Fast repair of deoxynucleotide radical cations by phenylpropanoid glycosides (PPGs) and their analogs

The repair effects on deoxynucleotide radical cations of phenylpropanoid gl ycosides (PPGs) and their analogs, isolated from a Chinese folk medicinal h erb, were studied using the pulse radiolysis technique. The radical cations of deoxynucleotides were formed by the reaction of SO4.- with deoxynucleot ides. On pulse irradiation of a nitrogen saturated deoxynucleotide aqueous solution containing 20 mM K2S2O8, 200 mM t-BuOH and one of the PPGs or thei r analogs, the transient absorption spectra of the radical cations of nucle otide decayed with the formation of those of the radical cation of PPGs or their analogs within several tens of microseconds after electron pulse irra diation. The result indicates that deoxynucleotide radical cations can be r epaired by PPGs or their analogs. The rate constants of the repair reaction s were determined to be 0.48-1.1 x 10(9), 0.64-1.80 x 10(9) and 2.12-4.4 x 10(9) M-1 . s(-1) for dAMP, dGMP and dCMP radical cations respectively. It is obvious that the rate constants of the repair reaction depend on the num ber of phenolic hydroxyl groups contained in the PPGs and their analogs. A deeper understanding of this new repair mechanism will undoubtedly help res earchers design strategies to prevent and/or intervene more effective in fr ee radical related diseases. (C) 1999 Elsevier Science B.V. All rights rese rved.