Action mechanism of the monoterpenes (+)-pulegone and 4-terpinyl acetate in isolated guinea pig ileum / Mecanismo de accion de los monoterpenos (+)-pulegona y acetato de 4-terpinil en íleon aislado de cobayo

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.

Antiulcer effect of epoxy-carvone

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.

Bioassay-guided evaluation of central nervous system effects of citronellal in rodents

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.

Anticonvulsant activity of thymoquinone and its structural analogues

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.

Anti-inflammatory and redox-protective activities of citronellal

The anti-inflammatory and redox protective effects of the citronellal (CT) were evaluated using in vivo and in vitro tests. Intraperitoneal (i.p.) administration of CT (50, 100, and 200 mg/kg) inhibited (p < 0.05) the carrageenan-induced leukocyte migration to the peritoneal cavity. Additionally, the carrageenan- and arachidonic acid-induced rat hind paw edema was significantly inhibited (p < 0.05) by i.p. administration of 100 and 200 mg/kg of the compound. When the redox activity was evaluated, CT (200 mg/kg) significantly reduced hepatic lipoperoxidation (p < 0.001), as well as oxidation of plasmatic (p < 0.05) and hepatic (p < 0.01) proteins. The results of the present study support the hypothesis that CT possesses anti-inflammatory and redox protective activities. It is suggested that its effects are associated with the inhibition of the enzymes in the arachidonic acid pathway, which prevent cell migration by inhibiting leukotriene production, edema formation and the increase of reactive oxygen species in tissues. Therefore, CT is of potential benefit to manage inflammatory disorders and correlated damages caused by oxidant agents.

Pharmacological effects of the monoterpene alpha, beta-epoxy-carvone in mice

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.

Preliminary study of the antimicrobial activity of Mentha x villosa Hudson essential oil, rotundifolone and its analogues / Estudo preliminar da atividade antimicrobiana do óleo essencial de Mentha x villosa Hudson, rotundifolona e seus análogos

Essential oils present antimicrobial activity against a variety of bacteria and yeasts, including species resistant to antibiotics and antifungicals. In this context, this work aims at the evaluation of the antimicrobial activity of the essential oil of Mentha x villosa Hudson ("hortelã da folha miúda"), its major component (rotundifolone) and four similar analogues of rotundifolone (limonene oxide, pulegone oxide, carvone epoxide and (+)-pulegone) against strain standards of Staphylococcus aureus ATCC 25923, E. coli ATCC 25922, Pseudomona aeruginosa ATCC 27853, Candida albicans ATCC 76645 and one strain of meticilin - resistant Staphylococcus aureus - MRSA (171c) from human clinic. The method of the diffusion in plates with solid medium was used. The results showed that the oil of Mentha x villosa, rotundifolone, limonene oxide and (+)-pulegone, are similar regarding the antimicrobial activity against the tested strains of S. aureus and C. albicans. All of the products present antimocrobial potential with antibacterial activity for S. aureus ATCC 25923 and antifungal activity for C. albicans ATCC 76645. None of the products presented antimicrobial activity for the strains of E. coli ATCC 25922 and P. aeruginosa ATCC 27853, representatives of the Gram negative bacteria.

Os óleos essenciais apresentam atividade antimicrobiana contra uma variedade de bactérias e fungos, incluindo espécies resistentes a antibióticos e antimicóticos. Neste contexto, este trabalho objetiva a avaliação da atividade de antimicrobiana do óleo essencial de Mentha x villosa Hudson (hortelã-da-folha-miúda) - seu componente majoritário (rotundifolona) e quatro análogos sintéticos da rotundifolona (epóxi-limoneno epóxi-pulegona, epóxi-carvona e (+)-pulegona) frente a cepas padrão de Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 76645 e uma cepa de Staphylococcus aureus meticilina - resistente - MRSA (171c) de clínica humana. Como método, foi utilizada a difusão em placas com médio sólido. Os resultados mostraram que o óleo de Mentha x villosa, rotundifolona, epóxi-limoneno e (+)-pulegona, são semelhante em função da atividade antimicrobiana para as cepas de S. aureus e C.albicans testadas. Todos os produtos apresentaram potencial antimicrobiano com atividade antibacteriana para S. aureus ATCC 25923 e atividade antifúngica para C. albicans ATCC 76645. Nenhum dos produtos apresentou atividade antimicrobiana para as cepas de E. coli ATCC 25922 e P. aeruginosa ATCC 27853, representantes das bactérias Gram negativas.