CAROTENOIDS 



trollixanthin, a hydroxy lutein (xanthophyll)-5 : 6-epoxide (C40H66O4), 

 from Trollius europaeus,^^^ Caltha palustris, Laburnum anagyroides 

 and Kerria japonica. ^ « * The position of the third hydroxyl group in 

 troUixanthin is still undecided. Chrysanthemaxanthin and flavoxanthin 

 are probably cis-trans isomers, differing only in the spatial disposition 

 of two oxygen atoms at positions 3 and 5 in the molecule. 



Auroxanl.htn (5.8, 5-8-diepo)iyzeaxanthin) 



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Chrysanthemaxanthin, Flavoxanthin 

 5 : 8-epoxylutein (xanthophyll) 



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Rublchrome (5 : S-epoxy-B-hydroxy-y-carotene) 



Little is known of the metabolism of carotenoids during the develop- 

 ment of flowers ; but Karrer, Jucker, Rutschmann and Steinlin ^ ' * 

 have found that in spring, petals of Viola tricolor contain only small 

 amounts of violaxanthin and auroxanthin, but that these increase con- 

 siderably by autumn, and it has recently been reported that the carotene 

 content of the petals of a number of plants increased from budding 

 until a maximum was reached at flowering. ^ s 4 Table 8 records some 

 characteristics of typical petal carotenoids and Table 9 the qualitative 

 distribution of carotenoids in petals. 



48 



