RESUMO
The action of a barbatimão extract on hepatic energy metabolism was investigated using isolated mitochondria and the perfused rat liver. In mitochondria the barbatimão extract inhibited respiration in the presence of ADP and succinate. Stimulation occurred, however, after ADP phosphorylation (state IV respiration). The ADP/O and respiratory control ratios were reduced. The activities of succinate-oxidase, NADH-oxidase and the oxidation of ascorbate were inhibited. The ATPase of intact mitochondria was stimulated, but the ATPases of uncoupled and disrupted mitochondria were inhibited. In perfused livers the extract caused stimulation of oxygen consumption, inhibition of gluconeogenesis and stimulation of glycolysis. Glucose release due to glycogenolysis was stimulated shortly after the introduction of the extract, but inhibition gradually developed as the infusion was continued. Apparently the barbatimão extract impairs the hepatic energy metabolism by three mechanisms: (1) uncoupling of oxidative phosphorylation, (2) inhibition of mitochondrial electron transport, and (3) inhibition of ATP-synthase.
Assuntos
Metabolismo Energético/efeitos dos fármacos , Fabaceae/química , Fígado/metabolismo , Plantas Medicinais/química , Difosfato de Adenosina/metabolismo , Adenosina Trifosfatases/metabolismo , Animais , Brasil , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Gluconeogênese/efeitos dos fármacos , Glicogênio/biossíntese , Técnicas In Vitro , Fígado/efeitos dos fármacos , Fígado/enzimologia , Masculino , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/enzimologia , Mitocôndrias Hepáticas/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Perfusão , Casca de Planta/química , Extratos Vegetais/farmacologia , Proteínas/metabolismo , Ratos , Ratos WistarRESUMO
This study was carried out to determine the acute toxicity of total barbatimão extract (LD(50)) after oral administration to mice, and its effect on certain biochemical parameters in plasma of rats after 30 days of administration. The LD(50) value of the extract was 2699 mg/kg. A daily oral administration of extracts at 800 and 1600 mg/kg doses for 30 days caused a decrease in body weight, thymic involution, and an increase of plasma glucose and aspartate aminotransferase levels in the animals. The results showed that the extract administered in a prolonged period produced toxic effects in the experimental animals.