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Oxidation of Phenols to Benzoquinones

Oxidation of Phenols to Benzoquinones: Biological Importance

Nature also takes advantage of the property of quinones to reversibly take up electrons during biochemical redox processes. Ubiquinones or coenzyme Q, a group of bioquinones widely distributed in nature, are involved in electron transfer in the respiratory chain in mitochondria. As plastoquinones they are responsible for electron transfer during photosynthesis.

Coenzyme Q

n = 6 to 12


e.g. n = 9

Vitamin E (or α-tocopherol), a phenol widely distributed in plants, apparently takes on various functions in the animal body. Especially important seems to be the function to act as a radical acceptor for peroxy radicals to protect membranes and other oxidation-sensitive molecules. Damage by radicals is also partially responsible for the aging process. Presumably, antioxidants (polyphenols) contained in red wine and the consumption of large amounts of vitamin C are shown to prolong lives.

Vitamin E, α-tocopherol
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