First chemical evaluation and toxicity of Casinga-cheirosa to Balb-c male mice.

Laetia suaveolens, known as "casinga-cheirosa", crude extract EB719 has previously shown cytotoxic activity against prostate cancer and squamous cell carcinoma. For the first time, seven molecules were isolated from its apolar-α-tocopherol (1) and sitosterol (2)-and polar-3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-feruloylquinic acid (5), hyperoside (6), and isoquercitrin (7)-fractions. Acute toxicity was determined in a two-stage experiment: (1) a reduced number of Balb-c male mice received 5000 mg/kg of EB719 to allow evaluation of general activity and other 27 parameters, plus death, up to the establishment of non-lethal dose (NLD), as well as lethal dose 50% (LD50); (2) NLD was administered and diazepam introduced as reference drug. EB719 showed LD50=178.0 mg/kg, and NLD 156.3 mg/kg. In stage one EB719 did not influence general activity, but provoked impairment in grasp reflexes, tail squeeze and breathing; piloerection and cyanosis were increased. In stage two, alterations occurred in auricular reflex, piloerection and breathing after diazepam administration, but not in response to EB719. Intestinal hemorrhage caused by local bleeding was observed after necropsy, and may be the main cause of animals' death other than a systemic effect of the extract. Although the isolated compounds are biologically and pharmacologically active in both men and animal systems, it is premature to relate their occurrence in EB719 to the observed intestine hemorrhage in mice.

Influence of levetiracetam on the anticonvulsant efficacy of conventional antiepileptic drugs against audiogenic seizures in DBA/2 mice.

Levetiracetam (LEV, [S]-alpha-ethyl-2-oxo-1-pyrrolidine acetamide) is a new antiepileptic that has been used as adjunctive therapy to treat patients with intractable epilepsy. Systemic administration of levetiracetam (2.5-30 mg/kg, intraperitoneally (i.p.)) was able to produce a dose-dependent decrease in DBA/2 audiogenic seizure severity score. In combination with conventional antiepileptic drugs, levetiracetam, 5mg/kg, i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of some antiepileptic drugs studied against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by levetiracetam was greater, approximately twice, for carbamazepine, diazepam, felbamate, topiramate, gabapentin, and valproate, less for lamotrigine, phenobarbital and phenytoin. This increase was associated with a comparable impairment in motor activity; however, the therapeutic index of combined treatment of antiepileptic drugs with levetiracetam was more favourable than the combination with saline with the exception of lamotrigine, phenytoin and phenobarbital. Since levetiracetam did not significantly influence the total and free plasma and the brain levels of antiepileptics studied. In addition, levetiracetam did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, levetiracetam showed an additive anticonvulsant effect when administered in combination with some classical anticonvulsants, most notably carbamazepine, diazepam, felbamate, gabapentin, topiramate and valproate, implicating a possible therapeutic relevance of such drug combinations.

Time course of biochemical and behavioural effects of a single high dose of chlorpyrifos.

The purpose the present study was to determine if tolerance is developed to all behavioural effects produced by a single high dose of chlorpyrifos (CPF). For this, the study was divided in two phases; in the first phase, we studied the time course of the effects produced by treatment with a high dose of CPF (250 mg/kg s.c.) on rat locomotor activity and anxiety behaviours recorded on an open-field, as well as on AChE inhibition. Results showed that CPF produced a maximum inhibition of AChE (72% of inhibition) 2 days after its administration, exhibiting a partial recovery of its activity by day 30 (55% of inhibition). On locomotor activity CPF produced a biphasic effect; a reduction only on day 2, and an increase on day 30. An anxiolytic-like effect was only observed within 2 and 5 days after CPF treatment. These results indicate that the tolerance has been developed to the behavioural effects produced by s.c. administration of CPF, but with a different time course. In the second phase, since disturbances in cholinergic system might trigger dopaminergic dysfunctions, we tested the locomotor activity following challenge with amphetamine (1mg/kg i.p.) at 11 and 30 days after CPF treatment. Data obtained showed that amphetamine produced an increase in total distances and rearing in vehicle and CPF groups on days 11 and 30. However, CPF group exhibited lower increase relative to vehicle group in both days. This effect is independent of the percentage of AChE inhibition and therefore, of change in the cholinergic system. Data are discussed under the light of the adaptative mechanisms underlying the recovery of the cholinergic overstimulation after s.c. exposure to high doses of CPF.

Disruption of prepulse inhibition after stimulation of central but not peripheral alpha-1 adrenergic receptors.

Prepulse inhibition (PPI) refers to the attenuation of startle when a weak prestimulus precedes the startling stimulus. PPI is deficient in several psychiatric illnesses involving poor sensorimotor gating. Previous studies indicate that alpha1 adrenergic receptors regulate PPI, yet the extent to which these effects are mediated by central vs peripheral receptors is unclear. The present studies compared the effects of intracerebroventricular (ICV) vs intraperitoneal (IP) delivery of several alpha1 receptor agonists on PPI. Male Sprague-Dawley rats received either cirazoline (0, 10, 25, 50 microg/5 microl), methoxamine (0, 30, 100 microg/5 microl), or phenylephrine (0, 3, 10, 30 microg/5 microl) ICV immediately before testing. Separate groups received either cirazoline (0, 0.25, 0.50, 0.75 mg/kg), methoxamine (0, 2, 5, 10 mg/kg), or phenylephrine (0, 0.1, 2.0 mg/kg) IP 5 min before testing. PPI, baseline startle responses, and piloerection, an index of autonomic arousal, were measured. Cirazoline disrupted PPI; effective ICV doses were approximately six times lower than effective IP doses. Methoxamine disrupted PPI after ICV infusion but failed to affect PPI with IP doses that were up to 30-fold higher than the effective ICV dose. Phenylephrine disrupted PPI with ICV administration, but did not alter PPI after IP injection of even a 20-fold higher dose. None of the ICV treatments altered baseline startle magnitude, but phenylephrine and methoxamine lowered startle after administration of high systemic doses. Piloerection was induced by cirazoline via either route of administration, and by IP methoxamine and phenylephrine, but not by ICV infusion of methoxamine or phenylephrine. These findings indicate that alpha1 receptor-mediated PPI disruption occurs exclusively through stimulation of central receptors and is dissociable from alterations in baseline startle or autonomic effects.

Life-threatening interaction between the root extract of Pueraria lobata and methotrexate in rats.

Isoflavone supplements are nowadays widely used as alternative for hormone replacement therapy. However, the safety remains unanswered. This study attempted to investigate the effect of Pueraria lobata root decoction (PLRD), an isoflavone-rich herb, on the pharmacokinetics of methotrexate (MTX), a bicarboxylate antimetabolite with narrow therapeutic window. Rats were orally and intravenously given methotrexate alone and coadministered with PLRD. Blood samples were withdrawn via cardiopuncture at specific time points after drug administration. Serum methotrexate concentrations were assayed by specific monoclonal fluorescence polarization immunoassay method. Pharmacokinetic parameters were calculated using noncompartment model of WINNONLIN for both oral and intravenous data of MTX. Our results showed that coadministration of 4.0 g/kg and 2.0 g/kg of PLRD significantly increased the AUC(0-t) by 207.8% and 127.9%, prolonged the mean residence time (MRT) by 237.8 and 155.2%, respectively, finally resulted in surprisingly high mortalities of 57.1% and 14.3% in rats. When MTX was given intravenously, the coadministration of PLRD at 4.0 g/kg significantly increased the half-life by 53.9% and decreased the clearance by 47.9%. In conclusion, the coadministration of PLRD significantly decreased the elimination and resulted in markedly increased exposure of MTX in rats.

Chemical constituents of gentianaceae XIV: tetraoxygenated and pentaoxygenated xanthones of Swertia purpurascens Wall.

The whole plant of Swertia purpurascens Wall. (Gentianaceae) has been shown to contain five tetraoxygenated and three pentaoxygenated zanthones. These are identified as 1,5,8-trihydroxy-3-methoxyxanthone, 1,3,8-trihydroxy-5-methoxyzanthone, 1-hydroxy-3,7,8-trimethoxyxanthone, 1,3,7,8-tetrahydroxyxanthone, 1,3,5,8-tetrahydroxyxanthone, and 1-hydroxy-3,4,7,8-tetramethoxyxanthone by chemical and spectral evidence. Additionally, the crude mixture of natural xanthones has been shown to include two partially emthylated pentaoxygenated xanthones as minor entities, which yield 1-hydroxy-3,4,7,8-tetramethoxyxanthone and 1-hydroxy-3,4,5,8-tetramethoxyxanthone on methylation. This is the first time that pentaoxygenated xanthones have been found in a member of the genus Swertia. 1-Hydroxy-3,4,7,8-tetramethoxyxanthone was previously known only as a synthetic compound. The total xanthones of S. purpurascens produce significant CNS stimulant actions, consistent with some therapeutic uses of the plant extract in the Indian system of medicine. The chemotaxonomic significance of the cooccurrence of various biogenetically related chemical characters in a single plant species is appraised.