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Preliminary pharmacological studies were performed on the methanol extract of Bixa orellana L. (Bixaceae) leaves to investigate neuropharmacological, anticonvulsant, analgesic, antidiarrhoeal activity and effect on gastrointestinal motility. All studies were conducted in mice using doses of 125, 250 and 500 mg/kg of body weight. In the pentobarbitone-induced hypnosis test, the extract statistically reduced the time for the onset of sleep at 500 mg/kg dose and (dose-dependently) increased the total sleeping time at 250 and 500 mg/kg dose. A statistically significant decrease in locomotor activity was observed at all doses in the open-field and hole-cross tests. In the strychnine-induced anticonvulsant test, the extract increased the average survival time of the test animals (statistically significant at 250 and 500 mg/kg). The extract significantly and dose-dependently reduced the writhing reflex in the acetic acid-induced writhing test. Antidiarrhoeal activity was supported by a statistically significant decrease in the total number of stools (including wet stools) in castor oil-induced diarrhoea model. A statistically significant delay in the passage of charcoal meal was observed at 500 mg/kg in the gastrointestinal motility test. The extract was further evaluated in vitro for antioxidant and antibacterial activity. It revealed radical scavenging properties in the DPPH assay (IC(50)=22.36 microg/ml) and antibacterial activity against selected causative agents of diarrhoea and dysentery, including Shigella dysenteriae.

Piper chaba Hunter (Piperaceae) is a common pepper in the southern part of Bangladesh. Various parts of this plant have been extensively used in different traditional formulations including ayurveda. In order to rationalize the ethnomedical uses of this plant in a number of ailments, the methanol extract of the stem bark was subjected to preliminary evaluation for analgesic, anti-inflammatory, diuretic, anti-diarrhoeal, effect on gastrointestinal motility and CNS depressant activity in mice and rat at 125, 250 and 500 mg/kg body weight doses. The extract at given doses significantly and dose dependently reduced the frequency of acetic acid induced writhing in mice, prolonged the tail flicking latency in mice, reduced Carrageenan-induced paw edema volume in rat, delayed the onset as well as reduced the frequency of castor oil induced diarrhoeal episodes in mice, decreased gastrointestinal motility as assessed by the charcoal motility test in mice and prolonged pentobarbitone induced sleeping time in mice. However at the same doses, the extract exhibited moderate diuretic activity only at the highest dose.