ABSTRACT
Each biological compartment contains a particular number of electrons stored in various cellular substances, characterizing thus the overall redox state of cells (Jomova and Valko 2011). Under normal physiological conditions, similarly to
11.1 Introduction .................................................................................................. 325 11.2 Sources of Free Radicals .............................................................................. 326
11.2.1 Reactive Oxygen Species .................................................................. 326 11.2.2 Reactive Nitrogen Species ................................................................ 327
11.3 Antioxidant Enzymes ................................................................................... 328 11.3.1 Superoxide Dismutase ...................................................................... 328 11.3.2 Catalase ............................................................................................. 329 11.3.3 Glutathione Peroxidases ................................................................... 330
11.4 Nonenzymatic Antioxidants ......................................................................... 330 11.4.1 Ascorbic Acid ................................................................................... 330 11.4.2 Vitamin E .......................................................................................... 332 11.4.3 Glutathione ....................................................................................... 333 11.4.4 Lipoic Acid ....................................................................................... 335 11.4.5 Carotenoids ....................................................................................... 335 11.4.6 Flavonoids ......................................................................................... 337
11.5 Conclusions ................................................................................................... 338 Acknowledgments .................................................................................................. 339 References .............................................................................................................. 339
regulation of intracellular pH, the redox state of a biological system is tightly controlled and is kept within a narrow range. Fluctuations in cellular redox state levels are typical for various cellular processes, such as the cell cycle control system. A more reducing cellular environment of the cell maintains proliferation, and a slight shift toward an oxidizing environment initiates cell differentiation (Matsuzawa and Ichijo 2005). A highly oxidizing environment in the cell is typical for apoptosis and necrosis.
