Tsvetanka Stefanova

Synthesis, characterization and cytotoxic/cytostatic activity of La(III) and Dy(III) complexes

New La(III) and Dy(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, (1)H NMR spectra, and elemental analyses. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The La(III) and Dy(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and they are stronger inhibitors of tumor cell proliferation compared to the ligand without influencing normal cell viability and NO release by mouse peritoneal macrophages.

Synthesis, characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.

Effect of a plant polyphenol-rich extract on the lung protease activities of influenza-virus-infected mice

Influenza infection was induced in white mice by intranasal inoculation of the virus A/Aichi/2/68 (H3N2). The lung protease and the protease-inhibitory activities were followed for 9 days after infection. The intranasal application of a polyphenol-rich extract (PC) isolated from Geranium sanguineum L. induced a continuous rise in the anti-protease activity but did not cause substantial changes in the lung protease activity of healthy mice. Influenza virus infection triggered a slight reduction in protease activity in the lungs at 5 and 48 h post infection (p.i.) and a marked increase at 24 h and 6 day p.i. Protease inhibition in the lungs was reduced at 24 and 48 h p.i. and an increase was observed at 5 h and 6 and 9 days p.i. PC treatment brought both activities to normal levels. The restoration of the examined parameters was consistent with a prolongation of mean survival time and reduction of mortality rate, infectious virus titre and lung consolidation. PC reinstated superoxide production by alveolar macrophages and increased their number in virus-infected mice. The favourable effect on the protease and the protease-inhibitory activities in the lungs of influenza-virus-infected mice apparently contributes to the overall protective effect of PC in the murine experimental influenza A/Aichi infection. The antiviral effect of the individual constituents was evaluated.

The oxidative stress response of the filamentous yeast Trichosporon cutaneum R57 to copper, cadmium and chromium exposure

Despite the intensive research in the past decade on the microbial bioaccumulation of heavy metals, the significance of redox state for oxidative stress induction is not completely clarified. In the present study, we examined the effect of redox-active (copper and chromium) and redox-inactive (cadmium) metals on the changes in levels of oxidative stress biomarkers and antioxidant enzyme defence in Trichosporon cutaneum R57 cells. This filamentous yeast strain showed significant tolerance and bioaccumulation capability of heavy metals. Our findings indicated that the treatment by both redox-active and redox-inactive heavy metal induced oxidative stress events. Enhanced concentrations of Cu2+, Cr6+ and Cd2+ caused acceleration in the production of reactive oxygen species (ROS), increase in the level of oxidatively damaged proteins and accumulation of reserve carbohydrates (glycogen and trehalose). Cell response against heavy metal exposure also includes elevation in the activities of antioxidant enzymes, superoxide dismutase and catalase, which are key enzymes for directly scavenging of ROS. Despite the mentioned changes in the stress biomarkers, T. cutaneum did not show a significant growth diminution. Probably, activated antioxidant defence contributes to the yeast survival under conditions of heavy metal stress.

Tyrosine Kinase Inhibitor Tyrphostin AG490 Retards Chronic Joint Inflammation in Mice

Tyrphostin AG490 is a Janus kinase (JAK) 2 inhibitor that is clinically used as an anticancer agent and is also effective in various models of inflammatory and autoimmune diseases. In this study, we examined the effects of tyrphostin AG490 on the development of collagenase-induced osteoarthritis (CIOA). Our results showed that tyrphostin-ameliorated cartilage and bone destructions. This effect was associated with decreased expression of signal transducers and activators of transcription 3 (STAT3), phosphorylated JAK2, Dickkopf homolog 1, and receptor activator of nuclear factor κB ligand (RANKL) in the joints of arthritic mice. Tyrphostin AG490 suppressed STAT3 phosphorylation and the expression of tumor necrosis factor-related apoptosis-inducing ligand and RANKL by synovial fluid cells. The drug inhibited RANKL-induced osteoclast differentiation in vitro. Molecules, such as tyrphostin AG490 that limit bone erosion and influence osteoclast generation, might have therapeutic utility in joint degenerative disorders.

Effect of Yeast Superoxide Dismutase Treatment on Some Mediators of Infl ammation during Adjuvant-Induced Arthritis in Mice

The superoxide radical (O2·̅), hydrogen peroxide (H2O2) and nitric oxide (NO) are pleiotropic infl ammatory mediators which play an important role in infl ammatory joint diseases. They are overproduced during rheumatoid arthritis and its experimental model - adjuvantinduced arthritis in rodents - and may be detected both systemically and intra-articularly. Their secretion is up-regulated by proinfl ammatory cytokines such as IFN-γ, IL-12, IL-6 and TNF-α, and they are responsible for the destruction of joint tissue. In this work, the effect of superoxide dismutase (SOD) from a thermotolerant yeast strain, Kluyveromyces marxianus, on the production of proinfl ammatory cytokines, reactive oxygen and nitrogen species was studied. Mice received three intraperitoneal injections of yeast SOD at a dose of 10 mg/ kg body weight (30,000 U/kg) on consecutive days starting on the day after arthritic induction. On days 3, 8 and 14 post induction peritoneal macrophages were isolated and both spontaneous and stimulated production of reactive oxygen and nitrogen metabolites were measured. Early in arthritic development yeast SOD treatment did not infl uence the O2·̅ production, but on day 14 both spontaneous and PMA-induced secretion were dramatically reduced. Spontaneous H2O2 release was inhibited on day 14, while PMA-stimulated production was decreased from the beginning of the arthritic development. Yeast SOD treatment effectively suppressed the spontaneous and recombinant mouse IFN-γ + LPS induced release of NO as well. Serum levels of proinfl ammatory cytokines, IL-12, IFN-γ, IL-6 and TNF-α, were also signifi cantly reduced. The obtained results show some of the mechanisms of action of SOD in reducing the severity of arthritic infl ammation. Besides direct inhibition of joint tissue destruction exogenous SOD substantially limits the existing positive feedback between secretion of reactive oxygen species and infl ammatory cytokine production.

Phagocytosis and killing of Salmonella by 7-hydroxycoumarin activated macrophages.

Coumarin and its derivatives have potent immunomodulatory activities. Here we describe the parameters of the protective effect of 7-hydroxycoumarin (7-OHC) in experimental Salmonella enterica Serovar Typhimurium infection in mice. The protective effect depended on the duration of treatment reaching its maximum after 10 days of pretreatment and lasted for at least 15 days after its end. Electron microscopy studies revealed that 7-OHC induced ultrastructural changes in macrophages consistent with their activation as well as faster destruction of ingested salmonellae. Superoxide and hydrogen peroxide secretion by macrophages was decreased in both healthy and Salmonella-infected 7-OHC treated animals, which is in line with the current view that some coumarins possess antioxidant and radical scavenging activity. Thus, 7-OHC pretreatment also appears beneficial to the host by limiting the harmful tissue damaging and immunosuppressive effects of the oxidative stress during a Salmonella infection but still activates the microbicidal capacity of exposed phagocytes.

A fungal Cu/Zn-containing superoxide dismutase enhances the therapeutic efficacy of a plant polyphenol extract in experimental influenza virus infection.

The combined protective effect of a polyphenol-rich extract, isolated from Geranium sanguineum L. (PC), and a novel naturally glycosylated Cu/Zn-containing superoxide dismutase, produced from the fungal strain Humicula lutea 103 (HL-SOD), in the experimental influenza A virus infection (EIVI) in mice, induced with the virus A/Aichi/2/68 (H3N2), was investigated. The combined application of HL-SOD and PC in doses, which by themselves do not defend significantly mice in EIVI, resulted in a synergistically increased protection, determined on the basis of protective indices and amelioration of lung injury. Lung weights and consolidation as well as infectious lung virus titers were all decreased significantly parallel to the reduction of the mortality rates; lung indices were raised. The excessive production of reactive oxygen species (ROS) by alveolar macrophages (aMØ) as well as the elevated levels of the lung antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), induced by EIVI, were brought to normal. For comparative reasons the combined protective effect of PC and vitamin C was investigated. The obtained results support the combined use of antioxidants for the treatment of influenza virus infection and in general indicate the beneficial protective role of combinations of viral inhibitors of natural origin with diverse modes of action.

Protective Effect of Polyphenol-Rich Extract on Acute Lung Injury in Influenza Virus Infected Mice

ABSTRACT We have followed the anti-oxidant effects of a plant polyphenol-rich extract (PC) in the lungs of albino mice in the experimental influenza A/Aichi/2/68 (H3N2) (A/Aichi) virus infection. The effect of PC on the superoxide (O2−) and peroxide (H2O2) production from alveolar macrophages (aMØ) and on the lung antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) was studied. We also investigated the effect on the lipid peroxidation (LPO) and the total antioxidant activity (TAOA) in the lung tissue. All of the mentioned effects were studied in parallel with the protection on mortality rates and lung virological parameters on days 2, 6 and 9 after the viral challenge. It was shown that the extract significantly restored and stimulated the antioxidant activities in the lungs of influenza virus (IV)-infected mice. The protective effect of PC in the experimental influenza virus infection (EIVI) was related to both the specific antiviral effect of the extract and its antioxidant activity.

Growth-Phase-Related Changes in Reactive Oxygen Species Generation as a Cold Stress Response in Antarctic Penicillium Strains

ABSTRACT The Free Radical/Oxidative Stress Theory of Aging postulated that the accumulation of damage caused by reactive oxygen species (ROS) was the underlying mechanism by which organisms age. Our previous studies reported that the growth at low temperature caused oxidative stress events in Antarctic strains, including enhanced ROS generation. However, there is no data about age-related differences in cold stress-induced ROS accumulation in microorganisms living permanently in cold environments. The aim of the present paper was to evaluate the growth-phase-related changes in ROS level in two Antarctic strains belonging to different thermal classes, psychrotolerant (Penicillium olsonii p14) and mesophilic (Penicillium waksmanii m12) and the role of cold adaptation in this process. Intact cells and mitochondrial fractions from the middle exponential phase or stationary phase at optimal temperature were exposure to temperature of 6°C and 15°C, respectively. The results demonstrated that the temperature downshift led to a significant induction in the superoxide and H2O2 level in a dose- and growth-phase-dependent manner. Additionally, cold-stress response is not dependent on cold-adaptation of the model strains.