Abstract
The straightfoward creation of an unreported glutathione-stabilised iron(iii) complex is disclosed. In contrast to previous reports, glutathione was shown to coordinate and stabilise iron directly under physiological conditions in the absence of additional sulfur containing molecules, such as sodium sulfide. The complex was extensively characterised; the molecular geometry was determined as two inequivalent octahedra, approximately 2/3 of which are slightly distorted towards more tetrahedral in character, with the remaining 1/3 more regularly octahedral. The dispersion of the iron(iii)-glutathione complex in aqueous solution yielded particles of 255 ± 4 nm in diameter that enhanced the growth and proliferation of L929 fibroblast cells over 7 days, and inhibited the activity of matrix metalloproteinase-13. Consequently, the unprecedented glutathione-stabilised iron(iii) complex disclosed has potential use as a simple-to-prepare growth factor for inclusion within cell culture media, and is an excellent candidate as a therapeutic for the treatment of metalloproteinase-13-associated diseases.
Highlights
Glutathione (GSH) is imperative for cellular defence against reactive oxygen species that cause apoptosis and tissue inflammation.[1]
A regular decrease in absorbance intensity was observed in solutions containing a decreasing molar ratio of FeCl3 : GSH (6 → 1), until no peak could be detected in solutions containing a molar ratio lower than 1 (Fig. S1†). This observation can be rationalised by the fact that when solutions with a FeCl3 : GSH molar ratio of 1 : 1.2 or lower were analysed, Fe2+ was present exclusively and so no Fe3+-associated absorbance could be recorded, illustrating that binding between Fe3+ and GSH occurred only at increased FeCl3 : GSH molar ratios (i.e. >1). This observation reveals that the thiol-induced reduction of Fe3+ to Fe2+ is expected to occur prior to Fe chelation in solutions with increased GSH content, and that the chelating interaction detected by UV-Vis spectroscopy was exclusively between GSH and Fe3+, rather than between GSH and Fe2+, in solutions with decreased GSH content
In contrast to mass spectrometry, X-ray photoelectron spectroscopy (XPS) investigations revealed the absence of S–S bridges, suggesting that the formation of the oxidised product in the mass spectra is attributed to the electron source forming ionised species, which form GSSG in the instrument channel
Summary
Glutathione (GSH) is imperative for cellular defence against reactive oxygen species that cause apoptosis and tissue inflammation.[1]. The dispersion of the iron(III)–glutathione complex in aqueous solution yielded particles of 255 ± 4 nm in diameter that enhanced the growth and proliferation of L929 fibroblast cells over 7 days, and inhibited the activity of matrix metalloproteinase-13.
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