APHANIN 



301 



tion is washed with water. The solvent is evaporated and the residue is recrystalHsed 

 from petrol. From 50 kg of fresh moist algae, which yield 2 ^4 kg of dry material, 

 a total of about 50 mg of pure aphanicin was obtained. 



b) Aphanin: The aphanin zone in the chromatogram is washed through into 

 the filtrate. After removal of the solvent by distillation, the pigment can readily 

 be obtained in a crystalline state. For further purification, the pigment is adsorbed 

 on alumina and crystallised from a mixture of benzene and methanol (1 : 10). The 

 yield of aphanin from 50 kg of algae amounted to about 110 mg. 



c) Flavacin: The pigments from the third zone of the first chromatogram are 

 repeatedly chromatographed on alumina. The colourless impurities are frozen out 

 from the petroleum ether solution, and the mother liquors are saponified with 

 inethanolic potassium hydroxide, and then extracted with petroleum ether. After 

 evaporation of the solvent a small amount of flavacin crystallises from the residue. 

 It can be purified by repeated re-crystallisation from a mixture of benzene and 

 methanol. 



The fourth zone of the chromatogram yields analytically pure /S-carotene. 



From the pyridine solution B and the ethanol extract C, aphanizophyll is 

 obtained. The pyridine solution B is evaporated to dryness in vacuum and the 

 residue is saponified with ethanolic potassium hydroxide. The reaction mixture is 

 acidified with acetic acid and the pigment extracted with ether. This solution is 

 adsorbed on sodium sulphate and the aphanizophyll is eluted with methanol and 

 crystallised from acetone. For further purification, the pigment is chromato- 

 graphed on calcium carbonate and repeatedly recrystallised from acetone, and 

 finally from chloroform. From 50 kg of fresh algae, about 10 mg aphanizophyll were 

 obtained in this wsiy. Working up of the e.xtract C yielded a further very small 

 quantity of the pigment^'. 



Chemical Constitution^^ 

 CH, CH, CH, CH, 



/\ 1 r I I /■•\ 



CH2 C-CH=CH-C=CHCH = CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C6 2 CHg 



CH2 .C-CHs HjC-CS' 3'C=0 



\ / Aphanin ( ?) \^'/ 



CHg CH2 



The main features of the constitution of aphanin were established by 

 TiscHER^ who proposed the above formula. Elementary analysis indicated the 

 molecular formula C4oH5^0. On microhydrogenation the pigment absorbed 11 

 mols of hydrogen rapidly and an additional mol of hydrogen slowly. This 

 behaviour suggested the presence of a carbonyl group which was confirmed 

 by the preparation of a well-crystallised oxime. It seems almost certain that 

 the carbonyl group is not conjugated with the system of conjugated double bonds 

 as the absorption maxima of the oxime and of the parent compound have the 

 same wavelength location. This is also in agreement with the fact that the 

 absorption maxima in different solvents such as petrol and ethanol are the 

 same, whereas carotenoids containing carbonyl groups conjugated with the 

 References p. 341-343. 



