Abstract
Insulin resistance and hepatotoxicity induced in high fructose fed rats may involve fructose derived
endogenous toxins formed by inflammation. Thus fructose was seventy-fold more toxic if hepatocytes
were exposed to non-toxic levels of hydrogen peroxide (H2O2) released by inflammatory cells. This was
prevented by iron (Fe) chelators, hydroxyl radical scavengers, and increased by Fe, copper (Cu) or catalase
inhibition. Fructose or glyceraldehyde/dihydroxyacetone metabolites were oxidized by Fenton radicals to
glyoxal. Glyoxal (15μM) cytotoxicity was increased about 200-fold by H2O2. Glycolaldehyde was enzymically
formed from glyceraldehyde, the fructokinase/aldolase B product of fructose. Glycolaldehyde cytotoxicity
was increased 20-fold by H2O2. The oxidative stress cytotoxicity induced was attributed to the Fenton
oxidation of glycolaldehyde forming glycolaldehyde radicals and glyoxal, since cytotoxicity was prevented
by aminoguanidine (glyoxal trap) or Fenton inhibitors. Glyoxal was also the Fenton product responsible
for glycolaldehyde protein carbonylation as carbonylation was prevented by aminoguanidine or Fenton
inhibitors.