Dietary Supplementation with Ipriflavone Decreases Liver Iron Loading in Wild Type Mice

Hepcidin, a peptide hormone produced in the liver, decreases intestinal iron absorption and macrophage iron release by causing internalization and degradation of the iron exporter ferroportin. Because its levels are inappropriately low in patients with iron overload syndromes, Hepcidin is a potential drug target. We previously conducted a chemical screen in human hepatocytes (HepG2 cells) to identify small molecules that upregulate Hepcidin transcript levels. One of the small molecules that we identified was ipriflavone, a synthetic isoflavone, which has been used to treat osteoporosis in postmenopausal women. To evaluate ipriflavone’s effect on iron homeostasis in a mammalian model, we placed groups of 5-week old C57BL/6 male mice on a soy-free, iron-sufficient diet, AIN-93G containing 220 mg/kg iron and 0, 250, 500 or 750 mg ipriflavone per kg of food (n=4 or 5 per group) for 50 days, then sacrificed the animals for analysis of changes in gene expression by quantitative realtime RT-PCR, liver and spleen iron content, blood indices, and intestinal ferroportin expression. While producing less than a two-fold increase in liver hepcidin transcript levels, ipriflavone supplementation was associated with a significant decrease in liver iron content (mean±SE): 39.22±2.06 µg iron/g tissue, p=0.0033, and 44.10±2.58 µg iron/g tissue, p=0.0124, at 500 and 750 mg ipriflavone per kg of food, respectively, vs 57.77±3.39 µg iron/g tissue in mice that did not receive ipriflavone. Ferroportin expression detected in intestinal epithelial cells by immunohistochemistry was notably decreased in mice receiving ipriflavone: 66.6% and 80% of the animals receiving 500 and 750 mg/kg groups, respectively, exhibited decreased ferroportin staining versus 40% of the group not receiving ipriflavone. There was no significant difference in hemoglobin, hematocrit, or spleen iron among the groups. In conclusion, we have shown that orally administered ipriflavone is effective in decreasing liver iron content and intestinal ferroportin expression in vivo. Future experiments will evaluate ipriflavone’s effects on iron homeostasis and hematopoiesis in genetic models of iron overload disorders.