Bartosz G, Pieńkowska N, Kut K, Cieniek B, Stefaniuk I, Sadowska-Bartosz I. Effect of Low Concentration of Nitroxides on SH-SY5Y Cells Transfected with the Tau Protein.
Int J Mol Sci 2023;
24:16675. [PMID:
38069000 PMCID:
PMC10706669 DOI:
10.3390/ijms242316675]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 11/17/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Nitroxides, stable synthetic free radicals, are promising antioxidants, showing many beneficial effects both at the cellular level and in animal studies. However, the cells are usually treated with high millimolar concentrations of nitroxides which are not relevant to the concentrations that could be attained in vivo. This paper aimed to examine the effects of low (≤10 μM) concentrations of three nitroxides, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), 4-hydroxy-TEMPO (TEMPOL) and 4-amino-TEMPO (TEMPAMINE), in pure chemical systems and on SH-SY5Y cells transfected with the human tau protein (TAU cells), a model of chronic cellular oxidative stress, and transfected with the empty plasmid (EP cells). All nitroxides were active in antioxidant-activity tests except for the 2,2'-azinobis-(3-ethylbenzthiazolin-6-sulfonate) radical (ABTS•) decolorization assay and reduced Fe3+, inhibited autoxidation of adrenalin and pyrogallol and oxidation of dihydrorhodamine123 by 3-morpholino-sydnonimine SIN-1. TEMPO protected against fluorescein bleaching from hypochlorite, but TEMPAMINE enhanced the bleaching. Nitroxides showed no cytotoxicity and were reduced by the cells to non-paramagnetic derivatives. They decreased the level of reactive oxygen species, depleted glutathione, and increased mitochondrial-membrane potential in both types of cells, and increased lipid peroxidation in TAU cells. These results demonstrate that even at low micromolar concentrations nitroxides can affect the cellular redox equilibrium and other biochemical parameters.
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