The accumulation of dioxygen in Earth's atmosphere allowed for the evolution of aerobic organisms that use O2 as the terminal electron acceptor, thus providing a higher yield of energy compared with fermentation and anaerobic respiration. For example, in aerobic metabolism, the complete breakdown of one molecule of glucose yields a total of 38 molecules of ATP, whereas the anaerobic breakdown o...

Oxidative stress-the production and accumulation of reduced oxygen intermediates such as superoxide radicals, singlet oxygen, hydrogen peroxide, and hydroxyl radicals-can damage lipids, proteins, and DNA. Many disease processes of clinical interest and the aging process involve oxidative stress in their underlying etiology. The production of reactive oxygen species is also prevalent in the worl...

glucose-6-phosphate dehydrogenase (g6pd) deficient subjects are vulnerable to oxidative stress. quercetin, a flavonoids, has been employed as a potent oxygen-free radical scavenger in order to assess the protective effects of quercetin against h2o2-induced oxidative damage in g6pd-deficient and normal human erythrocytes. erythrocytes of g6pd-deficient (n = 10) and normal (n = 10) subjects were ...

RATIONALE Although oxygen therapy is of clear benefit in patients with severe chronic obstructive pulmonary disease (COPD), recent studies have shown that short-term supplementary oxygen may increase oxidative stress and inflammation within the airways. OBJECTIVE We investigated whether systemic inflammation and oxidative stress at rest and during exercise in patients with COPD are influenced...

the first reaction between food components and biological tissues occurs in the oral cavity. saliva modulates the ecosystem in the oral cavity and plays a critical role in oral homeostasis. in addition, saliva is a first line of defense against free radical-mediated stress. salivary antioxidant defense mechanisms seem to be very important. in this study we discuss in detail free radicals (fr) a...

In Rhodobacter sphaeroides, carotenoids are essential constituents of the photosynthetic apparatus and are assumed to prevent the formation of singlet oxygen by quenching of triplet bacteriochlorophyll a (BChl a) in vivo. It was shown that small amounts of singlet oxygen are generated in vivo by incubation of R. sphaeroides under high light conditions. However, growth and survival rates were no...