Search results for "thione"

The protective effects of melanoidins in adriamycin-induced oxidative stress in isolated rat hepatocytes

2004

The importance of the antioxidants contained in foods is well recognized both for preserving the foods themselves and for supplying essential antioxidants in vivo. Among these, the melanoidins formed during food processing and storage represent a significant part of our diet, with an average intake of several grams per day. Melanoidins exhibit antioxidant properties in vitro through their protective effect against reactive oxygen species. Here we investigated the protective effect of the model glucose–glycine melanoidins on oxidative stress induced by adriamycin in hepatocytes isolated from rats. The study was performed by examining cell toxicity (lactate dehydrogenase) release in the mediu…

Glutathione-dependent defence system and monooxygenase enzyme activities in Arctic charr Salvelinus alpinus (L.) exposed to ozone

2000

Abstract One of the major obstacles of the increasing usage of ozone in aquaculture is the lack of relevant risk assessment in culture conditions. Before the apparent advantages of ozonation can be utilised efficiently, the safety margins and biological basis of ozone toxicity should be assessed. In this research, 1-year-old Arctic charr ( Salvelinus alpinus (L.)) were exposed to an ozone concentration high enough to inactivate Aeromonas sp. bacteria in freshwater, but too low to be directly lethal to the fish themselves. The effects of ozone exposure on the activity of glutathione-dependent antioxidant enzymes and monooxygenase reactions were studied in blood and in liver. The fish were ac…

Organic derivatives of mercury and tin as promoters of membrane lipid peroxidation.

2008

The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement …

Long term p38-a deficiency up-regulates antioxidant enzymes through compensatory NF-?B activation

2015

p38a MAPK may function as a mediator of reactive oxygen species signaling and thus p38a is considered a sensor of oxidative stress. In liver-specific p38a knock-out (KO) adult mice we previously found glutathione depletion and down-regulation of antioxidant enzymes. Our aim was to assess the influence of long-term p38a deficiency on oxidative stress and on the regulation of antioxidant enzymes in liver of old mice. To this end, wild type or liver-specific KO mice after weaning, at 4-6 months of age, or at 24 months of age were used. Reduced glutathione (GSH) and oxidized glutathione levels were determined by mass spectrometry, gene expression of antioxidant enzymes was determined by RT-PCR,…

Enzymic Control of Reactive Metabolites from Aromatic Carcinogens

1980

Mutation and transformation in C3H 10T 1/2 mouse fibroblasts were coordinately induced by 4-nitroquinoline N-oxide and identically modulated by caffeine strongly suggesting mutation as one necessary step in the sequence of events ultimately leading to transformation. The enzymic control of reactive metabolites derived from aromatic carcinogens was then investigated using bacterial mutagenicity as an analytical tool. It was shown that the correlation of bacterial mutagenicity with carcinogenicity of BP and four major metabolites was substantially better when these compounds were activated by intact hepatocytes as compared to commonly used broken cell preparations which suggests that the rela…

Chronic Lymphocytic Leukemia: Correlations Between Oxidative Stress Metabolism and Cytogenetic Subgroups

2008

Abstract The chronic lymphocytic leukemia (B cell-CLL) is a heterogeneous lymphoproliferative disorder susceptible to oxidative stress. The excessive production of reactive oxygen intermediates above the capability of naturally produced antioxidants may result in the instability of essential macromolecules, and represents the molecular basis of many diseases including cancer. Highly reactive radicals interact with DNA inducing a multitude of oxidative modifications, and are implicated in mutagenesis due to misreplication of the damaged base 8-oxo-2′-deoxiguanosine (8-oxo-dG). Furthermore, protooncogene activation and/or tumor suppressor gene inhibition has been reported as a consequence of …

Immediate early response of the marine sponge Suberites domuncula to heat stress: Reduction of trehalose and glutathione concentrations and glutathio…

1997

The marine sponge Suberites domuncula was used to identify early markers for thermal stress. Cubes from sponges have been kept for 30 min at 31°C (10 °C higher than the ambient temperature). After this treatment the sponge cubes were kept again at 21°C. To demonstrate that the animals reacted to the elevated temperature, the expression of heat shock protein (HSP) was determined. Using an antibody raised against HSP70, it was found by Western blotting that the animals specifically express a 45 kDa polypeptide after heat treatment. It was shown that even after 10 min of heat treatment the steady-state concentration of trehalose drops by 40% from a base level of 13 nmol/mg protein. The activit…

Oxidative stress and enzymatic antioxidant mechanisms in essential hypertension

2001

Metabolic Inactivation of Reactive Metabolites

1978

ABSTRACT Many compounds which are not electrophilically reactive as such are transformed by mammalian enzymes to reactive metabolites which are, in many cases, responsible for cytotoxic, mutagenic and/or carcinogenic effects of the compounds in question. The essential role of activating systems in this situation has become common knowledge during the last decade. However, many reactive metabolites are also subject to inactivation by mammalian enzymes. This important parameter is frequently not taken into account. Compounds possessing aromatic or olefinic moieties are very widely occurring and activation of these often proceeds via an electrophilically reactive epoxide. This may be transform…

Enzymes as Regulators of Toxic Reactions by Electrophilic Metabolites

1979

Conversion of many compounds which are not electrophilically reactive as such to metabolites responsible for cytotoxic, mutagenic and/or carcinogenic effects is catalyzed by mammalian enzymes. Many reactive agents, whether metabolites or parent compounds, are also subject to inactivation by mammalian enzymes.