1. Investigación

El estrés oxidativo celular ha sido reconocido en los últimos años como un jugador clave en diferentes enfermedades, entre ellas las neurodegenerativas. Debido a que el cerebro es un órgano metabólicamente hiperactivo y con menor capacidad para la regeneración celular en comparación con otros órganos, es extremadamente vulnerable a este daño. Dentro de los compuestos estudiados en los últimos años como posibles metabolitos reguladores del estrés oxidativo, la curcumina ha sido objeto de numerosos estudios como posible terapia frente al daño oxidativo. Debido a sus características farmacocinéticas y farmacodinámicas tales como su baja solubilidad en agua, su baja biodisponibilidad, su alta inestabilidad química y su mala absorción digestiva, esta molécula presenta dificultades a la hora de llegar a sus dianas fisiológicas. Por ello, en este trabajo se han evaluado las propiedades antioxidantes de catorce derivados asimétricos de la curcumina, con la finalidad de caracterizar aquellos derivados con mejor perfil antioxidante, de tal manera que pudiéramos seleccionar aquellos que además presentaran mejores características para actuar a nivel neuronal. Los ensayos realizados para estudiar la capacidad antioxidante han sido ABTS, FRAP y DPPH habiéndose encontrado que todos los compuestos presentan propiedades antioxidantes similares a la curcumina. Los estudios de viabilidad celular realizados en las líneas celulares SH-SY5Y, HT-22 y HepG2, han demostrado que estos derivados tienen menor citotoxicidad que la curcumina. De todos los quimiotipos la selecion de 6b y 7b ha evidenciado que estos dos derivados presentan excelente solubilidad y estabilidad química en medios biorrelevantes, que tienen comportamiento de quelación frente a Fe2+ similar a la curcumina, y que además, ambos han proporcionado una buena actividad neuroprotectora contra el estrés oxidativo inducido tanto por generadores de radicales libres (H2O2) , como por inhibidores de la cadena de transporte electrónico mitocondrial, o como excitotoxicidad inducida por glutamato. Teniendo en cuenta estos resultados, se ha evidenciado que los compuestos 6b y 7b poseen un prometedor perfil antioxidante, con baja actividad citotóxica y buena actividad neuroprotectora, lo que les hace candidatos para ser una nueva clase química interesante con alto potencial farmacológico como nuevos agentes terapéuticos contra enfermedades neurodegenerativas.

Scope : Fructose intake from added sugars correlates with the epidemic rise in metabolic syndrome and cardiovascular diseases. However, consumption of beverages containing fructose is allowed during gestation. Homocysteine (Hcy) is a well-known risk factor for cardiovascular diseases while hydrogen sulfide (H2S), a product of its metabolism, has been proved to exert opposite effects to Hcy. Methods and results : First, we investigated whether maternal fructose intake produces subsequent changes in Hcy metabolism and H2S synthesis of the progeny. Carbohydrates were supplied to pregnant rats in drinking water (10% wt/vol) throughout gestation. Adult female descendants from fructosefed, control or glucose-fed mothers were studied. Females from fructose-fed mothers had elevated homocysteinemia, hepatic H2S production, cystathionine -lyase (CSE) (the key enzyme in H2S synthesis) expression and plasma H2S, versus the other two groups. Second, we studied how adult female progeny from control (C/F), fructose- (F/F) and glucose-fed (G/F) mothers responded to liquid fructose and compared them to the control group (C/C). Interestingly, both hepatic CSE expression and H2S synthesis were diminished by fructose intake, this effect being more pronounced in F/F females. Conclusions : Maternal fructose intake produces a fetal programming that increases hepatic H2S production and, in contrast, exacerbates its fructose-induced drop in female progeny.

Scope: One of the features of metabolic syndrome caused by liquid fructose intake is an impairment of redox status. We have investigated whether maternal fructose ingestion modifies the redox status in pregnant rats and their fetuses. Methods and results: Fructose (10% wt/vol) in the drinking water of rats throughout gestation, leads to maternal hepatic oxidative stress. However, this change was also observed in glucose-fed rats and, in fact, both carbohydrates produced a decrease in antioxidant enzyme activity. Surprisingly, mothers fed carbohydrates displayed low plasma lipid oxidation. In contrast, fetuses from fructose-fed mothers showed elevated levels of plasma lipoperoxides versus fetuses from control or glucose-fed mothers. Interestingly, a clearly augmented oxidative stress was observed in placenta of fructose-fed mothers, accompanied by a lower expression of the transcription factor Nuclear factor-erythroid 2-related factor-2 (Nrf2) and its target gene, heme oxygenase-1 (HO-1), a potent antioxidant molecule. Moreover, histone deacetylase 3 (HDAC3) which has been proposed to upregulate HO-1 expression by stabilizing Nrf2, exhibited a diminished expression in placenta of fructose-supplemented mothers. Conclusions: Maternal fructose intake provoked an imbalanced redox status in placenta and a clear diminution of HO-1 expression, which could be responsible for the augmented oxidative stress found in their fetuses.

Free radicals generated as byproducts of normal metabolism can damage biologically relevant molecules. When their generation is increased, damage can also be increased, resulting in the development of many pathological cinditions. Antioxidant defenses protect the body from the detrimental effects of free radicals. Dietary fruits and vegetables provide a reasonable amount of compounds that act as physiological antioxidants. Although existing knowledge does not allow a final and conclusive assessment of the relevance of antioxidants for health, is does aspects of antioxidant supplementation in health and disease.

Glutathione plays a central role in metabolism and antioxidant defence. Several factors can influence the analytical efficiency and rapidity of the quantitative determination of glutathione. Procedures in sample pre-treatment have been compared in order to minimize analytical errors. Capillary electrophoresis has been chosen as a more adequate technique for obtaining a rapid and simple method for glutathione and glutathione disulfide determination in the blood and liver of the rat. The methods, once optimised, have been validated and applied for monitoring the oxidative stress in an animal model, such as the rat made diabetic by streptozotocin injection, when the animals are treated with antioxidants and compared with the corresponding controls.