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    Green bio-inspired synthesis, characterization and activity of silver nanoparticle forms of Centaurea virgata Lam. and the isolated flavonoid eupatorin
    (Walter De Gruyter Gmbh, 2018) Tuzun, Burcu Sumer; Hohmann, Judit; Kivcak, Bijen
    A green synthesis method of silver nanoparticles (AgNPs) using Centaurea virgata Lam. extract and the isolated compound eupatorin was investigated in this study. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis and zeta potential were used for characterization of AgNPs. The UV-Vis spectrum exhibited a characteristic absorption band at 420 nm for monodisperse nanoparticles. FTIR measurements also proved the formation. X-ray diffraction patterns showed peaks at (110) and (112), which are characteristic for hexagonal crystals and also showed peaks at (111), (200) and (240), which are characteristic for orthorhombic crystals. The TEM images of AgNPs show that the morphology of AgNPs was predominantly spherical. Obtained AgNPs were highly stable according to the zeta potential values. The nitric oxide scavenging activity, which is also related to anticancer activity, of AgNPs was evaluated. It can be concluded that C. virgata Lam. extract and eupatorin can be used as a reducing agent for potential antioxidant AgNP formation.
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    Isolation of Chemical Constituents of Centaurea virgata Lam. and Xanthine Oxidase Inhibitory Activity of the Plant Extract and Compounds
    (Bentham Science Publ Ltd, 2017) Tuezuen, Burcu S.; Hajdu, Zsuzsanna; Orban-Gyapai, Orsolya; Zomborszki, Zoltan P.; Jedlinszki, Nikoletta; Forgo, Peter; Kivcak, Bijen; Hohmann, Judit
    Background: Centaurea virgata Lam. is a species widely used in the traditional medicine in Turkey for the treatment of diabetes, allergy and gastric ulcers. The rationale of its use in the therapy has not been studied previously, therefore the present work aimed at the chemicalpharmacological evaluation of the plant. Objective: The xanthine oxidase (XO) inhibitory activity of the MeOH extract and its subextracts (n-hexane, CHCl3 and remaining MeOH-H2O) prepared from C. virgata was investigated in vitro. Moderate activity was exerted in case of the CHCl3 extract (98.9 +/- 15.8 mu g/mL), therefore constituents of this extract were analysed. Method: Different purification steps, such as VLC, CPC, PLC and crystallization were used for the isolation, and ESIMS, NMR, LC-MS and authentic standards were applied for identification of the compounds. XO inhibitory and DPPH assays were used for evaluation of the bioactivities. Results: Sesquiterpenes [8 alpha-hydroxysonchucarpolide, 8 alpha-(3,4-dihydroxy-2-methylenebutanoyloxy)-dehydromelitensine, and cnicin], flavones (apigenin, hispidulin, salvigenin, eupatorin, 3'-methyleupatorin), and the flavonol isokaempferide were isolated from the active extract. The XO-inhibitory activity of these compounds was analyzed using allopurinol as a positive control (IC50 7.49 +/- 0.29 +/- M). It was found that sesquiterpenes and flavonoids, containing 7OMe group, are inactive. Conclusion: 7-Hydroxyflavones (apigenin and hispidulin) exerted significant XO inhibitory effect with IC50 values of 0.99 +/- 0.33 +/- M and 4.88 +/- 1.21 +/- M, respectively. Therefore, these compounds are responsible for the XO-inhibitory effect of the extract. The free radical scavenging activity of the isolated flavonoids was determined by DPPH assay, and it was stated that none of the compounds have substantial antioxidant activity, therefore the reduced generation of reactive oxygen species may be the consequence only of XO inhibition.
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    Sesquiterpene Lactones and Flavonoids from Psephellus pyrrhoblepharus with Antiproliferative Activity on Human Gynecological Cancer Cell Lines
    (Mdpi, 2019) Tastan, Pelin; Hajdu, Zsuzsanna; Kusz, Norbert; Zupko, Istvan; Sinka, Izabella; Kivcak, Bijen; Hohmann, Judit
    Multistep chromatographic separations of the chloroform extract of the Turkish endemic plant Psephellus pyrrhoblepharus (Boiss.) Wagenitz (syn. Centaurea pyrrhoblephara Boiss.) resulted in the isolation of six guaianolid-type sesquiterpenes, chlorojanerin (1), 19-deoxychlorojanerin (2), 15-hydroxyjanerin (3), aguerin B (4), cynaropicrin (5), eleganin (6); three flavonoids, apigenin, 6-methoxyluteolin and jaceosidine; two glycosides, benzyl-1-O-beta-D-glucoside and 3(Z)-hexenyl-1-O-beta-D-glucoside; and the coumarin scopoletin. the structures were established by the interpretation of their ESI-MS and 1D and 2D NMR data including H-1-NMR, JMOD, H-1, H-1-COSY, HSQC, HMBC, and NOESY experiments. All compounds were isolated for the first time from P. pyrrhoblepharus. Compounds 1-6, the isolated flavonoids and scopoletin were evaluated for their antiproliferative activities on human gynecological cancer cell lines (SiHa, HeLa, and MDA-MB-231 cells) using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Chlorojanerin (1), 19-deoxychlorojanerin (2), aguerin B (4), cynaropicrin (5), eleganin (6) were shown to have noteworthy effects on all of the tested cell lines, while apigenin, jaceosidine, and 6-methoxyluteolin were moderately active on HeLa cells. the highest activities were demonstrated by the chlorine-containing derivatives chlorojanerin (1) and 19-deoxychlorojanerin (2) with IC50 values of 2.21 and 2.88 mu M, respectively, against the triple negative breast cancer model MDA-MB-231 cells.