Showing papers on "Neoxanthin published in 2005"

Determination of major carotenoids in a few Indian leafy vegetables by high-performance liquid chromatography.

Abstract: Leafy vegetables [Basella rubra L., Peucedanum sowa Roxb., Moringa oleifera Lam., Trigonella foenum-graecum L., Spinacia oleracea L., Sesbania grandiflora (L.) Poir., and Raphanus sativus L.] that are commonly used by the rural population in India were evaluated in terms of their main carotenoid pattern. The extracted carotenoids were purified by open column chromatography (OCC) on a neutral alumina column to verify their identity by their characteristic UV-visible absorption spectra. Reverse-phase high-performance liquid chromatography (HPLC) on a C18 column with UV-visible photodiode array detection under isocratic conditions was used for quantification of isolated carotenoids. Acetonitrile/methanol/dichloromethane (60:20:20 v/v/v) containing 0.1% ammonium acetate was used as a mobile phase. The major carotenoids identified by both methods were lutein, beta-carotene, violaxanthin, neoxanthin, and zeaxanthin. Among the carotenoids identified, lutein and beta-carotene levels were found to be higher in these leafy vegetables. Results show that P. sowa and S. oleracea are rich sources of lutein (77-92 mg/100 g of dry wt) and beta-carotene (36-44 mg/100 g of dry wt) compared with other leafy vegetables. The purity of carotenoids eluted by OCC was clarified by HPLC, and they were found to be 92% +/- 3% for neoxanthin, 94% +/- 2% for violaxanthin, 97% +/-2% for lutein and zeaxanthin, and 90% +/- 3% for beta-carotene. It could be recommended to use P. sowa and S. oleracea as rich sources of lutein and beta-carotene for health benefits. The OCC method proposed is relatively simple and provides purified carotenoids for feeding trials.

Carotenoid composition of kale as influenced by maturity, season and minimal processing

Abstract: The principal carotenoids of kale were identified by chemical reactions, high-performance liquid chromatography/mass spectrometry and high-performance liquid chromatography/photodiode array detection and were quantified by the last technique. In kale taken from conventional farms, the β-carotene and lutein contents were significantly higher in the mature leaves, violaxanthin was at an unusually high level in the young leaves, and neoxanthin had practically the same concentration at both stages of maturity. In samples taken from an organic farm, the carotenoid contents were essentially the same in the young and the mature leaves. Except for β-carotene, which did not differ with season, the carotenoid concentrations of marketed minimally processed kale were found to be significantly higher in the summer than in the winter, reflecting seasonal rather than processing effects. In minimally processed kale monitored during 5 days of storage at 7–9 °C, β-carotene, lutein, violaxanthin and neoxanthin were reduced by 14, 27, 20 and 31% respectively. Thus minimal processing, seasonal and maturity factors were found to have an influence on the carotenoid content of kale. Copyright © 2004 Society of Chemical Industry

Seasonal changes in photosynthesis and photoprotection in a Quercus ilex subsp. ballota woodland located in its upper altitudinal extreme in the Iberian Peninsula

Abstract: Summary Quercus ilex L. subsp. ballota (Desf.) Samp., a Mediterranean evergreen species growing in a continental Mediterranean climate, did not experience water stress and showed greater sensitivity to winter stress than to summer stress over a 12-month period. Net CO2 assimilation rates and photosystem II (PSII) efficiency decreased markedly during the cold months and recovered completely in spring. Lutein, neoxanthin and β-carotene to chlorophyll (Chl) molar ratios all showed the same trend throughout the year, increasing from September to March. This increase was a result of increases in carotenoid concentrations, because Chl concentration per unit leaf area remained stable, and was higher at the end than at the beginning of the first growing season. Lutein-epoxide was a minor component of the total lutein pool. Thermal energy dissipation and non-photochemical quenching (NPQ) were associated with the de-epoxidated forms of the xanthophyll cycle pigments in the warm months. Photosynthetic rates decreased slightly at midday in summer. These changes were accompanied by decreases in maximum potential PSII efficiency (which recovered during the night), actual and intrinsic PSII efficiencies, photochemical quenching and increases in NPQ. Overall, our data indicate down-regulation of photosynthesis during the summer. The diurnal de-epoxidation of violaxanthin to antheraxanthin and zeaxanthin occurred throughout the year, except in January. Antioxidant enzymatic activity increased in the winter months, especially during the coldest months, highlighting its key role in photoprotection against photo-oxidation. Structural and functional modifications protected PSII from permanent damage and allowed 1-year-old leaves to photosynthesize at high rates when temperatures increased in spring.

Balance of xanthophylls molecular and protonated molecular ions in electrospray ionization.

Abstract: This paper reports the chemical evidence of the balance between radical molecular ions and protonatedmolecules of xanthophylls (an oxygen-containing carotenoid) with a conjugated pi-system (polyene) and oxygen as a heteroatom in ESI and HRESI mass spectrometry. The ionization energy of neutral xanthophylls was calculated by semi-empirical methods. The results were compared with those previously published for carotenoids and retinoids, which have also been shown in ESI-MS to form M(+*) and [M + H](+), respectively. This study demonstrates, for the first time, the correlation of an extended conjugation and the presence of oxygen in the formation and balance of M(+*) or [M + H](+) for the carotenoids, neoxanthin, lutein, violaxanthin and zeaxanthin.

Carotenoid pigments in acerola fruits ( Malpighia emarginata DC.) and derived products

Abstract: Carotenoid composition has been investigated in acerola fruits (Malpighia emarginata DC. syn. Malpighia glabra L.) and derived products. In the ripe fruit, four major carotenoids were identified (β-carotene, β-cryptoxanthin, lutein, and violaxanthin) together with other minor carotenoids (neoxanthin, antheraxanthin, neochrome, luteoxanthin, auroxanthin, β-cryptoxanthin-5,6-epoxide, β-cryptoxanthin-5,8-epoxide, cis-β-carotene, and cis-lutein). An average composition for the ripe fruit has been estimated as follows: β-carotene (536.55 μg/100 g fw), β-cryptoxanthin (417.46 μg/100 g fw), lutein (99.21 μg/100 g fw), violaxanthin (395.33 μg/100 g fw), and total minor carotenoids (197.33 μg/100 g fw). Vitamin A values are similar to those described in tomatoes and some tropical fruits such as guava and papaya. After juice-making, including a pasteurization stage as thermal processing, decreases in carotenoid content were observed as well as progress of cis-isomers and structural rearrangement of xanthophylls containing 5,6 epoxide groups. The occurrence of such modifications affected the nutritional value of fruits as well as their antioxidant capability, properties that could be used as a measurement of processing quality.

Ultrafast excitation relaxation dynamics of lutein in solution and in the light-harvesting complexes II isolated from Arabidopsis thaliana

Abstract: Ultrafast excitation relaxation dynamics and energy-transfer processes in the light-harvesting complex II (LHC II) of Arabidopsis thaliana were examined at physiological temperature using femtosecond time-resolved fluorescence spectroscopy. Energy transfer from lutein to Chl a proceeded with a rate constant of kET = 1.8−1.9 × 1013 s-1 and a yield of approximately ΦET = 0.70, whereas that from neoxanthin to Chl a had a rate constant of kET = 6.5 × 1011 s-1 and a yield at the most of ΦET = 0.09. Fluorescence anisotropic decay of lutein in LHC II showed a value larger than 0.4 at the initial state and decayed to approximately 0.1 in 0.3 ps, indicating that two lutein molecules interact with each other in LHC II. In solution, anisotropy of lutein remained constant (0.38) independent of time, and thus a new excited state inferred between the S2 (1Bu) state and the S1 (2Ag) state was not applicable for lutein in solution. Energy migration processes among Chl a or Chl b molecules were clearly resolved by kinetic...

Temperature-induced isomerization of violaxanthin in organic solvents and in light-harvesting complex II.

Abstract: Three main xanthophyll pigments are bound to the major photosynthetic pigment-protein complex of Photosystem II (LHCII): lutein, neoxanthin and violaxanthin. Chromatographic analysis of the xanthophyll fraction of LHCII reveals that lutein appears mainly in the all-trans conformation, neoxanthin in the 9′-cis conformation and major fraction of violaxanthin in the all-trans conformation. Nevertheless, a small fraction of violaxanthin appears always in a cis conformation: 9-cis and 13-cis (approximately 4% and 2% in the darkness, respectively). Illumination of the isolated complex (5 min, 445 nm, 250 μmol m−2 s−1) results in the substantial increase in the concentration of the cis steric conformers of violaxanthin: up to 6% of 9-cis and 4% of 13-cis. Similar effect can be obtained by dark incubation of the same preparation for 30 min at 60 °C. Heating-induced isomerization of the all-trans violaxanthin can also be obtained in the organic solvent system but the formation of the 9-cis stereoisomer has not been observed under such conditions. The fact that the appearance of the 9-cis form of violaxanthin is specific for the protein environment suggests that violaxanthin may replace neoxanthin in LHCII in the N1 xanthophyll binding pocket and that the protein stabilizes this particular conformation. The analysis of the electronic absorption spectra of LHCII and the FTIR spectra of the protein in the Amid I band spectral region indicates that violaxanthin isomerization is associated with the disaggregation of the complex. It is postulated that this reorganization of LHCII provides conditions for desorption of violaxanthin from the pigment protein complexes, its diffusion within the thylakoid membrane and therefore, availability to the enzymatic deepoxidation within the xanthophyll cycle. It is also possible that violaxanthin isomerization plays the role of a security valve, by consuming an energy of excessive excitations in the antenna pigment network (in particular, exchanged at the triplet state levels).

Isolation and characterization of a xanthophyll-rich fraction from the thylakoid membrane of Dunaliella salina(green algae).

Abstract: Long-term acclimation to irradiance stress (HL) of the green alga Dunaliella salina Teod. (UTEX 1644) entails substantial accumulation of zeaxanthin along with a lowering in the relative amount of other pigments, including chlorophylls and several carotenoids. This phenomenon was investigated with wild type and the zea1 mutant of D. salina, grown under conditions of low irradiance (LL), or upon acclimation to irradiance stress (HL). In the wild type, the zeaxanthin to chlorophyll (Zea/Chl) (mol : mol) ratio was as low as 0.009 : 1 under LL and as high as 0.8 : 1 under HL conditions. In the zea1 mutant, which constitutively accumulates zeaxanthin and lacks antheraxanthin, violaxanthin and neoxanthin, the Zea/Chl ratio was 0.15 : 1 in LL and 0.57 : 1 in HL. The divergent Zea/Chl ratios were reflected in the coloration of the cells, which were green under LL and yellow under HL. In LL-grown cells, all carotenoids occurred in structural association with the Chl-protein complexes. This was clearly not the case in the HL-acclimated cells. A β-carotene-rich fraction occurred as loosely bound to the thylakoid membrane and was readily isolated by flotation following mechanical disruption of D. salina. A zeaxanthin-rich fraction was specifically isolated, upon mild surfactant treatment and differential centrifugation, from the thylakoid membrane of either HL wild type or HL-zea1 mutant. Such differential extraction of β-carotene and Zea, and their separation from the Chl-proteins, could not be obtained from the LL-grown wild type, although small amounts of Zea could still be differentially extracted from the LL-grown zea1 strain. It is concluded that, in LL-grown D. salina, xanthophylls (including most of Zea in the zea1 strain) are structurally associated with and stabilized by the Chl-proteins in the thylakoid membrane. Under HL-growth conditions, however, zeaxanthin appears to be embedded in the lipid bilayer, or in a domain of the chloroplast thylakoids that can easily be separated from the Chl-proteins upon mild surfactant treatment. In conclusion, this work provides biochemical evidence for the domain localization of accumulated zeaxanthin under irradiance-stress conditions in green algae, and establishes protocols for the differential extraction of this high-value pigment from the green alga D. salina.

Is the bark of shining gum (Eucalyptus nitens) a sun or a shade leaf

Abstract: Photoinhibition and pigment composition of green stem tissues of field-grown adult Eucalyptus nitens were measured on clear spring days with low morning temperatures—conditions that cause photoinhibition in leaves of many plant species. The sun-exposed (north-facing) bark contained less chlorophyll a+b (531 vs 748 μmol m−2), neoxanthin (29 vs 41), and β-carotene (54 vs 73), more xanthophyll cycle pigments per unit surface area and per unit chlorophyll (71 vs 53 μmol m−2 and 141 vs 66 mmol mol−1 chlorophyll), and less lutein per unit chlorophyll (239 vs 190) than the shaded (southern) side. Maximum electron flow rates were 60 μmol m−2 s−1 on the sun-exposed side, and about 10 μmol m−2 s−1 on the shaded side. Fv/Fm was always lower than 0.8 on the sun-exposed side and the de-epoxidation state (DEPS) of the xanthophyll cycle was dominated by zeaxanthin in midday samples. Fv/Fm increased quickly after darkening, but DEPS recovered more slowly to 40% overnight. This suggested that rapidly reversible pH-dependent quenching was responsible for the bulk of changes in PS II efficiency. Fv/Fm remained below 0.8 overnight, which may well be indicative of photo-damage to PSII. In contrast, DEPS of the shaded side was lower, and Fv/Fm was higher, than for the sun-exposed side. We conclude that E. nitens chlorenchyma on the sun-exposed stem side has a photosynthetic pigment composition similar to sun leaves and it experiences significant photoinhibition in the field.

Series No. 1 Identification and HPLC Quantification of Carotenoids of the Fruit Pulp of Chrysophyllum Roxburghii

Abstract: Carotenoids of the fruit pulp of Chrysophyllum roxburghii (Sinhala: laualu) amounted to about 180 mgkgl by fresh weight. The carotenoids were isolated by open column chromatography (Mg0:Celite 1:l) using mixtures of petroleum ether 40-60 "C and acetone and identified by UVIvisible spectra, chemical tests, and High Performance Liquid Chromatography (HPLC) using authentic standards and a photodiode array detector (PAD). The major carotenoid was trans-violaxanthin (113 mgkg-'1. Also present was cis- violaxanthin, neoxanthin, P-cryptoxanthin monoepoxide, lutein, p-cryptoxanthin, <-carotene and p-carotene. The retinol equivalent of the pulp was only 68 RE1100 g. The study shows that Chrysophyllum roxburghii is not a good source of pro- vitamin A. Further as violaxanthin is reported to be not absorbed by humans, it is of no use as a dietary antioxidant. However, as trans-violaxanthin can be obtained in quantity in the pure crystalline state, directly from the column and has the benefit of eluting at 20% acetone away from most carotenoids, the compound will be useful as a standard for HPLC analysis of carotenoids from other fruits and leaves. hydroxy sintaxanthin. Some of these are not listed in a recent compendium on carotenoids naturally occurring in plant^.^ Further, the experimental techniques and identification procedures used in the above study are not in line with modern analysis procedures. There is, therefore, a possibility that some of these are artifacts of isolation.

Carotenoids in representatives of the Protousnea (Parmeliaceae), endemic genus from South America

Abstract: Column, thin-layer and reverse-phase high-performance liquid chromatography revealed the presence of the following carotenoids in the thalli of 7 lichen species representatives of the Protousnea (Parmeliaceae) endemic genus from South America: α-carotene, β-carotene, retrodehydro-β-carotene, α-cryptoxanthin, β-cryptoxanthin, lycopene-5,6-epoxide, lutein, 3′-epilutein, zeaxanthin, antheraxanthin, cryptoflavin, loroxanthin, capsochrome, neoxanthin, violaxanthin, 3-hydroxyechinenone, adonixanthin, canthaxanthin, astaxanthin, rhodoxanthin, citranaxanthin and torularhodin methyl ester. The total content of carotenoids ranged from 32.45 (Protousnea dusenii) to 48.21 μg g–1 dry weight (Protousnea teretiuscula). (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Carotinoide in Vertretern der Protousnea (Parmeliaceae), einer in Sudamerika endemischen Gattung Untersuchungen mittels Saulen-, Dunnschicht- und Hochleistungs-Flussig-Chromatographie erbrachte den Nachweis folgender Carotinoide in den Thalli von sieben reprasentativen Arten von Protousnea (Parmeliaceae), einer in Sudamerika endemischen Gattung: α-Caroten, β-Caroten, Retrodehydro-β-Caroten, α-Cryptoxanthin, β-Cryptoxanthin, Lycopen-5,6-epoxid, Lutein, 3′-Epilutein, Zeaxanthin, Antheraxanthin, Cryptoflavin, Loroxanthin, Capsochrom, Neoxanthin, Violaxanthin, 3-Hydroxyechinenon, Adonixanthin, Canthaxanthin, Astaxanthin, Rhodoxanthin, Citranaxanthin und Torularhodin Methyl Ester. Der Gesamt-Carotin-Gehalt reicht von 32,45 μg–1(Protousnea dusenii) bis 48,21 μg–1 Trockengewicht (Protouesnea teretiuscula).