-343. 



