Improved quantification for non-transferrin-bound iron measurement using high-performance liquid chromatography by reducing iron contamination

Abstract

Abstract. Non-transferrin-bound iron (NTBI) refers to all forms of iron in the plasma that bind to ligands other than transferrin, and is considered to be a marker of iron toxicity. A variety of analytical approaches for measuring NTBI have been reported; however, a clinically relevant level of sensitivity has yet to be achieved. In addition, insufficient values of NTBI in some patients and healthy subjects have led to the assumption that there may be contamination of reagents with background iron. The present study re-evaluated the analytical procedures of the assay with regard to the potential points of iron contamination in each step. NTA and tris carbonatocobaltate (III) solutions were prepared with removal of iron contamination, and then quantification of NTBI was performed. As a result, the sensitivity of the high-performance liquid chromatography (HPLC)-based NTBI method was improved by the successful reduction of background iron contamination. Application of our modified method proved that NTBI was detected even in healthy volunteers, although the concentrations were extremely low; the average NTBI levels were 0.206±0.091 µM (males, n=20) and 0.212±0.095 µM (females, n=16). Thus, our modification of the NTBI assay may be clinically meaningful, and may contribute to the understanding of the clinical significance of relatively low, but elevated concentrations of NTBI in diseases other than typical iron overload.

Iron-depletion promotes mitophagy to maintain mitochondrial integrity in pathogenic yeastCandida glabrata

“…During systemic infections, the amount of free iron supplied to C. glabrata cells is thought to be severely limited by iron-chelating proteins such as transferrin. 17 Thus, the iron-deficiency response in C. glabrata cells and other pathogenic microorganisms probably has important roles in their survival inside the host's body. 18,19 To investigate the response to iron deficiency in C. glabrata , we performed transcriptome analyses of cells grown under iron-replete (synthetic glucose medium; SD) and iron-depleted (SD medium without iron but with 100 µM ferrozine, which is a chelator of iron; SD-Fe) conditions.…”

“…During systemic infections, the amount of free iron supplied for the growth of C. glabrata cells is severely suppressed by iron-chelating proteins such as transferrin. 17 It is considered that the iron deficiency response in C. glabrata cells is indispensable for their survival inside the host's body. Our transcriptome analysis showed that the expression level of the gene homologous to S. cerevisiae ATG32 , which encodes a mitochondrial outer membrane protein required for the initiation of mitophagy, was upregulated under iron-depleted conditions in C. glabrata ( Fig.…”

Bovine lactoferrin ameliorates ferric nitrilotriacetate-induced renal oxidative damage in rats

“…(10,40) Non-transferrin-bound iron (NTBI) in the sera is an emerging marker of iron toxicity. (41,42) Although we did not measure NTBI levels in the sera, quantification of NTBI might disclose evidence as a role of bLF in antioxidant modulation via chelation of Fe-NTA.…”

Alteration of Iron Concentration in Alzheimer’s Disease as a Possible Diagnostic Biomarker Unveiling Ferroptosis

“…[147] S Chemistry analyzers, i.e., colorimetric reaction with ferrine or ferrozine as a chromogen to form a color complex with iron. [149]; HPLC [148]; isotope dilution MS [150]; novel NTBI measuring system using nitrilotriacetate and PSAP as chromogen [151]; chelatable fluorescent beads based on flow cytometry [152]; fluorescent bead assay CP851 chelator based [153].…”