Avaliação do efeito do eucaliptol nas convulsões induzidas por pentilenotetrazol em camundongos

The developmental process of epilepsies involves diverse mechanisms that culminate in the hyperactivity of a population of neurons, resulting in a pattern of repeated and rhythmic depolarizations. Antiepileptic drugs act by increasing GABAergic neurotransmission, reducing the effects of glutamate, or blocking ion channels, and are endowed with serious adverse effects that make it difficult for patients to adhere to treatment. This fact has encouraged the search for compounds of natural origin with potential anticonvulsant effect. Thus, the present study aimed to evaluate the effect of eucalyptol in seizures induced by pentylenetetrazole (PTZ). For this, male Swiss mice, orally treated with monotrepene, were used. The first protocol evaluated the toxicity and the estimated LD50 of the compound. Based on the value of LD50, the doses of terpene used in the behavioral and neurochemical tests were selected. For the behavioral tests, groups of mice were pretreated with saline (10 mL/kg, vol), diazepam (2 mg/kg, ip) and eucalyptol (100, 200 and 400 mg/kg, vol) and then with pentylenetetrazole 80 mg/kg, ip) and evaluated for the following parameters: seizure intensity, latency for first seizure and time of death. For neurochemical tests, groups of mice were pretreated with saline (10 mL/kg, v.o.) and eucalyptol (400 mg/kg, i.p.) and subsequently with pentylenetetrazole (80 mg/kg, i.p.); The determination of the concentration of neurotransmitters (monoamines - dopamine, noradrenaline and serotonin) and oxidative stress markers (nitrite and thiobarbituric acid reactive substances - TBARs) were the parameters evaluated. The results were analyzed by ANOVA or Kruskal-Wallis, followed by Student-Newman-Keuls, and Dunns, respectively. Values of p <0.05 were considered significant. The results showed that oral administration of eucalyptol had low toxicity and the estimated LD50 was greater than 2000 mg / kg. In the PTZ-induced seizure test, only the higher dose of monoterpene (400 mg/kg) significantly reduced seizure intensity by 60%, increased latency for onset of the first seizure by 85% and time of death of the animals in 75% in relation to the control. Similarly, treatment with eucalyptol (400 mg/kg) significantly reduced the concentration of noradrenaline, dopamine and serotonin by 50%, 33% and 70%, respectively, in relation to the PTZ-treated group (80 mg/kg). In addition, treatment with eucalyptol (400 mg/kg) significantly reduced the concentration of TBARs by 33%, but not nitrite, relative to the PTZ treated group (80 mg/kg). Taken together, the results show that the monoterpene studied has low oral toxicity and an important anticonvulsant effect, since its administration is capable of attenuating the convulsions chemically induced by pentylenetetrazol with consequent reduction of the concentration of monoamines and the reactive substances of thiobarbituric acid, elements whose increase is associated with the epileptogenesis phenomenon.O processo de desenvolvimento das epilepsias envolve mecanismos diversos que culminam na hiperatividade de uma população de neurônios, resultando em um padrão de despolarizações repetidas e rítmicas. Os fármacos antiepilépticos agem através do aumento da neurotransmissão GABAérgica, da redução dos efeitos do glutamato, ou do bloqueio de canais iônicos, sendo dotados de efeitos adversos sérios que dificultam a adesão do paciente ao tratamento. Este fato tem incentivado a busca por compostos de origem natural com potencial efeito anticonvulsivante. Desta forma, o presente trabalho teve como objetivo avaliar o efeito do eucaliptol nas convulsões induzidas por pentilenotetrazol (PTZ). Para tanto, foram utilizados camundongos Swiss machos, tratados oralmente com o monotrepeno. O primeiro protocolo realizado avaliou a toxicidade e a DL50 estimada do composto. Com base no valor da DL50, foram selecionadas as doses do terpeno utilizadas nos testes comportamentais e neuroqímicos. Para os testes comportamentais, grupos de camundongos foram previamente tratados com salina (10 mL/kg, v.o.), diazepam (2 mg/kg, i.p.) e eucaliptol (100, 200 e 400 mg/kg, v.o.) e posteriormente com pentilenotetrazol (80 mg/kg, i.p.) e avaliados quanto aos seguintes parâmetros: intensidade das convulsões, latência para primeira convulsão e tempo de morte. Para os testes neuroquímicos, grupos de camundongos foram previamente tratados com salina (10 mL/kg, v.o.) e eucaliptol (400 mg/kg, i.p.) e posteriormente com pentilenotetrazol (80 mg/kg, i.p.); a determinação da concentração de neurotransmissores (monoaminas – dopamina, noradrenalina e serotonina) e dos marcadores de estresse oxidativo (nitrito e substâncias reativas do ácido tiobarbitúrico – TBARs) foram os parâmetros avaliados. Os resultados foram analisados por ANOVA ou Kruskal-Wallis, seguido dos testes de Student-Newman-Keuls, e Dunns, respectivamente. Foram considerados significativos os valores de p < 0,05. Os resultados mostraram que a administração oral do eucaliptol apresentou baixa toxicidade e a DL50 estimada foi superior a 2000 mg/kg. No teste das convulsões induzidas por PTZ apenas a dose maior do monoterpeno (400 mg/kg) reduziu de forma significativa a intensidade das convulsões em 60%, aumentou a latência para aparecimento da primeira convulsão em 85% e o tempo de morte dos animais em 75% em relação ao controle. De forma semelhante, o tratamento com eucaliptol (400 mg/kg) reduziu de forma significativa a concentração de noradrenalina, dopamina e serotonina, em 50%, 33% e 70%, respectivamente, em relação ao grupo tratado com PTZ (80 mg/kg). Além disso, o tratamento com eucaliptol (400 mg/kg) reduziu de forma significativa a concentração de TBARs em 33%, mas não de nitrito, em relação ao grupo tratado com PTZ (80 mg/kg). Tomados em conjunto, os resultados mostram que o monoterpeno estudado apresenta baixa toxicidade oral e importante efeito anticonvulsivante, visto que sua administração é capaz de atenuar as convulsões quimicamente induzidas por pentilenotetrazol com consequente redução da concentração de monoaminas e das substâncias reativas do ácido tiobarbitúrico, elementos cujo aumento está associado ao fenômeno da epileptogênese

Inhibition of rat liver microsomal fatty acid chain elongation by gemfibrozil in vitro

AbstractGemfibrozil, a hypolipidemic drug mainly used in the treatment of hypertriglyceridemic states, strongly inhibits the rat hepatic microsomal fatty acid chain elongation system in vitro. The inhibition is independent on the reducing cofactor used in the assay. Furthermore, gemfibrozil seems to act by inhibiting the rate-limiting step of the elongation process, the condensing reaction, without discriminating among the proposed three different condensing enzymes, devoted to condensation of saturated, mono-unsaturated and polyunsaturated acyl-CoA substrates

Essential oils from four Piper species

The essential oils from Piper capense, P. nigrum, P. guineense and P. umbellatum from S. Tomé e Príncipe were investigated for the first time. They were analysed by GC, GC-mass spectrometry and 13C NMR. Monoterpene hydrocarbons were the main group of constituents in three of the samples (P. capense, P. nigrum and P. umbellatum), whereas for the other species (P. guineense) phenylpropanoid derivatives were the most important ones. [beta]-Pinene (32.5%) and [beta]-caryophyllene (12.6%) were the major compounds in the volatile oil of P. capense. Dillapiole (44.8%), followed by myristicin (9.8%), were the main constituents of P. guineense. The most important constituents in the essential oil of P. nigrum were limonene (18.8%), [beta]-caryophyllene (15.4%), sabinene (16.5%) and [beta]-pinene (10.7%). The essential oil of P. umbellatum was characterised by its high [beta]-pinene (26.8%), [alpha]-pinene (17.6%) and (E)-nerolidol (12.4%) content.http://www.sciencedirect.com/science/article/B6TH7-40M54TJ-10/1/a5c8bec3d552f4aa2b7ee01483ad1e5