Thymine glycol (5,6-dihydroxy-5,6-dihydrothymine) is one of the principal DNA lesions that can be induced by

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

and ionizing radiation.

Aging, stroke

The rate at which oxidative reactions generate thymine glycol and thymidine glycol in the

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

of humans is estimated to be about 300 per cell per day. Oxidized DNA bases that are excised by

DNA repair DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is cons ...

processes are excreted in urine. On a body weight basis, mice excrete 18 times more thymine glycol plus thymidine glycol than humans, and monkeys four times more than humans. It was proposed that rate of occurrence of oxidative DNA damages correlates with

metabolic rate Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

, and that a higher rate of oxidative damage might cause a higher rate of cellular aging.

Base excision repair Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting base lesions from t ...

is a major DNA repair pathway for removal of oxidative DNA damages. The rate of repair of thymine glycol damage in human

fibroblast A fibroblast is a type of cell (biology), biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and ...

s was found to decrease with age. Brain samples from humans who died of

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

were found to be deficient in base excision repair of thymine glycol as well as other types of oxidative damages. It was suggested that impaired base excision repair is a risk factor for ischemic brain injury.

References

{{Reflist Pyrimidinediones Vicinal diols