On the relevance of hydroxyl radical to purine DNA damage.

Hydroxyl radical (HO) is the most reactive toward DNA among the reactive oxygen species (ROS) generated in aerobic organisms by cellular metabolisms. HO is generated also by exogenous sources such as ionizing radiations. In this review we focus on the purine DNA damage by HO radicals. In particular, emphasis is given on mechanistic aspects for the various lesion formation and their interconnections. Although the majority of the purine DNA lesions like 8-oxo-purine (8-oxo-Pu) are generated by various ROS (including HO), the formation of 5',8-cyclopurine (cPu) lesions and relies exclusively on the HO attack. Methodologies generally utilized for the purine lesions quantification in biological samples are reported and critically discussed. Recent results on cPu and 8-oxo-Pu lesions quantification in various types of biological specimens associated with the cellular repair efficiency as well as with distinct pathologies are presented, providing some insights on their biological significance.