Acute toxicity and long-term safety evaluation of the crude extract from rhizomes of Limonium brasiliense in mice and rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Limonium brasiliense (Boiss.) Kuntze, Plumbaginaceae, popularly known as baicuru, has been used in folk medicine to treat menstrual cramps and to regulate menstrual periods. However, little is known about its safety. This study evaluated the safety through in vivo tests of the acute, long-term, and liver toxicity, and the mutagenicity of the crude extract (CE) from rhizomes of L. brasiliense. MATERIALS AND METHODS: The acute toxicity was assessed in Swiss mice, and the chronic toxicity in Wistar rats. Male and female mice received the CE orally in single doses of 1.0, 2.0, 3.0, 4.0, or 5.0 g/kg. Clinical changes and mortality rate were used as parameters to assess the acute toxicity. In the long-term evaluation, male and female Wistar rats were treated orally with daily doses of the CE (50, 100, or 200 mg/kg) for 90 days. Assessments of weight, behavior and food intake, urinalysis, biochemical and hematological analyses, as well as macro- and microscopic observations of several organs were performed. The redox state of the liver was evaluated as a means of investigating the liver toxicity, and the micronucleus test to assess mutagenicity was also performed. RESULTS: Evaluation of acute toxicity indicated no apparent clinical change in the animals; the LD50 was 4.8 g/kg. Evaluation after 90 days administration showed that the CE, even in higher doses than are considered therapeutic, appeared to be safe. The micronucleus test demonstrated a low mutagenic potential for the CE. CONCLUSION: Our results showed that treatment with the CE from L. brasiliense caused low or no toxicity, as assessed using these doses and evaluation methods.

Liver mitochondrial function and redox status in an experimental model of non-alcoholic fatty liver disease induced by monosodium L-glutamate in rats.

The purpose of this work was to determine if mitochondrial dysfunction is involved in the development of non-alcoholic fatty liver disease (NAFLD). Using a model of obesity induced by the neonatal treatment of rats with monosodium L-glutamate (MSG), several parameters of liver mitochondrial function and their impact on liver redox status were evaluated. Specifically, fatty acid ß-oxidation, oxidative phosphorylation and Ca(2+)-induced mitochondrial permeability transition were assessed in isolated liver mitochondria, and reduced glutathione (GSH), linked thiol contents and the activities of several enzymes involved in the control of redox status were measured in the liver homogenate. Our results demonstrate that liver mitochondria from MSG-obese rats exhibit a higher ß-oxidation capacity and an increased capacity for oxidising succinate, without loss in the efficiency of oxidative phosphorylation. Also, liver mitochondria from obese rats were less susceptible to the permeability transition pore (PTP) opening induced by 1.0 µM CaCl(2). Cellular levels of GSH were unaffected in the livers from the MSG-obese rats, whereas reduced linked thiol contents were increased. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione peroxidase were increased, while catalase activity was unaffected and superoxide dismutase activity was reduced in the livers from the MSG-obese rats. In this model of obesity, liver fat accumulation is not a consequence of mitochondrial dysfunction. The enhanced glucose-6-phosphate dehydrogenase activity observed in the livers of MSG-obese rats could be associated with liver fat accumulation and likely plays a central role in the mitochondrial defence against oxidative stress.

Tibolone impairs glucose and fatty acid metabolism and induces oxidative stress in livers from female rats.

Tibolone is a synthetic steroid that has been extensively prescribed to treat climacteric symptoms and to prevent postmenopausal osteoporosis. Because menopause is a condition associated with increased incidence of metabolic disturbances and hepatic steatosis, the aim of this work was to evaluate the actions of tibolone on the liver. The effects of tibolone on glucose and fatty acid metabolism and on several parameters linked to mitochondrial energy metabolism, including the induction of cellular oxidative stress, were investigated in livers from female Wistar rats. Tibolone was assayed at concentrations ranging from 5 to 100 µM. In perfused livers, tibolone inhibited oxygen uptake, stimulated glycogenolysis and glycolysis, and inhibited gluconeogenesis from L-lactate and ketogenesis from exogenous octanotate. Tibolone also caused pronounced increases in both the cytosolic and mitochondrial NADH/NAD+ratios. In isolated mitochondria, tibolone inhibited oxygen uptake due to ß-hydroxybutyrate and fatty acid oxidation without affecting the succinate oxidation. The inhibitory action of tibolone at complex I of the mitochondrial respiratory chain was suggested by the inhibition of the NADH-oxidase activity. Tibolone also induced oxidative stress in both perfused livers and isolated mitochondria, as indicated by the increased production of thiobarbituric acid reactive substances. These metabolic alterations may increase the risk of metabolic disturbances during tibolone administration, particularly in the postmenopausal condition.