Keto, thione, selone, and tellone carotenoids — Changing antioxidants to antireductants

Heterocarotenoids can be considered as xenobiotic compounds as they are foreign to living organisms. Thione carotenoids are heterocarotenoids that are particularly interesting because the presence of sulfur shifted the absorption to longer wavelengths than the corresponding keto carotenoids. This may be important for further applications such as the development of new pigments. Keto carotenoids are well-known antiradical molecules, however, nothing is known about heterocarotenoids acting as free radical scavengers. Thus, the main goal of this investigation is to study the antiradical properties of some heterocarotenoids, such as thione, selone, and tellone carotenoids. For this purpose, the energy differences between singlets and triplets are used to analyze the singlet oxygen quenching mechanism, and the electron transfer mechanism is investigated, taking into account that these may constitute antiradical molecules either donating or accepting electrons (antioxidants or antireductants). To analyze these mechanisms, vertical ionization energy (I), vertical electron affinity (A), and electrodonating (χ−) and electroaccepting (χ+) electronegativities were evaluated by applying density functional theory calculations. The investigated heterocarotenoids are as effective as keto carotenoids in terms of being either electron donors or acceptors, and therefore, they have a similar capacity for scavenging free radicals. Changing the C=O group to C=S, C=Se, or C=Te converts an antioxidant to an antireductant.

Effects of dietary retinoids and carotenoids on immune development

Carotenoids and retinoids are groups of nutritionally-relevant compounds present in many foods of plant origin (carotenoids) and animal origin (mainly retinoids). Their levels in human subjects vary depending on the diversity and amount of the individual's nutrient intake. Some carotenoids and retinoids have been investigated for their effects on the immune system bothin vitroandin vivo. It has been shown that retinoids have the potential to mediate or induce proliferative and differentiating effects on several immune-competent cells, and various carotenoids are known to be inducers of immune function. The immune-modulating effects of retinoids have been well documented, while the effects of carotenoids on the immune system have not been investigated as extensively, because little is known about their molecular mechanism of action. The present review will mainly focus on the molecular mechanism of action of retinoids and particularly carotenoids, their nutritional origin and intake, their transfer from the maternal diet to the child and their effects or potential effects on the developing immune system.

Low serum selenium and total carotenoids predict mortality among older women living in the community: the women's health and aging studies

Selenium and the carotenoids play an important role in antioxidant defenses and in the redox regulation involved in inflammation. We tested the hypothesis that low selenium and carotenoids predict mortality in older women living in the community. Women who were enrolled in the Women's Health and Aging Studies I and II in Baltimore, MD (n = 632; 70-79 y old) had serum selenium and carotenoids measured at baseline and were followed for mortality over 60 mo. Median (minimum, maximum) serum selenium and carotenoids were 1.53 (0.73, 2.51) micromol/L and 1.67 (0.13, 9.10) micromol/L; 14.1% of the women died. The 5 major causes of death were heart disease (32.6%), cancer (18.0%), stroke (9.0%), infection (6.7%), and chronic obstructive pulmonary disease (5.6%). Adjusting for age, education, smoking, BMI, poor appetite, and chronic diseases, higher serum selenium [hazard ratio (HR) 0.71, 95% CI 0.56-0.90/1 SD increase in log(e) selenium; P = 0.005] and higher serum total carotenoids (HR 0.77, 95% CI 0.64-0.84/1 SD increase in log(e) total carotenoids; P = 0.009) were associated with a lower risk of mortality. Women living in the community who have higher serum selenium and carotenoids are at a lower risk of death.