Photoprotection of DNA (in vitro) by acyclothymidine dinucleosides.

Excessive exposure to sunlight is primarily implicated in ultraviolet (UV) induced skin cancers worldwide. Direct absorption of UV radiation by DNA leads to the formation of cyclobutane pyrimidine dimers (CPDs) resulting in DNA damage. The molecular mechanisms involved in the mutagenicity of CPDs are well established. Photoprotection of the skin from the detrimental effects of UV is essential in preventing skin damage. A variety of formulations, which essentially contain UV filters have been used as photoprotective agents of the skin. These comprise aromatic and inorganic molecules, whose mechanism of action involves either absorption, reflection, or scattering of UV radiation. However, the downstream photoproducts of some of these molecules have undesirable characteristics which compromise their utility. A biomimetic approach involving structural analogs of nucleic acids can help overcome these limitations. Herein, we show the photoprotective action of acyclothymidine dinucleosides on both plasmid and cellular DNA.