Investigation of Antidepressant, Anxiolytic and Sedative Activities of the Aqueous Leaf Extract of Musa sapientum Linn. (Banana; Musaceae).

BACKGROUND: Musa sapientum Linn. (Musaceae) is used in traditional African medicine in the management of mental disorders. This study was conducted to evaluate the central nervous system activities of the aqueous leaf extract of M. sapientum (MS). MATERIALS AND METHODS: MS (50, 100 and 200 mg/kg, p.o.) was administered to separate groups of mice 1 h before behavioural studies. The antidepressant effect was studied using the forced swimming test (FST) and tail suspension test (TST) while the elevated plus maze (EPM) and the hole-board tests were used to evaluate the anxiolytic effect. The probable mechanism of antidepressant-like effect was also investigated. RESULTS: MS (50, 100 and 200 mg/kg) produced significant (P<0.0001) reduction in the duration of immobility with peak effect at 200 mg/kg (79.6%) in FST and 66.9 % in TST respectively when compared with control. The pre-treatment of mice with prazosin (α1-adrenoceptor antagonist, 62.5 µg/kg, i.p.) and sulpiride (dopamine D2 receptor antagonist, 50 mg/kg, i.p.) significantly prevented the antidepressant effect produced by MS in FST. However, pre-treatment of mice with metergoline (5-HT2 receptor antagonist, 4 mg/kg, i.p.) and yohimbine (α2-adrenoceptor antagonist, 1 mg/kg, i.p.) did not prevent the antidepressant effect of MS. In the EPM test, MS did not significantly increase open arm exploration. It also did not significantly increase the number of head dips in the hole-board test. CONCLUSIONS: Results showed that MS had antidepressant activity possibly mediated through α1-adrenergic and D2 dopaminergic receptors, without significant anxiolytic effect.

Toxicological evaluation of the aqueous whole plant extract of Aerva lanata (l.) Juss. ex Schult (Amaranthaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Aerva lanata (L.) of the family Amaranthaceae is a Nigerian medicinal plant used traditionally for the management of lithiasis, headache, renal disorder, haematemesis, bronchitis, nasal bleeding, cough, scorpion stings, fractures and spermatorrhoea. Studies that show the pharmacological basis for some of such uses have been reported. There is, however, no scientific report on its toxicity profile to the best of our knowledge. AIM OF THE STUDY: This study was therefore aimed at investigating the toxicity profile of the aqueous extract of Aerva lanata. MATERIALS AND METHODS: Acute toxicity tests for the extract administered orally at 1-30g/kg and intraperitoneally at 0.1-2g/kg were carried out in albino mice; while a sub-chronic toxicity test was done by daily oral administration of the extract at 40-1000mg/kg to albino rats for 90 days. Anthropometric, biochemical and haematological parameters' assessments as well as vital organs histological examinations were performed in the sub-chronic toxicity study. RESULTS: The LD50 of the extract for oral and intraperitoneal acute toxicity tests were 22.62g/kg and 0.432g/kg respectively. The extract produced apparent changes in body weights of both male and female rats and significantly (p < 0.05) increased the weights of lungs, brain and pancreas of female rats while reducing the weight of testes in male rats. Haematological parameters were also altered with total leukocytes significantly (p < 0.05) increased and platelets significantly (p < 0.05) reduced in female rats; while neutrophils significantly (p < 0.05) increased in male rats. The extract (40-1000mg/kg) produced significant (p < 0.05) reduction of serum alanine transaminase concentration in both male and female rats. Aspartate transaminases and albumin were also significantly (p < 0.05) reduced in both male (at 1000mg/kg) and female (at 200mg/kg) rats. Alkaline phosphatase was also significantly (p < 0.05) reduced in female rats at 200mg/kg of the extract. Substantial alterations of creatinine, urea and uric acid were also observed. Triglyceride and cholesterol concentrations were significantly increased in male rats but decreased in female rats. At 1000mg/kg, the extract significantly elevated catalase and superoxide dismutase levels with no effect on malondialdehyde levels. It also reduced sperm count and motility of male rats. Mild to moderate cellular changes in the brain, kidney, liver, lungs, spleen and testes of treated rats were observed on histological examinations. Significant changes in biochemical and haematological parameters were also noted in treated animals when compared to control animals 30 days after cessation of treatment. CONCLUSION: The overall findings of this study suggest that the aqueous extract of A. lanata is relatively safe on acute oral exposure, moderately toxic on acute intraperitoneal administration and is relatively safe with antioxidant actions on prolonged exposure. It however shows potentials for toxic effects such as cellular damage to organs, dyslipidaemia and reduction in male reproductive capacity. Caution must therefore be applied in its use on a long term basis.

Antidiarrhoeal activity of aqueous leaf extract of Caladium bicolor (Araceae) and its possible mechanisms of action.

ETHNOPHARMACOLOGICAL RELEVANCE: Caladium bicolor (Araceae) is a horticulture plant also used by some traditional medicine practitioners in the treatment of diarrhoea and other gastrointestinal disorders. This study was conducted to evaluate the antidiarrhoeal activity of the aqueous leaf extract of C. bicolor and its possible mechanisms of action in rodents. MATERIALS AND METHODS: Normal and castor oil-induced intestinal transit and castor oil-induced diarrhoea tests were carried out in mice while gastric emptying and enteropooling tests were conducted in rats following the administration of distilled water (10 ml/kg, p.o.), C. bicolor extract (1-50mg/kg, p.o.) and loperamide (5mg/kg, p.o.). The probable mechanisms of action of C. bicolor was investigated following pre-treatment with yohimbine (10mg/kg, s.c.; α2-adrenoceptor antagonist), pilocarpine (1mg/kg, s.c.; non-selective muscarinic receptor agonist), prazosin (1mg/kg, s.c.; α1-adrenoceptor antagonist) and propranolol (1mg/kg, i.p.; non-selective ß-adrenoceptor antagonist) 15 min prior to administration of C. bicolor extract (50mg/kg, p.o.). After 30 min of pre-treatment with these drugs, the mice were subjected to the castor oil-induced intestinal transit test. RESULTS: C. bicolor extract did not produce significant (p>0.05) effect on normal intestinal transit unlike loperamide which caused significant (p<0.001) inhibition (61.57%). The extract caused significant (p<0.001) dose-dependent inhibition of castor oil-induced intestinal transit with peak effect, 100% inhibition, elicited at the dose of 50mg/kg compared to 86.97% inhibition for loperamide. Yohimbine and pilocarpine most significantly (p<0.001) reversed this effect of the extract. In the castor oil-induced diarrhoea test, the extract (1mg/kg) and loperamide significantly (p<0.05, 0.01) delayed the onset of diarrhoea. For diarrhoea score, the extract (1 and 50mg/kg) inhibited diarrhoea development (47.53% and 43.83% inhibition, respectively) like loperamide (5mg/kg; 54.94%). The in vivo antidiarrhoeal index of the extract at 1 and 50mg/kg was 50.07% and 42.81% respectively compared to 58.15% for loperamide. CONCLUSIONS: The results obtained in this study suggest that the aqueous leaf extract of C. bicolor possess antidiarrhoeal activity due to its anti-motility effect possibly via antagonist action on intestinal muscarinic receptors and agonist action on intestinal α2-adrenoceptors. This justifies the use of the extract in traditional medicine for the treatment of diarrhoea.