. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS IN LAND PLANTS Table 2 indicates the xanthophylls isolated by Strain and the relative amounts of each obtained; data reported subsequent to Strain's investigation are also included. Strain resolved mixtures I, II, and III (Table 2) into a number of components by further chromatography on CaCOg and povi^dered sucrose. None of these components was isolated or identified, although it seems unlikely that they were all oxidative artefacts. The flavoxanthins are designated b and c and violaxanthin, 6, to distinguish them from th
. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS IN LAND PLANTS Table 2 indicates the xanthophylls isolated by Strain and the relative amounts of each obtained; data reported subsequent to Strain's investigation are also included. Strain resolved mixtures I, II, and III (Table 2) into a number of components by further chromatography on CaCOg and povi^dered sucrose. None of these components was isolated or identified, although it seems unlikely that they were all oxidative artefacts. The flavoxanthins are designated b and c and violaxanthin, 6, to distinguish them from the pigments isolated by Kuhn and his colla- borators from flower petals (see p. 46); these pigments differ from Kuhn's pigments in chromatographic behaviour, and in optical rotations but are spectroscopically indistinguishable. Whether they are the separate pigments which Strain *^'® considers them is still doubtful. Assuming for the moment that they are not identical they must be very closely related to the corresponding flower pigments. It is only recently that the structures of violaxanthin and flavoxan- thin have been determined, although their empirical formulae have been known since 1931-2.^^^^ Karrer's school working on the oxidation of carotenoids discovered that those members containing a p-ionone residue could be oxidized to 5:6-expoxides by treatment. Me Me Me 3-carotene P«rb«nzoic acid Me Me Me Me Me—/—V \ /.Me Me Me Me Me ^-carotene -5 6- mono-epoxide Chloroform-HCI Me L ^^ ^^ ^^ J' ( Mutatochrome \ 3-carotene V3<^oten@-^ ' 8-epoxide/ 15. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Goodwin, T. W. (Trevor Walworth). New York, Chemical Pub. Co.
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