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Biomedical subjects

Agnieszka Grzelak

Publications and source records attributed to Agnieszka Grzelak.

5 recordsLinked to original sources
PubMed2006

Accumulation of oxidative damage during replicative aging of the yeast Saccharomyces cerevisiae.

Comparison of senescent yeast obtained by the "baby machine" technique with 2-day-old stationary phase cells revealed decreased activities of glutathione reductase, glutathione S-transferase, glutathione peroxidase and alcohol dehydrogenase, reduction of total antioxidant capacity, protein glycation and accumulation of products of oxidative damage: protein carbonyls and DNA damage assessed by augmented content of 8-oxoguanine and increased tail momentum of cellular DNA in the comet assay. These results are consistent with a role for oxidative damage during replicative senescence of Saccharomyces cerevisiae.

Antioxidants↗
PubMed2004

Melatonin does not react rapidly with hydrogen peroxide.

It has been claimed that melatonin reacts directly with hydrogen peroxide with a very high rate constant (2.5 x 10(5)-2.3 x 10(6) M(-1) s(-1)) Both these values were derived from inhibition by melatonin of peroxidase-catalyzed oxidation of Phenol Red by hydrogen peroxide, assuming that this inhibition is due to direct scavenging of hydrogen peroxide by melatonin. In this study, we show that this reasoning is illegitimate and melatonin decreases the yield of oxidation of Phenol Red as a competitive substrate. Monitoring changes of concentration of hydrogen peroxide incubated with melatonin using Xylenol Orange points to poor reactivity of melatonin with H2O2.

Chromans↗
PubMed2004

Pro-oxidative effects of Tempo in systems containing oxidants.

2,2,6,6-Tetramethylpiperidine-1-oxyl (Tempo), previously reported by us to augment oxidation of glutathione induced by peroxynitrite (Glebska J, Skolimowski J, Kudzin Z, Gwozdzinski K, Grzelak A, Bartosz G. Pro-oxidative activity of nitroxides in their reactions with glutathione. Free Radic Biol Med 2003; 35: 310-316) was found to increase oxidation of glutathione induced by various oxidants, including persulfate, tert-butyl hydroperoxide and hydrogen peroxide. Tempo augmented also the inactivation and thiol loss of alcohol dehydrogenase induced by 2,2'-azobis(2-amidinopropane) (AAPH) and oxidative degradation of deoxyribose induced by ammonium persulfate and tert-butyl hydroperoxide. These results point to a pro-oxidative effect of nitroxides on a range of biomolecules subjected to the action of various oxidants.

Alcohol Dehydrogenase↗
PubMed2003

Pro-oxidative activity of nitroxides in their reactions with glutathione.

Nitroxides are unreactive towards glutathione in vitro. Interaction of nitroxides with peroxynitrite does not lead to a significant loss of their electron paramagnetic resonance (EPR) signal. However, addition of peroxynitrite to a solution containing glutathione and nitroxides induces an irreversible disappearance of EPR signal of nitroxides and augmentation of glutathione oxidation which is a pro-oxidant effect of these compounds. Nitroxide loss leading to the formation of amine derivatives is initiated by products of glutathione oxidation by peroxynitrite. The pro-oxidant action of nitroxides at micromolar concentrations may be important in view of the proposed use of these compounds as antioxidants.

Dose-Response Relationship, Drug↗