Raman spectroscopic analysis of the carotenoid concentration in egg yolks depending on the feeding and housing conditions of the laying hens

Oxidative stress coping capacity (OSC) value: Development and validation of an in vitro measurement method for blood plasma using electron paramagnetic resonance spectroscopy (EPR) and vitamin C

Oxidative stress as a driver of disease is reinforcing the trend towards supplementation with antioxidants. While antioxidants positively influence the redox status when applied at physiological doses, higher concentrations may have pro-oxidative effects. Precise assessment methods for testing the supply of antioxidants are lacking. Using in-situ-irradiation as stressor and electron paramagnetic resonance (EPR) spectroscopy as readout system for formed radicals, a stress response assessment method was developed, using protein solutions and plasma samples from transfusion medicine. The method was validated in a double-blind placebo-controlled in vivo cross-over pilot study in blood plasma samples of individuals before and after vitamin C supplementation. Reference measurements were performed for the exogenous antioxidants β-carotene and vitamin C, and glutathione as an endogenous representative. Malondialdehyde was studied for oxidative stress indication. Protein solutions without antioxidants showed a linear increase in radical concentration during irradiation. The in-vitro-addition of vitamin C or plasma samples from subjects displayed two slopes (m₁, m₂) for radical production, whereby m₁ represented the amount of antioxidants and proteins, m₂ only the protein content. These two slopes in combination with the intervening transition area (T) were used to calculate the oxidative stress coping capacity (OSC), which correlated positively with vitamin C concentration in blood plasma, while oxidative stress biomarkers showed only fluctuations within their reference ranges. Furthermore, a selective radical quenching mechanism for vitamin C was observed: the proportion of reactive oxygen species (ROS) in the plasma samples was degraded in dependence to the vitamin C concentration ingested. The proportion of lipid oxygen species (LOS) remained stable while the ascorbyl radical increased with higher vitamin C intake. OSC may represent a sensitive method to detect treatment effects on the redox status in vivo in future validation and treatment studies, and potentially in clinical routine.

Analysis of the Status of the Cutaneous Endogenous and Exogenous Antioxidative System of Smokers and the Short-Term Effect of Defined Smoking Thereon

The daily consumption of tobacco products leads to a boost in free radical production in tissues, promoting the risk for malignancies, metabolic alterations and chronic-inflammatory diseases. This study aimed to broaden the knowledge of the status of the antioxidative (AO) system in the skin, compared to the blood, of healthy appearing smokers. Both, the basic status compared to non-smokers and the short-term impact of controlled cigarette consumption in smokers were analyzed. Our study showed that the basic level of the AO system of smokers significantly differed from that of non-smokers. As determined by resonant Raman spectroscopy (RRS), the levels of exogenous AOs were decreased in both, the skin, in vivo (β-carotene and lycopene), and blood plasma (β-carotene only). In contrast, the levels of glutathione (GSH), the prototypical endogenous AO, which were analyzed by fluorimetric assays in cutaneous tape strips and blood plasma, were increased in the skin, although unchanged in the blood of smokers. Elevated cutaneous GSH levels were reflected by an elevated overall radical scavenging activity in the skin, as quantified by non-invasive electron paramagnetic resonance (EPR) spectroscopy. Analysis of the expression of selected stress-associated genes in blood immune cells by quantitative RT-PCR in subgroups of non-smokers and smokers additionally demonstrated the downregulation of AKR1C2 in smokers, and its negative correlation with blood plasma levels of the protective immune mediator interleukin-22, assessed by the ELISA technique. Controlled cigarette consumption did not alter exogenous or endogenous AOs in the skin of smokers, but decreased lycopene levels in blood plasma. Moreover, there was a decline in blood IL-22 levels, while no relevant response of blood cell gene expressions was found after the considered short time. Our data therefore demonstrate a strengthened endogenous AO status in the skin of smokers, which may indicate a long-term adaptation to chronic oxidative stress in this specific organ. While this effect was not clearly visible in the blood, this compartment seems to be useful as an immediate indicator of the body's AO consumption. Moreover, decreased levels of AKR1C2, which we show for the first time to be expressed in immune cells, may be a candidate marker for long-term smoking. In addition, this study demonstrates that the rate constant of a spin probe decline determined by EPR spectroscopy mainly represents the endogenous AO status of a tissue.

Incorporation of Lutein on Layered Double Hydroxide for Improving the Environmental Stability

To overcome the poor stability of natural lutein to environmental factors, layered double hydroxide was incorporated by a green mechanical grinding process. The influences of external factors (chemical reagents, heating and light) on the stability of lutein before and after being loaded were evaluated. The results confirmed that lutein was mainly adsorbed on the surface of layered double hydroxide (LDH) via the chemical interaction. Compared with pure lutein, the thermal decomposition of lutein/LDH was improved from 100 °C to 300 °C, and the retention ratio of lutein was increased by about 8.64% and 21.47% after 96 h of light exposure and accelerated degradation, respectively. It is expected that the stable lutein/LDH composites may constitutean additive in animal feed.

Toward food analytics: fast estimation of lycopene and β-carotene content in tomatoes based on surface enhanced Raman spectroscopy (SERS)

The application of SERS toward the differentiation of two carotenoid molecules (namely, lycopene and β-carotene) in tomato samples is introduced.

Lutein Leads to a Decrease of Factor D Secretion by Cultured Mature Human Adipocytes

Purpose. Complement plays an important role in the pathogenesis of age related macular degeneration (AMD) and trials are currently being conducted to investigate the effect of complement inhibition on AMD progression. We previously found that the plasma level of factor D (FD), which is the rate limiting enzyme of the complement alternative pathway, was significantly decreased following lutein supplementation. FD is synthesized by adipose tissue, which is also the main storage site of lutein. In view of these findings we tested the hypothesis whether lutein could affect FD synthesis by adipocytes. Methods. A cell line of mature human adipocytes was incubated with 50 μg/mL lutein for 24 and 48 h, whereafter FD mRNA and protein expression were measured. Results. Lutein significantly inhibited adipocyte FD mRNA expression and FD protein release into adipocyte culture supernatants. Conclusions. Our earlier observations showing that a daily lutein supplement in individuals with early signs of AMD lowered the level of circulating FD might be caused by blocking adipocyte FD production.

The effect of modified eggs and an egg-yolk based beverage on serum lutein and zeaxanthin concentrations and macular pigment optical density: results from a randomized trial

Increasing evidence suggests a beneficial effect of lutein and zeaxanthin on the progression of age-related macular degeneration. The aim of this study was to investigate the effect of lutein or zeaxanthin enriched eggs or a lutein enriched egg-yolk based buttermilk beverage on serum lutein and zeaxanthin concentrations and macular pigment levels. Naturally enriched eggs were made by increasing the levels of the xanthophylls lutein and zeaxanthin in the feed given to laying hens. One hundred healthy volunteers were recruited and randomized into 5 groups for 90 days. Group one added one normal egg to their daily diet and group two received a lutein enriched egg-yolk based beverage. Group three added one lutein enriched egg and group four one zeaxanthin enriched egg to their diet. Group five was the control group and individuals in this group did not modify their daily diet. Serum lutein and zeaxanthin concentrations and macular pigment densities were obtained at baseline, day 45 and day 90. Macular pigment density was measured by heterochromatic flicker photometry. Serum lutein concentration in the lutein enriched egg and egg yolk-based beverage groups increased significantly (p<0.001, 76% and 77%). A strong increase in the serum zeaxanthin concentration was observed in individuals receiving zeaxanthin enriched eggs (P< 0.001, 430%). No changes were observed in macular pigment density in the various groups tested. The results indicate that daily consumption of lutein or zeaxanthin enriched egg yolks as well as an egg yolk-based beverage show increases in serum lutein and zeaxanthin levels that are comparable with a daily use of 5 mg supplements.

Trial Registration

ClinicalTrials.gov NCT00527553

Noninvasive measurements of carotenoids in bovine udder by reflection spectroscopy

For a long time, the antioxidative status in cattle has been discussed as an indicator for stress conditions resulting from disease or exertion. Until now, invasive approaches have been necessary to obtain blood samples or biopsy materials and gain insights into the antioxidative status of cattle. Due to these efforts and the costs of the analyses, serial sampling is feasible in an experimental setting, but not for measurements on a routine basis. The present study focuses on the feasibility of an innovative, noninvasive spectroscopic technique that allows in vivo measurements of carotenoids in the skin by reflection spectroscopy. To this end, in a first trial, repeated measurements of the carotenoid concentration of the udder skin were performed on 25 healthy cattle from different breeds. Carotenoid concentrations showed highly significant differences between individual animals (P<0.001), although they were kept under the same environmental conditions and received the same diet. The carotenoid concentrations in "sensitive" and "robust" cows (evaluated by a temperament test) differed significantly (P<0.005), with higher concentrations observed in robust cows.

Lutein: more than just a filter for blue light

Lutein is concentrated in the primate retina, where together with zeaxanthin it forms the macular pigment. Traditionally lutein is characterized by its blue light filtering and anti-oxidant properties. Eliminating lutein from the diet of experimental animals results in early degenerative signs in the retina while patients with an acquired condition of macular pigment loss (Macular Telangiectasia) show serious visual handicap indicating the importance of macular pigment. Whether lutein intake reduces the risk of age related macular degeneration (AMD) or cataract formation is currently a strong matter of debate and abundant research is carried out to unravel the biological properties of the lutein molecule. SR-B1 has recently been identified as a lutein binding protein in the retina and this same receptor plays a role in the selective uptake in the gut. In the blood lutein is transported via high-density lipoproteins (HDL). Genes controlling SR-B1 and HDL levels predispose to AMD which supports the involvement of cholesterol/lutein transport pathways. Apart from beneficial effects of lutein intake on various visual function tests, recent findings show that lutein can affect immune responses and inflammation. Lutein diminishes the expression of various ocular inflammation models including endotoxin induced uveitis, laser induced choroidal neovascularization, streptozotocin induced diabetes and experimental retinal ischemia and reperfusion. In vitro studies show that lutein suppresses NF kappa-B activation as well as the expression of iNOS and COX-2. Since AMD has features of a chronic low-grade systemic inflammatory response, attention to the exact role of lutein in this disease has shifted from a local effect in the eye towards a possible systemic anti-inflammatory function.