31661-06-0Relevant articles and documents
NADPH and protoporphyrin ix dependent conversion of violaxanthin to a retro-carotenoid in Narcissus pseudonarcissus chromoplasts in vitro
Luetzow,Haaf,Englert,Beyer,Kleinig
, p. 729 - 734 (1996)
In homogenates of chromoplasts isolated from petals of Narcissus pseudonarcissus, violaxanthin is efficiently converted into a novel retro-carotenoid [3S,5R,3′S,5′R, all-E)-5,5′-dihydro-3,5,3′,5′-tetrahydroxy-β,β- carotene]. Here we have purified and characterized this compound by NMR spectroscopy. Its formation took place in chromoplast homogenates after supplementation with NAD(P)H in the presence of protoporphyrin IX. The tetrapyrrole could either be biosynthetically formed from added δ-aminolevulinate or supplemented externally. The reaction was greatly stimulated under anaerobic conditions, probably due to inhibition of a respiratory redox pathway known to operate in chromoplast membranes. Saturating behaviour with respect to substrates, high substrate specificities and proteinase susceptibility show the enzymic nature of the reaction. Neither chromoplast membranes alone nor the soluble stroma components deprived of membranes were capable of carrying out the reaction, indicative of a differentially localized multi-component system being involved in catalysis. Copyright
Carotenoids and carotenoid esters in potatoes (Solanum tuberosum L.): New insights into an ancient vegetable
Breitbaupt, Dietmar E.,Bamedi, Ameneh
, p. 7175 - 7181 (2007/10/03)
The carotenoid pattern of four yellow- and four white-fleshed potato cultivars (Solanum tuberosum L.), common on the German market, was investigated using HPLC and LC(APCI)-MS for identification and quantification of carotenoids. In each case, the carotenoid pattern was dominated by violaxanthin, antheraxanthin, lutein, and zeaxanthin, which were present in different ratios, whereas neoxanthin, β-cryptoxanthin, and β,β-carotene generally are only minor constituents. In contrast to literature data, antheraxanthin was found to be the only carotenoid epoxide present in native extracts. The total concentration of the four main carotenoids reached 175,ug/100 g, whereas the sum of carotenoid esters accounted for 41-131 μg/100 g. Therefore, carotenoid esters are regarded as quantitatively significant compounds in potatoes. For LC(APCI)-MS analyses of carotenoid esters, a two-stage cleanup procedure was developed, involving column chromatography on silica gel and enzymatic cleavage of residual triacylglycerides by lipases. This facilitated the direct identification of several potato carotenoid esters without previous isolation of the compounds. Although the unequivocal identification of all parent carotenoids was not possible, the cleanup procedure proved to be highly efficient for LC(APCI)-MS analyses of very low amounts of carotenoid esters.
PREPARATION OF MONO-CIS ANTHERAXANTHINS AND DETERMINATION OF THEIR GEOMETRICAL CONFIGURATION BY (13)C-NMR SPECTRAL ANALYSIS
Molnar, P.,Radics, L.,Szabolcs, J.
, p. 477 - 486 (2007/10/02)
Using (13)C-NMR methods, the stereochemistry of eight mono-cis carotenoids obtained by stereomutation of natural (3S, 5R, 6S, 3'R)- and semisynthetic (3S, 5S, 6R, 3'R)-all-trans-antheraxanthins has been established.The carbon-13 data support our earlier p
