Browsing by Author "Ana Belen Granado Serrano"

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    Cocoa flavonoids up-regulate antioxidant enzyme activity via the ERK1/2 pathway to protect against oxidative stress-induced apoptosis in HepG2 cells
    (Elsevier, 2010) Maria Angeles Martin; Ana Belen Granado Serrano; Sonia Ramos; Maria Izquierdo Pulido; Laura Bravo; Luis Goya
    Oxidative stress is widely recognized as an important mediator of apoptosis in liver cells and plays a pivotal role in the pathogenesis of several diseases. Cocoa flavonoids have shown a powerful antioxidant activity providing protection against oxidation and helping prevent oxidative stress-related diseases. However, the molecular mechanisms responsible for this protection are not fully understood. Thus, in this study we investigated the protective effect of a cocoa polyphenolic extract (CPE) against tert-butyl hydroperoxide (t-BOOH)-induced apoptosis and the molecular mechanisms involved in this process. Incubation of HepG2 cells with t-BOOH induced apoptosis as evidenced by caspase-3 activation. This effect was accompanied by increased reactive oxygen species formation and by transient activation of the extracellular regulated kinases (ERKs) as well as sustained activation of the c-Jun N-terminal kinases (JNKs). On the contrary, pretreatment of HepG2 cells with CPE prevented apoptosis through the reduction of reactive oxygen species generation and the modulation of the apoptotic pathways activated by t-BOOH. CPE treatment also activated survival signaling proteins, such as protein kinase B (AKT) and ERKs, and increased the activities of two antioxidant enzymes, glutathione peroxidase (GPx) and glutathione reductase (GR). ERKs implication on GPx and GR induction and the protective effect of CPE against t-BOOH-induced oxidative stress and apoptosis were confirmed through experiments with selective inhibitors. These findings suggest that CPE is an effective inductor of GPx and GR activities via ERK activation and that this up-regulation seems to be required to attenuate t-BOOH-induced injury.
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    A diet rich in cocoa attenuates N-nitrosodiethylamine-induced liver injury in rats
    (2009) Ana Belen Granado Serrano; Maria Angeles Martin; Laura Bravo Luis Goya; Sonia Ramos
    The effects of cocoa feeding against N-nitrosodiethylamine (DEN)-induced liver injury were studied in rats. Animals were divided into five groups. Groups 1 and 2 were fed with standard and cocoa-diet, respectively. Groups 3 and 4 were injected with DEN at 2 and 4 weeks, and fed with standard and cocoa-diet, respectively. Group 5 was treated with DEN, received the standard diet for 4 weeks and then it was replaced by the cocoa-diet. DEN-induced hepatic damage caused a significant increase in damage markers, as well as a decrease in the hepatic glutathione, diminished levels of p-ERK and enhanced protein carbonyl content, caspase-3 activity and values of p-AKT and p-JNK. The cocoa-rich diet prevented the reduction of hepatic glutathione concentration and catalase and GPx activities in DEN-injected rats, as well as diminished protein carbonyl content, caspase-3 activity, p-AKT and p-JNK levels, and increased GST activity. However, cocoa administration did not abrogate the DEN-induced body weight loss and the increased levels of hepatic-specific enzymes and LDH. These results suggested that cocoa-rich diet attenuates the DEN-induced liver injury