Effect of alpha-tocopherol on antioxidant enzyme activities and lipid peroxidation in rainbow trout (Oncorhynchus mykiss).

In this study, the effect of alpha-tocopherol on the antioxidant capacity of rainbow trout (Oncorhynchus mykiss) was determined. For this purpose, activities of antioxidant enzymes such as catalase (CAT), peroxidase (POD) and glutathione reductase (GSSG-Rx) were investigated. Enzyme activities were measured at 0 (control), 1, 3 and 5 h after alpha-tocopherol injection. In addition, the levels of malondialdehyde (MDA) as a lipid peroxidation marker were determined in the erythrocytes. The results showed that alpha-tocopherol significantly activated the CAT, POD and GSSG-Rx enzymes as compared with the enzyme activities found in the controls (p < 0.05). However, MDA levels were significantly decreased by alpha-tocopherol treatment (p < 0.05). The results suggest that alpha-tocopherol may have a pro-oxidant tendency at a high dose and cause mild oxidative stress which could modulate signal transduction cascades, redirect gene expression, and influence many cellular responses such as proliferation, differentiation, and reproduction. For this reason, alpha-tocopherol should be used carefully in all applications in relation to fish.

Effect of vitamin E on carbonic anhydrase enzyme activity in rainbow trout (Oncorhynchus mykiss) erythrocytes in vitro and in vivo.

Considering that the excessive usage of vitamin E causes hypervitaminosis and thus reduces blood erythrocyte concentrations, therefore it is worth studying how its pharmacological dosage affects the activity of carbonic anhydrase (CA) enzyme found in erythrocytes of rainbow trout (Oncorhynchus mykiss) in vitro and in vivo. Vitamin E inhibited CA enzyme and the IC50 value of the vitamin was 0.039 mM in vitro. Similarly, it was seen that vitamin E inhibited CA enzyme activity after the first hour following vitamin E injections in vivo. The activities of CA in groups of trout given vitamin E injection were measured at 1, 3 and 5 h and the corresponding activities were found to be 772.7 +/- 290.5 (P < 0.05), 1286.4 +/- 378.2 and 1005.7 +/- 436.1 enzyme units (EU) g Hb(-1). The difference over the control was significant (P < 0.05) in the first hour and insignificant at 3 and 5 h (P > 0.05). The activity of CA in the control, which did not contain vitamin E, was determined as 1597.7 +/- 429.0 EU g Hb(-1).

The effects of some antibiotics on sheep lens glucose 6-phosphate dehydrogenase in vitro.

PURPOSE: To investigate the in vitro effects of gentamicin sulfate, vancomycin hydrochloride, sodium cefazolin and ceftriaxone on glucose 6-phosphate dehydrogenase enzyme (G6PD) purified from sheep lenses. METHODS: G6PD was purified from sheep lenses with a yield of 66.8% and a specific activity of 7.8 U/mg proteins, and 10,400-fold using ammonium sulfate fractionation and 2',5'-ADP Sepharose 4B affinity gel. The enzyme activity was determined by Beutler's method. RESULTS: Gentamicin sulfate and vancomycin hydrochloride strongly inhibited the enzyme in vitro. The concentrations causing 50% inhibition (IC50 were 15.34, and 8.0 mM, respectively. Conversely, cefazolin sodium strongly activated this enzyme, and ceftriaxone caused milder activation. CONCLUSIONS: If a patient with G6PD deficiency requires gentamicin sulfate or vancomycin hydrochloride, routine ophthalmic did not inhibit this enzyme. Postmortem studies are now needed to investigate the activity of G6PD and how it is affected by these antibiotics.

Effects of some medical drugs on enzyme activities of carbonic anhydrase from human erythrocytes in vitro and from rat erythrocytes in vivo.

In this study, firstly, the effects of sodium ampicillin, magnesium sulfate, and sodium dipyrone on human carbonic anhydrase (HCA) (EC 4.2.1.1.) isozymes have been investigated in vitro. Human erythrocyte CA-I and CA-II isozymes were separately purified by affinity chromatography. Inhibition or activation effects of three different medical drugs on HCA isozymes were determined using the CO(2)-Hydratase method by plotting activity %vs [medical drug]. I(50)values of the drugs exhibiting inhibition effects were found by means of these graphs. It was observed on HCA-I hydratase activity that sodium ampicillin and sodium dipyrone showed inhibition and activation effects, respectively. However, magnesium sulfate showed no effect. It was observed on HCA-II hydratase activity that sodium ampicillin and magnesium sulfate showed an inhibition effect, and sodium dipyrone showed an activation effect. In addition, in vivo studies were performed for these medical drugs in Sprague-Dawley rats. It was demonstrated that CA in erythrocytes was significantly inhibited by these drugs in 3 h.