Inhibition of NADPH oxidase-mediated superoxide radical formation in PMA-stimulated human neutrophils by 4-hydroxynonenal--binding to -SH and -NH2 groups.

4-Hydroxynonenal (HNE), a major lipid peroxidation product, effectively inhibits the superoxide radical formation by NADPH oxidase of phorbol myristate acetate (PMA)--stimulated human PMNL. The I50 value for the inhibition of NADPH oxidase-mediated superoxide radical formation by 4-hydroxynonenal was found to be 19 microM. The HNE inhibition involves the reaction with both -SH and -NH2 groups. Superoxide formation as final result of the NADPH oxidase cascade was almost completely restored by addition of dithiothreitol. In presence of hydroxylamine only a minor restoration of superoxide radical formation was found. A combination of dithiothreitol and hydroxylamine yielded the greatest recovery. Two other aldehydes with the same chain length as HNE but different binding to lysine, histidine and cysteine residues, trans-2,3-nonenal and nonanal, gave I50 values for the inhibition of NADPH oxidase-mediated superoxide formation rate of 110 microM or > 300 microM, respectively.