2o6 CAROTENOIDS CONTAINING HYDROXYL GROUPS XI 



9. XANTHOPHYLL EPOXIDE AND ITS TRANSFORMATION PRODUCTS 



Xanthophyll epoxide C4UH56O3: 



CH, CH, CH, CH, 



C CH3 CH3 CH, CH, C 



/\ I I I I /\ 



CHa C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-CH CHg 



)0 ' ' 



HsC-C CHOH 

 HOCH C \/ 



\ / \^ Xanthophyll epoxide CH 



CHg CHj 



Xanthophyll mono-epoxide was obtained by Karrer and Jucker^^^ by the 

 oxidation of xanthophyll diacetate with monoperphthalic acid. It crystallises 

 from a mixture of benzene and methanol in reddish-yellow crystals, m.p. 192° 

 (uncorr., evacuated capillary). Recent investigations^^^^ have shown that this 

 epoxide is widely distributed in blossoms and also occurs in large quantities 

 (as much as 40% of the xanthophyll content) in leaves of all kinds. Since 

 xanthophyll epoxide is readily isomerised to fiavoxanthin (see p. 207) by traces 

 of acids, it is probable that the latter is often an artefact. 



TABLE 44 



OCCURRENCE OF XANTHOPHYLL EPOXIDE 



Sources References 



Asters P. Karrer and E. Jucker, Helv. chim. Acta 26 (1943) 626. 



Elodea canadensis P. Karrer and J. Rutschmann, Helv. chim. Acta 28 



(1945) 1526. — D. Hey, Biochem. J. 31 (1937) 532. 



Green or etiolated leaves P. Karrer, E. Krause-Voith and K. Steinlin, Helv. 

 chim. Acta 31 (1948) 113. 



Kerria japonica DC P. Karrer and E. Jucker, Helv. chim. Acta 2g (1946) 



1539. 



Laburnum anagyroides do. 



Ranunculus acer P. Karrer, E. Jucker, J. Rutschmann and K. Stein- 



lin, Helv. chim. Acta 28 (1945) 1146. 



Sarothamnus scoparius P. Karrer and E. Jucker, Helv. chim. Acta 2y (1944) 

 1585. 



Stinging nettles P. Karrer, E. Jucker, J. Rutschmann and K. Stein- 



lin, Helv. chim. Acta 28 (1945) 1146. 



Tragopogoyi pratensis do. 



Trollius eiiropaeus P. Karrer and E. Jucker, Helv. chim. Acta 2g (1946) 



1539. 



The absorption spectrum of xanthophyll epoxide is very similar to that of 

 violaxanthin (p. 195) and the two pigments are best distinguished by treat- 

 ment with chloroform containing traces of hydrochloric acid when they are 

 converted into fiavoxanthin (maxima 478, 449 m/^ in carbon disulphide) and 

 auroxanthin (maxima 454, 423 m/^ in carbon disulphide), respectively. 

 References p. 214— 2iy. 



