Fast repair of dAMP hydroxyl radical adduct by verbascoside via electron transfer.

DNA damaged by oxygen radicals has been implicated as a causative event in a number of degenerative diseases, including cancer and aging. So it is very important to look for ways in which either oxygen radicals are scavenged prior to DNA damage or damaged DNA is repaired to supplement the cells' inadequate repair capacity. The repair activity and its mechanism of verbascoside, isolated from Pedicularis species, towards dAMP-OH . was studied with pulse radiolytic technique. On pulse irradiation of nitrous oxide saturated 2 mmol/L dAMP aqueous solution containing verbascoside, the transient absorption spectrum of the hydroxyl adduct of dAMP decayed with the formation of that of the phenoxyl radical of verbascoside well under 100 microseconds after electron pulse irradiation. The result indicated that dAMP hydroxyl adducts can be repaired by verbascoside. The rate constants of the repair reaction was deduced to be 5.9 x 10(8) dm(3) * mol(-1) * s(-1). A deeper understanding of this new repair mechanism will undoubtedly help researchers explore new prevent and/or intervening medicine.