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Start Over Creator Gergeľ, D.

1. An unusual temperature dependence of malondialdehyde formation in Fe2+/H2O2-initiated lipid peroxidation of phosphatidylcholine liposomes

Creator:
Mišík, V., Gergeľ, D., Alov, P., and Ondriaš, K.
Type:
article, model:article, and TEXT
Subject:
lipid peroxidation, malondialdehyde, temperature dependence, and oxygen consumption
Language:
English
Description:
Determination of malondialdehyde is a widely used procedure for measurement of lipid peroxidation. In this paper we report an unusual temperature dependence of malondialdehyde formation in egg yolk phosphatidylcholine liposomes oxidized by the Fenton system (0.1 mmol/1 FeSC>4 and 0.05 mmol/1 H2O2). The amount of malondialdehyde formed was 37 % higher in samples kept at 22 °C than at 50 °C. An alternative method for determination of lipid peroxidation, measurement of oxygen uptake, revealed complete consumption of dissolved oxygen to peroxidized lipids at 22 °C as well as 50 °C. Since oxygen is essential for the formation of cyclic peroxides - precursors of malondialdehyde - we conclude that the nature of the observed effect consists in limitation of oxygen availability at elevated temperatures.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Antioxidant and pro-oxidant effects of epinephrine and isoprenaline on peroxidation of LDL and lipid liposomes

Creator:
Ondriaš, K., Staško, A., Gergeľ, D., Hromadová, M., and Mišík, V.
Type:
article, model:article, and TEXT
Subject:
antioxidant, epinephrine, isoprenaline, peroxidation, low density lipoprotein, lipoxidase, and iron
Language:
English
Description:
Antioxidant or pro-oxidant properties of epinephrine (EPI) and isoprenaline (ISO) were studied in the absence and presence of Fe2+ , Fe3+ and Cu2+ ions. EPI and ISO (>2 /tmol/1) inhibited peroxidation of low density lipoprotein (LDL) induced by 2, 2’-azobis(2-amidino-propane) (AAPH). EPI had a similar inhibitory potency as ISO, but their potency was several times higher than the potency of a-tocopherol (a-TOC). When the LDL peroxidation was induced by 5 /tmol/1 CUSO4, EPI and ISO enhanced LDL peroxidation at low concentrations (10/mol/l) and decreased peroxidation at higher concentrations (30 /tmol/1). The compounds had a similar tendency to inhibit the peroxidation of phosphatidylcholine liposomes. EPI (3-30 //¿mol/1) inhibited lipid peroxidation of phosphatidylcholine liposomes induced by 2 mmol/1 of AAPH, but it was less effective and even increased the peroxidation, when the samples contained 2 mmol/1 AAPH with 50 /¿mol/l FeSC>4 or 2 mmol/1 AAPH with 20/imol/l FeCb. Inhibition of lipid peroxidation by EPI was also observed when studying decreased oxygen consumption, when the peroxidation of linoleic acid was induced by lipoxidase. In conclusion, EPI and ISO reduced lipid peroxidation, but they exhibit pro-oxidant properties in the presence of Fe2+, Fe3+ or Cu2+ ions, depending on the catecholamine and ionic concentration.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public