The effect of administration of thioacetamide on rat liver mitochondrial functions and the protective effect of an aqueous extract of
Phyllanthus fraternus against thioacetamide-induced damage were studied. When rats were treated with thioacetamide, the rate of mitochondrial respiration was decreased significantly with both NAD
+ linked and FAD linked substrates, and the respiratory control ratio, an index of membrane integrity and the P/O ratio, a measure of phosphorylation efficiency, decreased significantly. Also, there was a significant decrease in the activities of NADH dehydrogenase, succinate cytochrome
c reductase, and cytochrome oxidase; whereas succinate dehydrogenase was not affected. A significant decrease was seen in membrane potential and in the level of mitochondrial ATP. There was a significant decrease in the levels of phosphatidylcholine, phosphatidylethanolamine, and cardiolipin by thioacetamide treatment. The lipid peroxide level increased significantly in thioacetamide-treated rats. Administration of
P. fraternus prior to thioacetamide treatment relieved the inhibition of all the parameters studied, and brought down the lipid peroxide levels significantly in liver homogenates and mitochondria. This study shows that
P. fraternus protects against thioacetamide-induced toxicity by its ability to suppress the elevated lipid peroxide levels in the mitochondrial membrane.
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