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The secret destruction of hydroxide free radicals in living organisms: Why are they so dangerous?
Hydrogen radicals (•HO) are neutral forms of hydroxide anion (HO–), a compound known in chemical reactions for their high reactivity and short survival times.Although their lifetime is quite short, they occupy an important position in free radical chemistry.The form of hydroxide radicals mainly comes from the decomposition of peroxides and the reaction of excited atomic oxygen with water in atmospheric chemistry.
"Hydrooxygen radicals are often regarded as "cleaners" in the troposphere because they can react with a variety of pollutants and are often the first step to removing them."
In radiation chemistry, the formation of hydroxide radicals is crucial for the formation of hydroxide and oxygen, which further triggers the process of causing corrosion and stress corrosion cracks in cooling systems facing the radiation environment.In addition, hydrogen-oxygen radicals are also produced in the degradation of hydrogen peroxide caused by ultraviolet light, which was proposed as early as 1879 and may also be involved in the Fenton reaction.In organic synthesis, the most common method of producing hydrogen and oxygen radicals is the photodecomposition of the compound pyridinesulfonium.
Biological importance
In organisms, the presence of hydroxide radicals is sometimes a by-product of the immune process.When specific pathogens, such as certain bacteria, macrophages and microglia produce hydroxide radicals.This destructive behavior of free radicals is associated with a variety of neuronal autoimmune diseases, such as HIV-related dementia, which can arise when immune cells are overactivated and become toxic to neighboring healthy cells.
"Hydrooxygen radicals can damage almost all types of giant molecules, including carbohydrates, nucleic acids (causing mutations), lipids (lipid peroxidation), and amino acids."
In short, the half-life of the hydroxide radical is very short, about 10−9 seconds, and its reactivity is very high, making it a very dangerous compound in organisms.Unlike superoxides, hydroxide radicals cannot be eliminated through enzymatic reactions.To protect the cellular structure, antioxidants inside the cell, such as melatonin and glutathione, as well as dietary antioxidants such as mannitol and vitamin E, are one of the mechanisms to combat this danger.
Importance in Earth's atmosphere
Hydrogen free radicals are one of the main chemical substances in the earth's atmosphere. They are responsible for controlling the aerobic capacity and have a significant impact on the concentration and distribution of greenhouse gases and pollutants.As the most common oxidant in the troposphere, understanding • HO variation is essential for evaluating the impact of humans on the atmosphere and climate.
"•HO has a lifespan of less than one second in the Earth's atmosphere, so its concentration is very low, and direct detection requires precise technology."
Through the analysis of chloromethane (CH3CCl3) in the air, we can indirectly measure the global concentration of hydrogen and oxygen radicals.The study shows that •HO estimated from these measurements is relatively small in annual variation, which means that global hydroxide radicals have good buffering capabilities for perturbations.
The Importance of Astronomy
First detection of hydrogen and oxygen radicals
In 1963, scientists successfully detected the presence of hydroxide radicals in the radio absorption spectrum of Casiobia A for the first time.This discovery laid an important foundation for the study of interstellar chemistry.
Applied to water pollution control
Hydrooxygen radicals also play a key role in the oxidative destruction of organic pollutants, a process that further emphasizes its potential in environmentally friendly applications.
These examples clearly show the bilaterality of hydroxide radicals in organisms and environments: they are both powerful chemical weapons and may also be tools to protect us.Does such contradictory characteristics make you begin to reflect on the potential impact of these micromolecules in our daily lives?
