CAROTENOIDS IN LAND PLANTS 



FLOWER PETAL CAROTENOIDS 



The distribution of carotenoids in flower petals varies considerably ; 

 whilst some petals have a distribution somewhat similar to green leaves, 

 others contain little or no carotenoids and others contain xanthophylls 

 which, if not specific to a plant, are specific to petals. These specific 

 carotenoids are, however, mostly epoxides. 



Unique in carotenoid distribution are the flowers of the silky oak 

 (Grevillea robusta). The xanthophylls, which are a complicated mixture, 

 amount to only one-fifth of the total carotenoids {cf. leaves) ; the 

 remaining four-fifths are entirely p-carotene. These flowers are recom- 

 mended as a source of [^-carotene, for 270 mg. of the crystalline pigment 

 were obtained from 1 kg. of flowers. ^ « ^ 



The sky blue flowers of the Brazilian tree Jacaranda ovalifoHa also 

 contain ^-carotene almost exclusively but in comparatively small 

 amounts (about 0-06 mg. from 1 kg. of flowers). ^ ^ 4 Other flov^^ers, e.g., 

 Tagetes patula, ^ « * Crepis aurea, ^ « ^ Cytisus (Sarothamnus) scoparius, ^ « • 

 Lotus corniculatuSy ^ ' ^ Iris pseudacorus ^ " ' contain both a- and 

 ^-carotene, but Caltha palustris ^ « « and Maratia praecox ^ « » contain 

 mainly a-carotene, associated with traces of p-carotene. y-carotene 

 has been reported in C. scoparius ^ ^ ' and lycopene in T. patula ^ ' ^ and 

 Gazania rigens. ^ ' <>' ^ ' i a-Carotene-5 : 6-epoxide is found in Trago- 

 pogon pratensis. ^ ' ^ Phytofluene has been found in a number of species 

 (see Table 7) but, in particular, in Jacaranda ovalifoHa it is much more 

 abundant than p-carotene. ^ ^ « This is the first reported case in which 

 phytofluene predominates over the coloured carotenoids. 



Mo Me Me 



!e 



a-carotene-5 : 6-epoxide 



Of the xanthophylls found both in flowers and in leaves, lutein 

 (xanthophyll) is probably the major example and the most widely 

 distributed ; Kuhn and Winterstein ^ ' » give a list of flowers in which 

 it has been detected and Karrer has found it in almost all the petals 

 which he has been lately investigating ; it occurs in both free and ester 

 forms. Kuhn, Winterstein and Lederer ^ ? * have isolated from Helenium 

 autumnale lutein dipalmitate (m.p. 92°) which they have named helenien. 



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