FREE-RADICAL MEDIATED INTERACTION OF ASCORBIC-ACID AND ASCORBATE CU(II) WITH VIRAL AND PLASMID DNAS/

Previous studies indicate that ascorbic acid, when combined with coppe r or iron cleaves several viral DNAs. In this study, we generated the ascorbate radical anion electrochemically in a simple chemical environ ment without the participation of a metal ion. This solution possesses viral DNA scission activity. The absence of catalytic metal ions [Fe (III) and Cu(II)] in the incubation medium was evidenced by metal chel ating agents such as desferrioxamine and EDTA. The radical quenching a t high EDTA concentration was attributed to ionic strength of EDTA rat her than metal chelation. The effects of antioxidants, radical scavang ers, catalase, superoxide dismutase and some proteins on DNA cleavage have been tested. Cleavage may not arise directly from ascorbate free radical but the reaction of the radical form of ascorbate with oxygen may produce the actual reactive species. Aerobic oxidation of ascorbat e itself strictly requires transition metal catalysts, however electro chemically produced ascorbyl radical avoided the kinetic barrier that prevented direct oxidation of ascorbic acid with oxygen and eliminated the need for the transition metal ion catalysts.