Anxiolytic activity evaluation of four medicinal plants from Cameroon.

Afrormosia laxiflora (A. laxiflora), Chenopodium ambrosioides (C. ambrosioides), Microglossa pyrifolia (M. pyrifolia) and Mimosa pudica (M. pudica) are plants used in traditional medicine in Cameroon to treat insomnia, epilepsy, anxiety, and agitation. They were evaluated for their anxiolytic like activity in mice. Animal models (elevated plus maze and stress-induced hyperthermia tests) were used. The four plants showed anxiolytic activity. In stress-induced hyperthermia test, A. laxiflora, C. ambrosioides, M. pyrifolia and M. pudica significantly antagonised the increase of temperature. ΔT° decreased from 0.75°C in the control group to 0.36°C at the dose of 110 mg/kg for A. laxiflora; from 1°C in the control group to -1.1°C at the dose of 120 mg/kg for C. ambrosioides; from 1.7°C in the control group to 0.2°C at the dose of 128 mg/kg for M. pyrifolia and from 1.3°C in the control group to 0.5°C at the dose of 180 mg/kg for M. pudica. In the elevated plus maze test, the four plants increased the number of entries into, percentage of entries into, and percentage of time in open arms. A. laxiflora, C. ambrosioides and M. pudica also reduced the percentage of entries and time in closed arms. In addition, C. ambrosioides, M. pyrifolia and M. pudica showed antipyretic activity by reducing the body temperature. The results suggested that C. ambrosioides, M. pyrifolia and M. pudica posses anxiolytic-like and antipyretic activities while A. laxiflora possesses only anxiolytic-like properties. These plants could be helpful in the treatment of anxiety and fever in traditional medicine in Cameroon.

Validation of anticonvulsant and sedative activity of six medicinal plants.

Acanthus montanus, Alchornea laxiflora, Hyptis spicigera, Microglossa pyrifolia, Piliostigma reticulatum, and Voacanga africana were evaluated with respect to anticonvulsant and sedative activity in mice using animal models (maximal electroshock (MES), N-methyl-D-aspartate (NMDA), pentylenetetrazol (PTZ), isonicotinic hydrazide acid (INH), picrotoxin (PIC), and strychnine (STR)-induced convulsions or turning behavior and diazepam-induced sleep). Acanthus montanus protected 66.6% of mice against MES-, PIC-, and STR-induced convulsions and 83.3% of mice from PTZ-induced convulsions. Alchornea laxiflora protected 75% and 87.5% of mice in the STR and NMDA tests, respectively, at a dose of 120 mg/kg. Hyptis spicigera protected 100 and 87.5% of mice against STR- and PTZ-induced convulsions, respectively, at a dose of 160 mg/kg. Microglossa pyrifolia protected 50% to 100% of mice against convulsions. Piliostigma reticulatum protected 62.5% to 100% of mice against convulsions and turning behavior. Voacanga africana protected 62.5% to 87.5% of mice against convulsions and turning behavior. All of the plants except A. laxiflora also exerted sedative activity by strongly increasing the total duration of sleep induced by diazepam.

Ions and amino acid analysis of Cyperus articulatus L. (Cyperaceae) extracts and the effects of the latter on oocytes expressing some receptors.

Extracts from rhizomes of Cyperus articulatus L. (Cyperaceae) used in Africa and Amazonia to treat many diseases has been shown to possess sedative and anticonvulsant properties. The aim of this study is to determine the mechanism of action of Cyperus articulatus extracts. In Xenopus oocytes expressing receptors, using electrophysiological measurement, extracts of rhizomes of Cyperus articulatus (300 microg/ml) inhibited 50% of the EC(50) and EC(80) of glutamate (1.3 and 2.9 microM, respectively) induced inward current through hNMDAR1A/2A receptors. Extracts induced very small current through rGluR3 receptors. The largest current induced by the extract (30 mg/ml) represents 128% of the EC(100) of glutamate induced inward current, through rGluR3 receptors. The excess 28% current could be induced by aspartate and/or glutamate in the extracts. The effect on Xenopus oocytes expressing heteromeric GABA(B)R1b/R2 receptors and rectifying potassium channels (Kir3) is clear. A decoction and water extract of Cyperus articulatus induced a large inward current that represented 71 and 57% (respectively) of the EC(100) of gaba (30 microM) induced inward current. The water extract induced also a large current through rectifying potassium channels (Kir3). Part of the current induced through GABA(B) receptors could be related to rectifying potassium channels and GABA(B) site receptors. Cyperus articulatus extracts possessed components that could decrease excitation (NMDA receptor antagonists) and increase inhibition (GABA(B) receptor agonists) in the central nervous system.