Search results for "Reactive"

Deglycosylated bleomycin triggers apoptosis in laryngeal carcinoma cells in a caspase and reactive oxygen species independent manner

2008

Background:  Bleomycin-A2, a member of a family of glycopeptide antibiotics, has potent antitumor activity against a range of lymphomas, head and neck cancer and germ cell tumors. However, little is known about the biologic activity of the carbohydrate moiety in Bleomycin-A2-induced cytotoxicity. Methods:  We compared the capacity of Bleomycin-A2 and its deglycosylated form (deglycoBleomycin-A2) to induce cell death. Apoptosis was analyzed by cell nuclear staining with Hoechst 33342 dye and DNA fragmentation. The signal transduction pathway was measured through Western blotting and production of reactive oxygen species (ROS). Results:  When tested on HEp-2 laryngeal carcinoma cells, Bleomyc…

Antioxidant activity of cerium dioxide nanoparticles and nanorods in scavenging hydroxyl radicals

2019

Cerium oxide nanoparticles (CeNPs) have been shown to exhibit antioxidant capabilities, but their efficiency in scavenging reactive oxygen species (ROS) and the underlying mechanisms are not yet well understood. In this study, cerium dioxide nanoparticles (CeNPs) and nanorods (CeNRs) were found to exhibit much stronger scavenging activity than ·OH generation in phosphate buffered saline (PBS) and surrogate lung fluid (SLF). The larger surface area and higher defect density of CeNRs may lead to higher ·OH scavenging activity than for CeNPs. These insights are important to understand the redox activity of cerium nanomaterials and provide clues to the role of CeNPs in biological and environmen…

1989

Coefficients de diffusion de traceurs dans les melanges de PS avec poly(o-methylstyrene), poly(p-methylstyrene et un copolymere statistique p-m-methylstyrene

Coping with Oxygen

2010

Sometime before 2.7 BYA, a new and biologically toxic substance began to appear in the environment. Biologically produced dioxygen, O2, probably first began to accumulate in small pools or layers above cyanobacterial mats. These photosynthesizers must have already developed ways to at least partially deal with dioxygen and, with greater difficulty, the reactive oxygen species (ROS) derived from it (see Chap. 1 and below). But for primitive anaerobes in the vicinity, these new substances must have been especially toxic. Nevertheless, it is clear that they evolved ways to cope with the new threats. One way was to simply avoid dioxygen altogether.

Photoiodocarboxylation of Activated C═C Double Bonds with CO2 and Lithium Iodide

2018

The photolysis at 254 nm of lithium iodide and olefins 1 carrying an electron-withdrawing Z-substituent in CO2-saturated (1 bar) anhydrous acetonitrile at room temperature produces the atom efficient and transition metal-free photoiodocarboxylation of the C═C double bond. The reaction proceeds well for terminal olefins 1 to form the new C-I and C-C σ-bonds at the α and β-positions of the Z-substituent, respectively, and is strongly inhibited by polar protic solvents or additives. The experimental results suggest that the reaction channels through the radical anion [CO2•-] in acetonitrile, yet involves different intermediates in aqueous medium. The stabilizing ion-quadrupole and electron don…

Peptide-metal complexes: obtention and role in increasing bioavailability and decreasing the pro-oxidant effect of minerals.

2020

Bioactive peptides derived from food protein sources have been widely studied in the last years, and scientific researchers have been proving their role in human health, beyond their nutritional value. Several bioactivities have been attributed to these peptides, such as immunomodulatory, antimicrobial, antioxidant, antihypertensive, and opioid. Among them, metal-binding capacity has gained prominence. Mineral chelating peptides have shown potential to be applied in food products so as to decrease mineral deficiencies since peptide-metal complexes could enhance their bioavailability. Furthermore, many studies have been investigating their potential to decrease the Fe pro-oxidant effect by f…

Special issue on “Oxidative stress and redox signaling in the gastrointestinal tract and related organs”

2013

A Radical Signal Activates the Epigenetic Regulation of Longevity

2013

Hormesis is an adaptive stress response implicated in longevity regulation. Schroeder et al. (2013) have now connected stress, epigenetic changes, and aging in yeast by showing that mitochondria-derived reactive oxygen species modulate the chromatin binding capacity of the histone demethylase Rph1p at subtelomeres, resulting in lifespan extension.

Endogenous DNA Damage and Its Relevance for the Initiation of Carcinogenesis

2011

Hexanoic acid protects tomato plants againstBotrytis cinereaby priming defence responses and reducing oxidative stress

2014

Summary Treatment with the resistance priming inducer hexanoic acid (Hx) protects tomato plants from Botrytis cinerea by activating defence responses. To investigate the molecular mechanisms underlying hexanoic acid-induced resistance (Hx-IR), we compared the expression profiles of three different conditions: Botrytis-infected plants (Inf), Hx-treated plants (Hx) and Hx-treated + infected plants (Hx+Inf). The microarray analysis at 24 h post-inoculation showed that Hx and Hx+Inf plants exhibited the differential expression and priming of many Botrytis-induced genes. Interestingly, we found that the activation by Hx of other genes was not altered by the fungus at this time point. These genes…