Tissue iron distribution and urinary mineral excretion vary depending on the form of iron (FeSO4 or NaFeEDTA) and the route of administration (oral or subcutaneous) in rats given high doses of iron

Preclinical pharmacokinetics, biodistribution, excretion, and plasma protein binding study of 58Fe-labeled hemin by ICP-MS

BACKGROUND

Hemin, a stable form of heme iron, is a potential iron supplement for the treatment of iron deficiency. To date, the pharmacokinetics and in vivo ADME properties of hemin are to be elucidated.

METHODS

In this study, a rapid, sensitive, and validated inductively coupled plasma mass spectrometry (ICP-MS) method was used in combination with ⁵⁸Fe stable isotope labeling to systemically investigate the plasma pharmacokinetics, biodistribution, excretion, and plasma binding profiles of hemin in animals.

RESULTS

Results showed that the ICP-MS method is accurate and sensitive enough to quantitatively determine the in vivo disposition process of ⁵⁸Fe derived from ⁵⁸Fe-labeled hemin. Following intra-gastric administration, ⁵⁸Fe was rapidly absorbed in gastrointestinal tract, with C_max of 41.1 ± 23.1 ng/mL, T_max of 1.38 ± 0.48 h, and bioavailability of 1.12 ± 0.45 % in beagle dogs. Moreover, ⁵⁸Fe was distributed to various organs including stomach, small intestine, spleen, and liver, within a few hours after intra-gastric administration in rats. Excretion of ⁵⁸Fe in rats was predominantly via feces (76.3 ± 15.1 % of dosage), whereas minimally via urine (0.14 ± 0.08 % of dosage). Protein binding study revealed majority of ⁵⁸Fe in plasma was bound to proteins, with average binding rates of 81.0 % and 92.7 % in human and rat plasma, respectively.

CONCLUSION

In conclusion, the present study validated the work-flow of preclinical pharmacokinetic studies of iron-containing drug candidates with using ICP-MS and stable (trace) isotope labeling strategy. It also provided useful information to support the further development of hemin as a drug/nutrition supplement candidate.

Effects of various Fe compounds on the bioavailability of Pb contained in orally ingested soils in mice: Mechanistic insights and health implications

Reducing lead (Pb) exposure via oral ingestion of contaminated soils is highly relevant for child health. Elevating dietary micronutrient iron (Fe) intake can reduce Pb oral bioavailability while being beneficial for child nutritional health. However, the practical performance of various Fe compounds was not assessed. Here, based on mouse bioassays, ten Fe compounds applied to diets (100-800 mg Fe kg^-1) reduced Pb oral relative bioavailability (RBA) in two soils variedly depending on Fe forms. EDTA-FeNa was most efficient, which reduced Pb-RBA in a soil from 79.5 ± 14.7 % to 23.1 ± 2.72 % (71 % lower) at 100 mg Fe kg^-1 in diet, more effective than other 9 compounds at equivalent or higher doses (3.6-68 % lower). When EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous bisglycinate were supplemented, Fe-Pb co-precipitation was not observed in the intestinal tract. EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous sulfate suppressed duodenal divalent metal transporter 1 (DMT1)mRNA relative expression similarly (27-68 % lower). In comparison, among ten compounds, EDTA-FeNa elevated Fe concentrations in mouse liver, kidney, and blood (1.50-2.69-fold higher) most efficiently, suggesting the most efficient Fe absorption that competed with Pb. In addition, EDTA was unique from other organic ligands, ingestion of which caused 12.0-fold higher Pb urinary excretion, decreasing Pb concentrations in mouse liver, kidney, and blood by 68-88 %. The two processes (Fe-Pb absorption competition and Pb urinary excretion with EDTA) interacted synergistically, leading to the lowest Pb absorption with EDTA-FeNa. The results provide evidence of a better inhibition of Pb absorption by EDTA-FeNa, highlighting that EDTA-FeNa may be the most appropriate supplement for intervention on human Pb exposure. Future researches are needed to assess the effectiveness of EDTA-FeNa for intervention on human Pb exposure.

Design, synthesis and biological evaluation of novel dual-targeting fluorescent probes for detection of Fe3+ in the lysosomes of hepatocytes mediated by galactose-morpholine moieties

In this work, novel dual-targeting probes composed of galactose and morpholine were designed and synthesized for monitoring Fe³⁺ levels in the lysosome of hepatocyte. MP-Gal-1, MP-Gal-2 and MP-Gal-3 showed good selectivity and sensitivities toward Fe³⁺ with the detection limits of 9.40 × 10^-8 M, 7.68 × 10^-8 M and 7.10 × 10^-8 M, respectively. 1:2 stoichiometry is the most likely recognition mode between probe and Fe³⁺. Low toxic MP-Gal-1, MP-Gal-2 and MP-Gal-3 exhibited favorable hepatic targeting effect in both cell and tissue levels, which was because the galactose group of probe could be recognized by ASGPR overexpressed on the hepatocytes. The hepatocyte-targeting capacity followed MP-Gal-1 < MP-Gal-2 < MP-Gal-3 trend, which was attributed to the galactose cluster effect. MP-Gal-1, MP-Gal-2 and MP-Gal-3 also displayed good lysosomes-targeting capacities, because the basic morpholine moiety of probes could be easily attracted by the acidic lysosome. Therefore, MP-Gal-1, MP-Gal-2 and MP-Gal-3 have good dual targeting capacities (liver and lysosome) and could be used to detect lysosomal Fe³⁺ in the liver, which is great significant for precise diagnosis and treatment of liver lysosomal iron-related diseases.

Effect of wheat flour fortified with sodium iron EDTA on urinary zinc excretion in school-aged children

BACKGROUND

Foods fortified with sodium iron ethylenediaminetetraacetate (NaFeEDTA) have been shown to improve iron status in children, but little is known about the effect of this salt on urinary zinc excretion, particularly in children. This is particularly relevant, since zinc deficiency is known to limit growth and development in young children.

OBJECTIVE

To determine the effect of NaFeEDTA-fortified wheat flour on urinary zinc excretion.

METHODS

This study was a part of a randomized, controlled trial that was carried out among 6- to 13-year-old iron-depleted schoolchildren (n = 179) who had received either a NaFeEDTA-fortified wheat meal (iron group) or an identical control meal without added iron (control group) for a period of 7 months. Urinary zinc concentration was assessed at the end of the intervention period by spot urine samples.

RESULTS

Iron status in the iron group was significantly improved according to measurements of hemoglobin and serum ferritin (p < .001). However, there was no significant difference in urinary zinc excretion between the iron group (median, 38.4 microg/dL; 25th-75th percentiles, 18.2-67.1 microg/dL) and the control group (median, 33.1 microg/dL; 25th-75th percentiles, 12.4-54.2 microg/dL).

CONCLUSIONS

Iron fortification of foods with NaFeEDTA does not affect urinary zinc excretion in children.

Hepatitis C virus core protein compromises iron-induced activation of antioxidants in mice and HepG2 cells

One of the characteristics of hepatitis C virus (HCV) infection is the unusual augmentation of oxidative stress, which is exacerbated by iron accumulation in the liver, as observed frequently in hepatitis C patients. Using a transgenic mouse model, the core protein of HCV was shown previously to induce the overproduction of reactive oxygen species (ROS) in the liver. In the present study, the impact of iron overloading on the oxidant/antioxidant system was examined using this mouse model and cultured cells. Iron overloading caused the induction of ROS as well as antioxidants. However, the augmentation of some antioxidants, including heme oxygenase-1 and NADH dehydrogenase, quinone 1, was compromised by the presence of the core protein. The attenuation of iron-induced augmentation of heme oxygenase-1 was also confirmed in HepG2 cells expressing the core protein. This attenuation was not dependent on the Nrf2 transcription factor. Thus, HCV infection not only induces oxidative stress but also hampers the iron-induced antioxidant activation in the liver, thereby exacerbating oxidative stress that would facilitate hepatocarcinogenesis.

Comparing soluble ferric pyrophosphate to common iron salts and chelates as sources of bioavailable iron in a Caco-2 cell culture model

Iron bioavailability from supplements and fortificants varies depending upon the form of the iron and the presence or absence of iron absorption enhancers and inhibitors. Our objectives were to compare the effects of pH and selected enhancers and inhibitors and food matrices on the bioavailability of iron in soluble ferric pyrophosphate (SFP) to other iron fortificants using a Caco-2 cell culture model with or without the combination of in vitro digestion. Ferritin formation was the highest in cells treated with SFP compared to those treated with other iron compounds or chelates. Exposure to pH 2 followed by adjustment to pH 7 markedly decreased FeSO(4) bioavailability but had a smaller effect on bioavailabilities from SFP and sodium iron(III) ethylenediaminetetraacetate (NaFeEDTA), suggesting that chelating agents minimize the effects of pH on iron bioavailability. Adding ascorbic acid (AA) and cysteine to SFP in a 20:1 molar ratio increased ferritin formation by 3- and 2-fold, respectively, whereas adding citrate had no significant effect on the bioavailability of SFP. Adding phytic acid (10:1) and tannic acid (1:1) to iron decreased iron bioavailability from SFP by 91 and 99%, respectively. The addition of zinc had a marked inhibitory effect on iron bioavailability. Calcium and magnesium also inhibited iron bioavailability but to a lesser extent. Incorporating SFP in rice greatly reduced iron bioavailability from SFP, but this effect can be partially reversed with the addition of AA. SFP and FeSO(4) were taken up similarly when added to nonfat dry milk. Our results suggest that dietary factors known to enhance and inhibit iron bioavailability from various iron sources affect iron bioavailability from SFP in similar directions. However, the magnitude of the effects of iron absorption inhibitors on SFP iron appears to be smaller than on iron salts, such as FeSO(4) and FeCl(3). This supports the hypothesis that SFP is a promising iron source for food fortification and dietary supplements.

Oral supplementation with NaFeEDTA reduces blood lead in postmenopausal but not premenopausal Korean women with anemia

OBJECTIVE

The objective was to evaluate the effect of iron supplementation for 6 mo on blood lead (PbB) concentration in populations of premenopausal (PRE-M) and postmenopausal (POST-M) Korean women.

METHODS

We conducted a community intervention trial in Asan, Republic of Korea. Of the 137 enrolled women with hemoglobin (Hb) levels lower than 12 g/dL, 37 were PRE-M and 100 were POST-M. Each woman received the equivalent of 9 mg of supplemental iron per day in the form of sodium-iron ethylene-diaminetetra-acetic acid (NaFeEDTA) syrup for a period of 6 mo.

RESULTS

The initial PbB concentrations were 2.56 +/- 0.99 microg/dL (mean +/- SD) for the PRE-M women and 3.27 +/- 1.24 microg/dL for the POST-M women. The differences were statistically significant (P < 0.01). After 6 mo of NaFeEDTA supplementation, the PbB concentration decreased in the POST-M group but no change was observed in the PRE-M group. When age and baseline Hb levels were adjusted for, PbB concentrations decreased by 0.10 and 0.31 microg/dL in the PRE-M and POST-M groups, respectively, and the results were significant using a multivariate model (P = 0.016). Iron status determined by zinc protoporphyrin, transferrin saturation, and Hb improved significantly in both groups, but serum ferritin decreased significantly in the POST-M women (P < 0.001), with no change in the PRE-M group.

CONCLUSION

After 6 mo of supplementation with the equivalent of 9 mg of iron/d in the form of NaFeEDTA, the PbB concentrations in Korean women with anemia appeared to depend on their menopausal status.