Oxidative stress
As oxidative stress is called a metabolic condition in which a physiological extent amount exceeding reactive oxygen species (ROS - reactive oxygen species ) is formed or exists. These reactive oxygen species arise in the context of metabolic processes of the mitochondrial electron transport chain and cytochrome P450 oxidases. It is the superoxide Anionenradikal O2, hydrogen peroxide (H2O2) and the hydroxyl radical OH.
Normal cells in the body maintain its ability to neutralize reducing or oxidizing substances, upright, by stockpile oxidizing or reducing substances. An imbalance between these pools, which overwhelms the normal repair and detoxification function of a cell and, consequently, leads to damage of all cellular and extracellular macromolecules, is referred to as oxidative stress.
Effects
The consequences of oxidative stress include lipid peroxidation - the ultimately leads that cells must expend more energy to stabilize their membrane potential -, protein oxidation and DNA damage. These three operations are partly responsible for the aging process and life expectancy.
Protection systems
Cells and tissues, various protective mechanisms against oxidative stress are available:
Free radicals
Due to the respiratory chain free radicals are formed, which ( is causally close spatial relationship ) is preferable to a damage of mitochondrial DNA lead.
The net reaction in the respiratory chain of the cells is the exergonic reaction of oxygen with hydrogen ions to form water. Reactions are always held spontaneously when the atoms involved achieved by reordering a noble gas configuration. Such a configuration needs two oxygen and hydrogen eight valence electrons. Oxygen (O) atoms have six and hydrogen atoms (H ) one valence electron. Go both a connection to the water (H2O ) to each one, as the noble gas configuration is achieved for all three atoms. The known during this process, also known as " oxyhydrogen reaction," released energy is net of the amount of energy available to the body from the respiratory chain out for other processes. The majority of the resulting water is eliminated later, the urinary tract.
Despite extensive protective mechanisms of this process is faulty in about two percent of the cases, namely, when connecting only one hydrogen atom with an oxygen atom. Because the oxygen atom with seven electrons in the outer shell of the noble gas configuration is then already close, it seeks a " free radical " then to connect with the nearest atom.
Role in the development of diseases
Despite numerous correlations of oxidative stress with various disease states still could not allow a safe connection to be proved. In particular, any discrimination based on the treatment of oxidative stress and evidence- based therapy exists. More recently, the effect of reactive oxygen species in the development of oxidative stress, in particular in relation to neurodegenerative diseases such as stroke, Parkinson's disease, Alzheimer's disease, Huntington's disease or amyotrophic lateral sclerosis ( ALS) is examined. In this context, many studies have shown especially in Parkinson's disease, which is characterized by the destruction of dopaminergic nigrostriatal neurons in the basal ganglia, occurring at a prevalence of oxygen free radicals from iron participation and thereby generated oxidative stress by depleting conversion physiologically in the substantia nigra proteins ( zBα -synuclein ) back. Even in diabetic neuropathy signs increased oxidative stress are detectable. Discussed is also a genesis of oxidative stress after irradiation or by hypoxia or hyperoxia and the resultant favoring neurodegenerative diseases. Also, certain cardiovascular diseases such as Atherosclerosis or Coronary Artery Disease may be conditioned by oxidative stress, since the oxidation of LDL is considered in the endothelium as a precursor to plaque formation. Currently, it is generally assumed that disease-causing or - promoting factors for a preponderance of oxidative stress -generating compounds against detoxification mechanisms (see below) are responsible.
Therapy
In a variety of studies in humans, no benefit of antioxidant dietary supplements containing could be detected. On the contrary, many meta-analyzes indicate that the harmfulness of an unfounded, wide supply of antioxidants and vitamins, including increased mortality. One reason seems to be that reactive oxygen species represent not only dangerous waste products of a cell but essential signal and perform messenger functions. Antioxidants can but by definition between two qualities of the ROS is no different and interfere with both potentially harmful and protective ROS. Sufficient tests whether the antioxidants found in fresh foods such as fruits and vegetables have a therapeutic effect, are present not yet.