178 CAROTENOIDS CONTAINING HYDROXYL GROUPS XI 



Derivatives 



Cryptoxanthin monoacetate C42H58O2: This derivative is formed by treating 

 cryptoxanthin with acetic anhydride in pyridine^^. It crystalHses in red needles, 

 m.p. 117-118° (corr.). The absorption maxima are identical with those of 

 cryptoxanthin. The monoacetate is entirely epiphasic. 



Cryptoxanthin mono-epoxide C4QH5g02: This compound was obtained by 

 Karrer and Jucker^^ by the action of monoperphthalic acid on crypto- 

 xanthin acetate. The biological assay^^ of cryptoflavin derived from crypto- 

 xanthin epoxide showed that it is vitamin A-inactive even in high doses. It 

 thus contains no unsubstituted /5-ionone ring. For this reason the following 

 formula is ascribed to cryptoxanthin epoxide. 



CH3 CH3 CH, CH, 



\V \V 



/\ I I I I /\ 



CHj C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C CH^ 



HOCH C-CHj 



\/ C CR 



CH2 Crj^ptoxanthin epoxide / \/ 



H3C CHj 



The solubility of cryptoxanthin epoxide is similar to that of cryptoxanthin. 

 It crystallises from a mixture of benzene and methanol in beautiful needles or 

 plates, m.p. 154° (uncorr. in vacuum). 



Solvent: Absorption maxima: 



Carbon disulphide 512 479 m/z 



Benzene 494 461 m/i 



Chloroform 488 456 m// 



Ethanol 481 449 m/i 



On shaking an ethereal solution of the pigment with concentrated hydro- 

 chlorid acid, the latter assumes a somewhat unstable blue colouration. 



Cryptoflavin^^: By the action of mineral acids on cryptoxanthin mono- 

 epoxide, the latter is transformed into the furanoid oxide, cryptoflavin, which 

 is biologically inactive^^. 



CHo CHo 



\V 



C CHo CHo 



CHg C OH CH3 CH3 CH3 CHg C 



CH, C CH-C=CHCH=CH-C=CHCH=CHCH = C-CH=CHCH=C-CH=CH-C CH» 



CHJ HaC-C CHOH 



CH3 Cryptoflavin \^ y/ 



CHj 

 References p. 214-21'/. 



