title: Antidiarrhoeal activity of aqueous leaf extract of Caladium bicolor (Araceae) and its possible mechanisms of action.
abstract: BACKGROUND
  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.
  
  
  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 β-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.
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria.
authors.forename: Olanrewaju A
authors.initials: OA
authors.lastname: Salako
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria. Electronic address: ajakindele@cmul.edu.ng.
authors.forename: Abidemi J
authors.initials: AJ
authors.lastname: Akindele
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria.
authors.forename: Omotoyosi M
authors.initials: OM
authors.lastname: Shitta
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria.
authors.forename: Olajumoke O
authors.initials: OO
authors.lastname: Elegunde
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria. Electronic address: ooadeyemi@cmul.edu.ng.
authors.forename: Olufunmilayo O
authors.initials: OO
authors.lastname: Adeyemi
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D000930:Antidiarrheals / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D029064:Araceae; D002368:Castor Oil; D003967:Diarrhea / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects; D005772:Gastrointestinal Transit / Q000187:drug effects; D007419:Intestinal Secretions / Q000378:metabolism; D008297:Male; D051379:Mice; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D008517:Phytotherapy; D010862:Pilocarpine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D023382:Toxicity Tests, Acute; D014867:Water / Q000737:chemistry; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000930:Antidiarrheals; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010936:Plant Extracts; D010862:Pilocarpine; D014867:Water; D015016:Yohimbine; D002368:Castor Oil
keywords: Antidiarrhoeal activity; Araceae; Caladium bicolor; Mechanisms of action; Muscarinic receptors; α(2)-adrenoceptors