Effects of inhibitors on carotenoids biosynthesisin vivo inCapsicum annuum fruits

Diphenylamine (DPA), 2-hydroxybiphenyl (OHBP) and 9-fluorenone (9-F), known inhibitors of carotenoids (car) synthesis, altered the pattern of incorporation of 2-¹⁴C-mevalonate into car in ripening fruits ofCapsicum annuum. OHBP was the most powerful inhibitor of the whole process of biosynthesis, followed by DPA and 9-F. The most sensitive step was the dehydrogenation of phytofluene. Cyclization of β-carotene and isomerizations yielding the structure of hydroxy-cyclopentane were also affected, although to a lesser extent.     

Free and esterified carotenoids in green and red fruits of Capsicum annuum

Fully green and mature red fruits of the Yolo Wonder A variety of Capsicum annuum were analysed for their carotenoid content. The disappearance of chlorophyll was followed by an increased synthesis of carotenoids. Lutein was not detected in the red fruit in which capsanthin was the main carotenoid. It appeared as diester, monoester and free forms, while capsorubin occured as a diester only. Cryptocapsin was not esterified.     

Identification and quantification of carotenoids,tocopherols and chlorophylls in commonly consumed fruits and vegetables

The carotenoid, tocopherol and chlorophyll metabolic profiles and content of a selection of fruits and vegetables found commonly in the diet, have been determined using a rapid RP-HPLC technique with on-line PDA detection. Information gathered from the screening of secondary plant metabolites is vital for the accurate determination of the dietary intake of these micro-nutrients, and in the development of comprehensive food tables. Determination of basal levels is also necessary for the rational engineering of health-promoting phytochemicals in food crops. In addition this approach can also be applied to the routine screening of products to determine metabolic differences between varieties and cultivars, as well as between genetically modified and the corresponding non-genetically modified tissue.     

Supramolecular assemblies of carotenoids.

Carotenoid self-assemblies were formed by aqueous dilution of ethanolic solutions. The four 3',6'-epimers of capsanthol ((all-E,3R,5'R)-3,3',6'-trihydroxy-beta,kappa-carotene) give rise to right- and left-handed card-pack and head-to-tail types of self-assemblies detected by exciton couplets appearing in the CD spectra. Slow kinetics of formation followed for some of the aggregates indicate the complexity of the process. The exciton signals do not appear from equimolar mixtures of related compounds that produce identical type of aggregates of opposite sense on their own. Transformation of self-assembly may reflect the population of kappa-ring rotamers.     

类胡萝卜素的生物学功能

类胡萝卜素 (Carotenoids)是一类重要的植物色素 ,在自然界中 ,广泛存在于各种植物中 ,在动物及微生物中也有发现。类胡萝卜素种类很多 ,其中包括人们所熟知的 α-胡萝卜素、β-胡萝卜素、番茄红素等。到目前为止 ,已经鉴定的类胡萝卜素分子共有 6 0 0多种 ,其中具有重要生物学功能的约有 50几种。类胡萝卜素是类异戊二烯化合物 ,由尾 -尾相连的2个二十碳单位构成四十碳的分子母体碳架 ,并从中衍生出许多不同的化合物。类胡萝卜素分子最显著的结构特征是分子中含有由不同数目的双键或单键的长链所构成的中央分子区域 ,形成 1个共轭体系。多…     

The carotenoids of blue-green algae

The carotenoid compositions of Phormidium persicinum, P. luridum, P. faveolarum and Anabaena flos-aquae have been studied, both quantitatively and qualitatively. β-Carotene is the major carotenoid in all species. The xanthophylls comprise zeaxanthin, echinenone, canthaxanthin and the furanoid mutatochrome. Phormidium persicinum lacks glycosidic carotenoids. Myxoxanthophyll (myxol-2′-rhamnoside) and a 4-ketomyxol-2′-methylpentoside (tentatively 4-keto-myxoxanthophyll) are present in the other species. These distribution patterns are compared with those observed in other blue-green algae and some correlations with taxonomy are apparent.     

Low-lying electronic states of carotenoids.

Four all-trans carotenoids, spheroidene, 3,4-dihydrospheroidene, 3,4,5,6-tetrahydrospheroidene, and 3,4,7,8-tetrahydrospheroidene, have been purified using HPLC techniques and analyzed using absorption, fluorescence and fluorescence excitation spectroscopy of room temperature solutions. This series of molecules, for which the extent of pi-electron conjugation decreases from 10 to seven carbon-carbon double bonds, exhibits a systematic crossover from S2----S0 (1(1)Bu----1(1)Ag) to S1----S0 (2(1)Ag----1(1)Ag) emission with decreasing chain length. Extrapolation of the S1----S0 transition energies indicates that the 2(1)Ag states of longer carotenoids have considerably lower energies than previously thought. The energies of the S1 states of spheroidenes and other long carotenoids are correlated with the S1 energies of their chlorophyll partners in antenna complexes of photosynthetic systems. Implications for energy transfer in photosynthetic antenna are discussed.     

Are dietary carotenoids beneficial? Reactions of carotenoids with oxy-radicals and singlet oxygen.

Carotenoids play diverse roles in biology and medicine. Both the quenching of singlet oxygen (energy transfer) and interaction with oxy-radicals (electron transfer, H-atom transfer and addition reactions) are key processes in understanding many of these roles. Much previous work in 'simple' solvents is reviewed and new results in cell membrane models are presented. The possible consequences of using carotenoids as dietary supplements are discussed.