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- Buss, Joan L, et al.
(författare)
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Oxidative stress mediates toxicity of pyridoxal isonicotinoyl hydrazone analogs
- 2004
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861 .- 1096-0384. ; 421:1
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Tidskriftsartikel (refereegranskat)abstract
- Pyridoxal isonicotinoyl hydrazone (PIH) and many of its analogs are effective iron chelators in vivo and in vitro, and are of interest for the treatment of secondary iron overload. Because previous work has implicated the Fe3+-chelator complexes as a determinant of toxicity, the role of iron-based oxidative stress in the toxicity of PIH analogs was assessed. The Fe3+ complexes of PIH analogs were reduced by K562 cells and the physiological reductant, ascorbate. Depletion of the antioxidant, glutathione, sensitized Jurkat T lymphocytes to the toxicity of PIH analogs and their Fe 3+ complexes, and toxicity of the chelators increased with oxygen tension. Fe3+ complexes of pyridoxal benzoyl hydrazone (PBH) and salicyloyl isonicotinoyl hydrazone (SIH) caused lipid peroxidation and toxicity in K562 cells loaded with eicosapentenoic acid (EPA), a readily oxidized fatty acid, whereas Fe(PIH)2 did not. The lipophilic antioxidant, vitamin E, completely prevented both the toxicity and lipid peroxidation caused by Fe(PBH)2 in EPA-loaded cells, indicating a causal relationship between oxidative stress and toxicity. PBH also caused concomitant lipid peroxidation and toxicity in EPA-loaded cells, both of which were reversed as its concentration increased. In contrast, PIH was inactive, while SIH was equally toxic toward control and EPA-loaded cells, without causing lipid peroxidation, indicating a much smaller contribution of oxidative stress to the mechanism of toxicity of these analogs. In summary, PIH analogs and their Fe3+ complexes are redox active in the intracellular environment. The contribution of oxidative stress to the overall mechanism of toxicity varies across the series. © 2003 Elsevier Inc. All rights reserved.
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| 2. |
- Buss, Joan L, et al.
(författare)
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Pyridoxal isonicotinoyl hydrazone analogs induce apoptosis in hematopoietic cells due to their iron-chelating properties
- 2003
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Ingår i: Biochemical Pharmacology. - 0006-2952 .- 1356-1839. ; 65:2, s. 161-172
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Tidskriftsartikel (refereegranskat)abstract
- Analogs of pyridoxal isonicotinoyl hydrazone (PIH) are of interest as iron chelators for the treatment of secondary iron overload and cancer. PIH, salicylaldehyde isonicotinoyl hydrazone (SIH), and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (NIH), the toxicity of which vary over two orders of magnitude, were selected for a study of their mechanisms of toxicity. PIH analogs and their iron complexes caused concentration- and time-dependent apoptosis in Jurkat T lymphocytes and K562 cells. Bcl-2 overexpression was partially anti-apoptotic, suggesting mitochondrial mediation of apoptosis. Since the pan-caspase inhibitor zVAD-fmk did not reduce lysosomal and mitochondrial destabilization, these events occur upstream of caspase activation. In contrast, phosphatidylserine externalization and the development of apoptotic morphology were inhibited significantly, indicating the role of caspases in mediating these later events. Since overexpression of CrmA had no effect on apoptosis, caspase-8 is not likely involved. Fe3+ complexes of SIH and NIH, which accumulated in 59Fe-labeled mouse reticulocytes during incubation with the chelators, also caused apoptosis. BSA, which promotes release of the complexes from cells, reduced the toxicity of SIH and NIH, suggesting that the induction of apoptosis by PIH analogs involves toxic effects mediated by their Fe3+ complexes. Moreover, analogs of these agents lacking the iron-chelating moiety were non-toxic. ⌐ 2002 Published by Elsevier Science Inc.
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