Suppressive Effects of Lactoferrin on Bleomycin-dependent DNA Damage by the Iron Ion and Ascorbate

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The effects of the iron ion and reductones on bleomycin (BLM)-induced DNA degradation were observed by measuring the amount of malondialdehyde (MDA) formed. The formation of MDA was detected after adding Fe²⁺ or Fe³⁺ + Asc combined to a solution consisting of DNA and BLM, but not after adding Fe³⁺ alone, catecholamines or phenolic compounds. Marked suppressive effects of lactoferrin (Lf) and ovotransferrin on MDA formation were observed in the solution with Fe²⁺ or Asc. However, serum albumin, β-lactoglobulin, α-lactalbumin, and ovoalbumin had no effect on suppressing MDA formation. The suppression by bovine Lf (bLf) of MDA formation decreased with increasing iron saturation at 1.0mM Fe²⁺, but at 100% iron saturation, 51.2% of apo-bLf remained suppression. In the solution with 0.25mM Asc, 100% iron saturated bLf markedly enhanced MDA formation.