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    Wyświetlanie 1-6 z 6
    Tytuł:
    Cytotoxicity of anticancer aziridinyl-substituted benzoquinones in primary mice splenocytes
    Autorzy:
    Miliukienė, Valė
    Nivinskas, Henrikas
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1039227.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    aziridinyl-substituted quinones
    cytotoxicity
    oxidative stress
    Opis:
    The anticancer activity of aziridinyl-quinones is mainly attributed to their NAD(P)H:quinone oxidoreductase 1 (NQO1)-catalyzed two-electron reduction into DNA-alkylating products. However, little is known about their cytotoxicity in primary cells, which may be important in understanding their side effects. We found that the cytotoxicity of aziridinyl-unsubstituted quinones (n = 12) in mice splenocytes with a low amount of NQO1, 4 nmol × mg-1 × min-1, was caused mainly by the oxidative stress. Aziridinyl-benzoquinones (n = 6) including a novel anticancer agent RH1 were more cytotoxic than aziridinyl-unsubstituted ones with the similar redox properties, and their cytotoxicity was not decreased by an inhibitor of NQO1, dicumarol. The possible reasons for their enhanced cytotoxicity are discussed.
    Źródło:
    Acta Biochimica Polonica; 2014, 61, 4; 833-836
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Correlation between mammalian cell cytotoxicity of flavonoids and the redox potential of phenoxyl radical/phenol couple
    Autorzy:
    Marozienė, Audronė
    Nemeikaitė-Čėnienė, Aušra
    Vidžiūnaitė, Regina
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1039753.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    cytotoxicity
    antioxidants
    flavonoids
    oxidative stress
    Opis:
    Flavonoids exhibit prooxidant cytotoxicity in mammalian cells due to the formation of free radicals and oxidation products possessing quinone or quinomethide structure. However, it is unclear how the cytotoxicity of flavonoids depends on the ease of their single-electron oxidation in aqueous medium, i.e., the redox potential of the phenoxyl radical/phenol couple. We verified the previously calculated redox potentials for several flavonoids according to their rates of reduction of cytochrome c and ferricyanide, and proposed experimentally-based values of redox potentials for myricetin, fisetin, morin, kaempferol, galangin, and naringenin. We found that the cytotoxicity of flavonoids (n=10) in bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) and murine hepatoma (line MH-22a) increases with a decrease in their redox potential of the phenoxyl radical/phenol couple and an increase in their lipophilicity. Their cytotoxicity was decreased by antioxidants and inhibitors of cytochromes P-450, α-naphthoflavone and isoniazide, and increased by an inhibitor of catechol-O-methyltransferase, 3,5-dinitrocatechol. It shows that although the prooxidant action of flavonoids may be the main factor in their cytotoxicity, the hydroxylation and oxidative demethylation by cytochromes P-450 and O-methylation by catechol-O-methyltransferase can significantly modulate the cytotoxicity of the parent compounds.
    Źródło:
    Acta Biochimica Polonica; 2012, 59, 2; 299-306
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quinone- and nitroreductase reactions of Thermotoga maritima thioredoxin reductase
    Autorzy:
    Valiauga, Benjaminas
    Rouhier, Nicolas
    Jacquot, Jean-Pierre
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1039108.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    thioredoxin reductase
    quinones
    nitroaromatic compounds
    oxidative stress
    Thermotoga
    Opis:
    The Thermotoga maritima NADH:thioredoxin reductase (TmTR) contains FAD and a catalytic disulfide in the active center, and uses a relatively poorly studied physiological oxidant Grx-1-type glutaredoxin. In order to further assess the redox properties of TmTR, we used series of quinoidal and nitroaromatic oxidants with a wide range of single-electron reduction potentials (E17, -0.49-0.09 V). We found that TmTR catalyzed the mixed single- and two-electron reduction of quinones and nitroaromatic compounds, which was much faster than the reduction of Grx-1. The reactivity of both groups of oxidants increased with an increase in their E17, thus pointing to the absence of their structural specificity. The maximal rates of quinone reduction in the steady-state reactions were lower than the maximal rates of reduction of FAD by NADH, obtained in presteady-state experiments. The mixed-type reaction inhibition by NAD+ was consistent with its competition for a NADH binding site in the oxidized enzyme form, and also with the reoxidation of the reduced enzyme form. The inhibition data yielded a value of the standard potential for TmTR of -0.31±0.03 V at pH 7.0, which may correspond to the FAD/FADH2 redox couple. Overall, the mechanism of quinone- and nitroreductase reactions of T. maritima TR was similar to the previously described mechanism of Arabidopsis thaliana TR, and points to their prooxidant and possibly cytotoxic role.
    Źródło:
    Acta Biochimica Polonica; 2015, 62, 2; 303-309
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Enzymatic redox reactions of the explosive 4,6-dinitrobenzofuroxan (DNBF): implications for its toxic action.
    Autorzy:
    Nemeikaitė-Čėnienė, Aušra
    Šarlauskas, Jonas
    Misevièienė, Lina
    Anusevièius, Žilvinas
    Marozienė, Audronė
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1041528.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    cytotoxicity
    nitroaromatic explosives
    oxidative stress
    Opis:
    With an aim to understand the toxicity mechanisms of the explosive 4,6-dinitro- benzofuroxan (DNBF), we studied its single-electron reduction by NADPH:cytochrome P450 reductase and ferredoxin:NADP+ reductase, and two- electron reduction by DT-diaphorase and Enterobacter cloacae nitroreductase. The enzymatic reactivities of DNBF and another explosive 2,4,6-trinitrotoluene (TNT) were similar, except for the much lower reactivity of DNBF towards nitroreductase. DNBF was less cytotoxic in FLK cells than TNT. However, their action shared the same mechanisms, oxidative stress and activation by DT-diaphorase. The lower cytotoxicity of DNBF may be explained by the negative electrostatic charge of its adduct with water which may impede cellular membrane penetration, and by the formation of its less reactive adducts with intracellular reduced glutathione.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 4; 1081-1086
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Redox properties and prooxidant cytotoxicity of a neuroleptic agent 6,7-dinitrodihydroquinoxaline-2,3-dione (DNQX)
    Autorzy:
    Šarlauskas, Jonas
    Nemeikaitė-Čėnienė, Aušra
    Misevičienė, Lina
    Krikštopaitis, Kastis
    Anusevičius, Žilvinas
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1039581.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    flavoenzymes
    cytotoxicity
    DNQX
    oxidative stress
    Opis:
    In order to characterize the possible mechanism(s) of cytotoxicity of a neuroleptic agent 6,7-dinitrodihydroquinoxaline-2,3-dione (DNQX) we examined the redox properties of DNQX, and its mononitro- (NQX) and denitro- (QX) derivatives. The irreversible electrochemical reduction of the nitro groups of DNQX was characterized by the reduction peak potentials (Ep,7) of -0.43 V and -0.72 V vs. Ag/AgCl at pH 7.0, whereas NQX was reduced at Ep,7 = -0.67 V. The reactivities of DNQX and NQX towards the single-electron transferring enzymes NADPH:cytochrome P-450 reductase and NADPH:adrenodoxin reductase/adrenodoxin complex were similar to those of model nitrobenzenes with the single-electron reduction potential (E17) values of -0.29 V - -0.42 V. DNQX and NQX also acted as substrates for two-electron transferring mammalian NAD(P)H:quinone oxidoreductase (DT-diaphorase). The cytotoxicity of DNQX in bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) was prevented by antioxidants and an inhibitor of NQO1, dicoumarol, and was enhanced by the prooxidant alkylating agent 1,3-bis(2-chloromethyl)-1-nitrosourea. A comparison with model nitrobenzene compounds shows that the cytotoxicity of DNQX and NQX reasonably agrees with the ease of their electrochemical reduction, and/or their reactivities towards the used enzymatic single-electron reducing systems. Thus, our data imply that the cytotoxicity of DNQX in FLK cells is exerted mainly through oxidative stress.
    Źródło:
    Acta Biochimica Polonica; 2013, 60, 2; 227-231
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Single-electron reduction of quinone and nitroaromatic xenobiotics by recombinant rat neuronal nitric oxide synthase
    Autorzy:
    Anusevičius, Žilvinas
    Nivinskas, Henrikas
    Šarlauskas, Jonas
    Sari, Marie-Agnes
    Boucher, Jean-Luc
    Čėnas, Narimantas
    Powiązania:
    https://bibliotekanauki.pl/articles/1039577.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    antitumour agents
    nitroaromatic compounds
    electron transfer mechanism
    oxidative stress
    quinones
    Neuronal nitric oxide synthase (nNOS)
    Opis:
    We examined the kinetics of single-electron reduction of a large number of structurally diverse quinones and nitroaromatic compounds, including a number of antitumour and antiparasitic drugs, and nitroaromatic explosives by recombinant rat neuronal nitric oxide synthase (nNOS, EC 1.14.13.39), aiming to characterize the role of nNOS in the oxidative stress-type cytotoxicity of the above compounds. The steady-state second-order rate constants (kcat/Km) of reduction of the quinones and nitroaromatics varied from 102 M-1s-1 to 106 M-1s-1, and increased with an increase in their single-electron reduction potentials (E17). The presence of Ca2+/calmodulin enhanced the reactivity of nNOS. These reactions were consistent with an 'outer sphere' electron-transfer mechanism, considering the FMNH./FMNH2 couple of nNOS as the most reactive reduced enzyme form. An analysis of the reactions of nNOS within the 'outer sphere' electron-transfer mechanism gave the approximate values of the distance of electron transfer, 0.39-0.47 nm, which are consistent with the crystal structure of the reductase domain of nNOS. On the other hand, at low oxygen concentrations ([O2] = 40-50 μM), nNOS performs a net two-electron reduction of quinones and nitroaromatics. This implies that NOS may in part be responsible for the bioreductive alkylation by two-electron reduced forms of antitumour aziridinyl-substituted quinones under a modest hypoxia.
    Źródło:
    Acta Biochimica Polonica; 2013, 60, 2; 217-222
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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