Nóra Gyémánt

University of Pécs, Pécs, Baranya megye, Hungary

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Publications (12)18.88 Total impact

  • Article: Carotenoid composition and in vitro pharmacological activity of rose hips.
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    ABSTRACT: The aim of the present study was to compare carotenoid extracts of Rose hips (Rosa canina L.) with regard to their phytochemical profiles and their in vitro anti-Helicobacter pylori (H. pylori), cytotoxic, multidrug resistance (MDR) reversal and radical scavenging activity. Carotenoid composition was investigated in the different fractionation of rose hips, using extraction methods. Six main carotenoids - epimers of neochrome, lutein, zeaxanthin, rubixanthin, lycopene, β,β-carotene - were identified from Rose hips by their chromatographic behavior and UV-visible spectra, which is in accordance with other studies on carotenoids in this plant material. The active principles in the carotenoid extract might differ, depending upon the extraction procedures.
    Acta biochimica Polonica 03/2012; 59(1):129-32. · 1.49 Impact Factor
  • Article: Carotenoids with anti-Helicobacter pylori activity from Golden delicious apple.
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    ABSTRACT: Previously it was reported that hypophasic carotenoids of Golden delicious apple peel showed potent anti-H. pylori activity (MIC(50) = 36 microg/mL), comparable to metronidazole (MIC(50) = 45 microg/mL). To further investigate the involved active carotenoids of the apple peel extracts, seven carotenoids were isolated for the current study: (all-E)-luteoxanthin, (all-E)-neoxanthin, (9'Z)-neoxanthin, (all-E)-antheraxanthin, (all-E)-violaxanthin, (9Z)-violaxanthin and (all-E)-lutein. The MIC(50) values of (all-E)-luteoxanthin, (all-E)-neoxanthin and (9'Z)-neoxanthin were 7.9, 11 and 27 microg/mL, respectively. Other carotenoids and beta,beta-carotene did not exhibit potent anti-H. pylori activity (MIC(50) > 100 microg/mL). An examination of structure and function suggested that active carotenoids contained a monofuranoid ring or an allenic bond in addition to an epoxy group and an additional two or three hydroxyl substituents on the side group.
    Phytotherapy Research 07/2009; 24(5):644-8. · 2.09 Impact Factor
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    Article: Interaction of tomato lectin with ABC transporter in cancer cells: glycosylation confers functional conformation of P-gp.
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    ABSTRACT: Phospho-glycoprotein (P-gp) is a polytopic plasma membrane protein whose overexpression causes multidrug resistance (MDR) responsible for the failure of cancer chemotherapy. P-gp 170 is a member of the ATP-binding cassette (ABC) transporter superfamily and has two potentially interesting regions for drugs interfering with its efflux function, namely the oligosaccharides on the first extracellular loop with unknown function and the two intracellular ATP-binding regions providing the energy for drug efflux function. The polylactoseamine oligosaccharides on the first loop can specifically bind the tomato lectin (TL). The P-gp efflux activities of TL-pre-treated MDR resistant cells were measured in the presence of structurally unrelated resistance modifiers such as phenothiazines, terpenoids and carotenoids. The inhibition of efflux activity was measured via the increased rhodamine uptake by mouse lymphoma cells transfected in human MDR1 gene and in human brain capillary endothelial cells. The tested resistance modifiers inhibit the function of ABC transporter resulting in increased R123 accumulation in MDR1 expressing cells. TL prevented the inhibitory action of phenothiazine and verapamil on brain capillary endothelial and MDR1-lymphoma cells, presumably due to the stabilization of the functional active conformation of P-gp. Our results indicate that the polylactosamine chains of P-gp are part of the functionally active protein conformation.
    Acta histochemica 02/2009; 111(4):329-33. · 1.23 Impact Factor
  • Article: Inhibition of multidrug resistance of cancer cells by natural diterpenes, triterpenes and carotenoids.
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    ABSTRACT: The multidrug resistance (MDR) proteins are member of the ATP-binding cassette superfamily and are present in a majority of human tumors. Their activity is a crucial factor leading to therapeutic failure. It is likely that compounds which inhibit the function of the MDR-efflux proteins such as MDR1 will improve the cytotoxic action of anticancer chemotherapy. Therefore, a search for MDR reversing compounds was conducted among three classes of plant derived compounds such as diterpenes, triterpenes and carotenoids in a hope to find inhibitors without adverse effects in these natural compounds. The inhibition of efflux activity was determined by measuring the accumulation of substrate analogues such as rhodamine in tumor cells in the presence of potential inhibitors. Thus we determined the effect of structurally unrelated diterpenes, triterpenes and carotenoids on reversal of multidrug resistance in MDR-1 gene-transfected L1210 mouse lymphoma cells and MDR mediated multidrug resistance of human breast cancer cells MDA-MB-231 (HTB-26) and MCF-7. The majority of diterpenes, cycloartane triterpenes and carotenoids isolated from vegetables and medicinal plants were able to enhance rhodamine 123 accumulations of MDR-cells. Synergistic interaction was found between epirubicine and resistance modifier terpenoids in vitro. It is supposed that these MDR modulators bind into transmembrane domains and the action of ABC transporters is inhibited by induced conformational changes.
    Current Pharmaceutical Design 02/2006; 12(3):287-311. · 3.87 Impact Factor
  • Article: Biological activity of carotenoids in red paprika, Valencia orange and Golden delicious apple.
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    ABSTRACT: Carotenoid fractions were extracted from red paprika, Valencia orange peel and the peel of Golden delicious apple. Thus, hypophasic carotenoids of paprika (PM1), orange (PM3) and apple (PM4), and epiphasic extractions of paprika (PM2) and apple (PM5) were obtained by extraction, saponification and partition between MeOH-H(2)O (9:1) (hypophasic) and hexane (epiphasic). A high content of capsanthin was quantified in hypophasic carotenoids (PM1) from red spice paprika, whereas the hypophasic fractions from orange (PM3) and apple (PM4) were mainly composed of violaxanthin, zeaxanthin and lutein. On the other hand, a high content of beta,beta-carotene and beta-cryptoxanthin was found in epiphasic fractions (PM2 and PM5). The extracts were studied for their anti-Helicobacter pylori (H. pylori), anti-human immunodeficiency virus (HIV), cytotoxic, multidrug resistance (MDR) reversal and radical scavenging activity. Among five PM extracts and beta,betacarotene, PM4 showed potent anti-H. pylori activity (MIC(50) = 36 microg/mL), comparable to metronidazole (MIC(50) = 45 microg/mL). The extracts were inactive against HIV. PM3 and PM4 showed slightly higher cytotoxic activity against three human tumor cell lines (squamous cell carcinoma HSC-2, HSC-3, submandibular gland carcinoma HSG) and human promyelocytic leukemic HL-60 cells than against three normal human oral cells (gingival fibroblast HGF, pulp cell HPC, periodontal ligament fibroblast HPLF), suggesting a tumor-specific cytotoxic activity. PM1, PM3 and PM4 displayed much higher MDR-reversing activity than (+/-)-verapamil. ESR spectroscopy demonstrated that PM1-5 and beta,beta-carotene produced little or no detectable radical under alkaline conditions and did not scavenge the O(2) (-) produced by the hypoxanthine and xanthine oxidase reaction. On the other hand, PM1 and PM2 scavenged efficiently 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, whereas singlet oxygen was also quenched efficiently by PM5 and PM2. The data suggest the potential importance of carotenoids as possible anti-H. pylori and MDR reversal agents. The active principles in the carotenoid extract might differ, depending upon the types of fruits and vegetables.
    Phytotherapy Research 09/2005; 19(8):700-7. · 2.09 Impact Factor
  • Article: Biological activity of barbados cherry (acerola fruits, fruit of Malpighia emarginata DC) extracts and fractions.
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    ABSTRACT: Fractionation of barbados cherry (acerola fruit, a fruit of Malpighia emarginata DC.) extracts were performed by organic solvent extractions and column chromatographies, using two extraction methods. Higher cytotoxic activity was concentrated in fractions A4 and A6 (acetone extract), and H3 and HE3 (hexane extract). These four fractions showed higher cytotoxic activity against tumor cell lines such as human oral squamous cell carcinoma (HSC-2) and human submandibular gland carcinoma (HSG), when compared with that against normal cells such as human periodontal ligament fibroblasts (HPLF) and human gingival fibroblasts (HGF). HE2 (hexane extract), AE2 (ethyl acetate extract), AE3, AE4, AE5, A8, A9 and A10 showed some relatively higher anti-bacterial activity on the Gram-positive Staphylococcus epidermidis ATCC 1228 but were ineffective on the representative Gram-negative species E. coli and Ps. aeruginosa. The fractions were inactive against Helicobacter pylori, two representative Candida species, and human immunodeficiency virus (HIV). H3, H4 and HE3, which displayed higher tumor-specific cytotoxicity also showed higher multidrug resistance (MDR) reversal activity, than (+/-)-verapamil as positive control. ESR spectroscopy shows that the radical-mediated oxidation is not involved in the induction of tumor-specific cytotoxic activity. The tumor specific cytotoxic activity and MDR reversal activity of barbados cherry may suggest its possible application for cancer therapy.
    Phytotherapy Research 04/2004; 18(3):212-23. · 2.09 Impact Factor
  • Article: Bacterial models for tumor development. Mini-review.
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    ABSTRACT: The tumor-inducing effects of Agrobacterium, Bartonella and Helicobacter bacterial species are compared step by step. An analogy for the existence of these individual steps is considered in connection with the development of cancer. The transformations of eukaryotic cells occur in particular in the type IV secretion system, i.e. involving the simultaneous transmission of DNA and protein from bacterial cells to eukaryotic cells. Thus, transfected cells facilitate the indefinite growth of tissue cells and additionally produce growth factors, triggering further bacterial multiplication. The higher numbers of bacteria then produce more transfection and the cycle repeats as long as the host lives. The main limiting factor is the frequency of bacterial infection, while the secondary rate-limiting factors are the levels of transforming growth factors and factors triggering bacteria growth. CONCLUSIONS: Analogous processes are probably responsible for the tumor induction by the three different bacterial species; however, the critical points for eradication are different. The early eradication or limitation of B. henselae or H. pylori can prevent hemangiomas, stomach cancer and malignant cell proliferation. The crown gall formation by A. tumefaciens can only be avoided by prevention of the transforming activity of a single bacterial infection. Questions arise as to what is common in the three processes, and the nature of the rate-limiting step in the three different models. The frequency of transformation is the rate-limiting step, but the co-transmission of the DNA-protein complex is common in the three systems.
    Acta Microbiologica et Immunologica Hungarica 02/2004; 51(3):321-32. · 0.79 Impact Factor
  • Chapter: Multidrug Resistance Reversal on Cancer Cells by Selected Carotenoids, Flavonoids and Anthocyanins
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    ABSTRACT: The multidrug resistance (MDR) proteins which belong to the ATP-binding cassette superfamily are present in amajority of human tumors and are an important final cause of therapeutic failure. Therefore, some compounds which inhibit the function of the MDR-efflux proteins may improve the cytotoxic action in cancer chemotherapy. The mechanism of action was believed to be acompetition between their resistance modifiers and the cytotoxic agents for the same binding site of MDR P-glycoprotein (P-gp) due to acomplementarity with ahypothetic receptor site with unknown structure. In the absence of the crystal structures of the P-gp, areceptor fitting was not available. Therefore, we tried to indirectly define the receptor structure or mapping of human MDR1-encoded P-gp in the presence of the structurally unrelated carotenoids, flavonoids, isoflavones and terpenoids. The inhibition of the efflux activity was measured by the increase of rhodamine 123 (R123) uptake by cancer cells. The effects of flavonoids, carotenoids and anthocyanins were studied on the activity of the MDR-1 gene-encoded efflux pump system. The effective flavonoids were rotenone, chrysin, phloretin and sakuranetin, which could inhibit the MDR efflux pump in the mouse lymphoma and colon cancer cells. The carotenoids isolated from paprika and other vegetables were tested on the increase of R123 accumulation of human MDR-1 gene-transfected L1210 mouse lymphoma cells and human breast cancer cells MDA-MB-231 (HTB-26). Capsanthin and capsorubin enhanced the R123 accumulation 30-fold relative to the nontreated lymphoma cells. Lycopene, lutein, antheraxanthin and violaxanthin had moderate effects, whereas α- and β-carotene had no effect on the reversal of MDR in the cancer cells. The MDR reversal of anthocyanins such as callistephin chloride, pelargonin chloride, ideaninchloride and pelargonidin chloride were studied. Cyanin chloride slightly increased the activity of P-gp; however, all other flavonoids were ineffective as resistance modifiers. Their biological ineffectivity is possibly related to the differences on the polarities of their compounds and permanent positive charge.
    01/1970: pages 133-159;
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    Article: Cinnamylidene ketones as potential modulators of multidrug resistance in mouse lymphoma and human colon cancer cell lines.
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    ABSTRACT: The resistance to chemotherapy of cancer cells is mediated by the overexpression of P-glycoprotein, as an ATP-dependent membrane efflux pump. Two families of compounds have been screened, the cinnamylidenecycloalkanones and cinnamylidenebenzocycloalkanones, as promising multidrug resistance (MDR) reversal agents on mouse lymphoma and human colon cancer (COL0320) cell lines. The antiproliferative effects of the cinnamylidene derivatives were tested with the MTT method The MDR effect on drug accumulation was tested by flow cytometry. Combinations of resistance modifiers and cytostatics were tested on the two cell lines to obtain evidence for additive or synergistic interactions. Verapamil was applied as a resistance-modifying positive control. The best effects in the reversal of MDR in both cell lines were exhibited by the methoxy derivatives 2-(2-methaoxycinnamylidene)indan-1-one, 2-(2-methoxycinnamylidene)-3,4-dihydro-2H-naphthalen-1-one, 6-(2-methoxycinnamylidene)-6,7,8,9-tetrahydrocyclohepten-5-one), 2-cinnamylidene-3,4-dihydro-2H-naphthalen-1-one and 6-cinnamylidene-6,7,8,9-tetrahydrobenzocyclohepten-5-one. 2-(2-methoxycinnamylidene) indan-1-one and 2-(2-methoxy-cinnamylidene)-3,4-dihydro-2H-naphthalen-1-one were able to enhance the antiproliferative activity of doxorubicin in a synergistic way.
    In vivo (Athens, Greece) 20(1):119-24. · 1.17 Impact Factor
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    Article: Modulation of multidrug resistance and apoptosis of cancer cells by selected carotenoids.
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    ABSTRACT: The multidrug resistance (MDR) proteins that belong to the ATP-binding casette superfamily are present in a majority of human tumors and are an important final cause of therapeutic failure. Therefore, compounds which inhibit the function of the MDR-efflux proteins may improve the cytotoxic action of anticancer chemotherapy. The effects of carotenoids were studied on the activity of the MDR-1 gene-encoded efflux pump system. The carotenoids, isolated from paprika and other vegetables, were tested on the rhodamine 123 accumulation of human MDR-1 gene-transfected L1210 mouse lymphoma cells and human breast cancer cells MDA-MB-231 (HTB-26). Capsanthin and capsorubin enhanced the rhodamine 123 accumulation 30-fold relative to nontreated lymphoma cells. Lycopene, lutein, antheraxanthin and violaxanthin had moderate effects, while alfa- and beta-carotene had no effect on the reversal of MDR in the tumor cells. Apoptosis was induced in human MDR1 transfected mouse lymphoma cells and human breast cancer MDA-MB-231 (HTB-26) cell lines in the presence of lycopene, zeaxanthin and capsanthin. The data suggest the potential of carotenoids as possible resistance modifiers in cancer chemotherapy.
    In vivo (Athens, Greece) 18(2):237-44. · 1.17 Impact Factor
  • Article: Modelling of tumour--host coexistence In vitro in the presence of serine protease inhibitors.
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    ABSTRACT: The activities of cell surface serine proteases are markedly enhanced in malignant tumours. Proteolytic degradation of the extracellular matrix and basal membrane of normal cells is an important event for tumour cell growth and invasion. Two well-known broad-spectrum inhibitors of serine protease, Foy-305 and Ono-3403, were evaluated for their ability to affect the growth rate and survival of MCF7 breast cancer cells co-cultured with MRC5 lung fibroblasts as feeder cells in the absence of serum. Flow cytometry and differential staining demonstrated that in the mixed culture, the rate of tumor growth was dependent upon the presence of the feeder MRC5 lung fibroblasts and could be obviated by the additional presence of the inhibitors of serine proteases.
    In vivo (Athens, Greece) 23(5):711-5. · 1.17 Impact Factor
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    Article: Reversal of multidrug resistance of cancer cells in vitro: modification of drug resistance by selected carotenoids.
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    ABSTRACT: The development of multidrug resistance (MDR) causes difficulties in the chemotherapy of of human cancer. Investigation of the possibility of reversal of MDR has been greatly aided by the use of cell lines with acquired resitance to anticancer agents in vitro or transfected with the mdrl gene. The aim of this study was to examine new perspectives of chemotherapy focused on natural, carotenoid compounds, in connection with the modification of MDR. The function of the MDR protein was examined via the R123 drug accumulation of both cell lines in the presence of carotenoids. The fluorescence of the cell population was measured by flow cytometry. The most effective resistance modifiers Monoepoxy-beta-carotene, (SS, 8S)-capsochrome, (8'S) Luteoxanthin, (9Z)-Violaxanthin, (9Z)-Zeaxanthin, (13Z)-Zeaxanthin were assayed for their antiproliferative effects in combination with the anti-cancer drug epirubicin. (13Z)-Zeaxanthin was able to enhance the antiproliferative effect on human mdrl gene transfected mouse lymphoma and anthracycline resistant human breast cancer cell line MCF7. (8'S)-luteoxanthin, (5S, 8S)-capsochrome and (9Z)-zeaxanthin treatment revealed synergism with epirubicin on resistant mouse lymphoma. The enhanced antiproliferative activity of epirubicin combinated with (9Z)-Violaxanthin was more significant on MCF7 cells resistant to anthracycline.
    Anticancer research 26(1A):367-74. · 1.73 Impact Factor

Institutions

  • 2005
    • University of Pécs
      • Institute of Biochemistry and Medical Chemistry
      Pécs, Baranya megye, Hungary
  • 2004
    • Meiji Pharmaceutical University
      Tokyo, Tokyo-to, Japan
  • 1970–2004
    • University of Szeged
      • Department of Medical Microbiology and Immunbiology
      Szeged, Csongrad megye, Hungary