Astaxanthin attenuates hepatic steatosis in high-fat diet-fed rats by suppressing microRNA-21 via transactivation of nuclear factor erythroid 2-related factor 2

This study examined whether astaxanthin (ASX) could alleviate hepatic steatosis in rats fed a high-fat diet (HFD) by modulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/miR-21 axis. Rats (n = 8/group) were fed either a standard diet (3.8 kcal/g; 10% fat) or HFD (4.6 kcal/g; 40% fat) and treated orally with either the vehicle or ASX (6 mg/kg) daily for 8 days. Another group was fed HFD and treated with ASX and brusatol (an Nrf2 inhibitor) (2 mg/kg/twice per week/i.p.). ASX prevented the gain in body and liver weights and attenuated hepatic lipid accumulation in HFD-fed rats. In the control and HFD-fed rats, ASX did not affect food intake, serum free fatty acid (FFA) content, and glucose and insulin levels and tolerance. However, serum triglyceride (TG), cholesterol, and low-density lipoprotein-cholesterol levels; hepatic levels of TGs and FFAs; and hepatic levels of Srebp1, Srebp2, HMGCR, and fatty acid synthase mRNAs and miR-21 were reduced and the mRNA levels of Pparα were significantly increased in both the groups. These effects were associated with a reduction in the hepatic levels of reactive oxygen species, malondialdehyde, tumor necrosis factor-α, and interlukin-6 as well as an increase in superoxide dismutase levels, total glutathione content, and nuclear levels and activity of Nrf2. miR-21 levels were strongly correlated with the nuclear activity of Nrf2. Brusatol completely reversed the effects of ASX. In conclusion, ASX prevents hepatic steatosis mainly by transactivating Nrf2 and is associated with the suppression of miR-21 and Srebp1/2 and upregulation of Pparα expression. (AU)

Base de datos de carotenoides para valoración de la ingesta dietética de carotenos, xantofilas y de vitamina A; utilización en un estudio comparativo del estado nutricional en vitamina A de adultos jóvenes / Carotenoid data base to assess dietary intake of carotenes, xanthophyls and vitamin A; its use in a comparative study of vitamin A nutritional status in young adults

Objetivos: 1) Elaborar una base de datos de carotenoides (BD-carotenoides) de alimentos consumidos en España. 2) Valorar el estado nutricional en vitamina A (expresada en equivalentes de retinol (ER) y en equivalentes de actividad de retinol (EAR)) en adultos jóvenes. Métodos: La BD-carotenoides incluye datos de carotenos (β-caroteno, α-caroteno y licopeno) y xantofilas (β-critpoxantina, luteína y zeaxantina) generados mediante HPLC. La ingesta de vitamina A se valoró a partir de tres recuerdos de 24 horas, en 54 adultos, 20-35 años, no obesos y con retinol sérico (> 30 µg/dl), utilizando la BD-carotenoides y unas Tablas de Composición de Alimentos de amplio uso en España. Resultados: La BD-carotenoides incluye datos para 89 alimentos (9 en crudo y cocido y 14 son alimentos procesados). La ingesta de carotenoides provitamínicos-A es de 2,5 mg/p/d, la de ER 682 µg/p/d y la de EAR 499 µg/p/d. La vitamina A expresada en EAR es un 27% inferior que como ER. El 76% de las ingestas se adecuan a las ingestas recomendadas y el 63% a la ingesta diaria recomendada. Conclusiones: Los datos individualizados de carotenoides permiten mayor precisión en los estudios entre dieta y salud, y facilitan la valoración de la ingesta de vitamina A, expresada en ER, EAR o en otras formas de expresión futuras. La ingesta de vitamina A expresada como EAR implica una reducción importante en la contribución de los carotenoides a la ingesta de vitamina A, lo que conlleva un aumento en la detección de inadecuaciones en la ingesta de esta vitamina (AU)

Objectives: 1) Develop a database of carotenoids (BD-carotenoids) in foods widely consumed in Spain. 2) To assess the vitamin A nutritional status (expressed as retinol equivalents [RE] and retinol activity equivalents [RAE]) in young adults. Methods: The BD-carotenoids includes data on carotenes (β-carotene, α-carotene and lycopene) and xanthophylls (β-cryptoxanthin, lutein and zeaxanthin) generated by HPLC. Vitamin A intake was assessed by a 3-day food record in 54 adults (20-35 years of age, not obese and with serum retinol > 30 µg/dl), using the BD-carotenoids and a Food Composition Table widely used in Spain. Results: The BD-carotenoids includes data on 89 foods (9 raw or boiled and 14 processed). The intake of provitamin-A carotenoids is 2.5 mg/p/d, that of RE 682 µg/p/d and that of RAE 499 µg/p/d. The vitamin A intake expressed as RAE is 27% lower than that expressed as RE. Seventy-six percent of the intake meets the daily intake recommendations and 63% meets the reference daily intakes of vitamin A. Conclusions: Data on individual carotenoids ensure greater accuracy in studies on diet and health, and provide easier assessment of the vitamin A intake, expressed as RE, RAE, or any other future forms. The vitamin A intake expressed as RAE represents a substantial reduction in the carotenoid contribution to vitamin A intake, which enhances the detection of inadequacies of that intake (AU)

Genetic basis of microbial carotenogenesis / Bases genéticas de la carotenogénesis microbiana

The synthesis of carotenoids begins with the formation of a phytoene from geranylgeranyl pyrophosphate, a well conserved step in all carotenogenic organisms and catalyzed by a phytoene synthase, an enzyme encoded by the crtB ( spy) genes. The next step is the dehydrogenation of the phytoene, which is carried out by phytoene dehydrogenase. In organisms with oxygenic photosynthesis, this enzyme, which accomplishes two dehydrogenations, is encoded by the crtP genes. In organisms that lack oxygenic photosynthesis, dehydrogenation is carried out by an enzyme completely unrelated to the former one, which carries out four dehydrogenations and is encoded by the crtI genes. In organisms with oxygenic photosynthesis, dehydrogenation of the phytoene is accomplished by a zeta-carotene dehydrogenase encoded by the crtQ ( zds) genes. In many carotenogenic organisms, the process is completed with the cyclization of lycopene. In organisms exhibiting oxygenic photosynthesis, this step is performed by a lycopene cyclase encoded by the crtL genes. In contrast, anoxygenic photosynthetic and non-photosynthetic organisms use a different lycopene cyclase, encoded by the crtY ( lyc) genes. A third and unrelated type of lycopene beta-cyclase has been described in certain bacteria and archaea. Fungi differ from the rest of non-photosynthetic organisms in that they have a bifunctional enzyme that displays both phytoene synthase and lycopene cyclase activity. Carotenoids can be modified by oxygen-containing functional groups, thus originating xanthophylls. Only two enzymes are necessary for the conversion of beta-carotene into astaxanthin, using several ketocarotenoids as intermediates, in both prokaryotes and eukaryotes. These enzymes are a beta-carotene hydroxylase ( crtZ genes) and a beta-carotene ketolase, encoded by the crtW (bacteria) or bkt (algae) genes (AU)

La síntetis de carotenoides se inicia con la formación de fitoeno a partir de GGPP, un paso muy conservado en todos los organismos carotenogénicos y catalizado por la fitoeno sintasa, una enzima codificada por los genes crtB (spy). El siguiente paso es la deshidrogenación del fitoeno, llevada a cabo por la fitoeno deshidrogenasa. En los organismos con fotosíntesis oxigénica, esta enzima, que realiza dos deshidrogenaciones, está codificada por los genes crtP. En los organismos sin fotosíntesis oxigénica, la deshidrogenación es llevada a cabo por una enzima nada relacionada con la anterior, que realiza cuatro deshidrogenaciones y está codificada por los genes crtI. En los organismos con fotosíntesis oxigénica, la deshidrogenación del fitoeno se completa con una gamma-caroteno deshidrogenasa codificada por los genes crtQ (zds). En muchos organismos carotenogénicos este proceso se completa con la ciclación del licopeno. En los organismos con fotosíntesis oxigénica, este paso lo realiza la licopeno ciclasa, codificada por los genes crtL. Por contra, los organismos con fotosíntesis anoxigénica y los no fotosintéticos utilizan una licopeno ciclasa distinta, codificada por los genes crtY (lyc). Un tercer tipo de licopeno beta-ciclasa no relacionada ha sido descrita en ciertas bacterias y arqueas. Los hongos difieren del resto de los organismos no fotosintéticos en que poseen una enzima bifuncional con actividad fitoeno sintasa y licopeno ciclasa. Los carotenoides pueden ser modificados añadiendo grupos funcionales que contengan oxígeno, convirtiéndose en xantofilas. Sólo son necesarias dos enzimas para la conversión de beta-caroteno en astaxantina en procariotas y eucariotas, teniendo como intermediarios varios cetocarotenoides. Estas enzimas son la beta-caroteno hidroxilasa (genes crtZ) y una beta-caroteno cetolasa codificada por los genes crtW (en bacterias) o bkt (en algas) (AU)