Investigation of the Mechanisms Underlying the Gastroprotective Effect of Cymbopogon Citratus Essential Oil

Cymbopogon citratus is a medicinal plant popularly used in Brazil for the treatment of various diseases, and the research interest in this plant is justifiable because of its potential medicinal value in stomachache and gastric ulcer. This study was aimed to test the validity of this practice by using experimental models of gastric ulcer and to clarify the mechanisms of gastroprotection by C. citratus leaves essential oil (EOCC). EOCC was evaluated for the ability to protect the gastric mucosa against injuries caused by necrotizing agents (absolute ethanol and aspirin) in rodents. The results of this study revealed that EOCC posses a dose-independent anti-ulcer effect against the different experimental models. EOCC pretreatment depicted a higher preventive index in ethanol-(88%) and aspirin-induced (76%) acute ulceration. On pretreatment of mice with indomethacin, the cyclooxygenase inhibitor slightly suppressed the gastroprotective effect of EOCC (48.5%). Furthermore, EOCC gastroprotection was not attenuated in mice pretreated with L-NAME (85.2%), glibenclamide (100%), or yohimbine (79.7%), the respective inhibitors of nitric oxide synthase, K+ATP channel activation, and α2 receptors. These results confirmed the traditional use of C. citratus for the treatment of gastric ulcer. Thus, we provide the first evidence that EOCC reduces gastric damage induced by ethanol, at least in part, by mechanisms that involve endogenous prostaglandins

Essential oil of Lippia alba and its main constituent citral block the excitability of rat sciatic nerves

Lippia alba is empirically used for infusions, teas, macerates, and hydroalcoholic extracts because of its antispasmodic, analgesic, sedative, and anxiolytic effects. Citral is a mixture of trans-geranial and cis-neral and is the main constituent of L. alba essential oil and possesses analgesic, anxiolytic, anticonvulsant, and sedative effects. The present study evaluated the effects of the essential oil of L. alba (EOLa) and citral on compound action potentials (CAPs) in Wistar rat sciatic nerves. Both drugs inhibited CAP in a concentration-dependent manner. The calculated half-maximal inhibitory concentrations (IC50) of peak-to-peak amplitude were 53.2 µg/mL and 35.00 µg/mL (or 230 µM) for EOLa and citral, respectively. Peak-to-peak amplitude of the CAP was significantly reduced by 30 µg/mL EOLa and 10 µg/mL citral. EOLa and citral (at 60 and 30 µg/mL, values close to their respective IC50 for CAP blockade) significantly increased chronaxy and rheobase. The conduction velocity of the first and second CAP components was statistically reduced to ∼86% of control with 10 µg/mL EOLa and ∼90% of control with 3 µg/mL citral. This study showed that EOLa inhibited nerve excitability and this effect can be explained by the presence of citral in its composition. Both EOLa and citral showed inhibitory actions at lower concentrations compared with other essential oils and constituents with local anesthetic activity. In conclusion, these data demonstrate that EOLa and citral are promising agents in the development of new drugs with local anesthetic activity

Relaxant Effect of Monoterpene (-)-Carveol on Isolated Human Umbilical Cord Arteries and the Involvement of Ion Channels

Carveol is a monoterpene present in the structure of many plant products. It has a variety of biological activities: antioxidant, anticancer and vasorelaxation. However, studies investigating the effect of monoterpenoids on human vessels have not yet been described. Thus, the present study aimed to characterize the effect of (-)-carveol on human umbilical arteries (HUAs). HUA ring preparations were isolated and subjected to isometric tension recordings of umbilical artery smooth muscle contractions. (-)-Carveol exhibited a significant vasorelaxant effect on KCl and 5-HT-induced contractions, obtaining EC50 values of 344.25 \ub1 8.4 and 175.82 \ub1 4.05 \ub5M, respectively. The participation of calcium channels in the relaxation produced by (-)-carveol was analyzed using vessels pre-incubated with (-)-carveol (2000 \ub5M) in a calcium-free medium, where the induction of contractions was abolished. The vasorelaxant effect of (-)-carveol on HUAs was reduced by tetraethylammonium (TEA), which increased the (-)-carveol EC50 to 484.87 \ub1 6.55 \ub5M. The present study revealed that (-)-carveol possesses a vasorelaxant activity in HUAs, which was dependent on the opening of calcium and potassium channels. These results pave the way for further studies involving the use of monoterpenoids for the vasodilatation of HUAs. These molecules have the potential to treat diseases such as pre-eclampsia, which is characterized by resistance in umbilical arteries

Composição do óleo essencial de quatro espécies do gênero Plectranthus Essential oil composition of four Plectranthus species

O gênero Plectranthus é considerado um dos mais ricos em óleos essenciais dentro da família Lamiaceae, compreendendo muitas espécies com propriedades medicinais. Algumas destas são conhecidas popularmente como boldo, as quais possuem semelhanças taxonômicas e diversas sinonímias, possuindo ações anti-dispépticas, analgésicas e digestivas. O objetivo deste estudo foi avaliar quantitativa e qualitativamente os óleos essenciais presentes nas folhas das espécies P. amboinicus, P. barbatus, P. grandis e P. neochilus. A extração do óleo foi realizada por hidrodestilação, utilizando pentano como solvente extrator, repetida por três vezes para cada uma das espécies. A análise dos componentes dos óleos essenciais das quatro espécies de Plectranthus, através da CG/EM, permitiu identificar 14 componentes químicos, sendo a maioria sesquiterpenos. O trans-cariofileno se apresentou em elevada concentração nos óleos estudados. Alguns componentes químicos demonstraram ser específicos para cada espécie e outros apresentaram ocorrência comum a todas as quatro, possibilitando a diferenciação das mesmas em dois grupos, um formado por P. amboinicus e P. neochilus e o outro por P. grandis e P. barbatus. Conclui-se que as quatro espécies de boldo apresentam diferenças significativas quanto ao teor e à constituição química do óleo essencial<br>Plectranthus has been considered one of the richest genera in essential oils within the Lamiaceae family, which includes several species with medicinal properties. Some of them are commonly known as boldo and present taxonomic similarities and several synonymies, with antidyspeptic, analgesic and digestive actions. The aim of this study was to evaluate quantitatively and qualitatively the essential oils from P. amboinicus, P. barbatus, P. grandis and P. neochilus leaves. The oil was extracted by hydrodistillation using pentane as extracting solvent and was repeated three times for each species. The analysis of essential oil components by GC/MS in the four Plectranthus species identified 14 chemical components, mostly sesquiterpenes. High concentration of trans-caryophyllene was found in the studied oils. Some chemical components were specific for each species and other components had common occurrence in all four species, allowing their differentiation into two groups, one composed of P. amboinicus and P. neochilus and another one by P. grandis and P. barbatus. In conclusion, the four boldo species had significant differences as to essential oil yield and chemical compositio