Effects of iron-unsaturated human lactoferrin on hydrogen peroxide-induced oxidative damage in intestinal epithelial cells

Human milk (HM) contains various bioactive antioxidants. Lactoferrin (Lf) has been assumed to be one of the major antioxidants in HM. We examined the antioxidative properties of iron-unsaturated human Lf (apo-hLf, the major form of Lf in HM) in two intestinal epithelial cell lines: (1) An intestinal epithelial cell line (IEC-6) were preincubated for 24 h with either 50 mu g/mL of apo-hLf, iron-saturated human Lf (holo-hLf), iron-unsaturated bovine transferrin (apo-bTf), or 800 ng/mL of the iron-chelating compound deferoxamine (DFX), followed by hydrogen peroxide (H2O2) challenge to induce oxidative stress. Survival rates were significantly higher in the cells preincubated with apo-hLf and DFX than those preincubated with holo-hLf. (2) Caco-2 cells were preincubated with or without apo-hLf for 24 h, followed by an H2O2 challenge. Intracellular oxidative stress was assessed by a fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA). Fluorescent intensity of cell images and cell homogenates was significantly lower in the cells preincubated with apo-hLF than those preincubated without apo-hLF. Our study indicates that apo-hLf alleviates H2O2-induced oxidative damage in intestinal cells due to the iron-chelating capacity. Therefore, Lf in HM may act as an antioxidant in the gastrointestinal tract (GIT).