lo FUCOXANTHIN 309 



changes to violet. An ethereal solution of the pigment gives a slowly fading 

 bluish-green colour with 30 % hydrochloric acid. 



Detection and estimation: Aphanizophyll can be separated from accompa- 

 nying carotenoids by means of chromatographic analysis and can be identified 

 by determination of the absorption maxima, by partition between methanol 

 and petroleum ether, and by the blue colouration produced with concentrated 

 hydrochloric acid. 



Derivatives 



Aphanizophyll can be esterified with palmitic acid chloride. In contrast to 

 the parent pigment, the ester is readily soluble in benzene, petrol and caibon 

 disulphide. It crystallises from methanol in needles, which melt even on warming 

 by hand. 



Solvent Absorption maxima 



Carbon disulphide 547 506 474 m/z 



Benzene 524 489 457 m/i 



The ester exhibits the same absorption maxima in pyridine, chloroform and 

 methanol as the parent compound. It is more weakly adsorbed than aphanizo- 

 phyll. On alumina, the ester is adsorbed with an orange-red colour and can be 

 readily eluted, but it is not sufficiently adsorbed on calcium carbonate. On 

 partition between petroleum ether and 90 % methanol, it exhibits pronounced 

 epiphasic behaviour. With 95 % methanol, the lower layer is also definitely 

 coloured. It is possible that aphanizophyll occurs as the palmitic ester in algae, 

 as considerable amounts of palmitic acid could be isolated from the hypophasic 

 fraction^®. 



Apart from one or more hydroxyl groups, aphanizophyll also contains a 

 carbonyl group since an oxime can be prepared. The oxime is soluble in benzene 

 and is well adsorbed on calcium carbonate. It exhibits the same absorption 

 spectrum as aphanizophyll in different solvents. The absorption maxima in 

 benzene are located at 524, 489 and 457 m/^. In view of the spectroscopic 

 properties of the oxime it may be concluded that the carbonyl group is not in 

 conjugation with the system of conjugated double bonds. 



Neither the oxime nor the ester could be obtained in the crystalline state 

 and analysed. 



10. FUCOXANTHIN C4oH5e06 



History 



1867 RoSANOFF^'' suggests that brown algae contain a yellow pigment besides 

 chlorophyll. The pigment was also observed shortly afterwards by 

 Kraus and Millardet^^ and termed phycoxanthin. 



References p. 341-343. 



