Search results for "Xanthophyll"
showing 10 items of 52 documents
Supplementary Ultraviolet-B Radiation Induces a Rapid Reversal of the Diadinoxanthin Cycle in the Strong Light-Exposed DiatomPhaeodactylum tricornutu…
2002
AbstractA treatment of the diatom Phaeodactylum tricornutum with high light (HL) in the visible range led to the conversion of diadinoxanthin (Dd) to diatoxanthin (Dt). In a following treatment with HL plus supplementary ultraviolet (UV)-B, the Dt was rapidly epoxidized to Dd. Photosynthesis of the cells was inhibited under HL + UV-B. This is accounted for by direct damage by UV-B and damage because of the UV-B-induced reversal of the Dd cycle and the associated loss of photoprotection. The reversal of the Dd cycle by UV-B was faster in the presence of dithiothreitol, an inhibitor of the Dd de-epoxidase. Our results imply that the reversal of the Dd cycle by HL + UV-B was caused by an incre…
Degradation of Carotenoids in Apricot (Prunus armeniaca L.) During Drying Process
2013
"Carotenoids are natural compounds whose nutritional importance comes from the provitamin A activity of some of them and their protection against several serious human disorders. The degradation of carotenoids was investigated during apricot drying by microwave and convective hot-air at 60 and 70 A degrees C. Seven carotenoids were identified: antheraxanthin, lutein, zeaxanthin, beta-cryptoxanthin, 13-cis-beta-carotene, all-trans-beta-carotene and 9-cis-beta-carotene; among these, all-trans-beta-carotene was found to be about 50 % of total carotenoids. First-order kinetic models were found to better describe all-trans-beta-carotene reduction during drying, with a degradation rate constant (…
Kinetics of carotenoids degradation and furosine formation in dried apricots (Prunus armeniaca L.)
2017
Abstract The kinetics of carotenoid and color degradation, as well as furosine formation, were investigated in apricot fruits during convective heating at 50, 60 and 70 °C. Degradation of carotenoids and color, expressed as total color difference (TCD), followed a first and zero order kinetic, respectively. The activation energy (Ea) for carotenoids degradation ranged from 73.7 kJ/mol for 13- cis -β-carotene to 120.7 kJ/mol for lutein, being about 91 kJ/mol for all- trans -β-carotene. Violaxanthin and anteraxanthin were the most susceptible to thermal treatment. The furosine evolution was fitted at zero order kinetic model. The Ea for furosine formation was found to be 83.3 kJ/mol and the Q…
Biochemical and Immunological implications of Lutein and Zeaxanthin
2021
Throughout history, nature has been acknowledged for being a primordial source of various bioactive molecules in which human macular carotenoids are gaining significant attention. Among 750 natural carotenoids, lutein, zeaxanthin and their oxidative metabolites are selectively accumulated in the macular region of living beings. Due to their vast applications in food, feed, pharmaceutical and nutraceuticals industries, the global market of lutein and zeaxanthin is continuously expanding but chemical synthesis, extraction and purification of these compounds from their natural repertoire e.g., plants, is somewhat costly and technically challenging. In this regard microbial as well as microalga…
Chemoprotective effect of carotenoids from Lycium barbarum L. on SH-SY5Y neuroblastoma cells treated with beauvericin
2020
Goji berry has recently been introduced in Mediterranean diet and its consumption is increasing. This study aims to determine cytoprotection of lutein (LUT), zeaxanthin (ZEAX) and goji berry extract (GBE) rich in carotenoids against Beauvericin (BEA)-induced cytotoxicity on SH-SY5Y neuroblastoma cells. Both carotenoids and GBE showed cytoprotective effects. Cytoprotection was evaluated by simultaneous combination of the two xanthophylls LUT and ZEAX with BEA, as well as using pre-treatment assays. The highest protective effect occurred in 16%, 24% and 12% respectively for LUT, ZEAX and LUT + ZEAX incubating simultaneously with BEA, while by pre-treatment assay LUT showed a cytoprotection ef…
Effects of mountain grassland maturity stage and grazing management on carotenoids in sward and cow's milk
2006
Carotenoids are involved in the sensorial and nutritional values of dairy products. In grazing systems, both herbage maturity stage and grazing management may affect the amount of carotenoid ingested, thus these factors may affect carotenoid concentrations in milk. Two homogenous plots of mountain grassland (1.4 and 2.0 ha) were grazed during two cycles of growth by 6 dairy cows in mid lactation, in strip (SG) and rotational grazing (RG), respectively. We monitored the changes in carotenoid concentrations in sward and milk, measured by HPLC twice a week. Seven carotenoids were identified in the sward: violaxanthin, antheraxanthin, epilutein, lutein, zeaxanthin, ß-carotene and 13-cis ß-carot…
Xanthophylls: from blood to retina
2010
Xanthophylls are dietary lipophilic compounds. Among them, lutein and zeaxanthin are the major carotenoids found in the human lens and retina, and referred as macular pigment within the retina. Lutein and zeaxanthin cannot be synthesized endogenously. They may therefore be considered as essential and must be provided by adequate dietary intakes. Lutein and zeaxanthin are present in various food items, mainly in plants and fruits such as green vegetables or yellow-orange fruits, as well as in a few animal sources, such as egg yolk. Epidemiological studies consistently suggest that dietary lutein and zeaxanthin are protective factors against the development of Age-Related Maculopathies and Ag…
Protective role of xanthophylls
2010
Xanthophylls, also known as carotenoids are a group of natural fat-soluble pigments that are especially abundant in green and yellow-orange fruits and vegetables. Based on epidemiologic data, it is now evident that carotenoids provide health benefits and particularly in eye diseases. Molecular characterization of retinal carotenoids has shown that there were actually two xanthophylls that are concentrated in macular region, namely lutein and zeaxanthin. Thanks to a strategic position within inner retinal layers, lutein and zeaxanthin are suspected to act as antioxidants in the retina in order to limit oxidative stress that results from metabolism of light. In addition, they are also suppose…
The influence of phase transitions in phosphatidylethanolamine models on the activity of violaxanthin de-epoxidase
2008
In the present study, the influence of the phospholipid phase state on the activity of the xanthophyll cycle enzyme violaxanthin de-epoxidase (VDE) was analyzed using different phosphatidylethanolamine species as model lipids. By using (31)P NMR spectroscopy, differential scanning calorimetry and temperature dependent enzyme assays, VDE activity could directly be related to the lipid structures the protein is associated with. Our results show that the gel (L beta) to liquid-crystalline (L alpha) phase transition in these single lipid component systems strongly enhances both the solubilization of the xanthophyll cycle pigment violaxanthin in the membrane and the activity of the VDE. This pha…
Immune activation rapidly mirrored in a secondary sexual trait.
2003
A crucial assumption underlying most models of sexual selection is that sexual advertisements honestly reflect the phenotypic and/or genetic quality of their bearers ([1][1]). Here we show that experimental activation of the immune system is rapidly mirrored in the expression of a carotenoid-based