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Oxidative Stress and Antioxidants: Biological Response Modifiers of Oxidative Homeostasis in Cancer

Oxidative stress is defined as a misbalance in cell redox reactions resulting in the increase of reactive oxygen species (ROS) and/or decreased antioxidant defence. Crucial part of oxidative stress, which avoids protective effects of antioxidants, is lipid peroxidation (LPO). Since LPO comprises several chain reactions allowing the spread of ROS-caused damage to the macromolecules (proteins, nucleic acids and lipids) it is important in pathogenesis of various diseases such as cardiovascular diseases, neurodegenerative diseases, diabetes mellitus and cancer. On the other hand, research on physiology and pathology of lipid peroxidation revealed that not only ROS but also the LPO products such as 4-hydroxynonenal (HNE) are involved in physiological homeostasis of various tissues. This lead to conclusion that LPO and oxidative stress and not only pathological but also physiological processes. Accordingly, HNE was revealed as biomarker, growth regulating factor and signalling molecule. In this light, both natural as well as synthetic antioxidants could be considered as »biological response modifiers« maintaining oxidative homeostasis. Accordingly, some antioxidants might eventually become important components of advanced individual and integrative biomedicine. OXIDATIVE STRESS AND REACTIVE OXYGEN