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Radicals can undergo a disproportionation reaction through a radical elimination mechanism (See Fig. 1). Here a radical abstracts a hydrogen atom from another same radical to form two non-radical species: an alkane and an alkene. Radicals can also undergo an elimination reaction to generate a new radical as the leaving group.
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
English: The Passport For Open Science - A practical guide for PhD students is a guide designed to accompany you in any field of study, at every step of your research, from developing your scientific approach to the dissemination of your research results. It provides a set of tools and best practices that can be directly implemented and is ...
A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉ CH 2) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions.
The mitochondrial theory of ageing has two varieties: free radical and non-free radical. The first is one of the variants of the free radical theory of ageing. It was formulated by J. Miquel and colleagues in 1980 [1] and was developed in the works of Linnane and coworkers (1989). [2] The second was proposed by A. N. Lobachev in 1978. [3]
Lipid peroxidation is a self-propagating chain reaction and will proceed until the lipid substrate is consumed and the last two remaining radicals combine, or a reaction which terminates it occurs. [3] Termination can occur when two lipid hydroperoxyl radicals (LOO•) react to form peroxide and oxygen (O 2).
Antioxidants that are reducing agents can also act as pro-oxidants. For example, vitamin C has antioxidant activity when it reduces oxidizing substances such as hydrogen peroxide; [103] however, it will also reduce metal ions such as iron and copper [104] that generate free radicals through the Fenton reaction.
Development of the Free Radical Theory of Aging [ edit ] In 1954, between his internship and residency in internal medicine , Harman became a research associate at the Donner Laboratory of Medical Physics at UC Berkeley , [ 2 ] where he was able to pursue the puzzle of the cause of aging .