ABSTRACT
Recent studies have shown the spasmolytic activity of p-menthane monoterpenes (+)-pulegone and 4-terpinyl acetate (4-T) in guinea pig ileum. Since the action mechanism of these monoterpenes in intestinal smooth muscle is unknown, the present study was conducted to characterize their relaxant mechanism in isolated guinea pig ileum. We tested the involvement of voltage-dependent calcium and potassium channels and muscarinic antagonism. Both the monoterpenes caused a shift in the calcium curve to the right with reduction in the maximum effect. Pretreatment with tetraethylammonium chloride partially inhibited relaxation produced by both 4-T and (+)-pulegone. Both compounds caused a shift in the bethanechol curve to the right with reduction in the maximum effect. The results of this study indicate that the mechanisms of action of the smooth muscle relaxant monoterpenes (+)-pulegone and 4-T possibly involve the partial blockade of calcium channels, the activation of potassium channels, and the non-competitive antagonism of muscarinic receptors.
Estudios recientes han demostrado la actividad espasmolítica de los monoterpenos p-mentano de (+)-pulegona y acetato de 4-terpinilo (4-T) en el íleon de cobayo. Dado que el mecanismo de acción de estos monoterpenos en el músculo liso intestinal es desconocido, el presente estudio se llevó a cabo para caracterizar su mecanismo relajante en íleon aislado de conejillo de indias. Hemos probado la participación de tanto los canales calcio dependiente de voltaje como los canales de potasio y antagonistas muscarínicos. Ambos monoterpenos causaron un desplazamiento en la curva de calcio a la derecha con la reducción en el efecto máximo. El tratamiento previo con cloruro de tetraetilamonio inhibe parcialmente la relajación producida por tanto 4-T y (+)-pulegona. Ambos compuestos causaron un cambio en la curva de betanecol a la derecha con la reducción en el efecto máximo. Los resultados de este estudio indican que los mecanismos de acción de los monoterpenos relajantes del músculo liso (+)-pulegona y 4-T posiblemente implican el bloqueo parcial de los canales de calcio, la activación de los canales de potasio, y el antagonismo no competitivo de los receptores muscarínicos.
Subject(s)
Animals , Guinea Pigs , Ileum , Monoterpenes/pharmacology , Monoterpenes/chemistry , Plant Leaves , Parasympatholytics/pharmacology , Oils, Volatile/pharmacology , Muscarinic Antagonists/pharmacology , Ion Channels , Muscle, Smooth , Muscle RelaxationABSTRACT
Epoxy-carvone is a monoterpene present in essential oils of various plants. It is a derivative of carvone, which has an epoxy group instead of the α- and β-unsaturated ketone group present in carvone. As recent studies have shown that several alcohol terpenes and compounds containing α, β-unsaturated ketone groups present antiulcer effect, the main of the present study was to evaluate the antiulcer effect of epoxy-carvone. The models of ulcers induced by ethanol and indomethacin were used in this study. Epoxy-carvone at the dose of 1 mg/kg did not present antiulcer effect against ulcer induced by ethanol, but at the doses of 10, 30 and 50 mg/kg it presented gastroprotective effect in both ulcer models. Epoxy-carvone also did not affect the gastric secretion in the pylorus ligation test. Moreover, pretreatment with indomethacin or L-nitroarginine methyl ester did not reverse the gastroprotection produced by this monoterpene. This study showed that epoxy-carvone presents antiulcer effect and suggests that this effect does not involve either antisecretory activity or increase of the nitric oxide and prostaglandin synthesis.
ABSTRACT
The central nervous system (CNS) depressant and anticonvulsant activities of citronellal (CT) were investigated in animal models. The CT in doses of 100, 200 and 400 mg/kg injected by i.p. route in mice caused a significant decrease in the motor activity of animals when compared with the control group. The highest dose of CT significantly reduced the remaining time of the animals on the Rota-rod apparatus up to 2 h. Additionally, CT at doses 100, 200 and 400 mg/ kg (i.p.) was also capable to promote an increase of latency for development of convulsions induced by pentylenetetrazole (PTZ). It was efficient in prevents the tonic convulsions induced by maximal electroshock (MES) in doses of 200 and 400 mg/kg, resulting in 30 and 40 percent of protection, respectively. This compound was also capable to promote an increase of latency for development of convulsions induced by picrotoxin (PIC) at 400 mg/kg. In the same way, the anticonvulsant effect of CT was affected by pretreatment with flumazenil, a selective antagonist of benzodiazepine site of GABA A receptor. These results suggest a possible CNS depressant and anticonvulsant activities.
ABSTRACT
It has been widely reported that the crude oil of Nigella sativa L., Ranunculaceae, seeds and its major chemical component thymoquinone present anticonvulsant activity. These facts led us to verify the pharmacological potential of five structurally related para-benzoquinones on the pentylenotetrazol-induced seizures model, and establish the structural characteristics that influence the anticonvulsant activity of thymoquinone. The unsubstituted para-benzoquinone was the compound that exhibited the highest potency, while 2-methyl-p-benzoquinone was inactive. It was found that the presence of alkyl groups attached to the ring influence the pharmacological activity of the para-benzoquinones. In addition, the number, position, and size of these groups change the anticonvulsant potency of the compounds.
ABSTRACT
The monoterpene alpha,beta-epoxy-carvone (EC) in doses of 200, 300 or 400 mg/kg injected by i.p. route in mice caused a significant decrease in the motor activity of animals when compared with the control group, up to 120 minutes after the administration. The doses of 300 or 400 mg/kg had induced a significant increase of in the sleeping time of animals not having modified, however, the latency. The EC in the dose of 400 mg/kg reduced the remaining time of the animals on the rotating rod (Rotarod test). These results suggest a possible central effect.
O monoterpeno alfa,beta-epóxi-carvona (EC) nas doses de 200, 300 e 400 mg/kg administrado por via i.p. em camundongos diminuiu significativamente a atividade motora dos animais, quando comparado aos controles, até 120 minutos após a administração. As doses de 300 e 400 mg/kg induziram um aumento significativo do tempo de sono dos animais não alterando, no entanto, a sua latência. O EC na dose de 400 mg/kg induziu uma redução no tempo de permanência dos animais na barra giratória (teste do rotarod). Os resultados sugerem um possível efeito central.