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Prof. Jitka Viktorova
UCT Prague

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0 multidrug resistance
0 Chemotherapy resistance
0 antibiotic resistance bacteria
0 resistant mechanisms
0 Efflux pump inhibition

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multidrug resistance
Efflux pump inhibition

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Journal article
Published: 27 August 2021 in Journal of Applied Genetics
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Currently, it is clear that the luxS gene has an impact on the process of biofilm formation in Campylobacter jejuni. However, even within the species, naturally occurring strains of Campylobacter lacking the luxS gene exist, which can form biofilms. In order to better understand the genetic determinants and the role of quorum sensing through the LuxS/AI-2 pathway in biofilm formation, a set of mutant/complemented strains of C. jejuni 81–176 were prepared. Additionally, the impact of the mutagenic strategy used against the luxS gene was investigated. Biofilm formation was affected by both the presence and absence of the luxS gene, and by the mutagenic strategy used. Analysis by CLSM showed that all mutant strains formed significantly less biofilm mass when compared to the wild-type. Interestingly, the deletion mutant (∆luxS) showed a larger decrease in biofilm mass than the substitution (∙luxS) and insertional inactivated (\(\colon\colon\)luxS) mutants, even though all the mutant strains lost the ability to produce autoinducer-2 molecules. Moreover, the biofilm of the ∆luxS mutant lacked the characteristic microcolonies observed in all other strains. The complementation of all mutant strains resulted in restored ability to produce AI-2, to form a complex biofilm, and to develop microcolonies at the level of the wild-type.

ACS Style

Martin Teren; Ekaterina Shagieva; Lucie Vondrakova; Jitka Viktorova; Viviana Svarcova; Katerina Demnerova; Hana T. Michova. Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni. Journal of Applied Genetics 2021, 1 -13.

AMA Style

Martin Teren, Ekaterina Shagieva, Lucie Vondrakova, Jitka Viktorova, Viviana Svarcova, Katerina Demnerova, Hana T. Michova. Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni. Journal of Applied Genetics. 2021; ():1-13.

Chicago/Turabian Style

Martin Teren; Ekaterina Shagieva; Lucie Vondrakova; Jitka Viktorova; Viviana Svarcova; Katerina Demnerova; Hana T. Michova. 2021. "Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni." Journal of Applied Genetics , no. : 1-13.

Nano review
Published: 15 March 2021 in Nanoscale Research Letters
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Noble metals have played an integral part in human history for centuries; however, their integration with recent advances in nanotechnology and material sciences have provided new research opportunities in both academia and industry, which has resulted in a new array of advanced applications, including medical ones. Noble metal nanoparticles (NMNPs) have been of great importance in the field of biomedicine over the past few decades due to their importance in personalized healthcare and diagnostics. In particular, platinum, gold and silver nanoparticles have achieved the most dominant spot in the list, thanks to a very diverse range of industrial applications, including biomedical ones such as antimicrobial and antiviral agents, diagnostics, drug carriers and imaging probes. In particular, their superior resistance to extreme conditions of corrosion and oxidation is highly appreciated. Notably, in the past two decades there has been a tremendous advancement in the development of new strategies of more cost-effective and robust NMNP synthesis methods that provide materials with highly tunable physicochemical, optical and thermal properties, and biochemical functionalities. As a result, new advanced hybrid NMNPs with polymer, graphene, carbon nanotubes, quantum dots and core–shell systems have been developed with even more enhanced physicochemical characteristics that has led to exceptional diagnostic and therapeutic applications. In this review, we aim to summarize current advances in the synthesis of NMNPs (Au, Ag and Pt).

ACS Style

Giyaullah Habibullah; Jitka Viktorova; Tomas Ruml. Current Strategies for Noble Metal Nanoparticle Synthesis. Nanoscale Research Letters 2021, 16, 1 -12.

AMA Style

Giyaullah Habibullah, Jitka Viktorova, Tomas Ruml. Current Strategies for Noble Metal Nanoparticle Synthesis. Nanoscale Research Letters. 2021; 16 (1):1-12.

Chicago/Turabian Style

Giyaullah Habibullah; Jitka Viktorova; Tomas Ruml. 2021. "Current Strategies for Noble Metal Nanoparticle Synthesis." Nanoscale Research Letters 16, no. 1: 1-12.

Article
Published: 21 February 2021 in Phytochemistry Reviews
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The genus Selaginella belongs to the family Selaginellaceae, which is well known for its unique structural classes of natural products and their wide range of biological effects. This review provides a comprehensive list of unique secondary metabolites isolated from the genus Selaginella and also provides insight into their important biological activities. For the benefit of the readers, this review is divided into two main sections. The first section elaborates on the natural products isolated from Selaginella, with the emphasis on compounds exclusive to this genus, while the second section provides an in-depth discussion of a number of different pharmacological activities that the compounds and Selaginella extracts exhibited.

ACS Style

Rohitesh Kumar; Jitka Viktorova; Bara Krizkovska; Jan Lipov; Tomas Ruml. Structural diversity and biological activities of secondary metabolites isolated from the genus Selaginella. Phytochemistry Reviews 2021, 1 -35.

AMA Style

Rohitesh Kumar, Jitka Viktorova, Bara Krizkovska, Jan Lipov, Tomas Ruml. Structural diversity and biological activities of secondary metabolites isolated from the genus Selaginella. Phytochemistry Reviews. 2021; ():1-35.

Chicago/Turabian Style

Rohitesh Kumar; Jitka Viktorova; Bara Krizkovska; Jan Lipov; Tomas Ruml. 2021. "Structural diversity and biological activities of secondary metabolites isolated from the genus Selaginella." Phytochemistry Reviews , no. : 1-35.

Journal article
Published: 26 December 2020 in Pharmaceuticals
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Selaginella P. Beauv. is a group of vascular plants in the family Selaginellaceae Willk., found worldwide and numbering more than 700 species, with some used as foods and medicines. The aim of this paper was to compare methanolic (MeOH) and dichloromethane (DCM) extracts of eight Selaginella species on the basis of their composition and biological activities. Six of these Selaginella species are underinvestigated. Using ultra-high performance liquid chromatography–high-resolution mass spectrometry (UHPLC–HRMS) analysis, we identified a total of 193 compounds among the tested Selaginella species, with flavonoids predominating. MeOH extracts recovered more constituents that were detected, including selaginellins, the occurrence of which is only typical for this plant genus. Of all the tested species, Selaginellaapoda contained the highest number of identified selaginellins. The majority of the compounds were identified in S. apoda, the fewest compounds in Selaginellacupressina. All the tested species demonstrated antioxidant activity using oxygen radical absorption capacity (ORAC) assay, which showed that MeOH extracts had higher antioxidant capacity, with the half maximal effective concentration (EC50) ranging from 12 ± 1 (Selaginellamyosuroides) to 124 ± 2 (Selaginellacupressina) mg/L. The antioxidant capacity was presumed to be correlated with the content of flavonoids, (neo)lignans, and selaginellins. Inhibition of acetylcholinesterase (AChE) was mostly discerned in DCM extracts and was only exhibited in S. myosuroides, S. cupressina, Selaginellabiformis, and S. apoda extracts with the half maximal inhibitory concentration (IC50) in the range of 19 ± 3 to 62 ± 1 mg/L. Substantial cytotoxicity against cancer cell lines was demonstrated by the MeOH extract of S. apoda, where the ratio of the IC50 HEK (human embryonic kidney) to IC50 HepG2 (hepatocellular carcinoma) was 7.9 ± 0.2. MeOH extracts inhibited the production of nitrate oxide and cytokines in a dose-dependent manner. Notably, S. biformis halved the production of NO, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 at the following concentrations: 105 ± 9, 11 ± 1, and 10 ± 1 mg/L, respectively. Our data confirmed that extracts from Selaginella species exhibited cytotoxicity against cancer cell lines and AChE inhibition. The activity observed in S. apoda was the most promising and is worth further exploration.

ACS Style

Bára Křížkovská; Rohitesh Kumar; Kateřina Řehořová; David Sýkora; Simona Dobiasová; Denisa Kučerová; Maria Carmen Tan; Virgilio Linis; Glenn Oyong; Tomáš Ruml; Jan Lipov; Jitka Viktorová. Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species. Pharmaceuticals 2020, 14, 16 .

AMA Style

Bára Křížkovská, Rohitesh Kumar, Kateřina Řehořová, David Sýkora, Simona Dobiasová, Denisa Kučerová, Maria Carmen Tan, Virgilio Linis, Glenn Oyong, Tomáš Ruml, Jan Lipov, Jitka Viktorová. Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species. Pharmaceuticals. 2020; 14 (1):16.

Chicago/Turabian Style

Bára Křížkovská; Rohitesh Kumar; Kateřina Řehořová; David Sýkora; Simona Dobiasová; Denisa Kučerová; Maria Carmen Tan; Virgilio Linis; Glenn Oyong; Tomáš Ruml; Jan Lipov; Jitka Viktorová. 2020. "Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species." Pharmaceuticals 14, no. 1: 16.

Review
Published: 30 September 2020 in Toxins
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The determination of mycotoxins content in food is not sufficient for the prediction of their potential in vivo cytotoxicity because it does not reflect their bioavailability and mutual interactions within complex matrices, which may significantly alter the toxic effects. Moreover, many mycotoxins undergo biotransformation and metabolization during the intestinal absorption process. Biotransformation is predominantly the conversion of mycotoxins meditated by cytochrome P450 and other enzymes. This should transform the toxins to nontoxic metabolites but it may possibly result in unexpectedly high toxicity. Therefore, the verification of biotransformation and bioavailability provides valuable information to correctly interpret occurrence data and biomonitoring results. Among all of the methods available, the in vitro models using monolayer formed by epithelial cells from the human colon (Caco-2 cell) have been extensively used for evaluating the permeability, bioavailability, intestinal transport, and metabolism of toxic and biologically active compounds. Here, the strengths and limitations of both in vivo and in vitro techniques used to determine bioavailability are reviewed, along with current detailed data about biotransformation of mycotoxins. Furthermore, the molecular mechanism of mycotoxin effects is also discussed regarding the disorder of intestinal barrier integrity induced by mycotoxins.

ACS Style

Van Nguyen Tran; Jitka Viktorová; Tomáš Ruml. Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer. Toxins 2020, 12, 628 .

AMA Style

Van Nguyen Tran, Jitka Viktorová, Tomáš Ruml. Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer. Toxins. 2020; 12 (10):628.

Chicago/Turabian Style

Van Nguyen Tran; Jitka Viktorová; Tomáš Ruml. 2020. "Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer." Toxins 12, no. 10: 628.

Journal article
Published: 11 July 2020 in Antibiotics
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The inhibition and eradication of oral biofilms is increasingly focused on the use of plant extracts as mouthwashes and toothpastes adjuvants. Here, we report on the chemical composition and the antibiofilm activity of 15 methanolic extracts of Iris species against both mono-(Pseudomonas aeruginosa, Staphylococcus aureus) and multi-species oral biofilms (Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum subsp. nucleatum, and Actinomyces naeslundii). The phytochemical profiles of Iris pallida s.l., Iris versicolor L., Iris lactea Pall., Iris carthaliniae Fomin, and Iris germanica were determined by ultra-high performance liquid chromatography-high-resolution tandem mass spectroscopy (UHPLC-HRMS/MS) analysis, and a total of 180 compounds were identified among Iris species with (iso)flavonoid dominancy. I. pallida, I. versicolor, and I. germanica inhibited both the quorum sensing and adhesion during biofilm formation in a concentration-dependent manner. However, the extracts were less active against maturated biofilms. Of the five tested species, Iris pallida s.l. was the most effective at both inhibiting biofilm formation and disrupting existing biofilms, and the leaf extract exhibited the strongest inhibitory effect compared to the root and rhizome extracts. The cytotoxicity of the extracts was excluded in human fibroblasts. The inhibition of bacterial adhesion significantly correlated with myristic acid content, and quorum sensing inhibition correlated with the 7-β-hydroxystigmast-4-en-3-one content. These findings could be useful for establishing an effective tool for the control of oral biofilms and thus dental diseases.

ACS Style

Lan Hoang; František Beneš; Marie Fenclová; Olga Kronusová; Viviana Švarcová; Kateřina Řehořová; Eva Baldassarre Švecová; Miroslav Vosátka; Jana HajšLová; Petr Kaštánek; Jitka Viktorová; Tomáš Ruml. Phytochemical Composition and In Vitro Biological Activity of Iris spp. (Iridaceae): A New Source of Bioactive Constituents for the Inhibition of Oral Bacterial Biofilms. Antibiotics 2020, 9, 403 .

AMA Style

Lan Hoang, František Beneš, Marie Fenclová, Olga Kronusová, Viviana Švarcová, Kateřina Řehořová, Eva Baldassarre Švecová, Miroslav Vosátka, Jana HajšLová, Petr Kaštánek, Jitka Viktorová, Tomáš Ruml. Phytochemical Composition and In Vitro Biological Activity of Iris spp. (Iridaceae): A New Source of Bioactive Constituents for the Inhibition of Oral Bacterial Biofilms. Antibiotics. 2020; 9 (7):403.

Chicago/Turabian Style

Lan Hoang; František Beneš; Marie Fenclová; Olga Kronusová; Viviana Švarcová; Kateřina Řehořová; Eva Baldassarre Švecová; Miroslav Vosátka; Jana HajšLová; Petr Kaštánek; Jitka Viktorová; Tomáš Ruml. 2020. "Phytochemical Composition and In Vitro Biological Activity of Iris spp. (Iridaceae): A New Source of Bioactive Constituents for the Inhibition of Oral Bacterial Biofilms." Antibiotics 9, no. 7: 403.

Journal article
Published: 25 May 2020 in Antioxidants
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Silybin is considered to be the main biologically active component of silymarin. Its oxidized derivative 2,3-dehydrosilybin typically occurs in silymarin in small, but non-negligible amounts (up to 3%). Here, we investigated in detail complex biological activities of silybin and 2,3-dehydrosilybin optical isomers. Antioxidant activities of pure stereomers A and B of silybin and 2,3-dehydrosilybin, as well as their racemic mixtures, were investigated by using oxygen radical absorption capacity (ORAC) and cellular antioxidant activity (CAA) assay. All substances efficiently reduced nitric oxide production and cytokines (TNF-α, IL-6) release in a dose-dependent manner. Multidrug resistance (MDR) modulating potential was evaluated as inhibition of P-glycoprotein (P-gp) ATPase activity and regulation of ATP-binding cassette (ABC) protein expression. All the tested compounds showed strong dose-dependent inhibition of P-gp pump. Moreover, 2,3-dehydrosilybin A (30 µM) displayed the strongest sensitization of doxorubicin-resistant ovarian carcinoma. Despite these significant effects, silybin B was the only compound acting directly upon P-gp in vitro and also downregulating the expression of respective MDR genes. This compound altered the expression of P-glycoprotein (P-gp, ABCB1), multidrug resistance-associated protein 1 (MRP1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). 2,3-Dehydrosilybin AB exhibited the most effective inhibition of acetylcholinesterase activity. We can clearly postulate that silybin derivatives could serve well as modulators of a cancer drug-resistant phenotype.

ACS Style

Simona Dobiasová; Kateřina Řehořová; Denisa Kučerová; David Biedermann; Kristýna Káňová; Lucie Petrásková; Kamila Koucká; Radka Václavíková; Kateřina Valentová; Tomáš Ruml; Tomáš Macek; Vladimír Křen; Jitka Viktorová. Multidrug Resistance Modulation Activity of Silybin Derivatives and Their Anti-Inflammatory Potential. Antioxidants 2020, 9, 455 .

AMA Style

Simona Dobiasová, Kateřina Řehořová, Denisa Kučerová, David Biedermann, Kristýna Káňová, Lucie Petrásková, Kamila Koucká, Radka Václavíková, Kateřina Valentová, Tomáš Ruml, Tomáš Macek, Vladimír Křen, Jitka Viktorová. Multidrug Resistance Modulation Activity of Silybin Derivatives and Their Anti-Inflammatory Potential. Antioxidants. 2020; 9 (5):455.

Chicago/Turabian Style

Simona Dobiasová; Kateřina Řehořová; Denisa Kučerová; David Biedermann; Kristýna Káňová; Lucie Petrásková; Kamila Koucká; Radka Václavíková; Kateřina Valentová; Tomáš Ruml; Tomáš Macek; Vladimír Křen; Jitka Viktorová. 2020. "Multidrug Resistance Modulation Activity of Silybin Derivatives and Their Anti-Inflammatory Potential." Antioxidants 9, no. 5: 455.

Journal article
Published: 05 May 2020 in Foods
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With strong antimicrobial properties, citral has been repeatedly reported to be the dominant component of lemongrass essential oil. Here, we report on a comparison of the antimicrobial and anticancer activity of citral and lemongrass essential oil. The lemongrass essential oil was prepared by the vacuum distillation of fresh Cymbopogon leaves, with a yield of 0.5% (w/w). Citral content was measured by gas chromatography/high-resolution mass spectrometry (GC-HRMS) and determined to be 63%. Antimicrobial activity was tested by the broth dilution method, showing strong activity against all tested bacteria and fungi. Citral was up to 100 times more active than the lemongrass essential oil. Similarly, both citral and essential oils inhibited bacterial communication and adhesion during P. aeruginosa and S. aureus biofilm formation; however, the biofilm prevention activity of citral was significantly higher. Both the essential oil and citral disrupted the maturated P. aeruginosa biofilm with the IC50 7.3 ± 0.4 and 0.1 ± 0.01 mL/L, respectively. Although it may seem that the citral is the main biologically active compound of lemongrass essential oil and the accompanying components have instead antagonistic effects, we determined that the lemongrass essential oil-sensitized methicillin-resistant S. aureus (MRSA) and doxorubicin-resistant ovarian carcinoma cells and that this activity was not caused by citral. A 1 mL/L dose of oil-sensitized MRSA to methicillin up to 9.6 times and a dose of 10 µL/L-sensitized ovarian carcinoma to doxorubicin up to 1.8 times. The mode of multidrug resistance modulation could be due to P-glycoprotein efflux pump inhibition. Therefore, the natural mixture of compounds present in the lemongrass essential oil provides beneficial effects and its direct use may be preferred to its use as a template for citral isolation.

ACS Style

Jitka Viktorová; Michal Stupák; Kateřina Řehořová; Simona Dobiasová; Lan Hoang; Jana HajšLová; Tran Van Thanh; Le Van Tri; Nguyen Van Tuan; Tomáš Ruml. Lemon Grass Essential Oil does not Modulate Cancer Cells Multidrug Resistance by Citral—Its Dominant and Strongly Antimicrobial Compound. Foods 2020, 9, 585 .

AMA Style

Jitka Viktorová, Michal Stupák, Kateřina Řehořová, Simona Dobiasová, Lan Hoang, Jana HajšLová, Tran Van Thanh, Le Van Tri, Nguyen Van Tuan, Tomáš Ruml. Lemon Grass Essential Oil does not Modulate Cancer Cells Multidrug Resistance by Citral—Its Dominant and Strongly Antimicrobial Compound. Foods. 2020; 9 (5):585.

Chicago/Turabian Style

Jitka Viktorová; Michal Stupák; Kateřina Řehořová; Simona Dobiasová; Lan Hoang; Jana HajšLová; Tran Van Thanh; Le Van Tri; Nguyen Van Tuan; Tomáš Ruml. 2020. "Lemon Grass Essential Oil does not Modulate Cancer Cells Multidrug Resistance by Citral—Its Dominant and Strongly Antimicrobial Compound." Foods 9, no. 5: 585.

Journal article
Published: 28 February 2020 in Toxins
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Mycotoxins found in randomly selected commercial milk thistle dietary supplement were evaluated for their toxicity in silico and in vitro. Using in silico methods, the basic physicochemical, pharmacological, and toxicological properties of the mycotoxins were predicted using ACD/Percepta. The in vitro cytotoxicity of individual mycotoxins was determined in mouse macrophage (RAW 264.7), human hepatoblastoma (HepG2), and human embryonic kidney (HEK 293T) cells. In addition, we studied the bioavailability potential of mycotoxins and silibinin utilizing an in vitro transwell system with differentiated human colon adenocarcinoma cells (Caco-2) simulating mycotoxin transfer through the intestinal epithelial barrier. The IC50 values for individual mycotoxins in studied cells were in the biologically relevant ranges as follows: 3.57–13.37 nM (T-2 toxin), 5.07–47.44 nM (HT-2 toxin), 3.66–17.74 nM (diacetoxyscirpenol). Furthermore, no acute toxicity was obtained for deoxynivalenol, beauvericin, zearalenone, enniatinENN-A, enniatin-A1, enniatin-B, enniatin-B1, alternariol, alternariol-9-methyl ether, tentoxin, and mycophenolic acid up to the 50 nM concentration. The acute toxicity of these mycotoxins in binary combinations exhibited antagonistic effects in the combinations of T-2 with DON, ENN-A1, or ENN-B, while the rest showed synergistic or additive effects. Silibinin had a significant protective effect against both the cytotoxicity of three mycotoxins (T-2 toxin, HT-2 toxin, DAS) and genotoxicity of AME, AOH, DON, and ENNs on HEK 293T. The bioavailability results confirmed that AME, DAS, ENN-B, TEN, T-2, and silibinin are transported through the epithelial cell layer and further metabolized. The bioavailability of silibinin is very similar to mycotoxins poor penetration.

ACS Style

Van Nguyen Tran; Jitka Viktorova; Katerina Augustynkova; Nikola Jelenova; Simona Dobiasova; Katerina Rehorova; Marie Fenclova; Milena Stranska-Zachariasova; Libor Vitek; Jana Hajslova; Tomas Ruml. In Silico and In Vitro Studies of Mycotoxins and Their Cocktails; Their Toxicity and Its Mitigation by Silibinin Pre-Treatment. Toxins 2020, 12, 148 .

AMA Style

Van Nguyen Tran, Jitka Viktorova, Katerina Augustynkova, Nikola Jelenova, Simona Dobiasova, Katerina Rehorova, Marie Fenclova, Milena Stranska-Zachariasova, Libor Vitek, Jana Hajslova, Tomas Ruml. In Silico and In Vitro Studies of Mycotoxins and Their Cocktails; Their Toxicity and Its Mitigation by Silibinin Pre-Treatment. Toxins. 2020; 12 (3):148.

Chicago/Turabian Style

Van Nguyen Tran; Jitka Viktorova; Katerina Augustynkova; Nikola Jelenova; Simona Dobiasova; Katerina Rehorova; Marie Fenclova; Milena Stranska-Zachariasova; Libor Vitek; Jana Hajslova; Tomas Ruml. 2020. "In Silico and In Vitro Studies of Mycotoxins and Their Cocktails; Their Toxicity and Its Mitigation by Silibinin Pre-Treatment." Toxins 12, no. 3: 148.

Journal article
Published: 18 August 2019 in Antioxidants
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Numerous in vitro assays are used to characterize the antioxidant properties of natural-based matrices. However, many of them generate contradictory and non-compliant results. In our study, we focused on the characterization of traditionally used biochemical (2,2'-azino-bis-(3-ethylbenzothiazoline-6 sulfonic acid) (ABTS), Oxygen Radical Absorption Capacity (ORAC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH)) and cellular (CAA) antioxidant tests on a broad set of milk thistle dietary supplements containing silymarin. In addition to 26 commercially available preparations, also the natural silymarin extract available from Sigma Aldrich, St. Louis, MI, USA, and a model mixture of pure flavonoid/flavonolignans mimicking the silymarin composition were investigated as control samples. Significant differences in the antioxidant capacity of the supplements were observed. Unlike the DPPH, the results of the ABTS and ORAC methods correlated with the silymarin components determined by U-HPLC-HRMS/MS. The responses in CAA were considerably lower than in other assays. Silymarin exhibited a significantly higher antioxidant capacity than the artificially prepared flavonoid/flavonolignans mixture in all tests, indicating possible presence of other antioxidants of natural origin. The follow-up U-HPLC-HRMS/MS screening revealed the presence of tens of non-silymarin compounds with reported antioxidant activity (not only in the silymarin extract, but also in the milk thistle preparations). The sum of the total phenolics and the sum of the simple phenolics correlated with CAA results more than silymarin.

ACS Style

Jitka Viktorova; Milena Stranska-Zachariasova; Marie Fenclova; Libor Vitek; Jana Hajslova; Vladimir Kren; Tomas Ruml. Complex Evaluation of Antioxidant Capacity of Milk Thistle Dietary Supplements. Antioxidants 2019, 8, 317 .

AMA Style

Jitka Viktorova, Milena Stranska-Zachariasova, Marie Fenclova, Libor Vitek, Jana Hajslova, Vladimir Kren, Tomas Ruml. Complex Evaluation of Antioxidant Capacity of Milk Thistle Dietary Supplements. Antioxidants. 2019; 8 (8):317.

Chicago/Turabian Style

Jitka Viktorova; Milena Stranska-Zachariasova; Marie Fenclova; Libor Vitek; Jana Hajslova; Vladimir Kren; Tomas Ruml. 2019. "Complex Evaluation of Antioxidant Capacity of Milk Thistle Dietary Supplements." Antioxidants 8, no. 8: 317.

Journal article
Published: 14 August 2019 in Antioxidants
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Silychristin A is the second most abundant compound of silymarin. Silymarin complex was previously described as an antioxidant with multidrug resistance modulation activity. Here, the results of a classical biochemical antioxidant assay (ORAC) were compared with a cellular assay evaluating the antioxidant capacity of pure silychristin A and its derivatives (anhydrosilychristin, isosilychristin and 2,3-dehydrosilychristin A). All the tested compounds acted as antioxidants within the cells, but 2,3-dehydro- and anhydro derivatives were almost twice as potent as the other tested compounds. Similar results were obtained in LPS-stimulated macrophages, where 2,3-dehydro- and anhydrosilychristin inhibited NO production nearly twice as efficiently as silychristin A. The inhibition of P-glycoprotein (P-gp) was determined in vitro, and the respective sensitization of doxorubicin-resistant ovarian carcinoma overproducing P-gp was detected. Despite the fact that the inhibition of P-gp was demonstrated in a concentration-dependent manner for each tested compound, the sensitization of the resistant cell line was observed predominantly for silychristin A and 2,3-dehydrosilychristin A. However, anhydrosilychristin and isosilychristin affected the expression of both the P-gp (ABCB1) and ABCG2 genes. This is the first report showing that silychristin A and its 2,3-dehydro-derivative modulate multidrug resistance by the direct inhibition of P-gp, in contrast to anhydrosilychristin and isosilychristin modulating multidrug resistance by downregulating the expression of the dominant transmembrane efflux pumps.

ACS Style

Jitka Viktorová; Simona Dobiasová; Kateřina Řehořová; David Biedermann; Kristýna Káňová; Karolína Šeborová; Radka Václavíková; Kateřina Valentová; Tomáš Ruml; Vladimír Křen; Tomáš Macek. Antioxidant, Anti-Inflammatory, and Multidrug Resistance Modulation Activity of Silychristin Derivatives. Antioxidants 2019, 8, 303 .

AMA Style

Jitka Viktorová, Simona Dobiasová, Kateřina Řehořová, David Biedermann, Kristýna Káňová, Karolína Šeborová, Radka Václavíková, Kateřina Valentová, Tomáš Ruml, Vladimír Křen, Tomáš Macek. Antioxidant, Anti-Inflammatory, and Multidrug Resistance Modulation Activity of Silychristin Derivatives. Antioxidants. 2019; 8 (8):303.

Chicago/Turabian Style

Jitka Viktorová; Simona Dobiasová; Kateřina Řehořová; David Biedermann; Kristýna Káňová; Karolína Šeborová; Radka Václavíková; Kateřina Valentová; Tomáš Ruml; Vladimír Křen; Tomáš Macek. 2019. "Antioxidant, Anti-Inflammatory, and Multidrug Resistance Modulation Activity of Silychristin Derivatives." Antioxidants 8, no. 8: 303.

Journal article
Published: 23 July 2019 in Antioxidants
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Antioxidants protect the structural and functional components in organisms against oxidative stress. Most antioxidants are of plant origin as the plants are permanently exposed to oxidative stress (UV radiation, photosynthetic reactions). Both carotenoids and flavonoids are prominent antioxidant and anti-radical agents often occurring together in the plant tissues and acting in lipophilic and hydrophilic milieu, respectively. They are complementary in their anti-radical activity. This study describes the synthesis of a series of hybrid ester conjugates of retinoic acid with various flavonolignans, such as silybin, 2,3-dehydrosilybin and isosilybin. Antioxidant/anti-radical activities and bio-physical properties of novel covalent carotenoid-flavonoid hybrids, as well as various mixtures of the respective parent components, were investigated. Retinoyl conjugates with silybin—which is the most important flavonolignan in silymarin complex—(and its pure diastereomers) displayed better 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than both the parent compounds and their equimolar mixtures.

ACS Style

Christopher S. Chambers; David Biedermann; Kateřina Valentová; Lucie Petrásková; Jitka Viktorová; Marek Kuzma; Vladimír Křen. Preparation of Retinoyl-Flavonolignan Hybrids and Their Antioxidant Properties. Antioxidants 2019, 8, 236 .

AMA Style

Christopher S. Chambers, David Biedermann, Kateřina Valentová, Lucie Petrásková, Jitka Viktorová, Marek Kuzma, Vladimír Křen. Preparation of Retinoyl-Flavonolignan Hybrids and Their Antioxidant Properties. Antioxidants. 2019; 8 (7):236.

Chicago/Turabian Style

Christopher S. Chambers; David Biedermann; Kateřina Valentová; Lucie Petrásková; Jitka Viktorová; Marek Kuzma; Vladimír Křen. 2019. "Preparation of Retinoyl-Flavonolignan Hybrids and Their Antioxidant Properties." Antioxidants 8, no. 7: 236.

Research article
Published: 10 May 2019 in PLOS ONE
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Although many genetic manipulations of crops providing biofortified or safer food have been done, the acceptance of biotechnology crops still remains limited. We report on a transgenic barley expressing the multi-functional protein osmotin that improves plant defense under stress conditions. An Agrobacterium-mediated technique was used to transform immature embryos of the spring barley cultivar Golden Promise. Transgenic barley plants of the T0 and T1 generation were evaluated by molecular methods. Transgenic barley tolerance to stress was determined by chlorophyll, total protein, malondialdehyde and ascorbate peroxidase content. Methanol extracts of i) Fusarium oxysporum infected or ii) salt-stressed plants, were characterized by their acute toxicity effect on human dermal fibroblasts (HDF), genotoxicity and affection of biodiversity interactions, which was tested through monitoring barley natural virus pathogen-host interactions-the BYDV and WDV viruses transmitted to the plants by aphids and leafhoppers. Transgenic plants maintained the same level of chlorophyll and protein, which significantly declined in wild-type barley under the same stressful conditions. Salt stress evoked higher ascorbate peroxidase level and correspondingly less malondialdehyde. Osmotin expressing barley extracts exhibited a lower cytotoxicity effect of statistical significance than that of wild-type plants under both types of stress tested on human dermal fibroblasts. Extract of Fusarium oxysporum infected transgenic barley was not able to damage DNA in the Comet assay, which is in opposite to control plants. Moreover, this particular barley did not affect the local biodiversity. Our findings provide a new perspective that could help to evaluate the safety of products from genetically modified crops.

ACS Style

Jitka Viktorova; Barbora Klcova; Katerina Rehorova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Pavel Cejnar; Jiban Kundu; Ludmila Ohnoutkova; Tomas Macek. Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions. PLOS ONE 2019, 14, e0212718 .

AMA Style

Jitka Viktorova, Barbora Klcova, Katerina Rehorova, Tomas Vlcko, Lucie Stankova, Nikola Jelenova, Pavel Cejnar, Jiban Kundu, Ludmila Ohnoutkova, Tomas Macek. Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions. PLOS ONE. 2019; 14 (5):e0212718.

Chicago/Turabian Style

Jitka Viktorova; Barbora Klcova; Katerina Rehorova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Pavel Cejnar; Jiban Kundu; Ludmila Ohnoutkova; Tomas Macek. 2019. "Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions." PLOS ONE 14, no. 5: e0212718.

Preprint content
Published: 11 February 2019
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SummaryAlthough many genetic manipulations of crops providing biofortified or safer food have been prepared, the acceptance of biotechnology crops still remains limited. We report on a transgenic barley expressing the multi-functional protein osmotin that improves plant defense under stress conditions. An Agrobacterium–mediated technique was used to transform immature embryos of the spring barley cultivar Golden Promise. Transgenic barley plants of the T0 and T1 generations were evaluated by molecular methods.Transgenic barley tolerance to stress was determined by chlorophyll, total protein, malondialdehyde and ascorbate peroxidase content. Transgenic plants maintained the same level of chlorophyll and protein, which significantly declined in wild-type barley under the same stressful conditions. Salt stress evoked higher ascorbate peroxidase level and correspondingly less malondialdehyde. Methanol extracts of i) Fusarium oxysporum infected or ii) salt-stressed plants, were characterized by their acute toxicity effect on human dermal fibroblasts (HDF). Osmotin expressing barley extracts exhibited a lower cytotoxicity effect of statistical significance than that of wild-type plants under both types of stress tested on human dermal fibroblasts. Extract of Fusarium oxysporum infected transgenic barley was not able to damage DNA in Comet assay, which is in opposite to control plants. Moreover, this particular barley did not affect the local biodiversity interactions, which was tested through monitoring barley natural virus pathogen – host interactions – the BYDV and WDV viruses transmitted to the plants by aphids and leafhoppers. Our findings provide a new perspective which could help to evaluate the safety of products from genetically modified crops.

ACS Style

Jitka Viktorova; Barbora Klcova; Katerina Rehorova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Pavel Cejnar; Jiban Kumar Kundu; Ludmila Ohnoutkova; Tomas Macek. Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions. 2019, 546721 .

AMA Style

Jitka Viktorova, Barbora Klcova, Katerina Rehorova, Tomas Vlcko, Lucie Stankova, Nikola Jelenova, Pavel Cejnar, Jiban Kumar Kundu, Ludmila Ohnoutkova, Tomas Macek. Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions. . 2019; ():546721.

Chicago/Turabian Style

Jitka Viktorova; Barbora Klcova; Katerina Rehorova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Pavel Cejnar; Jiban Kumar Kundu; Ludmila Ohnoutkova; Tomas Macek. 2019. "Recombinant expression of osmotin in barley improves stress resistance and food safety during adverse growing conditions." , no. : 546721.

Journal article
Published: 08 November 2018 in Journal of Pharmacy and Pharmacology
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ACS Style

Katerina Rehorova; Jitka Viktorova; Barbora Macuchova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Ludmila Ohnoutkova; Tomas Macek. Limen, Non-Toxic Recombinant Plant Defensin and Its Effect against Pathogenic Yeast and Fungi. Journal of Pharmacy and Pharmacology 2018, 6, 1 .

AMA Style

Katerina Rehorova, Jitka Viktorova, Barbora Macuchova, Tomas Vlcko, Lucie Stankova, Nikola Jelenova, Ludmila Ohnoutkova, Tomas Macek. Limen, Non-Toxic Recombinant Plant Defensin and Its Effect against Pathogenic Yeast and Fungi. Journal of Pharmacy and Pharmacology. 2018; 6 (11):1.

Chicago/Turabian Style

Katerina Rehorova; Jitka Viktorova; Barbora Macuchova; Tomas Vlcko; Lucie Stankova; Nikola Jelenova; Ludmila Ohnoutkova; Tomas Macek. 2018. "Limen, Non-Toxic Recombinant Plant Defensin and Its Effect against Pathogenic Yeast and Fungi." Journal of Pharmacy and Pharmacology 6, no. 11: 1.