Electrochemical Reduction of Uridine in Dimethyl Sulfoxide: Effect of the Ribose Group

Adam-The easier electrochemical reduction of uridme (I-/LLLtibofirranosylumcil) in dimethyl sulfoxide as compared to uracil (2, 4dihydroxypyrimidine) by ca. 0.1 V is exphcable on the basii of the electronwithdrawing effect of the ribose group. This effect and possible steric hindrance by the ribose group markedly affect the reaction sequence following the initial one-electron reduction to generate a radical anion, which abstracts a proton from the parent uridine (father-son reaction) to form the neutral uridine free radical and the uridme anion. With increasing &dine concentration, Further eduction and protonstion reactions are favored, resulting in an increase in the effective faradaic n from CLI. 0.5 to 0.8. The availability of only one proton-donating site on uridine, ie, that on N(3). allows explication of the behavior of other hydroxypyrimidiues such as uracil.