Effect of oral administration of green tea extract in various dosage schemes on oxidative stress status of mice in vivo

Green tea is a favorite beverage and its extracts are popular components of dietary supplements. The aim of the present in vivo study was to obtain detailed information about the effect of a standard green tea extract (Polyphenon, P), at different doses, on antioxidant enzymes and oxidative stress markers in murine blood, liver, small and large intestine. In all doses, P improved the oxidative stress status via an increased content of plasmatic SH-groups (by 21–67 %). Regarding antioxidant enzymes in tissues, the low dose of P had the best effect as it elevated the activity of NADPH/quinone reductase in liver and small intestine, thioredoxin reductase in small intestine and hepatic superoxide dismutase. Based on these facts, consumation of green tea seems to be safe and beneficial, while consumption of dietary supplements containing high doses of catechins may disturb oxidative balance by lowering the activity of thioredoxin reductase, glutathione S-transferase, glutathione reductase and superoxide dismutase

Induction of xenobiotic-metabolizing enzymes in hepatocytes by beta-naphthoflavone: Time-dependent changes in activities, protein and mRNA levels

In the present study, time-dependency of the induction effect of a selective inducer on the activity, protein and mRNA levels of cytochromes P450 1A1/2 (CYP1A1/2), NAD(P)H:quinone oxidoreductase 1 (NQO1) and glutathione S-transferases (GSTA), in primary culture of rat hepatocytes was tested and evaluated. To show the differences in responses of tested enzymes, the common aryl hydrocarbon receptor (AhR) ligand agonist, beta-naphthoflavone (BNF), was used. Induction of CYP1A1/2 by BNF was detected at all time intervals and at all levels (i.e., mRNA, protein, enzyme activity). Different responses of NQO1 and GSTA upon BNF treatment were observed. Our results demonstrate that the responses of different xenobiotic-metabolizing enzymes to the inducer vary in time and depend on the measured parameter. For these reasons, an induction study featuring only one-time interval treatment and/or one parameter testing could produce misleading information

UDP-glycosyltransferase family in Haemonchus contortus: Phylogenetic analysis, constitutive expression, sex-differences and resistance-related differences

UDP-glycosyltransferases (UGT), catalysing conjugation of UDP-activated sugar donors to small lipophilic chemicals, are widespread in living organisms from bacteria to fungi, plant, or animals. The progress of genome sequencing has enabled an assessment of the UGT multigene family in Haemonchus contortus (family Trichostrongylidae, Nematoda), a hematophagous gastrointestinal parasite of small ruminants. Here we report 32 putative UGT genes divided into 15 UGT families. Phylogenetic analysis in comparison with UGTs from Caenorhabditis elegans, a free-living model nematode, revealed several single member homologues, a lack of the dramatic gene expansion seen in C. elegans, but also several families (UGT365, UGT366, UGT368) expanded in H. contortus only. The assessment of constitutive UGT mRNA expression in H. contortus adults identified significant differences between females and males. In addition, we compared the expression of selected UGTs in the drug-sensitive ISE strain to two benzimidazole-resistant strains, IRE and WR, with different genetic backgrounds. Constitutive expression of UGT368B2 was significantly higher in both resistant strains than in the sensitive strain. As resistant strains were able to deactivate benzimidazole anthelmintics via glycosylation more effectively then the sensitive strain, UGT368B2 enhanced constitutive expression might contribute to drug resistance in H. contortus

Effect of selected catechins on doxorubicin antiproliferative efficacy and hepatotoxicity in vitro

Catechins may influence both desirable and undesirable effects of many drugs. In this study, the in vitro effect of (+)-catechin, (–)-epicatechin, (–)-epigallocatechin, (–)-epicatechingallate, and (–)-epigallocatechingallate (EGCG)on the efficacy of anticancer drug doxorubicin (DOX) was studiedin HCT-8 cancer cells.Rat hepatocytes were used to study the influence of EGCG on DOX hepatotoxicity. Cell proliferation and viability were studied by 3-4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide and neutral red uptake assays. Formation of reactive oxigen species was determined using the dichlorofluorescein assay. All of the studied catechins(1–25 µmol L–1) had no effect on the proliferation of intestinal cancer cells and did not affect the antiproliferative effect of DOX (1–8 µmol L–1) in these cells. Moreover, EGCG at 25 µmol L–1 increased the viability of isolated hepatocytes and significantly protected these cells against DOX-induced toxicity and ROS production. Consumption of EGCG during DOX therapy seems to be safe and beneficial, since EGCG does not decrease DOX anticancer efficacy and could ameliorate DOX hepatotoxicity

Sesquiterpenes α-humulene and β-caryophyllene oxide enhance the efficacy of 5-fluorouracil and oxaliplatin in colon cancer cells

The present study is designed to find out if sesquiterpenes, α-humulene (HUM), valencene (VAL), β-caryphyllene-oxide (CAO) and trans-nerolidol (NER), are able to improve the antiproliferative effect of classical cytostatic drugs, 5-fluorouracil (FU) and oxaliplatin (1,2-diaminocyclohexaneoxalato-platinum, OxPt), in colon cancer cell lines Caco-2 and SW-620. In addition, the possible mechanisms of sesquiterpene action are studied. The results show significant ability of HUM and especially of CAO to enhance the antiproliferative effects of FU and OxPt in cancer cell lines Caco-2 and SW-620. On the other hand, VAL and NER are ineffective. The action of CAO could be partly based on its ability to disrupt the mitochondrial membrane potential and to activate initiator caspases, but other mechanisms are probably also involved. Based on these results, CAO seems to have the potential for combination therapy of colon cancers and deserves further study

Carbonyl Reduction of Flubendazole in the Human Liver: Strict Stereospecificity, Sex Difference, Low Risk of Drug Interactions

Flubendazole (FLU), an anthelmintic drug of benzimidazole type, is now considered a promising anti-cancer agent due to its tubulin binding ability and low system toxicity. The present study was aimed at determining more information about FLU reduction in human liver, because this information has been insufficient until now. Subcellular fractions from the liver of 12 human patients (6 male and 6 female patients) were used to study the stereospecificity, cellular localization, coenzyme preference, enzyme kinetics, and possible inter-individual or sex differences in FLU reduction. In addition, the risk of FLU interaction with other drugs was evaluated. Our study showed that FLU is predominantly reduced in cytosol, and the reduced nicotinamide adenine dinucleotide phosphate (NADPH) coenzyme is preferred. The strict stereospecificity of FLU carbonyl reduction was proven, and carbonyl reductase 1 was identified as the main enzyme of FLU reduction in the human liver. A higher reduction of FLU and a higher level of carbonyl reductase 1 protein were found in male patients than in female patients, but overall inter-individual variability was relatively low. Hepatic intrinsic clearance of FLU is very low, and FLU had no effect on doxorubicin carbonyl reduction in the liver and in cancer cells. All these results fill the gaps in the knowledge of FLU metabolism in human

Education and development of employees

Import 06/10/2008Prezenční152 - Katedra podnikohospodářskáNeuveden

Company management system diagnosis

Import 09/11/2006Prezenční152 - Katedra podnikohospodářsk

MicroRNAs as Potential Regulators of Glutathione Peroxidases Expression and Their Role in Obesity and Related Pathologies

Glutathione peroxidases (GPxs) belong to the eight-member family of phylogenetically related enzymes with different cellular localization, but distinct antioxidant function. Several GPxs are important selenoproteins. Dysregulated GPx expression is connected with severe pathologies, including obesity and diabetes. We performed a comprehensive bioinformatic analysis using the programs miRDB, miRanda, TargetScan, and Diana in the search for hypothetical microRNAs targeting 3′untranslated regions (3´UTR) of GPxs. We cross-referenced the literature for possible intersections between our results and available reports on identified microRNAs, with a special focus on the microRNAs related to oxidative stress, obesity, and related pathologies. We identified many microRNAs with an association with oxidative stress and obesity as putative regulators of GPxs. In particular, miR-185-5p was predicted by a larger number of programs to target six GPxs and thus could play the role as their master regulator. This microRNA was altered by selenium deficiency and can play a role as a feedback control of selenoproteins’ expression. Through the bioinformatics analysis we revealed the potential connection of microRNAs, GPxs, obesity, and other redox imbalance related diseases

The Effect of the Manure from Sheep Treated with Anthelmintics on Clover (Trifolium pratense)

The anthelmintics (regularly administered to livestock to control the infections caused by parasitic worms) and their metabolites formed in treated animals are excreted to the environment. This contamination might have a negative influence on non-target organisms including plants. Our previous studies described the uptake, metabolism, and effects of anthelmintics in plants using in vitro models exposed to anthelmintic drugs in solutions. The present study was performed in clover grown in soil fertilized with manure from sheep treated with the recommended dose of albendazole (ABZ), ivermectin (IVM), or monepantel (MOP). The uptake and metabolism of drugs in clover were monitored for six weeks using UHPLC-MS/MS, and several stress markers (proline accumulation, lipid peroxidation, and antioxidant enzymes activities) were evaluated. The results showed that ABZ and MOP were absorbed, metabolized, and translocated to leaves, while IVM was detected only in the roots. No or minimal drug-response was observed in monitored stress markers, and only a temporary increase of several antioxidative enzymes activities was observed. Overall, manure from sheep treated with anthelmintics does not evoke chronic stress in clover, but it can cause the entry of anthelmintics in other organisms and the food-chain