Behavioural effect of standardized aqueous whole plant extract of Acanthospermum hispidum: Ethnopharmacological Justification for its use in folkloric management of malaria

Acanthospermum hispidum DC is a medicinal plant commonly used locally for the treatment of malaria, cough, diarrhoea, typhoid, inability to sleep well and vomiting. The aim of the study was to evaluate the behavioural effects of the aqueous whole extract of Acanthospermum hispidum in young chicks and mice. The oral acute toxicity of Acanthospermum hispidum was carried out in young chicks and mice using the acute toxic class method. The antiemetic effect of the extract (50, 100 and 200 mg/kg body weight orally) and metoclopramide (5 mg/kg intramuscularly) was assessed using copper sulphate-induced retches in young chicks. The effect of the extract (50, 100 and 200 mg/kg body weight orally) on apomorphine-induced pecking in chicks, pentobarbitone-induced sleep, exploratory behaviour on hole board apparatus and motor coordination on rota rod were evaluated. The oral median lethal (LD50) dose of the extract was greater than 2000 mg/kg in chicks and mice. Acanthospermum hispidum extract significantly (F4, 49=222, p<0.0001) inhibited copper sulphate-induced retching when compared to negative control while metoclopramide significantly inhibited copper –induced retches. The extract (at 50, 100 and 200) and chlorpromazine at 2 mg/kg body weight significantly reduced (F 4 , 49 =331, p<0.0001) apomorphine-induced pecking in young chicks. The extract (50, 100 and 200 mg/kg) and diazepam (30 mg/kg) significantly (F4, 29=18, p<0.0001) shortened onset but prolonged (F 4, 29 =637, p<0.0001) duration of sleep in pentobarbitone –induced sleep. The extract significantly (F 4 , 29 =98, p<0.0001) reduced frequency of head dip in hole board apparatus but had no effect on motor coordination. The results suggested that Acanthospermum hispidum possesses potent anti-emetic and sedative effects but had no effect on motor function which explains its continued use for management of malaria symptoms in folk medicine. These effects may have been mediated by flavonoid and tannins present in the extract.