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Effect of fungicides and biological control agens on glutathione metabolism.
Vašková, Marie ; Hýsková, Veronika (advisor) ; Jaklová Dytrtová, Jana (referee)
Triazole fungicides are widely used in agriculture to treat a large number of crops. When they accumulate in soil, plants or water sources, they can also affect non-target organisms, in which they can have a negative effect on the endocrine system or re- production. Much less is known about the effect of triazoles on plants, specifically their antioxidant and detoxification systems. In this work, the effect of penconazole (P), tebuconazole (T) or their combination (PT) on tomato plants Solanum lycopersicum, cv. Cherrola was studied. In contrast to the conventional method of fungicide application by foliar spraying, the effect of soil drench containing P, T or PT was also studied. Soil drenching of fungicides had a worse impact on glutathione metabolism: on the thirty-fifth day after weekly fun- gicide application, the content of reduced thiols and glutathione peroxidase activity were reduced in roots, and the key conjugation enzyme of phase II biotransformation, glutathione-S-transferase (GST), was reduced in leaves by 43 to 20 % (depending on the fungicide) compared with untreated plants. In contrast, the content of reduced thiols and glutathione peroxidase activity were increased in leaves. In the case of spraying with both fungicides (PT), although at the same concentration as P and T alone, a...
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Biotransformation aspects on novel carbocyclic nucleoside analogs.
Rozumová, Nela ; Mertlíková Kaiserová, Helena (advisor) ; Rumlová, Michaela (referee)
Carbocyclic nucleoside analogs with norbornane moiety that have been synthesized at IOCB AS CR, represent new potential chemotherapeutic agents with significant activity against Coxsackieviruses. The main objective of this work was to study the metabolism and mechanism of action of the original analog carbocyclic nucleoside MS 254, which is characterized by its antiviral and cytostatic effects. The attention was partially paid also to the two structurally related substances (MS 255, MS 320). In this work, we determined cytotoxicity of these compounds in cell culture and the effect of MS 254 on the amount of total and oxidized glutathione, activity of glutathione-S-transferase (GST), glutathione reductase (GR) and the effect on cellular oxidative stress. The kinetics of the conjugation of MS 254 by human GST was also studied. It was found that of the three substances tested MS 255 was the most cytotoxic and MS 254 was the least cytotoxic compound. It was further found that MS 254 does not cause significant oxidative stress and that it increases the activity of GST and GR in a dose-dependent manner. Michaelis-Menten constant of the conjugation of MS 254 with the glutathione (main metabolic pathway) was determined in the milimolar range, indicating a relatively low affinity of MS 254 for GST.
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