title: Assessment of the antidiarrhoeal properties of the aqueous extract, the 80% methanol extract and its soluble fractions of the leaves of Alstonia congensis Engl. (Apocynaceae) in Wistar rats.
abstract: OBJECTIVE
  To evaluate the antidiarrhoeal properties of Alstonia congensis leaves claimed to be effective for the treatment of diarrhoea by traditional healers during our ethnopharmacological investigation conducted in Kinshasa, Democratic Republic of Congo.
  
  
  METHODS
  The aqueous extract (decoction), and the 80% hot methanol extract (Soxhlet extraction) were obtained. This last extract was fractionated. The antidiarrhoeal activity was evaluated using castor oil and magnesium sulphate-induced diarrhoea in animals. The potential antibacterial activity of all samples was also assessed in vitro.
  
  
  RESULTS
  At all oral doses of 100 and 200 mg/kg body weight, all A. congensis samples showed significant and dose-dependent antidiarrhoeal activity in treated Wistar rats characterised by significant increase of onset time and decrease of all other diarrhoeal parameters at various degrees compared to untreated groups in both models. At the highest oral dose of 200 mg/kg bodyweight, the 80% hot methanol and aqueous extracts produced 79.8 ± 2.1% and 78.6 ± 0.5%, and 75.0 ± 2.1% and 71.4 ± 2.1% inhibition of defecation and diarrhoea respectively against castor oil-induced diarrhoea, and 75.0 ± 1.2% and 73.3±1.2% inhibition of diarrhoea respectively against magnesium sulphate-induced diarrhoea. The 80% hot methanol and aqueous detannified extracts showed low activity (42-47% inhibition of defecation and/or diarrhoea in both tests) suggesting that tannins may be responsible for the observed activity. At the same oral doses, the total alkaloid extract, the chloroform soluble fraction rich in alkaloids, the 80% methanol and the alkaline aqueous soluble subfractions produced more than 50% inhibition of defecation and/or diarrhoea in both tests. From the antibacterial testing in vitro, results indicated that all A. congensis samples exhibited an antibacterial activity mainly against bacteria implicated in diarrhoea with MIC and MBC values in the range of 15.6-500 μg/ml. The most active samples were the aqueous (decoction) and the 80% hot methanol dried extracts, the chloroform subfraction rich in alkaloids and the total alkaloid extract (MIC: 15.7-125 μg/ml, MBC: 31.2-250 μg/ml). Proteus varibilis was found to be the most resistant microorganism.
  
  
  CONCLUSIONS
  These reported results can partly support and justify the traditional use of extracts from Alstonia congensis leaves for the treatment of diarrhoea in tradittional medicine.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Kinshasa, Kinshasa XI, Democratic Republique of Congo.
authors.forename: S
authors.initials: S
authors.lastname: Nsaka Lumpu
authors.forename: G
authors.initials: G
authors.lastname: Tona Lutete
authors.forename: O
authors.initials: O
authors.lastname: Kambu Kabangu
authors.forename: R
authors.initials: R
authors.lastname: Cimanga Kanyanga
authors.forename: S
authors.initials: S
authors.lastname: Apers
authors.forename: L
authors.initials: L
authors.lastname: Pieters
authors.forename: A J
authors.initials: AJ
authors.lastname: Vlietinck
mesh_terms: D031051:Alstonia; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000930:Antidiarrheals / Q000494:pharmacology / Q000627:therapeutic use*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D002368:Castor Oil; D003967:Diarrhea / Q000139:chemically induced / Q000188:drug therapy*; D008278:Magnesium Sulfate; D000432:Methanol / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012997:Solvents / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D000930:Antidiarrheals; D010936:Plant Extracts; D012997:Solvents; D008278:Magnesium Sulfate; D002368:Castor Oil; D000432:Methanol