148 CAROTENOID HYDROCARBONS OF KNOWN CONSTITUTION X 



between methanol and petroleum ether, the pigment is found almost quantita- 

 tively in the upper layer. 



Solvent: Absorption maxima: 



Carbon disulphide 457 428 ran 



Benzene 440 m/x 



Petroleum ether 428 m^ 



Chloroform 437 m/z 



Luteochronie CioHggOj: 



CH, CH3 C 



\V /\ 



C CH3 CH3 CH3 H3C CH:=C CHj 



/\ I I I I I I I 



CHj C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH C CH, 



)0 



I CH, 

 CH, C H3C 



\ / \ Luteochrome 



CH, CH3 , 



Luteochrome is formed together with /^-carotene mono-epoxide and 

 /5-carotene di-epoxide during the oxidation of /3-carotene with monoper- 

 phthalic acid^^*. The pigment crystalhses from a mixture of benzene and 

 methanol in thin yellow-orange leaflets, m.p. 176° (uncorr., in vacuum). Con- 

 centrated aqueous hydrochloric acid has the same effect as with ^^-carotene 

 di-epoxide and aurochrome. On partitioning between methanol and petroleum 

 ether, luteochrome is found mainly in the upper layer. 



Solvent: Absorption maxima: 



Carbon disulphide 482 451 m/x 



Properties of the ^-Carotene Oxides 



/5-Carotene epoxides and furanoid oxides can only be separated with 

 difficulty by chromatographic analysis, using petroleum ether as solvent and 

 calcium hydroxide as adsorbent. The solubihties of these compounds do not 

 differ appreciably from those of /9-carotene. They are easily soluble in carbon 

 disulphide, chloroform, benzene and ether, somewhat less easily in petroleum 

 ether, and only very sparingly soluble in methanol and ethanol. 



Physiological Properties 



The vitamin A activity of the various /5-carotene oxides has been examined 

 by VON EuLER^^^. It has been found that 177-doses of /3-carotene di-epoxide 

 and 187-doses of luteochrome produce full vitamin A activity in rats. It may 



References p. 165-170. 



