COMPARATIVE SUGAR DEGRADATION BY (OH)(CENTER-DOT) PRODUCED BY THE IRON-DRIVEN FENTON REACTION AND GAMMA-RADIOLYSIS

We compared the attack of deoxyribose and mannitol by (OH)(.) produced by gamma radiolysis or the iron-driven Fenton reaction. Deoxyribose ( DR) oxidation by gamma radiolysis gave rise to thiobarbituric reactive substances (TBARS) with a yield of 17 mol (OH)(.) per mole of TBARS. (OH)(.) scavengers (benzoate, formate, and pentoxifylline) protected D R from oxidation. Mannitol was similarly oxidized by (OH)(.) produced by gamma radiolysis, with a yield of 14 mol (OH)(.) per mole of TBARS produced. A mixture containing both DR and mannitol gave rise to TBARS production with a yield of 9 mol (OH)(.) per mole of TBARS superior t o that of each product separately, suggesting the formation of seconda ry radicals responsible for the degradation of DR or mannitol. When (O H)(.) was produced by the iron-driven Fenton reaction, DR gave rise to TBARS whereas mannitol did not. Furthermore, mannitol protected DR ag ainst degradation, apparently in the same way as desferrioxamine and d iethylenetriaminepentaacetic acid, suggesting that it acts as an iron chelator. It can thus be assumed that, according to the site of (OH)(. ) production, sugar molecules are degraded as a function of their rate constant with (OH)(.) or their iron chelating capacity. (C) 1994 Acad emic Press, Inc.