The antidiarrhoeal activity of the aqueous root extract of Aristolochia ringens (Vahl.) Aristolochiaceae.

BACKGROUND: Aristolochia ringens, an ornamental plant native to tropical America that now grows in a number of African countries has been reported to be used in African traditional medicine for the management of snake bite venom, gastrointestinal disturbances, rheumatoicd arthritis and insomnia among others. OBJECTIVE: Based on its use in traditional African medicine, the antidiarrhoeal activity of the aqueous root extract of Aristolochia ringens (AR) was evaluated to determine the pharmacological basis of its use in the management of diarrhoea. METHODS: Normal and castor oil (CO) induced intestinal transit, castor oil induced diarrhoea, gastric emptying and enteropooling models were carried out in mice and rats. Preliminary phytochemical screening and acute toxicity tests were also carried out. RESULTS: AR (100-400 mg/kg, p.o.) produced a dose-dependent and significant decrease in normal and castor oil-induced intestinal transit compared to the vehicle group. This effect was significantly (p < 0.001) inhibited by pilocarpine (10 mg/kg, s.c.), phentolamine and propranolol (1 mg/kg, i.p.) respectively but neither significantly inhibited by yohimbine (1 mg/kg, s.c.) nor significantly enhanced by isosorbide dinitrate (150 mg/kg, p.o.). AR produced a dose-dependent and significant increase in the latency of diarrhoeal onset. AR also reduced the diarrhoeal score, number and weight of wet stools. The in vivo antidarrhoeal index (ADI(in vivo)) of 81.79 produced by AR (400 mg/kg) is comparable to the 86.85 ADI(in vivo). produced by morphine (10 mg/kg, s.c.). AR also reduced the gastric enteropooling and emptying effects of castor oil. Preliminary screening showed the presence of tannins, saponins and alkaloids. In the acute toxicity study, no mortality was observed with AR administered orally up to 10,000 mg/kg, but an LD50 of 407.38 mg/kg was obtained with the intraperitoneal route of administration in mice. CONCLUSION: Results show that the aqueous root extract of Aristolochia ringens possesses antidiarrhoeal activity possibly mediated by its non selective action on adrenoceptors in the GIT and physiological antagonism of the parasympathetic nervous system.

Anticonvulsant, anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata Fresen.

AIM OF THE STUDY: The objective of this study is to investigate the anticonvulsant, anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata. MATERIALS AND METHODS: The anticonvulsant effect of the aqueous root extract (100, 200 and 400 mg/kg) was evaluated in mice using the strychnine- and picrotoxin-induced seizure models. Its anxiolytic activity was evaluated using the elevated plus maze (EPM) and the Y maze (YM) methods (Hogg, 1996; Yemitan and Adeyemi, 2003) while the hexobarbitone induced sleep and the hole board models were used to evaluate the sedative and exploratory activities in mice respectively. The acute toxicity studies and phytochemical analysis of the extract were also carried out. RESULTS: The extract (100-400 mg/kg) produced a significant (P<0.01) dose dependent increase in onset of convulsion compared to the control for strychnine- and picrotoxin-induced seizures. It also produced a significant (P<0.01) dose dependent prolongation of the cumulative time spent in the open arms of the elevated plus maze and Y maze compared with the control. The extract (100-400 mg/kg) produced significant (P<0.01) reduction in the time of onset of sleep induced by hexobarbitone. The prolongation of hexobarbitone sleeping time by the extract (200 mg/kg) was comparable to that produced by diazepam (3 mg/kg). At doses of 100-400 mg/kg, the extract produced a dose dependent decrease in exploratory activity of the mice. The reduction in exploratory activity produced by the extract (400 mg/kg) was greater than that of chlorpromazine (1 mg/kg). The results obtained from the experiments indicate that the extract has central nervous system depressant and anxiolytic activities. The LD(50) obtained for the acute toxicity studies using both oral and intraperitoneal routes of administration were 1.74 g/kg and 19.95 mg/kg respectively. CONCLUSION: These findings justify the use of Securidaca longepedunculata in traditional medicine for the management of convulsion and psychosis.