OXIDATIVE STRESS AND REACTIVE OXYGEN

Oxidative stress is defined as a misbalance in cell redox reactions result-ing in the increase of reactive oxygen species (ROS) and/or decreased anti-oxidant defence. Crucial part of oxidative stress, which avoids protective ef-fects 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, neurodege-nerative 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 in-volved in physiological homeostasis of various tissues. This lead to conclu-sion that LPO and oxidative stress and not only pathological but also physi-ological 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 con-sidered as »biological response modifiers « maintaining oxidative homeosta-sis. Accordingly, some antioxidants might eventually become important components of advanced individual and integrative biomedicine