scholarly journals In VitroToxicity of Epigallocatechin Gallate in Rat Liver Mitochondria and Hepatocytes

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Otto Kucera ◽  
Vojtech Mezera ◽  
Alena Moravcova ◽  
Rene Endlicher ◽  
Halka Lotkova ◽  
...  
Keyword(s):  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Epigallocatechin Gallate ◽  
Rat Hepatocytes ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Main Compound ◽  
Ros Formation ◽  
High Doses

Epigallocatechin-3-gallate (EGCG) is the main compound of green tea with well-described antioxidant, anti-inflammatory, and tumor-suppressing properties. However, EGCG at high doses was reported to cause liver injury. In this study, we evaluated the effect of EGCG on primary culture of rat hepatocytes and on rat liver mitochondria in permeabilized hepatocytes. The 24-hour incubation with EGCG in concentrations of 10 μmol/L and higher led to signs of cellular injury and to a decrease in hepatocyte functions. The effect of EGCG on the formation of reactive oxygen species (ROS) was biphasic. While low doses of EGCG decreased ROS production, the highest tested dose induced a significant increase in ROS formation. Furthermore, we observed a decline in mitochondrial membrane potential in cells exposed to EGCG when compared to control cells. In permeabilized hepatocytes, EGCG caused damage of the outer mitochondrial membrane and an uncoupling of oxidative phosphorylation. EGCG in concentrations lower than 10 μmol/L was recognized as safe for hepatocytesin vitro.

scholarly journals Effects of Epigallocatechin Gallate on Tert-Butyl Hydroperoxide-Induced Mitochondrial Dysfunction in Rat Liver Mitochondria and Hepatocytes

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Vojtech Mezera ◽  
Rene Endlicher ◽  
Otto Kucera ◽  
Ondrej Sobotka ◽  
Zdenek Drahota ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Rat Liver ◽  
Epigallocatechin Gallate ◽  
Rat Hepatocytes ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Retention Capacity ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide

Epigallocatechin gallate (EGCG) is a green tea antioxidant with adverse effects on rat liver mitochondria and hepatocytes at high doses. Here, we assessed whether low doses of EGCG would protect these systems from damage induced by tert-butyl hydroperoxide (tBHP). Rat liver mitochondria or permeabilized rat hepatocytes were pretreated with EGCG and then exposed to tBHP. Oxygen consumption, mitochondrial membrane potential (MMP), and mitochondrial retention capacity for calcium were measured. First, 50 μM EGCG or 0.25 mM tBHP alone increased State 4 Complex I-driven respiration, thus demonstrating uncoupling effects; tBHP also inhibited State 3 ADP-stimulated respiration. Then, the coexposure to 0.25 mM tBHP and 50 μM EGCG induced a trend of further decline in the respiratory control ratio beyond that observed upon tBHP exposure alone. EGCG had no effect on MMP and no effect, in concentrations up to 50 μM, on mitochondrial calcium retention capacity. tBHP led to a decline in both MMP and mitochondrial retention capacity for calcium; these effects were not changed by pretreatment with EGCG. In addition, EGCG dose-dependently enhanced hydrogen peroxide formation in a cell- and mitochondria-free medium.Conclusion. Moderate nontoxic doses of EGCG were not able to protect rat liver mitochondria and hepatocytes from tBHP-induced mitochondrial dysfunction.

Glyoxal toxicity in isolated rat liver mitochondria

2017 ◽  
Vol 37 (5) ◽  
pp. 532-539 ◽  
Author(s):  
M Goudarzi ◽  
H Kalantari ◽  
M Rezaei
Keyword(s):  
Lipid Peroxidation ◽  
Rat Liver ◽  
Electron Transport Chain ◽  
Mitochondrial Membrane ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Transport Chain ◽  
Ros Formation ◽  
Isolated Rat

Glyoxal is a physiological metabolite formed by lipid peroxidation, ascorbate autoxidation, oxidative degradation of glucose, and degradation of glycated proteins. Glyoxal has been linked to oxidative stress and can cause a number of cellular damages, including covalent modification of amino and thiol groups of proteins to form advanced glycation end products. However, the mechanism of glyoxal toxicity has not been fully understood. In this study, we have focused on glyoxal toxicity in isolated rat liver mitochondria. Isolated mitochondria (0.5 mg protein per milliliter) were prepared from the Wistar rat liver using differential centrifugation and incubated with various concentrations of glyoxal (1, 2.5, 5, 7.5, and 10 mM) for 30 min. The activity of mitochondrial complex II was determined by measurement of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) conversion. The mitochondrial membrane potential (MMP), lipid peroxidation (MDA), reactive oxygen species (ROS) formation, glutathione (GSH) content, and protein carbonylation were also assessed. After an incubation of isolated liver mitochondria with glyoxal, disrupted electron transport chain, increased mitochondrial ROS formation, lipid peroxidation, mitochondrial membrane damage, GSH oxidation, and protein carbonylation ensued as compared to the control group ( p < 0.05). Glyoxal toxicity in isolated rat liver mitochondria was dose-dependent. In conclusion, glyoxal impaired the electron transport chain, which is the cause of increased ROS and MDA production, depletion of GSH, and disruption of MMP. Mitotoxicity of glyoxal might be related to the pathomechanisms involved in diabetes and its complications.

scholarly journals Uptake of protoporphyrin IX by isolated rat liver mitochondria

1980 ◽  
Vol 188 (2) ◽  
pp. 329-335 ◽  
Author(s):  
M E Koller ◽  
I Romslo
Keyword(s):  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Protoporphyrin Ix ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Erythropoietic Protoporphyria ◽  
Inner Membrane ◽  
Isolated Rat Liver ◽  
Isolated Rat

Rat liver mitochondria accumulate protoporphyrin IX from the suspending medium into the inner membrane in parallel with the magnitude of the transmembrane K+ gradient (K+in/K+out). Only protoporphyrin IX taken up in parallel with the transmembrane K+ gradient is available for haem synthesis. Coproporphyrins (isomers I and III) are not taken up by the mitochondria. The results support the suggestion by Elder & Evans [(1978) Biochem. J. 172, 345-347] that the prophyrin to be taken up by the inner mitochondrial membrane belongs to the protoporphyrin(ogen) IX series. Protoporphyrin IX at concentrations above 15 nmol/mg of protein has detrimental effects on the structural and functional integrity of the mitochondria. The relevance of these effects to the hepatic lesion in erythropoietic protoporphyria is discussed.

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