36 



CHEMICAL CONSTITUTION 

 CH3 CH3 CH3 CH3 



HOOC- C=CHCH=CH- C=CHCH=CHCH=C- CH=CHCH=C- COOH 

 Crocetin 



IV 



CH3 CH3 CH3 CH3 



HOOC- CH=CH- C=CHCH=CH- C=CHCH=CHCH=C- CH=CHCH=C- CH=CH- COOCH3 



Bixin 



TABLE 8 



CLASSIFICATION OF SOME CAROTENOIDS AS DERIVATIVES OF LYCOPENE AND THE 



CAROTENES 



Lycopene 



Lycoxanthin = 3-Hydroxylycopene 

 Lycophyll = 3 : 3'-Dihydroxylycopene 

 Rhodoviolascin ( ? ) 



y-Carotene 



^-Carotene 



Rubixanthin = 3-Hydroxy-y-carotene 

 Rubichrome = Furanoid oxide of rubixanthin 

 Eschscholtzxanthin = Dihydroxy-y-carotene( ?) 



Cryptoxanthin = 3-Hydroxy-/5-carotene 

 Citroxanthin = Furanoid monoxide of /^-carotene 

 Zeaxanthin = 3 : 3'-Dihydroxy-/J-carotene 

 Antheraxanthin = Zeaxanthin mono-epoxide 

 Violaxanthin = Zeaxanthin di-epoxide 

 Auroxanthin = Furanoid zeaxanthin di-oxide 

 Aphanin = 3-Keto-/3-carotene( ?) 

 Rhodoxanthin = 3 : 3'-Diketo-/3-carotene 

 Astacene = 3:4:3': 4'-Tetraketo-/5-carotene 

 Astaxanthin = 3:3'-Dihydroxy-4: 4'-diketo-/3-carotene 

 Capsanthin 

 Capsorubin 



a-Carotene 



a-Carotene epoxide 



Xanthophyll = 3 : 3'-Dihydroxy-a-carotene 



Xanthoph^dl epoxide 



Flavoxanthin = Furanoid xanthophyll oxide 



Chrysanthemaxanthin = Furanoid xanthophyll oxide 



It is not known with certainty to what extent carotenoids are intercon- 

 vertible in nature. It seems very probable, however, that carotenoid epoxides, 

 such as a-carotene epoxide and xanthophyll epoxide, are formed in the plant 

 by oxidation of the corresponding carotenoids (a-carotene, xanthophyll), and 



