Anxiolytic and anticonvulsant activity of methanol extract of leaves of Alternanthera brasiliana (L.) Kuntze (Amaranthaceae) in laboratory animals.

Anxiety related disorders are the most common mental illnesses and major cause of disability in man. Anxiolytic activity of methanol extract of leaves of A. brasiliana (L.) Kuntze (MEAB) was evaluated using hole board (HB), open field (OF), elevated plus maze (EPM) and light/dark exploration test (LDE) in mice. Its locomotor activity was studied using actophotometer and anticonvulsant effect was studied using maximal electroshock-induced seizures and pentylenetetrazole-induced seizures in mice. Single oral administration of MEAB at different doses (100, 300 and 600 mg/kg, ip) significantly increased the number and duration of head poking in the HB test; rearing, assisted rearing and number of square traveled in the OF test; entries and time spent in open arm in the EPM test; time spent in lighted box, and numbers of crossings and transfer latency time in the LDE test. There was significant reduction in the time spent in close arm in the EPM test and time spent in dark box in LDE test. In the actophotometer, the activity count was reduced in MEAB and diazepam treated group than control group. All the three doses of the extract significantly reduced the duration of seizures induced by pentylenetetrazole (chemoshock convulsion). However, the extract did not show any appreciable effect in electroshock convulsion model. The results of the present study suggest promising anxiolytic and anticonvulsant activity of MEAB which might be accredited to different phytoconstituents like alkaloids, steroids and triterpenes present in the methanol extract of A. brasiliana.