The fresh leaves of Cymbopogon citratus are a good source of an essential oil (EO) rich in citral, and its tea is largely used in the Brazilian folk medicine as a sedative. A similar source of EO is Cymbopogon winterianus, rich in citronellal. The literature presents more studies on the EO of C. citratus and their isolated bioactive components, but only a few are found on the EO of C. winterianus. The objective of the present study was then to study, in a comparative way, the effects of both EOs on three models of convulsions (pentylenetetrazol, pilocarpine, and strychnine) and on the barbiturate-induced sleeping time on male Swiss mice. The animals (20-30 g) were acutely treated with 50, 100, and 200 mg kg(-1), intraperitoneally, of each EO, and 30 min later, the test was initiated. The observed parameters were: latency to the first convulsion and latency to death in seconds. Furthermore, the in vitro effects of the EOs were also studied on myeloperoxidase (MPO; a biomarker for inflammation) and lactate dehydrogenase (LDH; an index of cytotoxicity) releases from human neutrophils. The EOs radical-scavenging activities were also evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that both EOs were more active on the pentylenetetrazol-induced convulsion model, and C. citratus was even more efficient in increasing latency to the first convulsion and latency to death. Both parameters were potentiated in the presence of a lower dose of diazepam (reference drug) when associated to a lower dose of each EO (25 mg kg(-1)). Besides, their anticonvulsant effects were blocked by flumazenil, a known benzodiazepine antagonist. This effect was somewhat lower on the pilocarpine-induced convulsion, and better effects were seen only with the EOs' higher doses (200 mg kg(-1)). A similar result was observed on the strychnine-induced convulsion model. Both EOs potentiated the barbiturate-induced sleeping time. However, C. citratus was more efficient. Interestingly, both EOs completely blocked the MPO release from human neutrophils and showed no cytotoxic effect on the LDH release from human neutrophils. On the other hand, only a very low or no effect on the DPPH assay was observed with C. winterianus and C. citratus, respectively, indicating that the radical scavenging activity did not play a role on the EOs' effects. We conclude that the mechanism of action of the anticonvulsant effect of the EOs studied is, at least in part, dependent upon the GABAergic neurotransmission. In addition, their effects on inflammatory biomarkers can also contribute to their central nervous system activity.
Leaves of Croton adamantinus have been used to treat inflammation and skin wounds in the semi-arid area of the Northeast of Brazil. In order to evaluate if the essential oil (EO) was responsible for the claimed activities; antinociceptive, wound healing and antimicrobial tests were carried out. Twenty constituents were identified in C. adamantinus EO by GC-MS, ¹H-NMR and ¹³C-NMR, the major compounds being methyl-eugenol (14.81%) and 1,8-cineol (13.74%). Antinociceptive activity was evaluated by the formalin test and the abdominal contortion assay in mice. The EO (50 and 100 mg/kg) decreased the licking time of both phases of the formalin test when compared to the vehicle, but not to morphine (7.5 mg/kg). In the abdominal contortion assay, the EO (50 and 100 mg/kg) reduced the number of contortions compared to the vehicle and to indometacin (10 mg/kg). The wound healing activity was verified also using two experimental models: excisional wound and dead space. Topical treatment with the EO (1%) increased the wound contraction from the third day of treatment (compared with nitrofurazone 0.2%), while systemic treatment (50 mg/kg/day) increased granulation tissue formation and reduced the water content. C. adamantinus EO also showed antimicrobial activity against Staphylococcus aureus in disk diffusion method. These results corroborate the ethnobotanical use of this specie by Brazilian population.
A utilização de plantas medicinais é uma prática comum nos países, fazendo parte da cultura popular como forma de tratamento de diferentes patologias. A planta Chenopodium ambrosioides L., conhecida popularmente como mastruz, é utilizada na medicina popular no tratamento de bronquite crônica, tuberculose, contusões, hérnias e fraturas, tendo algumas atividades comprovadas cientificamente como ação vermífuga e antimicrobiana. Dessa forma, o presente estudo teve como objetivo avaliar o perfil químico e investigar a atividade antibacteriana, moduladora de antibióticos e anti-inflamatória tópica do extrato metanólico obtido das folhas de Chenopodium ambrosioides L. Na prospecção fitoquímica do extrato, foram verificados diferentes metabólitos que possuem várias atividades biológicas, e na dosagem dos fenóis totais foram verificados 21,0 mg/g equivalente de ácido gálico, sendo a quantificação de flavonoides encontrado um total de 135,4 mg/g de quercetina. Não houve atividade antibacteriana, porém detectou-se modulação quando o extrato foi associado aos aminoglicosídeos contra cepas de E. coli e Staphylococcus aureus. Nos testes para inflamação aguda, o extrato apresentou um potencial antiedematogênico nas concentrações de 25 e 50 mg. Diante dos resultados, pode-se correlacionar o conhecimento empírico das pessoas, às propriedades biológicas observadas nessa pesquisa, esta podendo ser importante para futura validação dessas propriedades etnomedicinais.
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