Antioxidants against oxidative stress

More recently, large human intervention trials were undertaken with P-carotene alone, or in combination with non-dietary amounts of vitamin E. These trials were undertaken because of promising animal studies that suggested that these antioxidants could offer chemo-preventive action against oxidative stress. The results, which are summarised in Table 11.1, were disappointing. Although the study population in two of the studies (ATBC and CARET)... 

This mechanism is now considered to be of importance for the protection of LDL against oxidation stress, Chapter 25.) The antioxidant effect of ubiquinones on lipid peroxidation was first shown in 1980 [237]. In 1987 Solaini et al. [238] showed that the depletion of beef heart mitochondria from ubiquinone enhanced the iron adriamycin-initiated lipid peroxidation whereas the reincorporation of ubiquinone in mitochondria depressed lipid peroxidation. It was concluded that ubiquinone is able to protect mitochondria against the prooxidant effect of adriamycin. Inhibition of in vitro and in vivo liposomal, microsomal, and mitochondrial lipid peroxidation has also been shown in studies by Beyer [239] and Frei et al. [240]. Later on, it was suggested that ubihydroquinones inhibit lipid peroxidation only in cooperation with vitamin E [241]. However, simultaneous presence of ubihydroquinone and vitamin E apparently is not always necessary [242], although the synergistic interaction of these antioxidants may take place (see below). It has been shown that the enzymatic reduction of ubiquinones to ubihydroquinones is catalyzed by NADH-dependent plasma membrane reductase and NADPH-dependent cytosolic ubiquinone reductase [243,244]. 

Vitamin C is a powerful antioxidant and protects cells against oxidative stress. Therefore, it has been investigated in a variety... 

Ishii et al., 2000]. Since the expression of a wide array of protective antioxidant genes are positively regulated by the ARE sequence, Nrf2 may serve as a regulator of ARE-driven cellular defense systems against oxidative stress induced by dietary isoflavones [Mann et al., 2007 Siow et al., 2007]. 

Scapagnini G, Colombrita C, Amadio M, D Agata V, Arcelli E, Sapienza M, Quattrona A, Calabrese Y. 2006. Curcumin activates defensive genes and protects neurons against oxidative stress. Antioxid Redox Signal 8 395-403. 

In search of novel natural antioxidant compounds that might posses a good brain bioavailability, our laboratory has focused attention on the phenolic compound ferulic acid ethyl ester (FAEE) (Fig. 18.1). Ferulic acid is a ubiquitous plant constituent that occurs primarily in seeds and leaves both in its free form and covalently linked to lignin and other biopolymers. Due to its phenolic nucleus and an extended side chain conjugation, it readily forms a resonance stabilized phenoxy radical that accounts for its potent antioxidant potential [Kanski et al., 2002 Kikuzaki et al., 2002], Ferulic acid has been shown to be protective against oxidative stress in vitro it is absorbed and excreted by humans, and may be a promising candidate for therapeutic intervention in AD [Yan et al., 2001]. Although ferulic acid has been demonstrated to be effective in vitro, the low lipophilicity impairs its in vivo efficiency, bioavailability, and stability. 

Scapagnini G, Butterfield DA, Colombrita C, Sultana R, Pascale A, Calabrese V. 2004. Ethyl ferulate, a lipophilic polyphenol, induces HO-1 and protects rat neurons against oxidative stress. Antioxid Redox Signal 6 811-818. 

Wang J. Y., Wen L. L., Huang Y. N., Chen Y. T., and Ku M. C. (2006). Dual effects of antioxidants in neurodegeneration Direct neuroprotection against oxidative stress and indirect protection via suppression of glia-mediated inflammation. Curr. Pharmaceut. Design 12 3521-3533. 

The infusion of spices and herbs not only gives vermouth its unique flavor and aroma but also imparts medicinal properties. Some of the benefits ascribed to vermouth are given in Table 8.1. Feher and Lugasi (2004) compared the antioxidant characteristics of young vermouth with three red, three white, and one rose wine. Consumption of one unit (100 mL) of vermouth provided 220 mg polyphenolics, whereas wine in the same quantity was reported to have 35 mg. Polyphenolic compounds are reported to play a substantial role in protection against oxidative stress. 

The Organization of Antioxidant Defense Against Oxidative Stress... 

It is clear that under in vitro assay conditions, anthocyanins can function as antioxidants. However, in vivo, anthocyanin absorption appears to be low. In animal models, dietary anthocyanins at relatively high doses (1 to 2 mg/kg diet) are protective against oxidative stress induced in a number of models, including ischemia reperfusion, paraquat, CCL4, and t-BHP. In humans, anthocyanins appear to have some vasopro-tective effects, but whether these are the result of antioxidant mechanisms is not clear. It appears that in most of the studies reviewed, the dose of anthocyanins was well above that which might be normally consumed in the diet with natural foods, except for perhaps one study in which 1 cup of blueberries was consumed for 30 days and small increases in plasma antioxidant capacity were observed." ... 

Punica pfrana turn extracts show antioxidant and neuronal protective effects against oxidative stress-induced cytotoxicity in PC12 cells and inhibit neuronal cell death caused by Ap-induced oxidative stress and Ap-induced learning and memory deficit [213]. 

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